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Sample records for venus express science

  1. Venus express - The first European mission to Venus

    OpenAIRE

    Svedhem, H.; Titov, Dv; Mccoy, D.; Lebreton, J-p; Barabash, S.; Bertaux, J-l; Drossart, P.; Formisano, V.; Haeusler, B.; Korablev, O.; Markiewicz, Wj; Nevejans, D.; Paetzold, M.; Piccioni, G.; Zhang, Tl

    2007-01-01

    Venus Express is the first European mission to planet Venus. The mission aims at a comprehensive investigation of Venus atmosphere and plasma environment and will address some important aspects of the surface physics from orbit. In particular, Venus Express will focus on the structure, composition, and dynamics of the Venus atmosphere, escape processes and interaction of the atmosphere with the solar wind and so to provide answers to the many questions that still remain unanswered in these fi...

  2. Venus Express Italian Day on 4 October

    Science.gov (United States)

    2004-09-01

    Venus Express is the first European mission to this, the second planet in the Solar System. Often referred to as ‘Earth’s twin’, Venus holds many mysteries that intrigue scientists. The main question is why a planet similar to Earth in size, mass and composition could have evolved so differently over the course of the last four thousand million years. Venus Express will make the first multispectral global examination of the atmosphere of Venus. Completely different from the one around Earth, the Venusian atmosphere appears to be hot and dense. Venus Express will investigate the choking ‘greenhouse’ effect, the hurricane-force winds that encircle the planet, and its mysteriously weak magnetic field. Completion of assembly of the Venus Express spacecraft, including integration and testing of the flight equipment and experiments, is an important milestone. Scheduled for launch on 26 October 2005, Venus Express is currently being made ready for shipment to Astrium, ESA’s prime contractor, in Toulouse, France in mid-October this year. There, further tests to prove the spacecraft's flight readiness will take place. The programme of the event is as follows: 10:30 - Welcoming addresses L.M. Quaglino, Director of Alenia Spazio Infrastructures and Scientific Satellites M. Coradini, ESA Solar System Missions Coordinator 10:45 - ESA presentations The Venus Express project, D. McCoy, ESA Project Manager for Venus Express The Scientific Mission, H. Svedhem, ESA Project Scientist for Venus Express 11:30 - Alenia Spazio: Role and activities on Venus Express G. Finocchiaro and M. Patroncini, Alenia Spazio Project Management for Venus Express The presentations will be followed by a visit to the Venus Express Hardware and a Q & A session. The programme will be concluded with a buffet lunch at 13:00.

  3. Tracking Clouds on Venus using Venus Express Data

    Science.gov (United States)

    Pertzborn, Rosalyn; Limaye, Sanjay; Markiewicz, Wojciech; Jasmin, Tommy; Udgaonkar, Nishant

    2014-05-01

    In the US, a growing emphasis has been placed on the development of inclusive and authentic educational experiences which promote active participation by the K-12 learning community as well as the general public in NASA's earth and space science research activities. In the face of growing national and international budgetary constraints which present major challenges across all scientific research organizations around the world, the need for scientific communities to dramatically improve strategies for effective public engagement experiences, demonstrating the relevance of earth and space science research contributions to the citizenry, have become paramount. This presentation will provide an introduction to the online Venus Express Cloud tracking applet, an overview of feedback from educational users based on classroom/pilot implementation efforts, as well as the concept's potential viability for the promotion of expanded public participation in the analysis of data in future planetary exploration and research activities, nationally and internationally. Acknowledgements: We wish to acknowledge the contributions of Mr. Nishant Udgaonkar, a summer intern with the S.N. Bose Scholars Program, sponsored by the Science and Engineering Board, Department of Science and Technology, Government of India, the Indo-U.S. Science and Technology Forum, and the University of Wisconsin-Madison. We also wish to acknowledge the Space Science and Engineering Center as well as NASA for supporting this project.

  4. Venus

    Science.gov (United States)

    Fegley, B., Jr.

    Venus is Earth's nearest planetary neighbor and has fascinated mankind since the dawn of history. Venus' clouds reflect most of the sunlight shining on the planet and make it the brightest object in the sky after the Sun and Moon. Venus is visible with the naked eye as an evening star until a few hours after sunset or as a morning star shortly before sunrise. Many ancient civilizations observed and worshipped Venus, which had a different name in each society, for example, Ishtar to the Babylonians, Aphrodite to the Greeks, Tai'pei to the Chinese, and Venus to the Romans. Venus has continued to play an important role in myth, literature, and science throughout history.

  5. Pioneer Venus occultation radio science data generation

    Science.gov (United States)

    Berman, A. L.; Ramos, R.

    1980-01-01

    The paper deals with the Pioneer Venus Orbiter (signal) occultation experiment. During Pioneer Venus Orbiter radio science operations, an open-loop receiver baseband frequency output bandwidth was substantially reduced. This was made possible by programming an open-loop receiver first local oscillator with the predicted Doppler frequency profile so as to maintain the baseband signal within a narrow receiver output bandwidth.

  6. ESA to present the latest Venus Express results to the media

    Science.gov (United States)

    2007-11-01

    The launch of Venus Express back in November 2005 represented a major milestone in the exploration of Venus — a planet unvisited by any dedicated spacecraft since the early 1990s. One of the fundamental questions being addressed by the Venus Express mission is why a world so similar to Earth in mass and size has evolved so differently, to become the noxious and inhospitable planet it is today. Since it started its scientific observations in July 2006, Venus Express has been making the most detailed study of the planet’s thick and complex atmosphere to date. The latest findings not only highlight the features that make Venus unique in the solar system but also provide fresh clues as to how the planet is — despite everything — a more Earth-like planetary neighbour than one could have imagined. The results will appear in a special section of the 29 November issue of the journal Nature containing nine individual papers devoted to Venus Express science activities. Media organisations interested in attending the press conference are invited to register via the form attached below. Media that cannot attend will have the opportunity to follow the press conference via the following phone line: +33 1 58 99 57 42 (listening-mode only).The results presented at the press conference are embargoed until 28 November 19:00 CET. For more information ESA Media Relations Office Tel: +33 1 5369 7299 Fax: +33 1 5369 7690 Media event programme ‘Venus: a more Earth-like planetary neighbour’ Latest results from Venus Express 28 November 2007, 15:00, room 137 ESA Headquarters, 8-10 rue Mario-Nikis, Paris 15:00 Introduction, by Håkan Svedhem, ESA Venus Express Project Scientist 15:07 Venus: What we knew before, by Fred Taylor, Venus Express Interdisciplinary Scientist 15:15 Temperatures in the atmosphere of Venus, by Jean-Loup Bertaux, SPICAV Principal Investigator 15:25 The dynamic atmosphere of Venus, by Giuseppe Piccioni, VIRTIS Principal Investigator 15:40 Venus’s atmosphere and the solar wind, by Stas Barabash, ASPERA Principal Investigator 15:50 Climate and evolution, by David Grinspoon, Venus Express Interdisciplinary Scientist 16:00 Conclusion, by Dmitri Titov, Venus Express Science Coordinator and VMC scientist 16:05 Questions and Answers 16:25 Individual interviews 17:30 End of event

  7. Venus Express uurib Maa kurja kaksikut / ref. Triin Thalheim

    Index Scriptorium Estoniae

    2005-01-01

    9. novembril startis Baikonuri kosmodroomilt Veenusele Euroopa Kosmoseagentuuri sond Venus Express, mis peaks planeedi atmosfääri sisenema aprillis. Teadlaste sõnul peab sondi saadetav info aitama mõista naaberplaneedi kliimat ja atmosfääri ning tooma selgust, kas Maa võib kunagi Veenuse sarnaseks muutuda. Lisaks joonis: Venus Express

  8. Venus Surface Investigation Using VIRTIS Onboard the ESA/Venus Express Mission

    Science.gov (United States)

    Marinangeli, L. L.; Baines, K.; Garcia, R.; Drossart, P.; Piccioni, G.; Benkhoff, J.; Helbert, J.; Langevin, Y.

    2004-01-01

    Venus Express Mission is the first ESA mission to Venus that will be launched in November 2005. In April 2006 after 150 days of cruise the spacecraft will be inserted into highly elliptical polar orbit around Venus. The observational phase will begin after about one month of commissioning phase. The nominal mission orbital life-time is two Venus sidereal days (486 Earth days). The scientific goals of Venus Express are related to the global atmospheric circulation and atmosphere chemical composition, the surfaceatmosphere physical and chemical interactions, the physics and chemistry of the cloud layer, the thermal balance and role of trace gases in the greenhouse effect, and the plasma environment and its interaction with the solar wind.

  9. Venus Express Chemical Propulsion System - The Mars Express Legacy

    Science.gov (United States)

    Hunter, C. J.

    2004-10-01

    ESA's ambition of inter-planetary exploration using a fast-track low cost industrial programme was well achieved with Mars Express. Reusing the platform architecture for the service module and specifically the Propulsion system enabled Venus Express to benefit from several lessons learnt from the Mars Express experience. Using all existing components qualified for previous programmes, many of them commercial telecommunication spacecraft programmes with components available from stock, an industrial organisation familiar from Mars Express was able to compress the schedule to make the November 2005 launch window a realistic target. While initial inspection of the CPS schematic indicates a modified Eurostar type architecture, - a similar system using some Eurostar components - would be a fairer description. The use of many parts of the system on arrival at the destination (Mars or Venus in this case) is a departure from the usual mode of operation, where many components are used during the initial few weeks of GTO or GEO. The system modifications over the basic Eurostar system have catered for this in terms of reliability contingencies by replacing components, or providing different levels of test capability or isolation in flight. This paper aims to provide an introduction to the system, address the evolution from Eurostar, and provide an initial assessment of the success of these modifications using the Mars Express experience, and how measures have been adopted specifically for Venus Express.

  10. Venus Express: five years of atmospheric observations

    Science.gov (United States)

    Titov, D. V.; Svedhem, H.; Wilson, C.

    2011-10-01

    Since April 2006 Venus Express has been performing a global survey of the remarkably dense, cloudy, and dynamic atmosphere of our near neighbour. More than 300 radio-occultation experiments covering all latitudes and local times on had been acquired so far. They reveal highly variable temperature structure in the mesosphere and within the clouds. Joint analysis of several experiments indicated coordinated latitudinal changes of the cloud top structure with high dispersed cloud tops in the low latitudes and relatively low dense clouds in the cold collar and the polar region. UV imaging monitors strongly variable cloud patterns showing for the first time middle latitudes and polar regions in unprecedented detail. Tracking cloud features at both UV and thermal infrared wavelengths characterizes the global wind field and its variations, including pioneering reconstruction of the velocity patterns inside the polar eye of the hemispheric vortex. The observations are supported by development of General Circulation Models. Spectroscopic observations in both nadir and occultation geometries continuously sound composition of the mesosphere and discover significant latitudinal variations of water vapour and sulphur dioxide that form cloud particles. Contrary to expectations the observations indicate no apparent correlations with UV brightness patterns. Non-LTE infrared emissions in the lines of O2, NO, CO2, OH originating near the mesopause at 95-105 km altitude are being mapped on the night side. The data show that the airglow peak intensity occurs close to the anti-solar point and its location depends on particular specie. A consistent picture of the climate on the neighbouring planet is emerging from the Venus Express observations supported by extensive modelling efforts. The results of the studies will be published in about 40 original papers in the special issue of Icarus to appear in 2011.

  11. Venus Express en route to probe the planet's hidden mysteries

    Science.gov (United States)

    2005-11-01

    Venus Express will eventually manoeuvre itself into orbit around Venus in order to perform a detailed study of the structure, chemistry and dynamics of the planet's atmosphere, which is characterised by extremely high temperatures, very high atmospheric pressure, a huge greenhouse effect and as-yet inexplicable "super-rotation" which means that it speeds around the planet in just four days. The European spacecraft will also be the first orbiter to probe the planet's surface while exploiting the "visibility windows" recently discovered in the infrared waveband. The 1240 kg mass spacecraft was developed for ESA by a European industrial team led by EADS Astrium with 25 main contractors spread across 14 countries. It lifted off onboard a Soyuz-Fregat rocket, the launch service being provided by Starsem. The lift-off from the Baikonur Cosmodrome in Kazakstan this morning took place at 09:33 hours local time (04:33 Central European Time). Initial Fregat upper-stage ignition took place 9 minutes into the flight, manoeuvring the spacecraft into a low-earth parking orbit. A second firing, 1 hour 22 minutes later, boosted the spacecraft to pursue its interplanetary trajectory. Contact with Venus Express was established by ESA's European Space Operations Centre (ESOC) at Darmstadt, Germany approximately two hours after lift-off. The spacecraft has correctly oriented itself in relation to the sun and has deployed its solar arrays. All onboard systems are operating perfectly and the orbiter is communicating with the Earth via its low-gain antenna. In three days' time, it will establish communications using its high-gain antenna. Full speed ahead for Venus Venus Express is currently distancing itself from the Earth full speed, heading on its five-month 350 million kilometre journey inside our solar system. After check-outs to ensure that its onboard equipment and instrument payload are in proper working order, the spacecraft will be mothballed, with contact with the Earth being reduced to once daily. If needed, trajectory correction manoeuvres can go ahead at the half-way stage in January. When making its closest approach, Venus Express will face far tougher conditions than those encountered by Mars Express on nearing the Red Planet. For while Venus's size is indeed similar to that of the Earth, its mass is 7.6 times that of Mars, with gravitational attraction to match. To resist this greater gravitational pull, the spacecraft will have to ignite its main engine for 53 minutes in order to achieve 1.3 km/second deceleration and place itself into a highly elliptical orbit around the planet. Most of its 570 kg of propellant will be used for this manoeuvre. A second engine firing will be necessary in order to reach final operational orbit: a polar elliptical orbit with 12-hour crossings. This will enable the probe to make approaches to within 250 km of the planet's surface and withdraw to distances of up to 66 000 km, so as to carry out close-up observations and also get an overall perspective. Exploring other planets to better understand planet Earth "The launch of Venus Express is a further illustration of Europe's determination to study the various bodies in our solar system", stressed Professor David Southwood, the Director of ESA's science programmes. "We started in 2003 with the launch of Mars Express to the Red Planet and Smart-1 to the Moon and both these missions have amply exceeded our expectations. Venus Express marks a further step forward, with a view to eventually rounding off our initial overview of our immediate planetary neighbours with the BepiColombo mission to Mercury to be launched in 2013." "With Venus Express, we fully intend to demonstrate yet again that studying the planets is of vital importance for life here on Earth", said Jean Jacques Dordain, ESA Director General. "To understand climate change on Earth and all the contributing factors, we cannot make do with solely observing our own planet. We need to decipher the mechanics of the planetary atmosphere in

  12. Venus Express Measurement of ULF and ELF Signals in the Venus Ionosphere: Evidence for Extensive Electrical Activity in the Venus Atmosphere

    Science.gov (United States)

    Hart, R.; Russell, C. T.; Leinweber, H.; Zhang, T.

    2013-05-01

    Even though the surface of Venus is currently very dry, the atmosphere has extensive cloud cover. These clouds contain sulfuric acid particles that have properties sufficiently similar to water-ice that they would be expected to become charged, as in terrestrial clouds. Also the nitric oxide content of the Venus atmosphere, which is formed by lightning on Earth is similar to the terrestrial values. Thus it is not surprising that numerous manifestations of lightning on Venus have been reported. In this paper we use the Venus Express magnetic measurements to extend our understanding of Venus lightning. The gradiometer magnetometer configuration installed on Venus Express allows the cleaning of the data up to 6 KHz. We exploit these data in the second year of operation to add statistics to our existing data base. We show how ULF and ELF signals appear to reach the spacecraft via different paths but could have the same physical cause: electrical discharges in the Venus ionosphere.

  13. Long-term variations of the UV contrast on Venus observed by the Venus Monitoring Camera on board Venus Express

    Science.gov (United States)

    Lee, Y. J.; Imamura, T.; Schröder, S. E.; Marcq, E.

    2015-06-01

    We analyze the Venus ultraviolet (UV) reflectivity as observed by the Venus Monitoring Camera on board Venus Express over 2000 orbits in the years 2006-2011. We compare several laws for the photometric correction of global images of Venus, and find that the combined law of Lambert and Lommel-Seeliger is most suitable for our study. Our analysis of the corrected images reveals strong fluctuations in the reflectivity contrast between low and high latitude regions of up to 40%, that follow variations of the SO2 abundance above the cloud top. Additionally, the phase angle dependence of the contrast gradually change from weak to strong, which may be related with the vertical distribution of the unknown UV absorber and the overlaying upper haze layer. We suggest that these variations result from a combination of two processes. One is the meridional transport of SO2, which forms sulfuric acid aerosol particles at high latitudes. The other is the presence of vertical winds near the cloud top level, which control the vertical mixing of the unknown UV absorber and the upper haze.

  14. Low-frequency magnetic field fluctuations in Venus' solar wind interaction region: Venus Express observations

    Directory of Open Access Journals (Sweden)

    L. Guicking

    2010-04-01

    Full Text Available We investigate wave properties of low-frequency magnetic field fluctuations in Venus' solar wind interaction region based on the measurements made on board the Venus Express spacecraft. The orbit geometry is very suitable to investigate the fluctuations in Venus' low-altitude magnetosheath and mid-magnetotail and provides an opportunity for a comparative study of low-frequency waves at Venus and Mars. The spatial distributions of the wave properties, in particular in the dayside and nightside magnetosheath as well as in the tail and mantle region, are similar to observations at Mars. As both planets do not have a global magnetic field, the interaction process of the solar wind with both planets is similar and leads to similar instabilities and wave structures. We focus on the spatial distribution of the wave intensity of the fluctuating magnetic field and detect an enhancement of the intensity in the dayside magnetosheath and a strong decrease towards the terminator. For a detailed investigation of the intensity distribution we adopt an analytical streamline model to describe the plasma flow around Venus. This allows displaying the evolution of the intensity along different streamlines. It is assumed that the waves are generated in the vicinity of the bow shock and are convected downstream with the turbulent magnetosheath flow. However, neither the different Mach numbers upstream and downstream of the bow shock, nor the variation of the cross sectional area and the flow velocity along the streamlines play probably an important role in order to explain the observed concentration of wave intensity in the dayside magnetosheath and the decay towards the nightside magnetosheath. But, the concept of freely evolving or decaying turbulence is in good qualitative agreement with the observations, as we observe a power law decay of the intensity along the streamlines. The observations support the assumption of wave convection through the magnetosheath, but reveal at the same time that wave sources may not only exist at the bow shock, but also in the magnetosheath.

  15. Boundary layer in the Venus ionosheath. Evidence from the Venus express plasma data

    International Nuclear Information System (INIS)

    Complete text of publication follows. Measurements conducted with the ASPERA-4 instrument in the Venus Express spacecraft further support the presence of a plasma transition located at the flanks of the Venus ionosheath downstream from the bow shock and that had been inferred in the data obtained from previous missions at Venus. Across this transition there are sudden changes in the plasma properties including lower speed and density values as well as higher temperatures of the shocked solar wind in its downstream side. In addition there is evidence that the planetary ion component becomes enhanced in the downstream side of that transition with fluxes that lead to significantly larger densities than those measured in the upstream side. That plasma transition has been interpreted as representing the outer extent of a viscous boundary layer formed by the transport of solar wind momentum to the Venus upper ionosphere, and the ASPERA-4 data provide for the first time information on the kinetic properties of the planetary ion population that is seen to stream mostly in the solar wind direction but with values that remain smaller than those of the solar wind. From the analysis of a collection of orbits with evidence of that transition it has been possible to derive that its position varies significantly with the downstream distance from the planet. Furthermore it has also been found that the momentum flux of the dominant component of planetary ions measured downstream from f planetary ions measured downstream from the plasma transition can be accounted for from the momentum flux of the solar wind protons. In most cases the latter quantity represents 80 to 90 % of the incident momentum flux of the solar wind and implies that there is an approximate balance in the momentum between both populations as would result from the transport of solar wind momentum.

  16. Venus Express Contributions to the Study of Planetary Lightning

    Science.gov (United States)

    Russell, C. T.; Hart, R. A.; Zhang, T. L.

    2014-04-01

    Jupiter, and Saturn are expected to generate the electrical potential differences in their clouds sufficient to cause a breakdown in the atmosphere,creating a conducting path for the electric potential to discharge. This high-energy phenomenon creates a hot, high-pressure channel that enables chemical reactions not possible under usual local thermodynamic conditions. Thus it is of some interest to determine if lightning occurs in an atmosphere. While Venus is not usually considered one of the wet planets, lightning has been an object of interest since the Venera landers. It was observed with electromagnetic coils on Venera 11, 12, 13, 14 landers [2]. It was observed with a visible spectrometer on the Venera 9 orbits [1]. It was mapped during solar occultations by the electric antenna on the Pioneer Venus Orbiter [4]. These measurements revealed extensive lightning activity with an electromagnetic energy flux similar to that on Earth. However, the observations were limited in number in the atmosphere and to the nightside from orbit. In order to improve the understanding of Venus lightning, the Venus Express magnetometer was given a 128-Hz sampling rate that could cover much of the ELF frequencies at which lightning could be observed in the weak magnetic fields of the Venus ionosphere [5]. This investigation was immediately successful [3], but mastering the cleaning of the broadband data took several years to accomplish. Furthermore, the high polar latitudes of VEX periapsis were not the ideal locations to conduct the more global survey that was desired. Fortunately, after precessing poleward over the first few years the latitude of periapsis has returned to lower latitudes(Figures 1 and 2) and active electrical storms are now being studied. The charged constituent of the Venus atmosphere need not be water. In fact, we believe it is H2SO4 which polarizes much as water does and which freezes and melts at similar temperatures. If it is H2SO4, we would expect the constituent to be sensitive to the rate of Venus volcanism releasing sulfur and sulfur dioxide into the atmosphere. This is one correlation we are anxious to pursue on future missions.

  17. Dynamics of Venus' southern polar vortex from over two years of VIRTIS/Venus Express observations

    Science.gov (United States)

    Luz, D.; Berry, D. L.; Peralta, J.; Piccioni, G.

    2011-10-01

    polar region of Venus, using measurements from the VIRTIS instrument from the Venus Express Mission, revealed it to be in constant dynamic change, with the southern polar vortex displaced from the rotational geometry of the planet [1]. Here, we place these results in the context of measurements taken over a two year period. We examine the dynamics of the southern polar region based on measurements of winds at the 45 and 65 km levels, detected from cloud motion monitoring by the VIRTIS instrument. The wind velocity components were determined by an automatic cloud-tracking technique based on evaluating the similarity between pairs of images of cloud structures at a specific atmospheric altitude, separated by a short time interval. The images were obtained at infrared wavelengths of 1.74 and 2.3 ?m, for the night side, and 3.9 and 5.0 ?m, for both the day and night sides. These wavelengths are sensitive to radiation originating from levels close to the base and to the top of the cloud deck, respectively. The technique assumes that the clouds are passive tracers of the atmospheric mass flow, and that the cloud structure does not change substantially between the two images. Our objectives have been 1) to provide horizontal maps of direct wind measurements at cloud tops and in the lower cloud level with a high spatial resolution; 2) to characterize the southern polar vortex as to its motion, rotation rate and dynamical stability; 3) to constrain the contribution of the circumpolar circulation to the angular momentum budget; and 4) to provide valuable information for Venus climate modelling, for the planning of future probe or balloon missions, and to examine the Venus polar vortex in the context of other planetary vortices. The circulation in the southern polar region is dominated by the zonal flow, which is much stronger than the meridional circulation. The latitudinal profiles show a relatively smooth variation and the vertical shear between the 45-km and 65-km levels is on the order of 5-10 ms-1. The horizontal structure of the zonal and meridional wind components indicate that wavenumber-2 thermal tides are likely to be present.

  18. First results of an Investigation of Sulfur Dioxide in the Ultraviolet from Pioneer Venus through Venus Express

    Science.gov (United States)

    McGouldrick, Kevin; Molaverdikhani, K.; Esposito, L. W.; Pankratz, C. K.

    2010-10-01

    The Laboratory for Atmospheric and Space Physics is carrying on a project to restore and preserve data products from several past missions for archival and use by the scientific community. This project includes the restoration of data from Mariner 6/7, Pioneer Venus, Voyager 1/2, and Galileo. Here, we present initial results of this project that involve Pioneer Venus Orbiter Ultraviolet Spectrometer (PVO UVS) data. Using the Discrete Ordinate Method for Radiative Transfer (DISORT), we generate a suite of models for the three free parameters in the upper atmosphere of Venus in which we are interested: sulfur dioxide abundance at 40mb, scale height of sulfur dioxide, and the typical radius of the upper haze particles (assumed to be composed of 84.5% sulfuric acid). We calculate best fits to our radiative transfer model results for multi-spectral images taken with PVO UVS, as well as the 'visible' channel (includes wavelengths from 290nm to about 1000nm) of the mapping mode of the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS-M-Vis) on the Venus Express spacecraft, currently orbiting Venus. This work is funded though the NASA Planetary Mission Data Analysis Program, NNH08ZDA001N.

  19. The variable upper atmosphere of Venus, as determined by data from drag and torque measurements by Venus Express

    Science.gov (United States)

    Svedhem, Håkan; Müller-Wodarg, Ingo; Rosenblatt, Pascal

    2013-04-01

    Until recently the only information on the structure of the polar upper atmosphere of Venus available has been based on the reference atmosphere models such as the VTS3 or VIRA models. These models extrapolate the values from low latitudes to high latitudes by using equivalent solar zenith angles. New measurements by Venus Express show that such extrapolations not always give correct results and that there is a permanent overestimate of the density at high latitudes. These new results have been reached by using two different but related techniques, both using an atmospheric drag effect on the spacecraft. By reducing the pericentre altitude the total mass density in the altitude range 150-200km can be measured in situ by monitoring the orbital decay caused by the drag on the spacecraft by the atmosphere via direct tracking of the Doppler signal on the telecommunication link. Such measurements have been performed with Venus Express several times during the last years as part of the Venus Express Atmospheric Drag Experiment (VExADE). The results indicate a large variability within only a few days and have led to questions if these variations are real or within the uncertainty of the measurements. A completely different and independent measurement is given by monitoring the torque asserted by the atmosphere on the spacecraft. This is done by monitoring the momentum accumulated in the reaction wheels during the pericenter pass and at the same time considering all other perturbing forces. This requires the spacecraft to fly in an asymmetric attitude with respect to the center of gravity, center of drag and the velocity vector. This technique has proven very sensitive, in particular if the geometric asymmetry is large, and offers an additional method of measuring atmospheric densities in-situ that previously had not been explored with the Venus Express spacecraft. Similar measurements have been done in the past by Magellan at Venus and by Cassini at Titan. Between 2009 and 2012 several campaigns, with altitudes going as low as 165 km, were held. The highest density measured was 7.7 10-12kg/m3 which is significantly less than earlier models predict. The results largely confirm the density measurements by the VExADE drag measurements and add to the confidence in the results from these measurements. By using these drag and torque results and assuming a hydrostatic diffusive equilibrium atmosphere a new model has been constructed. The model is fitted to the Venus Express remote sensing measurements in the upper mesosphere (VeRa radio occultation data) and lower thermosphere (SpicaV/SOIR data) to give a continuous transition across the different regions.

  20. A search for optical evidence for lightning on Venus with VIRTIS on Venus Express

    Science.gov (United States)

    Abildgaard, Sofie; Cardesin, Alejandro; Garcia Múnoz, Antonio; Piccioni, Giuseppe

    2015-04-01

    Lightning is known to occur on the atmospheres of Earth, Jupiter, Saturn, Uranus and Neptune, but although the occurrence of lightning in the Venusian atmosphere has been published several times in the past years, always on the basis of detected electromagnetic pulses, the subject is still controversial. It is generally agreed that an optical observation of the phenomenon would settle the issue. In this work we analyse the data collection of hyper-spectral images produced by the Visible and InfraRed Thermal Imaging Spectrometer (VIRTIS) on Venus Express, that has been observing the Venusian atmosphere continuously since 2006. A dedicated search algorithm for transient events was developed and a detailed analysis of the archive was performed in all wavelengths. The first preliminary analysis have been performed and we have proven that transient events can easily be identified in the data. Work is ongoing for optimizing search parameters and performing a statistical analysis. In this contribution, we will present a summary of the data analysis process and some of the preliminary conclusion in the lightning detection/nondetection.

  1. Solar Tides in the winds of the southern polar region of Venus using VIRTIS-M/Venus Express images

    Science.gov (United States)

    Peralta, J.; Luz, D.; Berry, D. L.; Piccioni, G.; Drossart, P.; Hueso, R.; Sánchez-Lavega, A.

    2011-10-01

    The effect of the solar tides on the winds at the top of the clouds in Venus has been studied using cloud tracking technique applied to the Venus Express/VIRTIS-M images taken at wavelengths of 3.8 and 5.0 ?m. Both these wavelengths probe about the same altitude on the clouds top, allowing for the first time to retrieve winds in the dayside and nightside simultaneously. The dataset included observations from 17 orbits, covering a time span of 290 days and a latitude range between 70ºS and 85ºS, a region where resides the so called cold collar. Both the diurnal (wavenumber 1) and the semidiurnal (wavenumber 2) tides are present, with the diurnal tide being the dominant harmonic for both the zonal and meridional components of the wind. The diurnal tide induces wind oscillations with amplitudes of about 4.5 m/s and 8.0 m/s for the zonal and meridional winds respectively. These amplitudes are in good accordance with the Rayleigh friction expected for this level of the Venus atmosphere, and support the important role of the diurnal tide in the maintenance of the mean zonal flow and in determining the sense of the meridional flow. While the tidal amplitude seems not to undergo important changes, the phase displays a temporal variability of about 1.4 hours in the local time coordinate. The rate of change of the phase seems different for the diurnal and semidiurnal component, indicative of a dispersive character of the solar tides, and is consistent with the expected change due to the tidal vertical propagation. Finally, a persistent lag is apparent in most cases between the tidal phases of zonal and meridional disturbances, implying that the diurnal tides tend to force equatorward winds when in the sense of the mean flow, and poleward winds when in the opposite sense.

  2. Carbon monoxide and temperature in the upper atmosphere of Venus from VIRTIS/Venus Express non-LTE limb measurements

    Science.gov (United States)

    Gilli, G.; López-Valverde, M. A.; Peralta, J.; Bougher, S.; Brecht, A.; Drossart, P.; Piccioni, G.

    2015-03-01

    The upper mesosphere and the lower thermosphere of Venus (from 90 to 150 km altitude) seems to play a transition region in photochemistry, dynamics and radiation, but is still very poorly constrained observationally. Since 2006 VIRTIS on board Venus Express has been obtaining limb observations of CO fluorescent infrared emissions in a systematic manner. This study represents the scientific exploitation of this dataset and reports new information on the composition and temperature at those altitudes. This work is focused on the 4.7 ? m emission of CO as observed by VIRTIS, which contains two emission bands, the fundamental and the first hot of the main CO isotope. A specific scheme for a simultaneous retrieval of CO and temperature is proposed, based on results of a comprehensive non-LTE model of these molecular emissions. A forward model containing such non-LTE model is used at the core of an inversion scheme that consists of two steps: (i) a minimization procedure of model-data differences and (ii) a linear inversion around the solution of the first step. A thorough error analysis is presented, which shows that the retrievals of CO and temperature are very noisy but can be improved by suitable averaging of data. These averages need to be consistent with the non-LTE nature of the emissions. Unfortunately, the data binning process reduced the geographical coverage of the results. The obtained retrieval results indicate a global distribution of the CO in the Venus dayside with a maximum around the sub-solar point, and a decrease of a factor 2 towards high latitudes. Also a gradient from noon to the morning and evening sides is evident in the equator, this being smaller at high latitudes. No morning-afternoon differences in the CO concentration are observed, or are comparable to our retrieval errors. All this argues for a CO distribution controlled by dynamics in the lower thermosphere, with a dominant sub-solar to anti-solar gradient. Similar variations are found with the Venus Thermospheric General Circulation Model (VTGCM), but the VIRTIS CO is systematically larger than in the model. The thermal structure obtained by VIRTIS presents a hint of local maximum around 115 km near the terminator at equatorial latitudes, but not at noon, in clear contrast to VTGCM predictions and to an upper mesosphere in pure radiative balance. A few tentative ideas to explain these model-data discrepancies are discussed.

  3. Photochemical Control of the Distribution of Venusian Water and Comparison to Venus Express SOIR Observations

    Science.gov (United States)

    Parkinson, Chris; Yung, Yuk; Esposito, Larry; Gao, Peter; Bougher, Steve

    2014-11-01

    We use the JPL/Caltech 1-D KINETICS photochemical model to solve the continuity diffusion equation for the atmospheric constituent abundances and total number density as a function of radial distance from the planet Venus. The photochemistry of the Venus atmosphere from 58 to 112 km is modeled using an updated and expanded chemical scheme (Zhang et al., 2010; 2012), guided by the results of recent observations. We mainly follow Zhang et al. (2010; 2012) to guide our choice of boundary conditions for 40 species. We fit the SOIR Venus Express results of 1 ppm at 70-90 km (Bertaux et al (2007) by modeling water from between 10 - 35 ppm at our 58 km lower boundary and using an SO2 mixing ratio of 25 ppm as our nominal reference value. We then vary the SO2 mixing ratio at the lower boundary between 5 and 75 ppm and find that it can control the water distribution at higher altitudes.

  4. Venus Atmospheric Maneuverable Platform (VAMP) Science Vehicle Concept

    Science.gov (United States)

    Lee, G.; Polidan, R.; Sokol, D.; Bolisay, L.; Barnes, N.

    2015-04-01

    We will update the VAMP design and discuss plans for future trade studies, analyses, and prototyping to advance the concept and we will discuss how VAMP will enable opportunities for novel long duration scientific studies of the Venus atmosphere.

  5. Ionospheric inversion of the Venus Express radio occultation data observed by Shanghai 25 m and New Norcia 35 m antennas

    CERN Document Server

    Zhang, Su-jun; Li, Jin-ling; Ping, Jin-song; Chen, Cong-yan; Zhang, Ke-fei

    2015-01-01

    Electron density profiles of the Venus' ionosphere are inverted from the Venus Express (VEX) one-way open-loop radio occultation experiments carried out by Shanghai 25 m antenna from November 2011 to January 2012 at solar maximum conditions and by New Norcia 35 m antenna from August 2006 to June 2008 at solar intermediate conditions. The electron density profile (from 110 km to 400 km) retrieved from the X-band egress observation at Shanghai station, shows a single peak near 147 km with a peak density of about $2 \\times 10^4 \\rm{cm}^{-3}$ at a solar zenith angle of 94$^{\\circ}$. As a comparison, the VEX radio science (VeRa) observations at New Norcia station were also examined, including S-, X-band and dual-frequency data in the ingress mode. The results show that the electron density profiles retrieved from the S-band data are more analogous to the dual-frequency data in the profile shape, compared with the X-band data. Generally, the S-band results slightly underestimate the magnitude of the peak density, w...

  6. The 2004 Transit of Venus as a Space Science Education Opportunity

    Science.gov (United States)

    Odenwald, S.; Mayo, L.; Vondrak, R.; Thieman, J.; Hawkins, I.; Schultz, G.

    2003-12-01

    We will present some of the programs and activities that NASA and its missions are preparing in order to support public and K12 education in space science and astronomy using the 2004 transit of Venus as a focal event. The upcoming transit of Venus on June 8 offers a unique opportunity to educate students and the general public about the scale of the solar system and the universe, as well as basic issues in comparative planetology. NASA's Sun-Earth Connection Education Forum is offering a number of programs to take advantage of this rare event. Among these are a live web cast from Spain of the entire transit, a series of radio and TV programs directed at students and the general public, a web cast describing extra-solar planet searches using the transit geometry, and archived observations produced by public observatories and student-operated solar viewers. The NASA/OSS Education Forums will also partner with science museums, planetaria and teachers across the country to bring the transit of Venus 'down to Earth'. In addition to offering enrichment activities in mathematics and space science, we also describe collaborations that have yielded unique historical resources including online archives of newspaper articles from the 1874 and 1882 transits. In addition, in collaboration with the Library of Congress Music Division, we have supported a modern re-orchestration of John Philip Sousa's Transit of Venus March which has not been performed since 1883. We anticipate that the transit of Venus will be a significant event of considerable public interest and curiosity, if the newspaper headlines from the transit seen in 1882 are any indication.

  7. Meeting Venus

    Science.gov (United States)

    Sterken, Christiaan; Aspaas, Per Pippin

    2013-06-01

    On 2-3 June 2012, the University of Tromsoe hosted a conference about the cultural and scientific history of the transits of Venus. The conference took place in Tromsoe for two very specific reasons. First and foremost, the last transit of Venus of this century lent itself to be observed on the disc of the Midnight Sun in this part of Europe during the night of 5 to 6 June 2012. Second, several Venus transit expeditions in this region were central in the global enterprise of measuring the scale of the solar system in the eighteenth century. The site of the conference was the Nordnorsk Vitensenter (Science Centre of Northern Norway), which is located at the campus of the University of Tromsoe. After the conference, participants were invited to either stay in Tromsoe until the midnight of 5-6 June, or take part in a Venus transit voyage in Finnmark, during which the historical sites Vardoe, Hammerfest, and the North Cape were to be visited. The post-conference program culminated with the participants observing the transit of Venus in or near Tromsoe, Vardoe and even from a plane near Alta. These Proceedings contain a selection of the lectures delivered on 2-3 June 2012, and also a narrative description of the transit viewing from Tromsoe, Vardoe and Alta. The title of the book, Meeting Venus, refers the title of a play by the Hungarian film director, screenwriter and opera director Istvan Szabo (1938-). The autobiographical movie Meeting Venus (1991) directed by him is based on his experience directing Tannhauser at the Paris Opera in 1984. The movie brings the story of an imaginary international opera company that encounters a never ending series of difficulties and pitfalls that symbolise the challenges of any multicultural and international endeavour. As is evident from the many papers presented in this book, Meeting Venus not only contains the epic tales of the transits of the seventeenth, eighteenth and nineteenth centuries, it also covers the conference participants' encounter with "Venus on the Sun" in historical archives as well as face-to-face at several locations in the Troms and Finnmark counties.

  8. Geographic distribution of zonal wind and UV albedo at cloud top level from VMC camera on Venus Express: Influence of Venus topography through stationary gravity waves vertical propagation.

    Science.gov (United States)

    Bertaux, Jean-Loup; Khatunstsev, Igor; Hauchecorne, Alain; Markiewicz, Wojciech; Marcq, Emmanuel; Lebonnois, Sébastien; Patsaeva, Marina; Turin, Alexander

    2015-04-01

    UV images (at 365 nm) of Venus cloud top collected with VMC camera on board Venus Express allowed to derive a large number of wind measurements at altitude 67±2 km from tracking of cloud features in the period 2006-2012. Both manual (45,600) and digital (391,600) individual wind measurements over 127 orbits were analyzed showing various patterns with latitude and local time. A new longitude-latitude geographic map of the zonal wind shows a conspicuous region of strongly decreased zonal wind, a remarkable feature that was unknown up to now. While the average zonal wind near equator (from 5°S to 15°s) is -100.9 m/s in the longitude range 200-330°, it reaches -83.4 m/s in the range 60-100°, a difference of 17.5 m/s. When compared to the altimetry map of Venus, it is found that the zonal wind pattern is well correlated with the underlying relief in the region of Aphrodite Terra, with a downstream shift of about 30° (˜3,200 km). We interpret this pattern as the result of stationary gravity waves produced at ground level by the up lift of air when the horizontal wind encounters a mountain slope. These waves can propagate up to cloud top level, break there and transfer their momentum to the zonal flow. A similar phenomenon is known to operate on Earth with an influence on mesospheric winds. The LMD-GCM for Venus was run with or without topography, with and without a parameterization of gravity waves and does not display such an observed change of velocity near equator. The cloud albedo map at 365 nm varies also in longitude and latitude. We speculate that it might be the result of increased vertical mixing associated to wave breaking, and decreased abundance of the UV absorber which makes the contrast in images. The impact of these new findings on current super rotation theories remains to be assessed. This work was triggered by the presence of a conspicuous peak at 117 days in a time series of wind measurements. This is the length of the solar day as seen at the ground of Venus. Since VMC measurements are done preferably in a local time window centred on the sub-solar point, any parameter having a geographic longitude dependence will show a peak at 117 days.

  9. Electron optical study of the Venus Express ASPERA-4 Electron Spectrometer (ELS) top-hat electrostatic analyser

    International Nuclear Information System (INIS)

    The performance of the Venus Express (VEX) ASPERA-4 Electron Spectrometer (ELS) is different from the nominal response shown by the ASPERA-3 ELS aboard Mars Express due to machining tolerance. Up to now, the precise mechanism for this was unknown and, therefore, the results of the experimental calibration could not be supported with a theoretical understanding of the fundamental instrument science behind the device. In this study, we show that the difference is due to a misalignment of the inner hemisphere and a widening of the entrance aperture of the instrument. The response of the VEX ELS can be approximated by a combination of a vertical offset of the inner hemisphere of ?0.6 mm and a lateral offset of less than 0.125 mm, combined with an aperture that is ?0.54 mm wider than nominal. The resulting K-factor, geometric factor, energy resolution and peak elevation are in good agreement with those observed experimentally. Therefore, we now have a good agreement between both laboratory calibration data and computer simulation, giving a firm foundation for future scientific data analysis

  10. The Scientific Exploration of Venus

    Science.gov (United States)

    Taylor, Fredric W.

    2014-12-01

    Part I. Views of Venus, from the Beginning to the Present Day: 1. The dawn of Venus exploration; 2. Mariner and Venera; 3. Pioneer Venus and Vega: orbiters, balloons and multi-probes; 4. Images of the surface; 5. The forgotten world; 6. Earth-based astronomy delivers a breakthrough; 7. Can't stop now; 8. Europe and Japan join in: Venus Express and Akatsuki; Part II. The Motivation to Continue the Quest: 9. Origin and evolution: the solid planet; 10. Atmosphere and ocean; 11. A volcanic world; 12. The mysterious clouds; 13. Superwinds and polar vortices; 14. The climate on Venus, past, present and future; 15. Could there be life on Venus?; Part III. Plans and Visions for the Future: 16. Solar system exploration; 17. Coming soon to a planet near you: planned Venus missions; 18. Towards the horizon: advanced technology; 19. Beyond the horizon: human expeditions; Epilogue; Appendix A. Chronology of space missions to Venus; Appendix B. Data about Venus.

  11. Progress towards a Venus reference cloud model

    Science.gov (United States)

    Wilson, Colin; Ignatiev, Nikolay; Marcq, Emmanuel

    Venus is completely enveloped by clouds. The main cloud layers stretch from altitudes of 48 - 75 km, with additional tenuous hazes found at altitudes 30 - 100 km. Clouds play a crucial role in governing atmospheric circulation, chemistry and climate on all planets, but particularly so on Venus due to the optical thickness of the atmosphere. The European Space Agency’s Venus Express (VEx) satellite has carried out a wealth of observations of Venus clouds since its arrival at Venus in April 2006. Many VEx observations are relevant to cloud science - from imagers and spectrometers to solar, stellar and radio occultation - each covering different altitude ranges, spectral ranges and atmospheric constituents. We have formed an International Team at the International Space Science Institute to bring together scientists from each of the relevant Venus Express investigation teams as well as from previous missions, as well as those developing computational and analytical models of clouds and hazes. The aims of the project are (1) to create self-consistent reference cloud/haze models which capture not only a mean cloud structure but also its main modes of variability; and (2) to bring together modelers and observers, to reach an understanding of clouds and hazes on Venus which matches all observables and is physically consistent. Our approach is to first to assemble an averaged cloud profile for low latitudes, showing how cloud number abundances and other observables vary as a function of altitude, consistent with all available observations. In a second step, we will expand this work to produce a reference cloud profile which varies with latitude and local solar time, as well as optical thickness of the cloud. We will present our status in progressing towards this goal. We acknowledge the support of the International Space Science Institute of Berne, Switzerland, in hosting our Team’s meetings.

  12. Maximilianus Hell (1720-1792) and the eighteenth-century transits of Venus : a study of jesuit science in Nordic and Central European contexts

    OpenAIRE

    Aspaas, Per Pippin

    2012-01-01

    In the years 1761 and 1769, the planet Venus passed in front of the Sun as seen from Earth. In that century of Enlightenment, these events – known as transits of Venus – attracted massive interest from the entire world of learning. The monograph "Maximilianus Hell (1720-1792) and the Eighteenth-Century Transits of Venus. A Study of Jesuit Science in Nordic and Central-European Contexts" is a source-based, historical case study that aims to explore and contextualise Venus transit act...

  13. Japanese Venus Mission, VCO: A Challenge to Answer an Outstanding Question of Planetary Science

    Science.gov (United States)

    Satoh, T.; Nakamura, M.; Ueno, M.; Iwagami, N.; Sugita, S.; Kasaba, Y.; Abe, T.; Imamura, T.; Oyama, K.; WG, V.

    2002-05-01

    We plan a mission, called ``Venus Climate Orbiter'', in which we carry out a detailed and long-term monitoring observation of the mysterious atmosphere of the Earth's twin planet. The mission is scheduled to put a spacecraft, equipped with imaging cameras and plasma instruments, into Venus' orbit in 2009 after a cruise from the Earth by means of a M-V launching vehicle of ISAS. An outstanding and the most fundamental question regarding Venus is how its environment has been differentiated from the Earth's in spite of nearly identical dimensions of these twins. This should not be the question only to Venus but also a general question to every planet. One key to answer the question is believed to be obtained through the study of a generation and maintenance mechanism of so-called super-rotation of the Venusian atmosphere, a high-speed wind which encircles the planet in only 4 Earth days. Although the phenomenon itself has been well known, the mechanism of it remains still unsolved primarily because there has been no 3-D information of the atmospheric circulation which underlies an opaque cloud layer. The VCO mission is designed to acquire data sets essential to answer the above question. The imaging cameras utilize a recently-developed (and powerful) technique to remote probe the atmosphere, snapshots of Venus' night side in several atmospheric windows in the near IR region (1--2.4 ? m). This allows us to monitor the motion of cloud patches well below the visible cloud layer, our previous limit of visibility. Using a set of narrow-band filters, we image cloud features at several altitudes with spatial resolutions of 15--20 km at the sub-spacecraft point, good enough to achieve a few m/s of accuracy in determining the wind velocity. The column densities of carbon monoxide and water vapor will be also measured, yielding additional information on the atmospheric circulation. With the plasma instruments, on the other hand, we explore the upper atmosphere and the ionosphere. Observations of neutral and charged particle escapes from the planetary atmosphere are especially important, because of their significant influence on the atmospheric evolution as well as a general interest in the particle acceleration process including the solar-wind interactions. The cameras are expected to be active even in the cruising phase because it will be a unique opportunity to observe the infrared sky in a wide field of view with very low background level. The resonance structure of zodiacal dust disk rippled by the twins of our planetary system and its radial profile will be demonstrated by series of observations at different radial distances from the Sun. The VCO mission, which by itself is unique, will be valuable as part of an international collaborative work in a comprehensive study of Venus with several spacecraft, which include Lovoisier, Venus Express, and Ishtar missions of ESA, and Vespar mission of NASA. The basic concept, a mission overview, plus some details of VCO (including the onboard instruments) will be presented.

  14. Transformative ocean science through the VENUS and NEPTUNE Canada ocean observing systems

    International Nuclear Information System (INIS)

    The health of the world's oceans and their impact on global environmental and climate change make the development of cabled observing systems vital and timely as a data source and archive of unparalleled importance for new discoveries. The VENUS and NEPTUNE Canada observatories are on the forefront of a new generation of ocean science and technology. Funding of over $100M, principally from the Governments of Canada and BC, for these two observatories supports integrated ocean systems science at a regional scale enabled by new developments in powered sub-sea cable technology and in cyber-infrastructure that streams continuous real-time data to Internet-based web platforms. VENUS is a coastal observatory supporting two instrumented arrays in the Saanich Inlet, near Victoria, and in the Strait of Georgia, off Vancouver. NEPTUNE Canada is an 800 km system on the Juan de Fuca Plate off the west coast of British Columbia, which will have five instrumented nodes in operation over the next 18 months. This paper describes the development and management of these two observatories, the principal research themes, and the applications of the research to public policy, economic development, and public education and outreach. Both observatories depend on partnerships with universities, government agencies, private sector companies, and NGOs. International collaboration is central to the development of the research programs, including partnerships with initiatives in the EU, US, Japaships with initiatives in the EU, US, Japan, Taiwan and China.

  15. Transformative ocean science through the VENUS and NEPTUNE Canada ocean observing systems

    Science.gov (United States)

    Martin Taylor, S.

    2009-04-01

    The health of the world's oceans and their impact on global environmental and climate change make the development of cabled observing systems vital and timely as a data source and archive of unparalleled importance for new discoveries. The VENUS and NEPTUNE Canada observatories are on the forefront of a new generation of ocean science and technology. Funding of over $100M, principally from the Governments of Canada and BC, for these two observatories supports integrated ocean systems science at a regional scale enabled by new developments in powered sub-sea cable technology and in cyber-infrastructure that streams continuous real-time data to Internet-based web platforms. VENUS is a coastal observatory supporting two instrumented arrays in the Saanich Inlet, near Victoria, and in the Strait of Georgia, off Vancouver. NEPTUNE Canada is an 800 km system on the Juan de Fuca Plate off the west coast of British Columbia, which will have five instrumented nodes in operation over the next 18 months. This paper describes the development and management of these two observatories, the principal research themes, and the applications of the research to public policy, economic development, and public education and outreach. Both observatories depend on partnerships with universities, government agencies, private sector companies, and NGOs. International collaboration is central to the development of the research programs, including partnerships with initiatives in the EU, US, Japan, Taiwan and China.

  16. A new view of Earth's sister: Insights following nine years of Venus Express observations

    Science.gov (United States)

    Titov, Dmitrij; Svedhem, Håkan; Drossart, Pierre; Taylor, Fredric W.; Zhang, Tielong; Barabash, Stas; Paetzold, Martin; Piccioni, Giuseppe; Markiewicz, Wojciech; Vandaele, Ann C.; Wilson, Colin; Bertaux, Jean-Loup

    Since April 2006 ESA’s Venus Express has been performing a global survey of the remarkably dense, cloudy, and dynamic atmosphere of our near neighbour. The mission delivers comprehensive data on the temperature structure, the atmospheric composition, the cloud morphology, the atmospheric dynamics, the solar wind interaction and the escape processes. Vertical profiles of the atmospheric temperature show strong latitudinal trend in the mesosphere and upper troposphere correlated with changes in the cloud top structure and indicate convective instability in the main cloud deck at 50-60 km. Observations reveal significant latitudinal variations and temporal changes in the global cloud top morphology, which modulate the solar energy deposited in the atmosphere. The cloud top altitude varies from 72 km in the low and middle latitudes to 64 km in the polar region, correlated with decrease of the aerosol scale height from 4±1.6 km to 1.7±2.4 km, marking vast polar depression. UV imaging shows for the first time the middle latitudes and polar regions in unprecedented detail. The eye of the Southern polar vortex was found to be a strongly variable feature with complex dynamics. Solar occultation observations and deep atmosphere spectroscopy in spectral transparency windows mapped the distribution of the major trace gases H _{2}O, SO _{2}, CO, COS and their variations above and below the clouds, revealing key features of the dynamical and chemical processes at work. Tracking motions of cloud features provided the most complete characterization of the mean atmospheric circulation as well as its variability. Low and middle latitudes show an almost constant zonal wind speed at the cloud tops and vertical wind shear of 2-3 m/s/km. The zonal wind speed increased from 84±20 m/s to 110±16 m/s over the course of the mission. Towards the pole, the wind speed drops quickly and the vertical shear vanishes. The meridional poleward wind ranges from 0 at equator to about 15 m/s in the middle latitudes. Comparison of the thermal wind field derived from temperature sounding to the cloud-tracked winds confirms the validity of cyclostrophic balance, at least in the latitude range from 30S to 70S. The observations are supported by development of General Circulation Models. Non-LTE infrared emissions in the lines of O _{2}, NO, CO _{2}, OH originating near the mesopause at 95-105 km were detected and mapped. The data show that the peak intensity occurs in average close to the anti-solar point for O _{2} emission, which is consistent with current models of the thermospheric circulation. For almost complete solar cycle the Venus Express instruments continuously monitoring the induced magnetic field and plasma environment established the global escape rates being 3•10 (24) s (-1) , 7•10 (24) s (-1) , 8•10 (22) s (-1) for O (+) , H (+) , and He (+) ions and identified the main acceleration process. For the first time it was shown that the reconnection process takes place in the tail of a non-magnetized body. It was confirmed that the lightning tentatively detected by PVO indeed occurs on Venus. The thermal mapping of the surface in the near-IR spectral “windows” on the night side indicated the presence of recent volcanism on the planet, as do the high and variable SO _{2} abundances.

  17. The Role of Different Parameters in the Pressurant Budget of Venus Express and its Dynamic Evolution during the Mission

    Science.gov (United States)

    Valencia Bel, F.; Lang, M.

    2004-10-01

    An insufficient amount of pressurant gas in the propulsion system or a working temperature in the pressurant tank outside the qualification limits can cause a decrease in the performance of the thrusters or even the loss of the mission. This paper presents an engineering tool used able to compute the Pressurant budget of a mission and the effects of influencing parameters. The updated tool allows to also compute the temperature, pressure and mass evolution inside the pressurant tank during the various mission phases. The tool has been used to verify the calculations done by Astrium Stevenage for Mars Express and Venus Express [1]. The pressurant gas used for both cases was helium. The tool permits to use other combinations of pressurant gases and propellants for different propellant systems (monopropellant and bipropellant systems).

  18. Venus Surface Composition and Weathering

    Science.gov (United States)

    Gilmore, M.; Helbert, J.; Smrekar, S.; Treiman, A.

    2014-04-01

    Imagine interpreting the geologic history of the Earth from radar images at ~100 m/pixel, topography with a footprint of ~10 km and major-element analyses at 3 random sites. This is our challenge for Venus after Magellan. This abstract is a summary of a Venus III chapter, which will describe what we have learned about the Venus surface primarily from Venus Express (VEx), which has for the first time provided regional mapping of surface radiance that includes compositional variability. Critical to the interpretation of these data are measurements of the 1 ?m emissivity of rocks under Venus conditions and a better understanding of the chemistry of potential Venus surface-atmosphere interactions.

  19. Towards Understanding the Climate of Venus Applications of Terrestrial Models to Our Sister Planet

    CERN Document Server

    Bonnet, Roger-Maurice; Grinspoon, David; Koumoutsaris, Symeon; Lebonnois, Sebastien; Titov, Dmitri

    2013-01-01

    ESA’s Venus Express Mission has monitored Venus since April 2006, and scientists worldwide have used mathematical models to investigate its atmosphere and model its circulation. This book summarizes recent work to explore and understand the climate of the planet through a research program under the auspices of the International Space Science Institute (ISSI) in Bern, Switzerland. Some of the unique elements that are discussed are the anomalies with Venus’ surface temperature (the huge greenhouse effect causes the surface to rise to 460°C, without which would plummet as low as -40°C), its unusual lack of solar radiation (despite being closer to the Sun, Venus receives less solar radiation than Earth due to its dense cloud cover reflecting 76% back) and the juxtaposition of its atmosphere and planetary rotation (wind speeds can climb up to 200 m/s, much faster than Venus’ sidereal day of 243 Earth-days).

  20. Venus Atmospheric Maneuverable Platform (VAMP)

    Science.gov (United States)

    Polidan, R.; Lee, G.; Sokol, D.; Griffin, K.; Bolisay, L.; Barnes, N.

    2014-04-01

    Over the past years we have explored a possible new approach to Venus upper atmosphere exploration by applying recent Northrop Grumman (non-NASA) development programs to the challenges associated with Venus upper atmosphere science missions. Our concept is a low ballistic coefficient (CONOPs and the science objectives. We will show how the these factors provide constraints as well as enable opportunities for novel long duration scientific studies of the Venus upper atmosphere that support VEXAG goals I.A, I.B, and I.C.. We will also discuss how the VAMP platform itself can facilitate some of these science measurements.

  1. Photochemical Control of the Distribution of Water and Sulphuric Acid Aerosols in the Clouds and Upper Haze of Venus with Comparison to Venus Express SOIR Observations

    Science.gov (United States)

    Parkinson, C. D.; Gao, P.; Yung, Y. L.; Bougher, S. W.; Bardeen, C.

    2014-12-01

    Observations of the middle and lower cloud layers of Venus has established the water vapour mixing ratio there as ~ 30-35 ppm (Ignatiev et al. 1997), while more recent data suggests that the water vapor mixing ratio of the upper haze of Venus is ~ 1 ppm (Bertaux et al. 2007). The transition region between these two regimes, the upper cloud, is an active site of photochemistry and production of sulfuric acid, which occurs through the formation of SO3 from the oxidation of SO2, and subsequent reactions between SO3 and water. These reactions have been shown by Parkinson et al. (2014a, submitted) as capable of causing an order of magnitude decrease of the water vapor mixing ratio in the upper cloud and upper haze if the SO2 mixing ratio at the upper cloud base were increased by only ~20%, as the resulting high SO3 concentrations rapidly react with any available water to form sulfuric acid. The opposite is true when water is in high abundance. This is likely to have profound effects on the sulfuric acid clouds and hazes themselves, as 1) the depletion of either species will decrease the production rate of sulfuric acid and 2) the saturation vapor pressure of the cloud droplets increases with decreasing water fraction, and thus a "drying" of the clouds may result in decreased cloud thickness. In this work we will use the Venus microphysical cloud models of Gao et al. (2014) and Parkinson et al. (2014b, submitted) to simulate the sulfuric acid clouds and hazes of Venus from 40 to 100 km altitude and evaluate how their structure and particle sizes depend on the background water vapor profile and sulfuric acid production rate as determined by Parkinson et al. (2014a, submitted). We also show how they respond to transient episodes of increased/decreased SO2/H2O mixing ratios and discuss the plausibility of possible causes, such as volcanic activity.

  2. Venus within ESA probe reach

    Science.gov (United States)

    2006-03-01

    Venus Express mission controllers at the ESA Space Operations Centre (ESOC) in Darmstadt, Germany are making intensive preparations for orbit insertion. This comprises a series of telecommands, engine burns and manoeuvres designed to slow the spacecraft down from a velocity of 29000 km per hour relative to Venus, just before the first burn, to an entry velocity some 15% slower, allowing the probe to be captured into orbit around the planet. The spacecraft will have to ignite its main engine for 50 minutes in order to achieve deceleration and place itself into a highly elliptical orbit around the planet. Most of its 570 kg of onboard propellant will be used for this manoeuvre. The spacecraft’s solar arrays will be positioned so as to reduce the possibility of excessive mechanical load during engine ignition. Over the subsequent days, a series of additional burns will be done to lower the orbit apocentre and to control the pericentre. The aim is to end up in a 24-hour orbit around Venus early in May. The Venus orbit injection operations can be followed live at ESA establishments, with ESOC acting as focal point of interest (see attached programme). In all establishments, ESA specialists will be on hand for interviews. ESA TV will cover this event live from ESOC in Darmstadt. The live transmission will be carried free-to-air. For broadcasters, complete details of the various satellite feeds are listed at http://television.esa.int. The event will be covered on the web at venus.esa.int. The website will feature regular updates, including video coverage of the press conference and podcast from the control room at ESA’s Operations Centre. Media representatives wishing to follow the event at one of the ESA establishments listed below are requested to fill in the attached registration form and fax it back to the place of their choice. For further information, please contact: ESA Media Relations Division Tel : +33(0)1.53.69.7155 Fax: +33(0)1.53.69.7690 Venus Express Orbit Insertion - Tuesday 11 April 2006 ESA/ESOC, Robert Bosch Strasse, 5 - Darmstadt (Germany) PROGRAMME 07:30 - Doors open 08:45 - Start of local event, welcome addresses 09:10 - ESA TV live from Mission Control Room (MCR) starts 09:17 - Engine burn sequence starts 09:45 - Occultation of spacecraft by Venus starts 09:55 - Occultation ends 10:07 - Main engine burn ends 10:20 - Address by Jean-Jacques Dordain, ESA’s Director General, and other officials Break and buffet Interview opportunities 11:30-12:15 - Press Conference Jean-Jacques Dordain, Director General, ESA Prof. David Southwood, Director of Science, ESA Gaele Winters, Director of Operations and Infrastructure, ESA Manfred Warhaut, Flight Operations Director, ESA Håkan Svedhem, Venus Express Project Scientist, ESA Don McCoy, Venus Express Project Manager, ESA 13:15 - End of event at ESOC ACCREDITATION REQUEST FORM Venus Express Orbit Insertion - ESA/ESOC Darmstadt - 11 April 2006 First name:___________________ Surname:_____________________ Media:______________________________________________________ Address: ___________________________________________________ ____________________________________________________________ Tel:_______________________ Fax: ___________________________ Mobile :___________________ E-mail: ________________________ I will be attending the Venus Express Orbit Insertion event at the following site: [ ] Germany Location: ESA/ESOC Address: Robert Bosch Strasse 5, Darmstadt, Germany Opening hours: 07:30 - 13:00 Contact: Jocelyne Landeau-Constantin, Tel: +49.6151.902.696 - Fax: +49.6151.902.961 [ ] France Location: ESA HQ Address: 8/10, rue Mario Nikis - Paris 15, France Opening hours: 08:00 - 13:00 Contact: Anne-Marie Remondin - Tel: +33(0)1.53.69.7155 - fax: +33(0)1.53.69.7690 [ ] The Netherlands Location: Newton Room, ESA/ESTEC Address: Keplerlaan 1, Noordwijk, The Netherlands Opening hours: 08:30 - 12:30 Contact: Michel van Baal, tel. + 31 71 565 3006, fax + 31 71 565 5728 [ ] Italy Location: ESA/ESRIN Address: Via Galileo Galilei, Frascati (Rome), Italy Opening hours: 07:00 - 14:

  3. Chasing Venus

    Science.gov (United States)

    2009-05-20

    Periodically the planet Venus passes directly between Earth and the Sun, appearing as a small black dot on the Sun's disk. Since astronomers first became aware of them in 1631, these "transits of Venus" have fascinated astronomers because of their rarity and their potential to help scientists measure the solar system. The expeditions that set out to observe transits from remote locations paved the way for a new era of scientific exploration - yet never managed to unlock the transits' secrets. "Chasing Venus" tells the story of astronomers' pursuit of this phenomenon, through rare books and articles written on the subject over the last four centuries. The exhibit also marks the sixth observed transit of Venus, in June 2004.

  4. Venus Transit

    Science.gov (United States)

    This is an activity about the Venus Transit and how it helped astronomers determine the scale of the solar system. Learners will use measurement, ratios, and graphing to construct a model of the solar system and determine the relationship of each planet to the Sun. They will explore the scales needed to represent the size of the planets and the distances to the Sun. This activity corresponds to the NASA CONNECT video, titled Venus Transit, and has supplemental questions to support the video viewing.

  5. In-situ exploration of Venus on a global scale : direct measurements of origins and evolution, meterology, dynamics, and chemistry by a long-duration aerial science station

    Science.gov (United States)

    Baines, Kevin H.; Atreya, Sushi; Carlson, Robert W.; Chutjian, Ara; Crisp, David; Hall, Jeffrey L.; Jones, Dayton L.; Kerzhanovich, Victor V.; Limaye, Sanjay S.

    2005-01-01

    Drifting in the strong winds of Venus under benign Earth-like temperature and pressure conditions, an instrumented balloon-borne science station presents a viable means to explore, in-situ, the Venusian atmosphere on a global scale. Flying over the ground at speeds exceeding 240 km/hour while floating in the Venusian skies near 55 km altitude for several weeks, such an aerostat can conduct a 'world tour' of our neighboring planet, as it circumnavigates the globe multiple times during its flight from equatorial to polar latitudes. Onboard science sensors can repeatedly and directly sample gas compositions, atmospheric pressures and temperatures and cloud particle properties, giving unprecedented insight into the chemical processes occurring within the sulfuric clouds. Additionally, interferometric tracking via Earth-based radio observatories can yield positions and windspeeds to better than 10 cm/sec over one-hour periods, providing important information for understanding the planet's meridional circulation and enigmatic zonal super-rotation, as well as local dynamics associated with meteorological processes. As well, hundreds of GCMS spectra collected during the flight can provide measurements of noble gas compositions and their isotopes with unprecedented accuracy, thereby enabling fundamental new insights into Venus's origin and evolution.

  6. The Venus Balloon Project

    Science.gov (United States)

    Stelzried, C. T.; Preston, R. A.; Hildebrand, C. E.; Wilcher, J. H.; Ellis, J.

    1986-05-01

    On June 11 and 15, 1985, two instrumental balloons were released from the Soviet VEGA 1 and VEGA 2 spacecraft and deployed in the atmosphere of Venus. The VEGA probes flew by the planet on their way to a rendezvous with comet Halley in March 1986. Drifting with the wind at altitudes of 54 km, the balloons traveled one-third of the way around the planet during their 46-hour lifetimes. Sensors on-board the gondolas made periodic measurements of pressure, temperature, vertical wind velocity, cloud particle density, ambient light level, and frequency of lightning. The data were transmitted to Earth and received at the Deep Space Network (DSN) 64-m stations and at several large antennas in the USSR. Approximately 95 percent of the telemetry data were successfully decoded at the DSN complexes and in the Soviet Union, and were provided to the international science team for analysis. Very Long Baseline Interferometry (VLBI) data were acquired by 20 radio observatories around the world for the purpose of monitoring the Venus winds. The DSN 64-m subnet was part of a 15-station VLBI network organized by the Centre National d'Etudes Spatiales (CNES) of France. In addition, five antennas of the Soviet network participated. VLBI data from the CNES network are currently being processed at the Jet Propulsion Laboratory.

  7. Colonization of Venus

    Science.gov (United States)

    Landis, Geoffrey A.

    2003-01-01

    Although the surface of Venus is an extremely hostile environment, at about 50 kilometers above the surface the atmosphere of Venus is the most earthlike environment (other than Earth itself) in the solar system. It is proposed here that in the near term, human exploration of Venus could take place from aerostat vehicles in the atmosphere, and that in the long term, permanent settlements could be made in the form of cities designed to float at about fifty kilometer altitude in the atmosphere of Venus.

  8. High Temperature Mechanisms for Venus Exploration

    Science.gov (United States)

    Ji, Jerri; Narine, Roop; Kumar, Nishant; Singh, Sase; Gorevan, Steven

    Future Venus missions, including New Frontiers Venus In-Situ Explorer and three Flagship Missions - Venus Geophysical Network, Venus Mobile Explorer and Venus Surface Sample Return all focus on searching for evidence of past climate change both on the surface and in the atmospheric composition as well as in the interior dynamics of the planet. In order to achieve these goals and objectives, many key technologies need to be developed for the Venus extreme environment. These key technologies include sample acquisition systems and other high-temperature mechanisms and mobility systems capable of extended operation when directly exposed to the Venus surface or lower atmosphere environment. Honeybee Robotics has developed two types of high temperature motors, the materials and components in both motors were selected based on the requirement to survive temperatures above a minimum of 460° C, at earth atmosphere. The prototype Switched Reluctance Motor (SRM) has been operated non-continuously for over 20 hours at Venus-like conditions (460° C temperature, mostly CO2 gas environment) and it remains functional. A drilling system, actuated by two SRMs was tested in Venus-like conditions, 460° C temperature and mostly CO2 gas environment, for more than 15 hours. The drill successfully completed three tests by drilling into chalk up to 6 inches deep in each test. A first generation Brushless DC (BLDC) Motor and high temperature resolver were also tested and the feasibility of the designs was demonstrated by the extended operation of both devices under Venus-like condition. Further development of the BLDC motor and resolver continues and these devices will, ultimately, be integrated into the development of a high temperature sample acquisition scoop and high temperature joint (awarded SBIR Phase II in October, 2007). Both the SR and BLDC motors will undergo extensive testing at Venus temperature and pressure (TRL6) and are expected to be mission ready before the next New Frontiers AO release. Scalable high temperature motor, resolver and bearing developments allow for creation of long lasting sample acquisition systems, booms, robot arms and even mobility systems that operate outside of an environment-controlled landed platform on the surface of Venus. The SR and BLDC motors are no longer expected to limit the life of Venus surface operations. With the accompanying high temperature bearing and other mechanisms development, surface operations will be limited only by available power. Therefore, the motor and resolver's capability to survive for hours (and potentially longer) in the environment is a major benefit to future Venus science missions and they also allow time for communication ground loops to optimize sample target selection and the possibility for acquiring multiple samples from the surface. The extreme temperature motors, resolver and other high temperature mechanisms therefore revolutionize the exploration of Venus.

  9. Salt tectonics on Venus?

    International Nuclear Information System (INIS)

    The discovery of a surprisingly high deuterium/hydrogen ratio on Venus immediately led to the speculation that Venus may have once had a volume of surface water comparable to that of the terrestrial oceans. The authors propose that the evaporation of this putative ocean may have yielded residual salt deposits that formed various terrain features depicted in Venera 15 and 16 radar images. By analogy with models for the total evaporation of the terrestrial oceans, evaporite deposits on Venus should be at least tens to hundreds of meters thick. From photogeologic evidence and in-situ chemical analyses, it appears that the salt plains were later buried by lava flows. On Earth, salt diapirism leads to the formation of salt domes, anticlines, and elongated salt intrusions - features having dimensions of roughly 1 to 100 km. Due to the rapid erosion of salt by water, surface evaporite landforms are only common in dry regions such as the Zagros Mountains of Iran, where salt plugs and glaciers exist. Venus is far drier than Iran; extruded salt should be preserved, although the high surface temperature (4700C) would probably stimulate rapid salt flow. Venus possesses a variety of circular landforms, tens to hundreds of kilometers wide, which could be either megasalt domes or salt intrusions colonizing impact craters. Additionally, arcurate bands seen in the Maxwell area of Venus could be salt intrusions formed in a region of tectonic stress. These large structures may not be salt features; nonetheless, salt features should exist on Venus

  10. Gallium Nitride high temperature electronics for Venus 90-day Lander

    Science.gov (United States)

    Frampton, Robert; Peltz, Leora; Rubin, Seymour

    2008-09-01

    NASA Science exploration Roadmap includes a "Venus Mobile Lander" mission to operate on the surface of Venus for at least 90 days. Venus Mobile Lander will explore Venus surface as either an aerial vehicle or rover for several months. Previous missions to Venus operated for less than 2 hours. Electronics available today is not capable of supporting design of spacecraft avionics, power systems, or science instruments to operate in the Venus surface environment for 90 days. Thus this long duration mission will spawn a technology development program that can support science instrument and spacecraft design to meet mission requirements. Boeing, together with HRL Laboratory, is developing high temperature electronics for the Venus environment (480 Celsius, 90 bars carbon dioxide atmosphere) using the gallium nitride technology. Examples from our recent validation tests in harsh environments illustrate the performance of the electronic components and modules. In addition to the GaN-based semiconductor material, the characteristics, reliability and viability of the electronics is affected by constituent materials (metallization, dielectric layers) and by the packaging (die attach, wire bonding).

  11. Three 2012 Transits of Venus: From Earth, Jupiter, and Saturn

    Science.gov (United States)

    Pasachoff, Jay M.; Schneider, G.; Babcock, B. A.; Lu, M.; Edelman, E.; Reardon, K.; Widemann, T.; Tanga, P.; Dantowitz, R.; Silverstone, M. D.; Ehrenreich, D.; Vidal-Madjar, A.; Nicholson, P. D.; Willson, R. C.; Kopp, G. A.; Yurchyshyn, V. B.; Sterling, A. C.; Scherrer, P. H.; Schou, J.; Golub, L.; McCauley, P.; Reeves, K.

    2013-01-01

    We observed the 2012 June 6/5 transit seen from Earth (E/ToV), simultaneously with Venus Express and several other spacecraft not only to study the Cytherean atmosphere but also to provide an exoplanet-transit analog. From Haleakala, the whole transit was visible in coronal skies; among our instruments was one of the world-wide Venus Twilight Experiment's nine coronagraphs. Venus's atmosphere became visible before first contact. SacPeak/IBIS provided high-resolution images at H?/carbon-dioxide. Big Bear's NST also provided high-resolution observations of the Cytherean atmosphere and black-drop evolution. Our liaison with UH's Mees Solar Observatory scientists provided magneto-optical imaging at calcium and potassium. Solar Dynamics Observatory's AIA and HMI, and the Solar Optical Telescope (SOT) and X-ray Telescope (XRT) on Hinode, and total-solar-irradiance measurements with ACRIMSAT and SORCE/TIM, were used to observe the event as an exoplanet-transit analog. On September 20, we imaged Jupiter for 14 Hubble Space Telescope orbits, centered on a 10-hour ToV visible from Jupiter (J/ToV), as an exoplanet-transit analog in our own solar system, using Jupiter as an integrating sphere. Imaging was good, although much work remains to determine if we can detect the expected 0.01% solar irradiance decrease at Jupiter and the even slighter differential effect between our violet and near-infrared filters caused by Venus's atmosphere. We also give a first report on our currently planned December 21 Cassini UVIS observations of a transit of Venus from Saturn (S/ToV). Our E/ToV expedition was sponsored by the Committee for Research and Exploration/National Geographic Society; supplemented: NASA/AAS's Small Research Grant Program. We thank Rob Ratkowski, Stan Truitt, Rob Lucas, Aram Friedman, and Eric Pilger '82 at Haleakala, and Joseph Gangestad '06 at Big Bear for assistance, and Lockheed Martin Solar and Astrophysics Lab and Hinode science and operations teams for support for coordinated observations with NASA satellites. Our J/ToV observations were based on observations made with HST, operated by AURA, Inc., under NASA contract NAS 5-26555; these observations are associated with program #13067.

  12. Transits of Venus and Mercury as muses

    Science.gov (United States)

    Tobin, William

    2013-11-01

    Transits of Venus and Mercury have inspired artistic creation of all kinds. After having been the first to witness a Venusian transit, in 1639, Jeremiah Horrocks expressed his feelings in poetry. Production has subsequently widened to include songs, short stories, novels, novellas, sermons, theatre, film, engravings, paintings, photography, medals, sculpture, stained glass, cartoons, stamps, music, opera, flower arrangements, and food and drink. Transit creations are reviewed, with emphasis on the English- and French-speaking worlds. It is found that transits of Mercury inspire much less creation than those of Venus, despite being much more frequent, and arguably of no less astronomical significance. It is suggested that this is primarily due to the mythological associations of Venus with sex and love, which are more powerful and gripping than Mercury's mythological role as a messenger and protector of traders and thieves. The lesson for those presenting the night sky to the public is that sex sells.

  13. Venus Transit 2004

    Science.gov (United States)

    In just several weeks, Venus, the Earth's sister planet, will pass in front of the sun, affording astronomers and the general public the ability to take part in a extremely rare event. While persons in Europe, Africa, and Asia will have the best vantage point for this occurrence, those interested in the Venus transit will want to take a detailed look at this lovely website in order to find out more about the event. Launched by the European Southern Observatory and the European Association for Astronomy Education (in cooperation with three other organizations), the site contains ample information about the latest news from the project, detailed background material about this astronomical event, the network of institutions involved with the project, and information on how individuals may participate in the Venus Transit 2004 project. One of the most helpful areas contains animations of the Venus transit from different perspectives.

  14. The surface of Venus

    Science.gov (United States)

    Pettengill, G. H.; Campbell, D. B.; Masursky, H.

    1980-08-01

    Radar images of Venus were assembled from observations made at the Arecibo Observatory in Puerto Rico in 1975 and 1977 when Venus made close approaches to the earth. The empty band below the equator is a region where in 1975 and 1977 the imaging method was unable to resolve the radar echoes. Shrouded by clouds, the surface of Venus is now mapped by radar from the earth and from a spacecraft in orbit around Venus and the images suggest a geology intermediate between that of the earth and that of Mars. From a synthesis of all the data now available there begins to emerge the picture of a planet nearly the size of the earth whose surface has been modified by all the processes that have shaped the earth's surface except erosion by rain.

  15. Astrobiology and Venus exploration

    Science.gov (United States)

    Grinspoon, David H.; Bullock, Mark A.

    For hundreds of years prior to the space age, Venus was considered among the most likely homes for extraterrestrial life. Since planetary exploration began, Venus has not been considered a promising target for Astrobiological exploration. However, Venus should be central to such an exploration program for several reasons. At present Venus is the only other Earth-sized terrestrial planet that we know of, and certainly the only one we will have the opportunity to explore in the foreseeable future. Understanding the divergence of Earth and Venus is central to understanding the limits of habitability in the inner regions of habitable zones around solar-type stars. Thus Venus presents us with a unique opportunity for putting the bulk properties, evolution and ongoing geochemical processes of Earth in a wider context. Many geological and meteorological processes otherwise active only on Earth at present are currently active on Venus. Active volcanism most likely affects the climate and chemical equilibrium state of the atmosphere and surface, and maintains the global cloud cover. Further, if we think beyond the specifics of a particular chemical system required to build complexity and heredity, we can ask what general properties a planet must possess in order to be considered a possible candidate for life. The answers might include an atmosphere with signs of flagrant chemical disequilibrium and active, internally driven cycling of volatile elements between the surface, atmosphere and interior. At present, the two planets we know of which possess these characteristics are Earth and Venus. Venus almost surely once had warm, habitable oceans. The evaporation of these oceans, and subsequent escape of hydrogen, most likely resulted in an oxygenated atmosphere. The duration of this phase is poorly understood, but during this time the terrestrial planets were not isolated. Rather, due to frequent impact transport, they represented a continuous environment for early microbial life. Life, once established in the early oceans of Venus, may have migrated to the clouds which, on present day Venus, may represent a habitable niche. Though highly acidic, this aqueous environment enjoys moderate temperatures, surroundings far from chemical equilibrium, and potentially useful radiation fluxes. Observations of unusual chemistry in the clouds, and particle populations that are not well characterized, suggest that this environment must be explored much more fully before biology can be ruled out. A sulfur-based metabolism for cloud-based life on Venus has recently been proposed (Schulze-Makuch et al., 2004). While speculative, these arguments, along with the discovery of terrestrial extremophile organisms that point toward the plausibility of survival in the Venusian clouds, establish the credibility of astrobiological exploration of Venus. Arguments for the possible existence of life on Mars or Europa are, by convention and repetition, seen as more mainstream than arguments for life elsewhere, but their logical status is similar to plausibility arguments for life on Venus. With the launch of COROT in 2006 and Kepler in 2008 the demographics of Earth-sized planets in our galaxy should finally become known. Future plans for a Terrestrial Planet Finder or Darwin-type space-based spectrograph should provide the capability of studying the atmospheric composition and other properties of terrestrial planets. One of the prime rationales for building such instruments is the possibility of identifying habitable planets or providing more generalized observational constraints on the habitable zones of stellar systems. Given the prevalence of CO2 dominated atmospheres in our own solar system, it is quite likely that a large fraction of these will be Venus-like in composition and evolutionary history. We will be observing these planets at random times in their evolution. In analogy with our own solar system, it is just as likely that we will find representatives of early Venus and early Earth type planets from the first 2 billion years of their evolution as i

  16. Venus Landsailing Rover Project

    National Aeronautics and Space Administration — The surface of Venus is the most hostile environment in the solar system, with a surface temperature hotter than an oven, and a high-pressure, corrosive...

  17. Limb imaging of the Venus O2 visible nightglow with the Venus Monitoring Camera

    CERN Document Server

    Muñoz, A García; Sánchez-Lavega, A; Markiewicz, W J; Titov, D V; Witasse, O; Opitz, A

    2013-01-01

    We investigated the Venus O2 visible nightglow with imagery from the Venus Monitoring Camera on Venus Express. Drawing from data collected between April 2007 and January 2011, we study the global distribution of this emission, discovered in the late 70s by the Venera 9 and 10 missions. The inferred limb-viewing intensities are on the order of 150 kiloRayleighs at the lower latitudes and seem to drop somewhat towards the poles. The emission is generally stable, although there are episodes when the intensities rise up to 500 kR. We compare a set of Venus Monitoring Camera observations with coincident measurements of the O2 nightglow at 1.27 {\\mu}m made with the Visible and Infrared Thermal Imaging Spectrometer, also on Venus Express. From the evidence gathered in this and past works, we suggest a direct correlation between the instantaneous emissions from the two O2 nightglow systems. Possible implications regarding the uncertain origin of the atomic oxygen green line at 557.7 nm are noted.

  18. Quantifying shapes of volcanoes on Venus

    Science.gov (United States)

    Garvin, J. B.

    1994-01-01

    A large population of discrete volcanic edifices on Venus has been identified and cataloged by means of Magellan SAR images, and an extensive database describing thousands of such features is in final preparation. Those volcanoes categorized as Intermediate to Large in scale, while relatively small in number (approx. 400), nonetheless constitute a significant volumetric component (approx. 13 x 10(exp 6) cu km) of the total apparent crustal volume of Venus. For this reason, we have focused attention on the morphometry of a representative suite of the larger edifices on Venus and, in particular, on ways of constraining the eruptive histories of these possibly geologically youthful landforms. Our approach has been to determine a series of reproducible morphometric parameters for as many of the discrete volcanoes on Venus that have an obvious expression within the global altimetry data acquired by Magellan. In addition, we have attempted to objectively and systematically define the mathematical essence of the shapes of these larger volcanoes using a polynomial cross-section approximation involving only parameters easily measured from digital topography, as well as with simple surface cylindrical harmonic expansions. The goal is to reduce the topological complexities of the larger edifices to a few simple parameters which can then be related to similar expressions for well-studied terrestrial and martian features.

  19. Comparison of ion Escape From the Wake-side Ionospheres of Venus and Titan

    Science.gov (United States)

    Hartle, R. E.; Sittler, E. C.; Lipatov, A. S.

    2008-12-01

    Upward flow of ionospheric plasma into the induced magnetic tail of Venus was inferred some time ago from Pioneer Venus Orbiter (PVO) measurements, which were used to derive upward flow and acceleration of H+, D+ and O+ within the nightside ionosphere [1]. The measurements revealed that the polarization electric field in the nightside ionosphere produced the principal upward force on these light ions. Other electrodynamic forces were unimportant because the plasma beta in the nightside ionosphere is much greater than one. The resulting vertical flow of H+ and D+ was found to be the dominant escape mechanism of hydrogen and deuterium, corresponding to loss rates consistent with large oceans in early Venus [2]. Recently, plasma measurements made from Venus Express have clearly identified H+, D+ and O+ flowing away from Venus, down its magnetic tail [3]. The primary source of tail-flowing O+ is from the high altitude day-to-night flow system. Similarly, at unmagnetized Titan, ions have been observed to flow away from the moon along its induced magnetic tail by the Plasma Science Instrument (PLS) on Voyager 1 and the Casini Plasma Spectrometer (CAPS) on Cassini. In both cases, the ions have been inferred to be of ionospheric origin. Although the plasma beta is also greater than one in much of Titan's ionosphere, ion acceleration is expected to be more complex, especially because the subsolar point and the subflow points can be 180 degrees apart. Following what we learned at Venus, upward acceleration of light ions by the polarization electric field opposing gravity in the wake-side ionosphere of Titan is described. Additional electrodynamic forces resulting from the interaction of Saturn's magnetosphere with Titan's ionosphere will be examined using a recent hybrid model [4]. Comparisons between the wake-side flows on Venus and Titan will be made. [1] Hartle, R. E. and J. M. Grebowsky, Adv. Space Res., 15, (4)117, 1995. [2] Donahue, T. M. and R. E. Hartle, Geophys. Res. Lett., 19, 2449, 1992. [3] Barabash, S., et al., Nature, 450, 650, 2007. [4] Lipatov, A. S., E. C. Sittler, Jr. and R. E. Hartle, 2007 Fall AGU mtg., EOS, P23B-1366, 2007.

  20. From CERN to VENUS Express

    CERN Multimedia

    2005-01-01

    Participants in the 'Schweizer Jugendforscht' projects at CERN under the supervision of Günther Dissertori, professor at the Swiss Federal Institute of Technology (ETH Zürich) and other members of ETH Zürich, Werner Lustermann and Michael Dittmar. In Switzerland, as in many other countries, this year has seen a long list of activities, celebrating the centenary of Einstein's 'Annus mirabilis'. Having formerly employed Einstein, the Swiss Federal Institute of Intellectual Property in Bern made its contribution by sponsoring a special 'study week' for young high-school students, under the tutorship of 'Schweizer Jugendforscht', an organisation which supports the scientific activities of very talented young people. The organisers chose 'Mission to Jupiter's Moon, Europa' as the general theme for this study week. From 2 to 8 October 2005 several groups of students (between 16 and 19 years old) had to investigate some mission-related questions, ranging from the choice of the orbit and different ways of explor...

  1. Project Venus 2004

    Science.gov (United States)

    "Venus 2004" is a project of the Astroinfo Society, which was organized to study and publish findings on the transit of Venus that occurred in 2004. Historically, the planet's transit across the sun has been used to make many calculations about the sun and the earth. The technology available today, as opposed to the last transit in 1882, has made it possible for amateur astronomers to join in making observations and testing some of those historical calculations. Two publications, "Measurements of the Solar Parallaxe from Observations of the Transit of Mercury" and "Calculation of the Solar Parallaxe from Observations" are available on this site in PDF format. Both publications contain detailed information, photographs, charts and mathematical equations used to calculate their findings. These are excellent resources for students and other amateur astronomers who are gearing up for the next Venus transit in 2012.

  2. The surface of Venus

    Science.gov (United States)

    Saunders, R. Stephen

    1990-01-01

    NASA's Magellan spacecraft first revealed the true nature of Venus's surface when it began to transmit photos in September 1990, and it continues its planned mission to map the whole surface of the planet. The very sharp images obtained and processed to date leave the overall impression that Venus is a dynamic world that has been shaped by processes fundamentally similar to those that have taken place on earth, but often with dramatically different results. Magellan's synthetic aperture radar reveals details as small as 120 meters across, one tenth the size of those detected previously. Venus will be mapped eight times over the next five years, which will improve the resolution and fill in missing areas. A number of images are provided along with explanatory descriptions.

  3. Dynamics of the Venus atmosphere

    Science.gov (United States)

    Ingersoll, A. P.

    1992-01-01

    The superrotation of the Venus atmosphere is a major unanswered problem in planetary science. At cloud-top levels (65-70 km altitude) the atmosphere rotates with a five-day period, corresponding to an equatorial wind speed of 90 m/s. Angular velocity is roughly constant on spherical shells, and decreases linearly with altitude to zero at the surface. The direction of rotation is the same as that of the solid planet, which is retrograde--opposite to the direction of orbital motion, but the 5-day period is short compared to the 243-day spin period of the solid planet or to the mean solar day, which is 117 Earth-days at the surface. The problem with the superrotation is that shearing stresses tend to transfer angular momentum downward, and would slow the atmosphere until it is spinning with the solid planet. Some organized circulation pattern is counteracting the tendency, but the pattern has not been identified. A simple Hadley-type circulation cannot do it because such a circulation is zonally symmetric and Hide's Theorem states that in an axisymmetric circulation an extremum in angular momentum per unit mass M can exist only at the surface. Venus violates the last condition, having a maximum of retrograde M on the equator at 70-80 km altitude. This leaves waves and eddies to maintain the superrotation but the length scales and forcing mechanisms for these motions need to be specified. Possible forcing mechanisms associated with waves, eddies and tides are discussed.

  4. MEETING VENUS. A Collection of Papers presented at the Venus Transit Conference Tromsoe 2012

    Science.gov (United States)

    Sterken, Christiaan; Aspaas, Per Pippin

    2013-05-01

    On 2-3 June 2012, the University of Tromsoe hosted a conference about the cultural and scientific history of the transits of Venus. The conference took place in Tromsoe for two very specific reasons. First and foremost, the last transit of Venus of this century lent itself to be observed on the disc of the Midnight Sun in this part of Europe during the night of 5 to 6 June 2012. Second, several Venus transit expeditions in this region were central in the global enterprise of measuring the scale of the solar system in the eighteenth century. The site of the conference was the Nordnorsk Vitensenter (Science Centre of Northern Norway), which is located at the campus of the University of Tromsoe. After the conference, participants were invited to either stay in Tromsoe until the midnight of 5-6 June, or take part in a Venus transit voyage in Finnmark, during which the historical sites Vardoe, Hammerfest, and the North Cape were to be visited. The post-conference program culminated with the participants observing the transit of Venus in or near Tromsoe, Vardoe and even from a plane near Alta. These Proceedings contain a selection of the lectures delivered on 2-3 June 2012, and also a narrative description of the transit viewing from Tromsoe, Vardoe and Alta. The title of the book, Meeting Venus, refers the title of a play by the Hungarian film director, screenwriter and opera director Istvan Szabo (1938-). The autobiographical movie Meeting Venus (1991) directed by him is based on his experience directing Tannhauser at the Paris Opera in 1984. The movie brings the story of an imaginary international opera company that encounters a never ending series of difficulties and pitfalls that symbolise the challenges of any multicultural and international endeavour. As is evident from the many papers presented in this book, Meeting Venus not only contains the epic tales of the transits of the seventeenth, eighteenth and nineteenth centuries, it also covers the conference participants' encounter with "Venus on the Sun" in historical archives as well as face-to-face at several locations in the Troms and Finnmark counties.

  5. Plains Tectonics on Venus

    Science.gov (United States)

    Banerdt, W. B.; McGill, G. E.; Zuber, M. T.

    1996-01-01

    Tectonic deformation in the plains of Venus is pervasive, with virtually every area of the planet showing evidence for faulting or fracturing. This deformation can be classified into three general categories, defined by the intensity and areal extent of the surface deformation: distributed deformation, concentrated deformation, and local fracture patterns.

  6. Transit of Venus

    Science.gov (United States)

    The Transit of Venus is similar to a solar eclipse, where -- from the perspective on Earth -- Venus passes in front of the Sun. This event does not happen very often. In fact, no one alive today has experienced this phenomenon, which will take place on June 8 and will be visible for most of Europe, Asia, and Africa.First, the Armagh Planetarium created a great, expansive informational site all about the Transit of Venus (1). Users can find basic facts, observing information, histories of past transits, and much more. Next, the European Southern Observatory presents the VT-2004 project's aim to gain knowledge and encourage public interest in the event (2). Users can observe Venus's progression towards the transit with the daily images from April 17, 2004 to present news updates. Educators can discover transit-related activities and educational materials. The third site, created by NASA, discusses the details of the Sun-Earth Connection Education Forum and San Francisco's Exploratorium's live webcast of the Transit (3). The site supplies enjoyable, educational materials for students, educators, museums, scientists, and amateur astronomers. The next site, also created by NASA, provides an introduction to the Venus Transits that will take place June 2004 and 2012 (4). Visitors can find helpful figures and text about the geographic visibility of the events. The site offers an observer's handbook as well as a discussion about the predictions of the event. Next, Professor Backhaus presents a project where schools, amateur astronomers, and universities will collaborate to gather transit data and learn about observing (5). Users can discover the six parts of the project as well as learn how to participate in the worldwide endeavor. The sixth site also discusses a Venus Transit project (6). Endorsed by the Astronomical Association of Zurich, this project's goals are to process data collected by amateur astronomers by different observation methods, to act as a data exchange center, and to determine the astronomical unit. Next, the Exploratorium furnishes general information about the Transit, its history, how viewers observe it, what it looks like, and why it is an important event (7). Users can find out about the live webcast that will begin on June 7, 2004 from Athens, Greece. Educators can find student activities developed to integrate discussions into the classroom. Lastly, Willie Koorts, an employee at the South African Astronomical Observatory, recounts the observations of scientists in Africa of the last transit of Venus (8). The site contains many historical photographs along with informational diagrams and figures.

  7. Aeolian processes on Venus

    International Nuclear Information System (INIS)

    This review assesses the potential aeolian regime on Venus as derived from spacecraft observations, laboratory simulations, and theoretical considerations. The two requirements for aeolian processes (a supply of small, loose particles and winds of sufficient strength to move them) appear to be met on Venus. Venera 9, 10, 13, and 14 images show particles considered to be sand and silt size on the surface. In addition, dust spurts (grains 5 to 50 microns in diameter) observed via lander images and inferred from the Pioneer-Venus nephalometer experiments suggest that the particles are loose and subject to movement. Although data on near surface winds are limited, measurements of 0.3 to 1.2 m/sec from the Venera lander and Pioneer-Venus probes appear to be well within the range required for sand and dust entrainment. Aeolian activity involves the interaction of the atmosphere, lithosphere, and loose particles. Thus, there is the potential for various physical and chemical weathering processes that can effect not only rates of erosion, but changes in the composition of all three components. The Venus Simulator is an apparatus used to simulate weathering under venusian conditions at full pressure (to 112 bars) and temperature (to 800 K). In one series of tests, the physical modifications of windblown particles and rock targets were assessed and it was shown that particles become abraded even when moved by gentle winds. However, little abrasion occurs on the target faces. Thle abrasion occurs on the target faces. Thus, compositional signatures for target rocks may be more indicative of the windblown particles than of the bedrock. From these and other considerations, aeolian modifications of the venusian surface may be expected to occur as weathering, erosion, transportation, and deposition of surficial materials. Depending upon global and local wind regimes, there may be distinctive sources and sinks of windblown materials

  8. Transit Observations of Venus's Atmosphere in 2012 from Terrestrial and Space Telescopes as Exoplanet Analogs

    Science.gov (United States)

    Pasachoff, Jay M.; Schneider, G.; Babcock, B. A.; Lu, M.; Penn, M. J.; Jaeggli, S. A.; Galayda, E.; Reardon, K. P.; Widemann, T.; Tanga, P.; Ehrenreich, D.; Vidal-Madjar, A.; Nicholson, P. D.; Dantowitz, R.

    2013-06-01

    We extensively observed the 8 June 2012 transit of Venus from several sites on Earth; we provide this interim status report about this and about two subsequent ToVs observed from space. From Haleakala Obs., we observed the entire June transit over almost 7 h with a coronagraph of the Venus Twilight Experiment B filter) and with a RED Epic camera to compare with simultaneous data from ESA's Venus Express, to study the Cytherean mesosphere; from Kitt Peak, we have near-IR spectropolarimetry at 1.6 µm from the aureole and during the disk crossing that compare well with carbon dioxide spectral models; from Sac Peak/IBIS we have high-resolution imaging of the Cytherean aureole for 22 min, starting even before 1st contact; from Big Bear, we have high-resolution imaging of Venus's atmosphere and the black-drop effect through 2nd contact; and we had 8 other coronagraphs around the world. For the Sept 21 ToV as seen from Jupiter, we had 14 orbits of HST to use Jupiter's clouds as a reflecting surface to search for an 0.01% diminution in light and a differential drop that would result from Venus's atmosphere by observing in both IR/UV, for which we have 170 HST exposures. As of this writing, preliminary data reduction indicates that variations in Jovian clouds and the two periods of Jupiter's rotation will be too great to allow extraction of the transit signal. For the December 20 ToV as seen from Saturn, we had 22 hours of observing time with VIMS on Cassini, for which we are looking for a signal of the 10-hr transit in total solar irradiance and of Venus's atmosphere in IR as an exoplanet-transit analog. Our Maui & Sac Peak expedition was sponsored by National Geographic Society's Committee for Research and Exploration; HST data reduction by NASA: HST-GO-13067. Some of the funds for the carbon dioxide filter for Sac Peak provided by NASA through AAS's Small Research Grant Program. We thank Rob Ratkowski of Haleakala Amateur Astronomers; Rob Lucas, Aram Friedman, Eric Pilger, Stan Truitt, and Steve Bisque/Software Bisque for Haleakala support/operations; Vasyl Yurchyshyn and Joseph Gangestad '06 of The Aerospace Corp. at Big Bear Solar Obs; LMSAL and Hinode science/operations team.

  9. Cosmic Art: Artistic Expressions of the Universe in Science

    Science.gov (United States)

    Papacosta, P.

    2013-04-01

    Students in some of the science classes at Columbia College Chicago are encouraged to use their artistic talents to express their fascination with, understanding of, or sense of mystery about the cosmos. These creative expressions have numerous educational benefits that reinforce the learning process. Furthermore, this type of assignment often improves the students' attitude towards science, instilling in them a life-long interest for learning. These projects also break down barriers between the disciplines, particularly those of science and art. In this paper, I describe the pedagogy and benefits of the art/science partnership in my science classes with examples of student artworks that depict cosmic phenomena.

  10. On the Frequency of Potential Venus Analogs from Kepler Data

    Science.gov (United States)

    Kane, Stephen R.; Kopparapu, Ravi Kumar; Domagal-Goldman, Shawn D.

    2014-10-01

    The field of exoplanetary science has seen a dramatic improvement in sensitivity to terrestrial planets over recent years. Such discoveries have been a key feature of results from the Kepler mission which utilizes the transit method to determine the size of the planet. These discoveries have resulted in a corresponding interest in the topic of the Habitable Zone and the search for potential Earth analogs. Within the solar system, there is a clear dichotomy between Venus and Earth in terms of atmospheric evolution, likely the result of the large difference (approximately a factor of two) in incident flux from the Sun. Since Venus is 95% of the Earth's radius in size, it is impossible to distinguish between these two planets based only on size. In this Letter we discuss planetary insolation in the context of atmospheric erosion and runaway greenhouse limits for planets similar to Venus. We define a "Venus Zone" in which the planet is more likely to be a Venus analog rather than an Earth analog. We identify 43 potential Venus analogs with an occurrence rate (??) of 0.32^{+0.05}_{-0.07} and 0.45^{+0.06}_{-0.09} for M dwarfs and GK dwarfs, respectively.

  11. Innovative Seismological Techniques for Investigating the Interior Structure of Venus

    Science.gov (United States)

    Stevenson, D. J.; Cutts, J. A.; Mimoun, D.

    2014-12-01

    The formation, evolution and structure of Venus remain a mystery more than fifty years after the first visit by a robotic spacecraft. Radar images have revealed a surface that is much younger than those of the Moon, Mercury and Mars as well as a variety of enigmatic volcanic and tectonic features quite unlike those generated by plate tectonics on Earth. To understand how Venus works as a planet it is necessary to probe the interior of Venus. To accomplish this seismology must play a key role. Conventional seismology employs sensors in contact with the planetary surface but for Venus theses sensors must tolerate the Venus environment (460oC and 90 bars) for up to a year. The dense atmosphere of Venus, which efficiently couples seismic energy into the atmosphere as infrasonic waves, enables an alternative: detection of infrasonic waves in the upper atmosphere using either high altitude balloons or orbiting spacecraft. In June 2014, the Keck Institute for Space Studies (KISS) at the California Institute of Technology sponsored a one week workshop with 30 specialists in the key techniques and technologies that can bring these technique to readiness. In this paper, we describe the key synergies with earth science drawing on methods from terrestrial seismology and oceanography and identify key technical issues that need to be solved as well as important precursor measurements that should be made.

  12. ON THE FREQUENCY OF POTENTIAL VENUS ANALOGS FROM KEPLER DATA

    International Nuclear Information System (INIS)

    The field of exoplanetary science has seen a dramatic improvement in sensitivity to terrestrial planets over recent years. Such discoveries have been a key feature of results from the Kepler mission which utilizes the transit method to determine the size of the planet. These discoveries have resulted in a corresponding interest in the topic of the Habitable Zone and the search for potential Earth analogs. Within the solar system, there is a clear dichotomy between Venus and Earth in terms of atmospheric evolution, likely the result of the large difference (approximately a factor of two) in incident flux from the Sun. Since Venus is 95% of the Earth's radius in size, it is impossible to distinguish between these two planets based only on size. In this Letter we discuss planetary insolation in the context of atmospheric erosion and runaway greenhouse limits for planets similar to Venus. We define a ''Venus Zone'' in which the planet is more likely to be a Venus analog rather than an Earth analog. We identify 43 potential Venus analogs with an occurrence rate (??) of 0.32?0.07+0.05 and 0.45?0.09+0.06 for M dwarfs and GK dwarfs, respectively

  13. (abstract) Venus Gravity Field

    Science.gov (United States)

    Konopliv, A. S.; Sjogren, W. L.

    1995-01-01

    A global gravity field model of Venus to degree and order 75 (5772 spherical harmonic coefficients) has been estimated from Doppler radio tracking of the orbiting spacecraft Pioneer Venus Orbiter (1979-1992) and Magellan (1990-1994). After the successful aerobraking of Magellan, a near circular polar orbit was attained and relatively uniform gravity field resolution (approximately 200 km) was obtained with formal uncertainties of a few milligals. Detailed gravity for several highland features are displayed as gravity contours overlaying colored topography. The positive correlation of typography with gravity is very high being unlike that of the Earth, Moon, and Mars. The amplitudes are Earth-like, but have significantly different gravity-topography ratios for different features. Global gravity, geoid, and isostatic anomaly maps as well as the admittance function are displayed.

  14. Sun-Earth Day 2004: Transit of Venus

    Science.gov (United States)

    2004-02-01

    On June 8th, 2004 a celestial event of historical scientific importance occured when the silhouette of the planet Venus crossed the face of the Sun as seen from the Earth. This event, known as the transit of Venus, last occurred in 1882. Through parallax measurements, it allowed astronomers to define, for the first time, a fairly accurate number for the A.U. and therefore, the distance to all the other known planets. This article describes resources that science teachers can use to enhance their classroom teaching by incorporating this spectacular event into their science curriculum.

  15. Spectral analysis of the solar wind turbulence in the vicinity of Venus

    Science.gov (United States)

    Teodorescu, Eliza; Echim, Marius; Munteanu, Costel; Voitcu, Gabriel; Zhang, Tielong; Barabash, Stanislav; Budnik, Elena; Fedorov, Andrei

    2014-05-01

    In this study we analyze magnetic field data provided by Venus Express (VEX) between 2007 and 2008. During each of the probe's eccentric polar orbit around Venus, VEX performs plasma and magnetic field measurements in the environment around the planet both in Venus induced magnetosphere and in the solar wind at several tens of thousands of kilometers away from the magnetosphere. This latter data set has a unique scientific value as it provides observations of magnetic turbulence in the solar wind around 0.72 AU, in the vicinity of Venus. We discuss a semi-automated method to select solar wind magnetic field data at 1 Hz from Venus Express Magnetometer (MAG) data by using plasma data from the Analyser of Space Plasma and Energetic Atoms (ASPERA). The time intervals when VEX is in the solar wind are automatically determined for 2007 and 2008. We apply a Fourier transform on the selected data and calculate the power spectral densities (PSD) of the turbulent magnetic field through Welch's algorithm. We compute the PSD of the three components of the magnetic field for the time intervals when both MAG and ASPERA were operating in the solar wind, for each VEX orbit between 1st of January 2007 and 31st of December 2008. The data base includes a number of 374 individual spectra. We discuss the spectral properties of turbulence and illustrate similarities between fast and slow wind during the minimum phase of the solar cycle for each of VEX's orbit which satisfies the selection criteria for a period of two years. Research supported by the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement no 313038/STORM, and a grant of the Romanian Ministry of National Education, CNCS - UEFISCDI, project number PN-II-ID-PCE-2012-4-0418. Data analysis was done with the AMDA science analysis system provided by the Centre de Données de la Physique des Plasmas (IRAP, Université Paul Sabatier, Toulouse) supported by CNRS and CNES.

  16. The VENUS detector at TRISTAN

    International Nuclear Information System (INIS)

    The design of the VENUS detector is described. In this paper, emphasis is placed on the central tracking chamber and the electromagnetic shower calorimeters. Referring to computer simulations and test measurements with prototypes, the expected performance of our detector system is discussed. The contents are, for the most part, taken from the VENUS proposal /2/. (author)

  17. Pioneer Venus gas chromatography of the lower atmosphere of Venus

    International Nuclear Information System (INIS)

    A gas chromatograph mounted in the Pioneer Venus sounder probe measured the chemical composition of the atmosphere of Venus at three altitudes. Ne, N2, O2, Ar, CO, H2O, SO2, and CO2 were measured, and upper limits set for H2, COS, H2S, CH4, Kr, N2O, C2H4, C2H6, and C3H8. Simulation studies have provided indirect evidence for sulfuric acid--like droplets and support the possibility of water vapor at altitudes of 42 and 24 km. The paper discusses the implications of these results for the origin, evolution, and present state of Venus' atmosphere

  18. To Venus with spare parts

    Science.gov (United States)

    Bell, Peter M.

    The Jet Propulsion Laboratory (JPL) is studying the possibilities of developing a special spacecraft to fly to Venus to replace the more costly Venus Orbiting Imaging Radar (VOIR) mission. According to a recent JPL Newsletter, the new Venus Radar Mapper (VRM) spacecraft is to be constructed mainly of spare parts left over from other missions. The VRM is to be landed in the spring of 1988 by means of either the space shuttle/ two-stage inertial upper-stage (IUS) combination or, preferably, with the much more powerful shuttle/Centaur upper-stage rocket. Once boosted into orbit around Venus, the scientific objections of VRM are clear. Venus has about the same mass and composition as the earth, and yet little is known about its geology. It will be possible for the VRM to map Venus by radar from an elliptical orbit, which is a lower cost option than would have been possible with the VOIR. VRM will carry a synthetic aperture radar (SAR) that operates with variable angles ranging from 51° for the lowest altitudes (250 km) to 24° for the highest altitudes (1900 km). A total of about 92% of Venus' surface will be mapped at a resolution of 1 km/line or better.

  19. The transit of Venus enterprise in Victorian Britain

    CERN Document Server

    Ratcliff, Jessica

    2008-01-01

    In nineteenth century, the British Government spent money measuring the distance between the earth and the sun using observations of the transit of Venus. This book presents a narrative of the two Victorian transit programmes. It draws out their cultural significance and explores the nature of 'big science' in late-Victorian Britain.

  20. Venus - Atmospheric rotation.

    Science.gov (United States)

    Scott, A. H.; Reese, E. J.

    1972-01-01

    Photographs of Venus taken in ultraviolet light from Sept. 29, 1963, to May 29, 1971, indicate a general planet-wide circulation in the upper atmosphere of that planet having velocities which varied with time from -87 to -127m/sec at the equator. Positional measurements on 67 pairs of photographs which show the recurrence of similar patterns after intervals of one to three rotations suggest an asymmetric bimodal distribution of these velocities. The ultraviolet markings appear to be randomly distributed and quite ephemeral in nature, rarely enduring in a recognizable pattern for more than 20 days and usually much less. Attention is directed to an apparent but fictitious mean sidereal rotation period of approximately 4.06 days derived from observations which are made at a single station and span many months or years. Under such conditions this fictitious value for the rotation period is produced by the commensurability of the one-day period of earth and the assumed four-day period of the atmosphere of Venus.

  1. The Venus Zone: Seeking the Twin of Earth's Twin

    Science.gov (United States)

    Kane, Stephen R.; Kopparapu, Ravi Kumar; Domagal-Goldman, Shawn

    2015-01-01

    The field of exoplanetary science has seen a dramatic improvement in sensitivity to terrestrial planets over recent years. Such discoveries have been a key feature of results from the Kepler mission which utilizes the transit method to determine the size of the planet. These discoveries have resulted in a corresponding interest in the topic of the Habitable Zone (HZ) and the search for potential Earth analogs. Within the Solar System, there is a clear dichotomy between Venus and Earth in terms of atmospheric evolution, likely the result of the large difference in incident flux from the Sun. Since Venus is 95% of the Earth's radius in size, it is impossible to distinguish between these two planets based only on size. In this talk I will discuss planetary insolation in the context of atmospheric erosion and runaway greenhouse limits for planets similar to Venus. Using the ``Venus Zone'' (VZ), I will present identified potential Venus analogs from Kepler data and subsequent occurance rates of such planets.

  2. On the Frequency of Potential Venus Analogs from Kepler Data

    CERN Document Server

    Kane, Stephen R; Domagal-Goldman, Shawn D

    2014-01-01

    The field of exoplanetary science has seen a dramatic improvement in sensitivity to terrestrial planets over recent years. Such discoveries have been a key feature of results from the {\\it Kepler} mission which utilizes the transit method to determine the size of the planet. These discoveries have resulted in a corresponding interest in the topic of the Habitable Zone (HZ) and the search for potential Earth analogs. Within the Solar System, there is a clear dichotomy between Venus and Earth in terms of atmospheric evolution, likely the result of the large difference ($\\sim$ factor of two) in incident flux from the Sun. Since Venus is 95\\% of the Earth's radius in size, it is impossible to distinguish between these two planets based only on size. In this paper we discuss planetary insolation in the context of atmospheric erosion and runaway greenhouse limits for planets similar to Venus. We define a ``Venus Zone'' (VZ) in which the planet is more likely to be a Venus analog rather than an Earth analog. We iden...

  3. Hinode SOT Plate Scale Reinvestigated by G-Band Images on the 2012 Transit of Venus

    Science.gov (United States)

    Kanao, M.; Shimizu, T.; Imamura, T.; Nakamura, M.

    2015-05-01

    The Hinode Solar Optical Telescope (SOT) successfully observed the transit of Venus with an unprecedented high spatial resolution on 5 - 6 June 2012, providing images of the aureole refracted by the atmosphere of Venus and the dark Venus disk against the bright solar surface. The transit of Venus provided a unique opportunity for calibrating the plate scale of SOT images. With the examination of the radius of the dark Venus disk, we determined the plate scale of G-band 430.5 nm images with high accuracy: 0.05369±0.00005 arcsec pixel-1. The radius was defined at the intensity level of the 0.5 transmittance and compared with the angular radius of Venus including the thickness of the atmosphere determined with the measurements of SPICAV onboard Venus Express. Thanks to the high spatial resolution, SOT images show that the dark Venus can be well represented by an ellipse. We observed 7.6 km difference in altitude between the equator and the polar regions.

  4. Venus näitas lillekleite / Regina Hansen

    Index Scriptorium Estoniae

    Hansen, Regina

    2001-01-01

    Sunflower Beauty Contest esitles ööklubis Venus eluslilledest valmistatud kleite. Parimaks tunnistati kaupluse Annilill floristid tööga "My Bunny", teiseks tunnistati Katrin Pedaru ja Ninell Soosaare "C'est la vie", kolmanda koha pälvis Karina Saberi töö "Unistus"

  5. Decadal variations in a Venus general circulation model

    Science.gov (United States)

    Parish, Helen F.; Schubert, Gerald; Covey, Curtis; Walterscheid, Richard L.; Grossman, Allen; Lebonnois, Sebastien

    2011-03-01

    The Community Atmosphere Model (CAM), a 3-dimensional Earth-based climate model, has been modified to simulate the dynamics of the Venus atmosphere. The most current finite volume version of CAM is used with Earth-related processes removed, parameters appropriate for Venus introduced, and some basic physics approximations adopted. A simplified Newtonian cooling approximation has been used for the radiation scheme. We use a high resolution (1° by 1° in latitude and longitude) to take account of small-scale dynamical processes that might be important on Venus. A Rayleigh friction approach is used at the lower boundary to represent surface drag, and a similar approach is implemented in the uppermost few model levels providing a ‘sponge layer’ to prevent wave reflection from the upper boundary. The simulations generate superrotation with wind velocities comparable to those measured in the Venus atmosphere by probes and around 50-60% of those measured by cloud tracking. At cloud heights and above the atmosphere is always superrotating with mid-latitude zonal jets that wax and wane on an approximate 10 year cycle. However, below the clouds, the zonal winds vary periodically on a decadal timescale between superrotation and subrotation. Both subrotating and superrotating mid-latitude jets are found in the approximate 40-60 km altitude range. The growth and decay of the sub-cloud level jets also occur on the decadal timescale. Though subrotating zonal winds are found below the clouds, the total angular momentum of the atmosphere is always in the sense of superrotation. The global relative angular momentum of the atmosphere oscillates with an amplitude of about 5% on the approximate 10 year timescale. Symmetric instability in the near surface equatorial atmosphere might be the source of the decadal oscillation in the atmospheric state. Analyses of angular momentum transport show that all the jets are built up by poleward transport by a meridional circulation while angular momentum is redistributed to lower latitudes primarily by transient eddies. Possible changes in the structure of Venus’ cloud level mid-latitude jets measured by Mariner 10, Pioneer Venus, and Venus Express suggest that a cyclic variation similar to that found in the model might occur in the real Venus atmosphere, although no subrotating winds below the cloud level have been observed to date. Venus’ atmosphere must be observed over multi-year timescales and below the clouds if we are to understand its dynamics.

  6. Crustal deformation: Earth vs Venus

    Science.gov (United States)

    Turcotte, D. L.

    1989-01-01

    It is timely to consider the possible tectonic regimes on Venus both in terms of what is known about Venus and in terms of deformation mechanisms operative on the earth. Plate tectonic phenomena dominate tectonics on the earth. Horizontal displacements are associated with the creation of new crust at ridges and destruction of crust at trenches. The presence of plate tectonics on Venus is debated, but there is certainly no evidence for the trenches associated with subduction on the earth. An essential question is what kind of tectonics can be expected if there is no plate tectonics on Venus. Mars and the Moon are reference examples. Volcanic constructs appear to play a dominant role on Mars but their role on Venus is not clear. On single plate planets and satellites, tectonic structures are often associated with thermal stresses. Cooling of a planet leads to thermal contraction and surface compressive features. Delamination has been propsed for Venus by several authors. Delamination is associated with the subduction of the mantle lithosphere and possibly the lower crust but not the upper crust. The surface manifestations of delamination are unclear. There is some evidence that delamination is occurring beneath the Transverse Ranges in California. Delamination will certainly lead to lithospheric thinning and is likely to lead to uplift and crustal thinning.

  7. NASA CONNECT: Venus Transit

    Science.gov (United States)

    2004-01-01

    In this program, students learn about the importance of using scale models to represent the size and distance of objects in the Solar System and beyond. They are introduced to the astronomical unit (AU), the baseline distance from the Earth to the Sun, which astronomers use to determine the relative distances from Earth to other planets, stars, asteroids, and objects in space. They also discover facts about the Venus Transit, a celestial and historical event, which helped astronomers determine the scale of the Solar System. Students use measurement, ratios, and graphing to construct a model of the solar system and determine the relationship of each planet to the Sun. They will explore the scales needed to represent the size of the planets and the distances to the Sun.

  8. Clouds and aerosols on Venus: an overview

    Science.gov (United States)

    Titov, Dmitri; Ignatiev, Nikolay; McGouldrick, Kevin; Wilquet, Valerie; Wilson, Colin

    2015-04-01

    The past decade demonstrated significant progress in understanding of the Venus cloud system. Venus Express observations revealed significant latitudinal variations and temporal changes in the global cloud top morphology. The cloud top altitude varies from ~72 km in the low and middle latitudes to ~64 km in the polar region, correlated with decrease of the aerosol scale height from 4 ± 1.6 km to 1.7 ± 2.4 km marking a vast polar depression. The UV imaging shows the middle latitudes and polar regions in unprecedented detail. The eye of the Southern polar vortex was found to be a strongly variable feature with complex morphology and dynamics. Solar and stellar occultations give access to a vertical profiling of the light absorption by the aerosols in the upper haze. The aerosol loading in the mesosphere of Venus investigated by SPICAV experiment onboard Venus Express between 2006 and 2010 was highly variable on both short and long time scales. The extinction at a given altitude can vary with a factor of 10 for occultations separated by a few Earth days. The extinction at a given altitude is also significantly lower towards the poles (by a factor 10 at least) compared to the values around the equator, while there is apparently no correlation between the extinction and the latitude in the region comprised between ±40° around the equator. Based on the Mie theory and on the observed spectral dependence of light extinction in spectra recorded simultaneously in the UV (SPICAV-UV), in the near IR (SPICAV-IR), and in the short-and mid-wavelength IR (SPICAV-SOIR), the size distribution of aerosols in the upper haze of Venus was retrieved, assuming H2SO4/water composition of the droplets. The optical model includes H2SO4 concentrations from 60% to 85%. A number of results are strikingly new: (1) an increase of the H2SO4 concentration with a decreasing altitude (from 70-75% at about 90 km to 85% at 70 km of altitude) and (2) Many SOIR/SPICAV data cannot be fitted when using size distributions found in the literature, with an effective radius below 0.3 ?m and a variance of about 2. The scale height of the upper haze is found to be 6.9 ± 5.1 km. The lower and middle cloud layers - those at 48 - 60 km altitudes - are difficult to observe, as they are hidden by upper clouds. Nevertheless, both nightside near-IR sounding and radio occultation has provided valuable insight into cloud processes in this region. Near IR sounding reveals the morphology of the lower/middle clouds 'backlit' by thermally emitted photons from the lower atmosphere. The morphology of these clouds changes on timescales of order of 24 hours. The vertically integrated cloud optical depth is twice as great in the polar collar (at 75 degrees latitude) compared to low latitudes. Spectral band ratio analysis, if interpreted strictly in terms of Mode 1 / 2 / 2' / 3 particles of H2SO4:H2O mixtures, suggests that the acidity of the cloud particles is higher near the polar collar and in regions of optically thick cloud. Particles in the centre of the polar vortex exhibit anomalously high band ratios so are significantly larger and/or of different composition than those at low latitudes. Radio occultation from Venus Express confirms that the atmosphere is in convective equilibrium from 50-60 km. Sulphuric acid vapour profiles calculated from the absorption of the radio signals show an atmosphere saturated with sulphuric acid in the cloud layer. Both of these results are consistent with the understanding of convective condensational cloud at altitudes of 50-60 km. Microphysical simulations of the aerosol populations in the atmosphere of Venus have received a boost from the recent exploration of particle properties carried out by various teams using Venus Express over the last decade or so. Numerous groups are applying separate models to the coupled problems of the Venus clouds. Quasi-periodic variability of aerosol population properties has been found in model simulations by several groups under both forced and unforced conditions. Since the clouds play such a significant

  9. Venus-13, Venus-14: mass-spectrometry of the atmosphere

    International Nuclear Information System (INIS)

    Mass spectrometric measurements of the Venus atmosphere composition are carried out using the radio-frequency mass-spectrometer installed on ''Venera-13'' and ''Venera-14'' apparatusus. Isotopic composition of neon (20Ne/22Ne) in Venus atmosphere differs from neon composition in the Earth atmosphere and in solar wind. Measurements carried out using ''Venera-13'' and ''Venera-14'' give magnitudes of nitrogen concentration which are in agreement with known measurements. The total concentration of three argon concentration with mass numbers of 36, 38 and 40 are in good agreement with the data obtained on ''Venera-11'' and ''Venera-12'' satellites. A magnitude of carbon isotopic ratio 13C/12C comes to agreement with a magnitude of isotopic ratio for the Earth atmosphere. Preliminary data on krypton 84, xenon 131, and xenon 132 concentrations in Venus atmosphere are presented

  10. Venus - 'Transitional' Crater

    Science.gov (United States)

    1991-01-01

    During orbits 423 through 424 on 22 September 1990, Magellan imaged this impact crater that is located at latitude 10.7 degrees north and longitude 340.7 degrees east. This crater is shown as a representative of Venusian craters that are of the proper diameter (about 15 kilometers) to be 'transitional' in their morphology between 'complex' and irregular' craters. Complex craters account for about 96 percent of all craters on Venus with diameters larger than about 15 kilometers; they are thought to have been formed by the impact of a large, more or less intact, mass of asteroidal material that has not been excessively effected during its passage through the dense Venusian atmosphere. Complex craters are characterized by circular rims, terraced inner wall slopes, well developed ejecta deposits, and flat floors with a central peak or peak ring. Irregular craters make up about 60 percent of the craters with diameters less than about 15 kilometers. Irregular craters are thought to form as the result of the impact of asteroidal projectiles that have been aerodynamically crushed and fragmented during their passage through the atmosphere. Irregular craters are characterized by irregular and/or discontinuous rims and hummocky or multiple floors. The 'transitional' crater shown here has a somewhat circular rim like larger complex craters, but has the hummocky floor and asymmetric ejecta characteristic of smaller irregular craters.

  11. Venus - Rhea Mons Volcano

    Science.gov (United States)

    1990-01-01

    Two mosaiced pieces of Magellan image strips display the area east of the Rhea Mons volcano on Venus. This image is centered at about 32.5 degrees north latitude and 286.6 degrees east longitude. The mosaic is 47 kilometers (28 miles) wide and 135 km (81 miles) long. This region has been previously identified as 'tessera' from Earth-based radar (Arecibo) images. The center of the image is dominated by a network of intersecting ridges and valleys. The radar bright north south trending features in this image range from 1 km (0.6 mile) to 3 km (1.8 miles) in length. The average spacing between these ridges is about 1.5 km (0.9 mile). The dark patches at the top of the image are smooth surfaces and may be lava flows located in lowlands between the higher ridge and the valley terrain. This image is a mosaic of two orbits obtained in the first Magellan radar test and played back to Earth to the Deep Space Network stations near Goldstone, Calif. and Canberra, Australia, respectively. The resolution of this image is approximately 120 meters (400 feet).

  12. Clouds of Venus. Input to VIRA.

    Science.gov (United States)

    Ignatiev, Nikolay; Zasova, Ludmila

    2012-07-01

    Venus is completely covered by a thick clod deck. Its' total optical depth in the visible is equal to 30+/-10. Original VIRA model based on the measurements from Pioneer Venus descent probes and orbiter described mainly cloud particle sizes, properties and their vertical distribution. Later measurements from Venera-15 and Venus Express permitted more detailed studies of horizontal and vertical variations. Imaging of Venus in the UV range shows variety of cloud features that include mottled and streaky clouds in the low latitudes, bright mid-latitude belt and ``polar cap'' with imbedded oval polar dipole. Despite this non-uniform picture the location of the upper boundary of the clouds, derived from the observation of the absorption bands in the reflected IR spectrum, demonstrates a smooth systematic behavior with the latitudinal trends symmetric with respect to equator. In low and middle latitudes the cloud top is located at 72+/-1 km. It decreases poleward of +/-50 degrees and reaches 63--69 km in polar regions. This depression coincides with the eye of the planetary vortex. The effective average particle size radius is equal to (1.3+/-0.5) micron at latitudes of 0--70, with a peak value some 50% larger in the polar regions. Cloud top can experience fast variations of about metricconverterProductID1 km1 km in tens of hours, while larger long-term variations of several kilometers have been observed only at high latitudes. UV markings correlate with the cloud altimetry, however the difference between adjacent UV dark and bright regions never exceeds few hundred meters. Ultraviolet dark spiral arms, which are often seen at about --70 degress, correspond to higher altitudes or to the regions with strong latitudinal gradient of the cloud top altitude. In contrast to the relatively uniform upper cloud boundary, strong variations of the brightness temperature at specific near infrared wavelengths, especially in low latitudes, are related to variations of the cloud thickness in the middle and low cloud decks consistent with significant convective activity at these levels. The morphology of the holes tends from highly variable orientations of features with aspect ratios of nearly one at low latitudes, to very large aspect ratios and zonally oriented features at higher latitudes.

  13. Spaceborne radar studies of Venus

    International Nuclear Information System (INIS)

    Data obtained from the Pioneer Venus radar mapper experiment are discussed. The mission was primarily developed to study the atmosphere of Venus. A highly eccentric orbit (eccentricity of 0.84, period of 24 h) was selected. The instrumentation has two operating modes: altimetry and imaging. Three parameters were measured for every radar spot size: altitude, surface roughness and radar reflectivity at a normal incidence. The measurements have been extended to a topographic map. The results suggest that the Beta region consists of two large shields and that the equatorial region is dominated by Aphrodite Terra. It also appears that the surface of Venus is very smooth and that it lacks great basins and the global plate tectonics present on earth

  14. Venus project : experimentation at ENEA's pilot site

    International Nuclear Information System (INIS)

    The document describes the ENEA's (Italian Agency for New Technologies, Energy and the Environment) experience in the Venus Project (Esprit III 6398). Venus is an advanced visual interface based on icon representation that permits to end-user to inquiry databases. VENUS interfaces to ENEA's databases: cometa materials Module, Cometa Laboratories Module and European Programs. This report contents the results of the experimentation and of the validation carried out in ENEA's related to the Venus generations. Moreover, the description of the architecture, the user requirements syntesis and the validation methodology of the VENUS systems have been included

  15. Transmission spectrum of Venus as a transiting exoplanet

    CERN Document Server

    Ehrenreich, David; Widemann, Thomas; Gronoff, Guillaume; Tanga, Paolo; Barthélemy, Mathieu; Lilensten, Jean; Etangs, Alain Lecavelier des; Arnold, Luc

    2011-01-01

    On 5-6 June 2012, Venus will be transiting the Sun for the last time before 2117. This event is an unique opportunity to assess the feasibility of the atmospheric characterisation of Earth-size exoplanets near the habitable zone with the transmission spectroscopy technique and provide an invaluable proxy for the atmosphere of such a planet. In this letter, we provide a theoretical transmission spectrum of the atmosphere of Venus that could be tested with spectroscopic observations during the 2012 transit. This is done using radiative transfer across Venus' atmosphere, with inputs from in-situ missions such as Venus Express and theoretical models. The transmission spectrum covers a range of 0.1-5 {\\mu}m and probes the limb between 70 and 150 km in altitude. It is dominated in UV by carbon dioxide absorption producing a broad transit signal of ~20 ppm as seen from Earth, and from 0.2 to 2.7 {\\mu}m by Mie extinction (~5 ppm at 0.8 {\\mu}m) caused by droplets of sulfuric acid composing an upper haze layer above th...

  16. A mantle plume model for the Equatorial Highlands of Venus

    Science.gov (United States)

    Kiefer, Walter S.; Hager, Bradford H.

    1991-01-01

    The possibility that the Equatorial Highlands are the surface expressions of hot upwelling mantle plumes is considered via a series of mantle plume models developed using a cylindrical axisymmetric finite element code and depth-dependent Newtonian rheology. The results are scaled by assuming whole mantle convection and that Venus and the earth have similar mantle heat flows. The best model fits are for Beta and Atla. The common feature of the allowed viscosity models is that they lack a pronounced low-viscosity zone in the upper mantle. The shape of Venus's long-wavelength admittance spectrum and the slope of its geoid spectrum are also consistent with the lack of a low-viscosity zone. It is argued that the lack of an asthenosphere on Venus is due to the mantle of Venus being drier than the earth's mantle. Mantle plumes may also have contributed to the formation of some smaller highland swells, such as the Bell and Eistla regions and the Hathor/Innini/Ushas region.

  17. Stability of the Venus ionopause

    International Nuclear Information System (INIS)

    One of the previously proposed mechanisms for the formation of magnetic ropes in the Venus ionosphere -breakup of the ionopause as a result of the development of the Kelvin-Helmholtz instability - is analyzed. Because the plasma flow in the transitional region is axisymmetric disturbances greater than 50 km in size (characteristic size of the magnetic ropes near the ionopause) are stable for zenith angles 0 ? 100. It was found that existing data, obtained on the American Pioneer-Venus space probe, also apparently indicate that the ionopause is stable for low dynamic solar-wind pressure

  18. Pancakelike domes on Venus

    Science.gov (United States)

    Mckenzie, Dan; Ford, Peter G.; Liu, Fang; Pettengill, Gordon H.

    1992-01-01

    The shape of seven large domes on the plains of Venus, with volumes between 100 and 1000 cu km, is compared with that of an axisymmetric gravity current spreading over a rigid horizontal surface. Both the altimetric profiles and the horizontal projection of the line of intersection of domes on the SAR images agree well with the theoretical similarity solution for a newtonian fluid, but not with the shape calculated for a rigid-plastic rheology, nor with that for a static model with a strong skin. As a viscous current spreads, it generates an isotropic strain rate tensor whose magnitude is independent of radius. Such a flow can account for the randomly oriented cracks that are uniformly distributed on the surface of the domes. The stress induced by the flow in the plains material below is obtained, and is probably large enough to produce the short radial cracks in the surface of the plains beyond the domes. The viscosity of the domes can be estimated from their thermal time constants if spreading is possible only when the fluid is hot, and lies between 10(exp 14) and 10(exp 17) Pa s. Laboratory experiments show that such viscosities correspond to temperatures of 610 - 690 C in dry rhyolitic magmas. These temperatures agree with laboratory measurements of the solidus temperature of wet rhyolite. These results show that the development of the domes can be understood using simple fluid dynamical ideas, and that the magmas involved can be produced by wet melting at depths below 10 km, followed by eruption and degassing.

  19. Abstracts for the Venus Geoscience Tutorial and Venus Geologic Mapping Workshop

    Science.gov (United States)

    1989-01-01

    Abstracts and tutorial are presented from the workshop. Representative titles are: Geology of Southern Guinevere Planitia, Venus, Based on Analyses of Goldstone Radar Data; Tessera Terrain: Characteristics and Models of Origin; Venus Volcanism; Rate Estimates from Laboratory Studies of Sulfur Gas-Solid Reactions; and A Morphologic Study of Venus Ridge Belts.

  20. Status and recent results from VENUS

    International Nuclear Information System (INIS)

    Status of the upgraded VENUS detector is presented along with the recent results from the physics analysis. Summarized in the former part of this talk is the upgrade of the VENUS detector since the last KEK Topical Conference on e+e- collision physics. The in-situ performance of the newly installed detector parts are also presented. In the latter, part, the physics results from VENUS, especially focused on the QCD studies are presented. (author)

  1. Radar observation of Venus' terrestrial analogues using TecSAR X-band SAR

    Science.gov (United States)

    Blumberg, D. G.

    2012-04-01

    Venus is shrouded in a dense CO2 atmosphere that prevents us from viewing the surface in visible light or with optronic sensors. Long wavelengths are required to 'see' through the dense atmosphere. In the early 1990s, the S-band synthetic aperture radar of the Magellan spacecraft acquired images of a variety of surface features on Venus, including morphologies attributed to wind processes. These include sand dunes, wind-sculpted hills (yardangs), and almost 6000 wind streaks. These aeolian landscapes were formed and shaped by near surface atmospheric circulation and local winds. These can serve as local markers, each providing an integrated wind direction. Since the Magellan mission, there were no missions to Venus until the Venus Express Mission of 2005 to examine the upper atmosphere. The future will probably include high-resolution SAR images of Venus. This poster will demonstrate high resolution SAR images in X-band from the TecSAR sensor launched by Israel in 2008. Observations of wind streaks, dunes and impact craters in desert areas will show the wealth of information that is extracted from high-res X-band data. Detailed images of Aurounga impact crater in Chad, Kelso dunes, California and Pisgah lava flow show immense detail of the morphologies associated with these features. These are compared with Magellan images of sites on Venus and SRL data in C and L-bands. The X-band provides extremely high resolution and resembles optical data much more than the longer wavelengths.

  2. Russia's contribution to regional geologic mapping of Venus

    Science.gov (United States)

    Burba, G. A.; Bobina, N. N.; Shashkina, V. P.

    1993-03-01

    Geologic maps in Magellan C1-format were produced by six geologists and three cartographer in Russia during 1992. More sheets are in progress. The work is coordinated by Vernadsky Institute. The Magellan SRR images in form of C1-format photomaps were used as a base for geologic-geomorphic regional mapping of Venus at approximately 1:8,000,000 scale. This work took place in Russia at Vernadsky Institute and at the Department of Geology, Lomonosov Moscow University. The aim is to produce a preliminary geologic survey of Venus with the new high resolution images obtained by Magellan. It took place at the cartographic division, Laboratory of Comparative Planetology and Meteoritics, Vernadsky Institute, Russsia's Academy of Sciences.

  3. Tectonism on Venus: A review

    International Nuclear Information System (INIS)

    Venus is more similar to Earth than to any other planet. It has elevated regions associated with marginal fold and thrust belts, fracture zones that extend tens of thousands of kilometers, crustal swells and shields that are hundreds of kilometers in diameter and 1 to 2 km high, and sublinear accumulations of volcanic cones and domes that stretch for thousands of kilometers across the plains. The Venusian surface is, however, distinctly different from Earth's in that: (1) its elevated terrains cannot be distinguished from its low plains on a hypsometric curve; (2) trenches have not been found plainsward of the marginal belts; (3) fracture zones bear no resemblance to mid-oceanic ridges; and (4) some features, such as the ridge-belt zone near 210 deg E, seem to have no terrestrial analog. Various theories about tectonism on Venus and Earth of other authors are reviewed

  4. Characteristics of Ionospheric Magnetic Flux Ropes on Venus

    Science.gov (United States)

    Steichen, Elise; McEnulty, T. R.; Molaverdikhani, K.; Brain, D.; Zhang, T.

    2013-10-01

    Because Venus has no intrinsic magnetic field, its atmosphere is more directly exposed to the solar wind than an atmosphere of a magnetized planet such as Earth. One observed consequence of this solar wind-atmosphere interaction is the presence of magnetic flux ropes, approximately cylindrical structures consisting of twisted magnetic field lines. The central region of a flux rope contains current that can transport charged particles and may therefore aid in atmospheric escape from Venus. Flux ropes in the ionosphere are observed more often during solar maximum periods, when increased photoionization creates an ionospheric thermal pressure sufficient to exclude the solar wind magnetic field. Despite the discovery of flux ropes more than 30 years ago and the availability of new observations since the arrival of Venus Express (VEX) in 2006, the formation mechanism for ionospheric flux ropes is still unresolved. We present the results of a manual survey of magnetic field data from the VEX magnetometer (MAG) for magnetic flux ropes, which present as localized peaks in magnetic field strength with field rotations consistent with flux rope geometry. We survey data from evenly spaced month-long time intervals from 2006 - 2012 to examine the effects of different stages of the solar cycle on flux rope properties such as location, half-length, and orientation relative to the planet. We present trends in the properties of observed flux ropes, how they are affected by the solar wind, and how they compare to previous results. This research is supported by a NASA Venus Express Supporting Investigator grant.

  5. Memristors in the Venus flytrap.

    Science.gov (United States)

    Volkov, Alexander G; Forde-Tuckett, Victoria; Reedus, Jada; Mitchell, Colee M; Volkova, Maya I; Markin, Vladislav S; Chua, Leon

    2014-05-16

    A memristor is a nonlinear element because its current-voltage characteristic is similar to that of a Lissajous pattern for nonlinear systems. We investigated the possible presence of memristors in the electrical circuitry of the Venus flytrap's upper and lower leaves. The electrostimulation of this plant by bipolar sinusoidal or triangle periodic waves induces electrical responses in the upper and lower leaves of the Venus flytrap with fingerprints of memristors. The analysis was based on cyclic voltammetric characteristics where the memristor, a resistor with memory, should manifest itself. Tetraethylammonium chloride, an inhibitor of voltage gated K(+) channels, or NPPB, a blocker of voltage gated Cl(-) and K(+) channels, transform a memristor to a resistor in plant tissue. Uncouplers carbonylcyanide-3-chlorophenylhydrazone (CCCP) and carbonylcyanide-4-trifluoromethoxy-phenyl hydrazone (FCCP) decrease the amplitude of electrical responses at low and high frequencies of bipolar periodic electrostimulating waves. Our results demonstrate that voltage gated K(+) channels in the Venus flytrap have properties of memristors of type 1 and type 2. The discovery of memristors in plants creates a new direction in the modeling and understanding of electrical phenomena in plants. PMID:24837439

  6. Venus Express - Status and major results

    Science.gov (United States)

    Svedhem, H.; Titov, D.

    2011-10-01

    Studies of the surface in the near infrared have shown several areas of recent geologic activity. These areas correspond well to the suspected 'hot spots' previously identified in the Magellan radar and gravity field maps. Recently the atmospheric density has been probed in situ by reducing the pericentre altitude such that the drag force on the spacecraft has become significant and thus measureable. In this way the altitude range 165-200 km, which is not possible to address with remote measurements, has been characterized. For the first time a new technique has been applied whereby the solar panels are set in an asymmetric position with respect to each other such that a torque is acting on the spacecraft during the atmospheric pass. Since the spacecraft attitude is maintained automatically be the reaction wheels the rotation rate changes of the wheels provide a very sensitive measure of the atmospheric density.

  7. ESA `Huygens and Mars Express' science highlights - call to press

    Science.gov (United States)

    2005-11-01

    Almost one year has passed since ESA’s Huygens probe landed on Saturn’s largest moon, Titan. Today, a set of new wide-ranging results from the probe’s two-and-a-half hour descent and landing, part of the extraordinary NASA/ESA/ASI Cassini-Huygens mission to Saturn and its moons, is ready for release. At the same time, ESA’s Mars Express mission is continuing its investigations of Mars, painting a new picture of the 'red planet'. This includes the first ever probing below the surface of Mars, new geological clues with implications for the climate, newly-discovered surface and atmospheric features and, above all, traces of the presence of water on this world. These and other exciting findings from just one year of observations and data analysis - in the context of ESA’s overall scientific achievements - will be the focus of a press conference to be held at ESA Headquarters in Paris at 16:00 on 30 November 2005. Media interested in attending are invited to complete the following registration form. Press conference programme Space Science Highlights 2005 From Huygens to Mars Express 30 November 2005, 16:00 hrs Room 137, European Space Agency Headquarters 8-10 Rue Mario-Nikis, F-75738 Paris Cedex, France 15:30 - Registration 16:00 - A Year of European Space Science Successes Prof. David Southwood, ESA Director of Science Programme 16:10 - Highlights of the Huygens Mission Results Jean-Pierre Lebreton, ESA Huygens Project Scientist 16:15 - Robin Duttaroy, Co-Investigator, Doppler Wind Experiment, University of Bonn, Germany 16:20 - Marcello Fulchignoni , Principal Investigator, Huygens Atmospheric Structure Instrument, Université de Paris 7, France 16:25 - John Zarnecki, Principal Investigator, Surface Science Package, Open University, UK 16:30 - François Raulin, Co-Investigator, Gas Chromatograph Mass Spectrometer, Université de Paris 12 - Créteil, France 16:35 - Guy Israel, Principal Investigator, Aerosol Collector and Pyrolyser, Service d'Aéronomie/CNRS, France 16:40 - Bruno Bezard, Co-Investigator, Descent Imager/Spectral Radiometer, Laboratoire d'études spatiales et d'instrumentation en astrophysique, Observatoire de Paris, France 16:45 - Jonathan Lunine, Interdisciplinary Scientist, Titan surface-atmosphere interactions, LPL/U, Arizona (USA) and INAF/IFSI, Rome (Italy) 16:55 - Questions and AnswersV 17:05 - Coffee break 17:10 - Mars Express: results in the overall context of Martian science, Agustin Chicarro, ESA Mars Express Project Scientist 17:15 - Giovanni Picardi, MARSIS Radar Principal Investigator, University of Rome La Sapienza, Italy Jeffrey Plaut, MARSIS Co-Principal Investigator, NASA/JPL, USA 17:25 - Martin Pätzold, Mars Radio Science Experiment, Principal Investigator, Universität Koln, Cologne, Germany 17:30 - Jean-Pierre Bibring, OMEGA Principal Investigator, Institut d’Astrophysique spatiale, Orsay, France 17:40 - Gerhard Neukum, HRSC Camera Principal Investigator, Freie Universität Berlin, Germany 17:45 - Questions and Answers 17:55 - Interview opportunities

  8. Topic in Depth - Transit of Venus

    Science.gov (United States)

    The Transit of Venus is similar to a solar eclipse, where -- from the perspective on Earth -- Venus passes in front of the Sun. This event does not happen very often. In fact, no one alive had witnessed this phenomenon until June of 2004, and these sites detail that experience.

  9. Observations of quasi-perpendicular propagating electromagnetic waves near the ionopause current sheet of Venus

    Science.gov (United States)

    Wei, H. Y.; Russell, C. T.; Daniels, J. T. M.; Zhang, T. L.; Strangeway, R. J.; Luhmann, J. G.

    2012-05-01

    Due to the lack of an intrinsic magnetic field at Venus, the Venus ionosphere acts as the obstacle to the incoming solar wind flow. Induced currents flowing on the ionopause resist the penetration of the solar wind magnetic fields into the ionosphere. The Venus Express magnetometer occasionally observes plasma waves near the ionopause. These waves propagate quasi-perpendicularly to the background magnetic field, which are distinctively different from the lightning-generated whistler waves. Both case and statistical studies are performed on the Venus Express magnetometer data in 32 Hz and 128 Hz resolutions for these quasi-perpendicular propagating waves. These waves are found to be strongly associated with current sheets near the ionopause, either occurring at the center of a sharp current, or occurring at the edge of a current. The earlier Pioneer Venus Orbiter electric field observations also detected plasma waves associated with field-aligned currents near the ionopause region, and the wave studies in this paper are possibly the magnetic counterparts of those earlier observations. These waves could be generated from the free energy of currents at the ionopause and could lead to dissipation of those currents.

  10. Recent progress on the superconducting ion source VENUS.

    Science.gov (United States)

    Benitez, J Y; Franzen, K Y; Hodgkinson, A; Loew, T; Lyneis, C M; Phair, L; Saba, J; Strohmeier, M; Tarvainen, O

    2012-02-01

    The 28 GHz Ion Source VENUS (versatile ECR for nuclear science) is back in operation after the superconducting sextupole leads were repaired and a fourth cryocooler was added. VENUS serves as an R&D device to explore the limits of electron cyclotron resonance source performance at 28 GHz with its 10 kW gryotron and optimum magnetic fields and as an ion source to increase the capabilities of the 88-Inch Cyclotron both for nuclear physics research and applications. The development and testing of ovens and sputtering techniques cover a wide range of applications. Recent experiments on bismuth demonstrated stable operation at 300 e?A of Bi(31+), which is in the intensity range of interest for high performance heavy-ion drivers such as FRIB (Facility for Rare Isotope Beams). In addition, the space radiation effects testing program at the cyclotron relies on the production of a cocktail beam with many species produced simultaneously in the ion source and this can be done with a combination of gases, sputter probes, and an oven. These capabilities are being developed with VENUS by adding a low temperature oven, sputter probes, as well as studying the RF coupling into the source. PMID:22380158

  11. Promoting Creative Thinking and Expression of Science Concepts among Elementary Teacher Candidates through Science Content Movie Creation and Showcasing

    Science.gov (United States)

    Hechter, Richard P.; Guy, Mark

    2010-01-01

    This article reports the phases of design and use of video editing technology as a medium for creatively expressing science content knowledge in an elementary science methods course. Teacher candidates communicated their understanding of standards-based core science concepts through the creation of original digital movies. The movies were assigned…

  12. Venus' thermospheric temperature field using a refraction model at terminator : comparison with 2012 transit observations using SDO/HMI, VEx/SPICAV/SOIR and NSO/DST/FIRS

    Science.gov (United States)

    Widemann, Thomas; Jaeggli, Sarah; Reardon, Kevin; Tanga, Paolo; Père, Christophe; Pasachoff, Jay M.; Vandaele, Ann Carine; Wilquet, Valerie; Mahieux, Arnaud; Wilson, Colin

    2014-11-01

    The transit of Venus in June 2012 provided a unique case study of the Venus' atmosphere transiting in front of the Sun, while at the same time ESA's Venus Express orbiter observed the evening terminator at solar ingress and solar egress.We report on mesospheric temperature at Venus' morning terminator using SDO/HMI aureole photometry and comparison with Venus Express. Close to ingress and egress phases, we have shown that the aureole photometry reflects the local density scale height and the altitude of the refracting layer (Tanga et al. 2012). The lightcurve of each spatially resolved aureole element is fit to a two-parameter model to constrain the meridional temperature gradient at terminator. Our measurements are in agreement with the VEx/SOIR temperatures obtained during orbit 2238 at evening terminator during solar ingress (46.75N - LST = 6.075PM) and solar egress (31.30N - LST = 6.047PM) captured from the Venus Express orbiter at the time Venus transited the Sun.We also performed spectroscopy and polarimetry during the transit of Venus focusing on extracting signatures of CO2 absorption. Observations were taken during the first half of the transit using the Facility InfraRed Spectropolarimeter (FIRS) on the Dunn Solar Telescope (DST). Although the predicted CO2 transmission spectrum of Venus was not particularly strong at 1565 nm, this region of the H-band often used in magnetic field studies of the Sun's photosphere provides a particularly flat solar continuum with few atmospheric lines. Sun-subtracted Venus limb observations show intensity distribution of vibrational CO2 bands 221 2v+2v2+v3 at 1.571?m and 141 v1+4v2+v3 at 1.606?m.

  13. Gamma rays and cosmic rays at Venus: The Pioneer Venus gamma ray detector and considerations for future measurements

    Science.gov (United States)

    Lorenz, Ralph D.; Lawrence, David J.

    2015-05-01

    We draw attention to, and present a summary archive of the data from, the Pioneer Venus Orbiter Gamma-ray Burst Detector (OGBD), an instrument not originally conceived with Venus science in mind. We consider the possibility of gamma-ray flashes generated by lightning and model the propagation of gamma rays in the Venusian atmosphere, finding that if gamma rays originate at the upper range of reported cloud top altitudes (75 km altitude), they may be attenuated by factors of only a few, whereas from 60 km altitude they are attenuated by over two orders of magnitude. The present archive is too heavily averaged to reliably detect such a source (and we appeal to investigators who may have retained a higher-resolution archive), but the data do provide a useful and unique record of the cosmic ray flux at Venus 1978-1993. We consider other applications of future orbital gamma ray data, such as atmospheric occultations and the detection of volcanic materials injected high in the atmosphere.

  14. A Teaching Expression Method based on Systems Science

    Directory of Open Access Journals (Sweden)

    Yingchun Li

    2014-12-01

    Full Text Available The key of teaching is to design some "Teaching Main Line ", and ultimately to impart the knowledge and its structure of teachers and teaching materials to students themselves knowledge and its structure. This research indicates that the knowledge /system inner logic are differ from students comprehension logic, the teaching process in general is a kind of linearization process of teaching knowledge. Discussed the linearization of teaching process, as for transformation and restoration of the knowledge/system structure. Therefore given a Systems-Science Based Knowledge Model (SSBKM for structure and organization methods of a knowledge; especially focuses on “the teaching mainline method based on SSBKM”. Think that only organizing teaching based on a certain Teaching Mainline, making teaching process linearization and finally restoring the original knowledge and its structure, can we really take for acquire and mastery of the knowledge. The article also mentioned the method that promote Teaching Mainline: the multiple cycle teaching methods of “ponging over, browsing, reading, learning, exercising, practicing and applying”. The article also takes this paper as "a knowledge" example, the Y, given the teaching expression method of Y based on systems science.

  15. Enabling Venus In-Situ Science - Deployable Entry System Technology, Adaptive Deployable Entry and Placement Technology (ADEPT): A Technology Development Project funded by Game Changing Development Program of the Space Technology Program

    Science.gov (United States)

    Wercinski, Paul F.; Venkatapathy, Ethiraj; Gage, Peter J.; Yount, Bryan C.; Prabhu, Dinesh K.; Smith, Brandon; Arnold, James O.; Makino, alberto; Peterson, Keith Hoppe; Chinnapongse, Ronald I.

    2012-01-01

    Venus is one of the important planetary destinations for scientific exploration, but: The combination of extreme entry environment coupled with extreme surface conditions have made mission planning and proposal efforts very challenging. We present an alternate, game-changing approach (ADEPT) where a novel entry system architecture enables more benign entry conditions and this allows for greater flexibility and lower risk in mission design

  16. Characterization of a transiting exo-Venus : lessons from the 2012 Transit

    Science.gov (United States)

    Widemann, Thomas; Jaeggli, S. A.; Reardon, K. P.; Tanga, P.; Pasachoff, J. M.; Schneider, G.

    2013-10-01

    The transit of Venus in June 2012 provided a unique chance to view a well studied planetary atmosphere as we might see that of a transiting exoplanet, through scattered and refracted illumination of its parent star. We report on mesospheric temperature at Venus' morning terminator using SDO/HMI aureole photometry and comparison with Venus Express. Close to ingress and egress phases, we have shown that the aureole photometry reflects the local density scale height and the altitude of the refracting layer (Tanga et al. 2012). The lightcurve of each spatial resolution element of the aureole is compared to a two-parameter model to constrain the meridional temperature gradient along the terminator. Our measurements are in agreement with the VEx/SOIR temperatures obtained during orbit 2238 at evening terminator during solar ingress (46.75N - LST = 6.075PM) and solar egress (31.30N - LST = 6.047PM) as seen from the orbiter. Imaging data using IBIS/ROSA on the Dunn Solar Telescope in the G-band (430 nm) are also presented. We also performed spectroscopy and polarimetry during the transit of Venus focusing on extracting signatures of CO2 absorption. Observations were taken during the first half of the transit using the Facility InfraRed Spectropolarimeter on the Dunn Solar Telescope. Although the predicted CO2 transmission spectrum of Venus was not particularly strong at 1565 nm, this region of the H-band often used in magnetic field studies of the Sun's photosphere provides a particularly flat solar continuum with few atmospheric and molecular lines. Sun-subtracted Venus limb observations show intensity distribution of vibro-rotational CO2 band 221 2? + 2?2 + ?3 at 1.571?m allowing for an additional constraint on Venus' thermospheric temperature.

  17. Distant interplanetary wake of Venus: plasma observations from pioneer Venus

    International Nuclear Information System (INIS)

    In June 1979 the Pioneer Venus orbiter made its first series of passes through the distant solar wind wake of Venus at distances of 8--12 R/sub V/ behind the planet. During this period the plasma analyzer aboard the spacecraft detected disturbed magnetosheath plasma that intermittently disappeared and reappeared, suggesting a tattered, filamentary cavity trailing behind the planet. The magnetosheath dropouts almost always occurred inside the region of 'magnetotail' observed by Russell et al. Sporadic bursts of energetic ions (E/q> or approx. =4kV) are detected inside and, occasionally, outside the magnetotail; all such bursts are consistent with identification of the ion as O+ of planetary origin moving at the local magnetosheath flow speed. The morphology of the plasma dropouts and of the O+ bursts is analyzed in detail. The cavity appears to contract at times of high solar wind dynamic pressure. The intensity of the O+ component is highly variable, and appears not to be strongly correlated with solar wind dynamic pressure. The most intense bursts correspond to a flux 7 ions cm-2 s-1. This maximum flux, if steady and filling a cylinder 1 R/sub V/ in radius would correspond to a mass loss rate of 25 ions s-1; the intermittency and variability of the flux suggest that the true mean loss rate is very much lower. The kinmean loss rate is very much lower. The kinetic temperature of the O+ component is estimated as 105--106 K in order of magnitude

  18. Zephyr: A Landsailing Rover for Venus

    Science.gov (United States)

    Landis, Geoffrey A.; Oleson, Steven R.; Grantier, David

    2014-01-01

    With an average temperature of 450C and a corrosive atmosphere at a pressure of 90 bars, the surface of Venus is the most hostile environment of any planetary surface in the solar system. Exploring the surface of Venus would be an exciting goal, since Venus is a planet with significant scientific mysteries, and interesting geology and geophysics. Technology to operate at the environmental conditions of Venus is under development. A rover on the surface of Venus with capability comparable to the rovers that have been sent to Mars would push the limits of technology in high-temperature electronics, robotics, and robust systems. Such a rover would require the ability to traverse the landscape on extremely low power levels. We have analyzed an innovative concept for a planetary rover: a sail-propelled rover to explore the surface of Venus. Such a rover can be implemented with only two moving parts; the sail, and the steering. Although the surface wind speeds are low (under 1 m/s), at Venus atmospheric density even low wind speeds develop significant force. Under funding by the NASA Innovative Advanced Concepts office, a conceptual design for such a rover has been done. Total landed mass of the system is 265 kg, somewhat less than that of the MER rovers, with a 12 square meter rigid sail. The rover folds into a 3.6 meter aeroshell for entry into the Venus atmosphere and subsequent parachute landing on the surface. Conceptual designs for a set of hightemperature scientific instruments and a UHF communication system were done. The mission design lifetime is 50 days, allowing operation during the sunlit portion of one Venus day. Although some technology development is needed to bring the high-temperature electronics to operational readiness, the study showed that such a mobility approach is feasible, and no major difficulties are seen.

  19. Investigating the Origin and Evolution of Venus with In Situ Mass Spectrometry

    Science.gov (United States)

    Trainer, M. G.; Mahaffy, P. R.; Brinckerhoff, W. B.; Johnson, N. M.; Glaze, L. S.

    2015-01-01

    The exploration of Venus continues to be a top priority of planetary science. The Planetary Decadal Survey goals for inner-planet exploration seek to discern the origin and diversity of terrestrial planets, understand how the evolution of terrestrial planets relates to the evolution of life, and explore the processes that control climate on Earth-like planets. These goals can only be realized through continued and extensive exploration of Venus, the most mysterious of the terrestrial planets, remarkably different from the Earth despite the gross similarities between these "twin planets". It is unknown if this apparent divergence was intrinsic, programmed during accretion from distinct nebular reservoirs, or a consequence of either measured or catastrophic processes during planetary evolution. Even if the atmosphere of Venus is a more "recent" development, its relationship to the resurfacing of the planet's enigmatic surface is not well understood. Resolving such uncertainties directly addresses the hypothesis of a more clement, possibly water-rich era in Venus' past as well as whether Earth could become more Venus-like in the future.

  20. Carbon dioxide opacity of the Venus' atmosphere

    Science.gov (United States)

    Snels, Marcel; Stefani, Stefania; Grassi, Davide; Piccioni, Giuseppe; Adriani, Alberto

    2014-11-01

    Venus' atmosphere consists of about 95% of carbon dioxide, which accounts for most of the absorption of the radiation emitted by its hot surface. The large densities and high temperatures of Venus' atmosphere make the absorption much more complex than for low density atmospheres such as Earth or Mars. Available experimental data are at present insufficient and theoretical models inadequate to describe complex absorption line shapes and collision-induced phenomena. Here we present a survey of all absorption and scattering processes which influence the transparency of Venus' atmosphere for what concerns carbon dioxide.

  1. Comet Halley: The view from Pioneer Venus

    International Nuclear Information System (INIS)

    The plans to scan Halley's Comet at close range using the Pioneer Venus Orbiter are discussed. The composition of comets, their paths through space, and the history of comet encounters are examined. An ultraviolet spectrometer aboard the spacecraft will determine the composition of the gaseous coma and will measure the total gas production during its passage. The Pioneer Venus Orbiter will observe the comet for five weeks before solar interference with communications occurs as Venus passes on the far side of the Sun from Earth. Diagrams of the solar system and the relationship of the comet to the planets and the Sun are provided

  2. Comet Halley: The view from Pioneer Venus

    Science.gov (United States)

    1989-01-01

    The plans to scan Halley's Comet at close range using the Pioneer Venus Orbiter are discussed. The composition of comets, their paths through space, and the history of comet encounters are examined. An ultraviolet spectrometer aboard the spacecraft will determine the composition of the gaseous coma and will measure the total gas production during its passage. The Pioneer Venus Orbiter will observe the comet for five weeks before solar interference with communications occurs as Venus passes on the far side of the Sun from Earth. Diagrams of the solar system and the relationship of the comet to the planets and the Sun are provided.

  3. Jean-Charles Houzeau and the 1882 Belgian Transit of Venus Expeditions

    Science.gov (United States)

    Sterken, Christiaan

    2013-05-01

    In 1871, the Belgian astronomer Jean-Charles Houzeau developed a new approach to determine the solar parallax. His "heliometer with unequal focal lengths" produces a large and a small solar image, as well as a large and a small image of Venus. Making the small solar and the large Venus image coincide yields a measure of the angular distance of the centers of both objects. Two such instruments were built for two Belgian expeditions to observe the Venus transit of December 6, 1882: one to San Antonio, Texas, and another one to Santiago de Chile. These were the first major expeditions in the history of Belgian science. This paper documents the expeditions, and clarifies the principal instrument and its present-day whereabouts.

  4. Summing Up the Unique Venus Transit 2004 (VT-2004) Programme

    Science.gov (United States)

    2004-11-01

    On June 8, 2004, Venus - the Earth's sister planet - passed in front of the Sun. This rare event - the last one occurred in 1882 - attracted the attention of millions of people all over the world. In a few days' time, on November 5-7, 2004, about 150 educators, media representatives, as well as amateur and professional astronomers will gather in Paris (France) at the international conference "The Venus Transit Experience" to discuss the outcome of the related Venus Transit 2004 (VT-2004) public education programme. This unique project was set up by the European Southern Observatory (ESO), together with the European Association for Astronomy Education (EAAE), the Institut de Mécanique Céleste et de Calcul des Éphémérides (IMCCE) and the Observatoire de Paris in France, as well as the Astronomical Institute of the Academy of Sciences of the Czech Republic. It was also supported by the European Commission in the framework of the European Science and Technology Week, cf. ESO PR 03/04. The VT-2004 programme successfully exposed the broad public to a number of fundamental issues at the crucial interface between society and basic science. It ensured the most comprehensive real-time coverage of the event via an extremely dynamic Central Display that was updated a short intervals. Thanks to the prior establishment of hundreds of mirror sites, the VT-2004 website was easily accessible all through the transit, even though it experienced about 55 million webhits during a period of 8 hours. The VT-2004 programme established a wide international network of individuals (including school teachers and their students, amateur astronomers, interested laypeople, etc.) and educational institutions (astronomical observatories, planetaria, science centres, etc.), as well as 25 National Nodes with their own websites about the Venus Transit in as many local languages. It collected a large number of photos and drawings. It also included an international Video Contest, inviting all interested parties to expose a theme around the transit, e.g., preparations for the event and the actual observations, as well as conveying the personal impressions. A professional jury has now selected among the many excellent entries the laureates (see the list below) who will present their videos at the Paris conference this week, competing for one of the top prizes, including a trip by the winning team to the ESO Paranal Observatory (Chile), home of the Very Large Telescope. The "Venus Transit Experience" Conference The Venus Transit Experience conference will take place at "Le Carré des Sciences" at the French Ministry of Research in Paris. It brings together the main participants in this project from many different European countries. A main aim is to discuss the impact of the project, identifying possible differences from country to country and showing how to share good practices in the future. The VT-2004 programme provided an exciting field test for the execution of large-scale public activities relating to a particular, scientific event with strong operational constraints, including the requirement to act in real-time as this event progressed. Much valuable experience was gathered for future continent-wide activities involving the same mechanisms and carried out under similar conditions. Thus, the overall outcome of this unique public education project is clearly of very wide interest, not just in the field of astronomy. The Distance to the Sun Remeasured A central feature of the VT-2004 programme was the VT-2004 Observing Campaign, aimed at re-enacting the historical determination of the distance to the Sun (the "Astronomical Unit") by collecting timings of the four contacts made by participating observers and combining them in a calculation of the AU. A large number of groups of observers registered; at the end, there were 2763 all over the world. Among these were almost 1000 school classes, demonstrating the large interest among students and teachers to participate actively in this unique celestial event. As exp

  5. Energetic Neutral Atom Emissions From Venus: VEX Observations and Theoretical Modeling

    Science.gov (United States)

    Fok, M.-C.; Galli, A.; Tanaka, T.; Moore, T. E.; Wurz, P.; Holmstrom, M.

    2007-01-01

    Venus has almost no intrinsic magnetic field to shield itself from its surrounding environment. The solar wind thus directly interacts with the planetary ionosphere and atmosphere. One of the by-products of this close encounter is the production of energetic neutral atom (ENA) emissions. Theoretical studies have shown that significant amount of ENAs are emanated from the planet. The launch of the Venus Express (VEX) in 2005 provided the first light ever of the Venus ENA emissions. The observed ENA flux level and structure are in pretty good agreement with the theoretical studies. In this paper, we present VEX ENA data and the comparison with numerical simulations. We seek to understand the solar wind interaction with the planet and the impacts on its atmospheres.

  6. The Ancient Mariner and the transit of Venus.

    Science.gov (United States)

    Griffin-Short, Rita

    2003-12-01

    The achievements of William Wales FRS - astronomer, classical scholar, demographer, editor, mathematician, meteorologist and humane teacher - have been overshadowed by the fame of Cook's extraordinary voyages, and overlooked as a significant influence on Samuel Taylor Coleridge's early development. The Royal Society sent Wales to Hudson Bay, Canada, and James Cook to Tahiti, both to observe the 1769 transit of Venus as part of an international project to calculate solar parallax, and hence the distance to the Sun. Wales later taught mathematics and navigation science at Christ's Hospital School to a precocious Coleridge, whose creative mind translated tales of polar adventures into memorable poetry. PMID:14652042

  7. Novel Architecture for a Long-Life, Lightweight Venus Lander

    Science.gov (United States)

    Bugby, D.; Seghi, S.; Kroliczek, E.; Pauken, M.

    2009-03-01

    This paper describes a novel concept for an extended lifetime, lightweight Venus lander. Historically, to operate in the 480° C, 90 atm, corrosive, mostly CO2 Venus surface environment, previous landers have relied on thick Ti spherical outer shells and thick layers of internal insulation. But even the most resilient of these landers operated for only about 2 hours before succumbing to the environment. The goal on this project is to develop an architecture that extends lander lifetime to 20-25 hours and also reduces mass compared to the Pioneer Venus mission architecture. The idea for reducing mass is to: (a) contain the science instruments within a spherical high strength lightweight polymer matrix composite (PMC) tank; (b) surround the PMC tank with an annular shell of high performance insulation pre-pressurized to a level that (after landing) will exceed the external Venus surface pressure; and (c) surround the insulation with a thin Ti outer shell that contains only a net internal pressure, eliminating buckling overdesign mass. The combination of the PMC inner tank and thin Ti outer shell is lighter than a single thick Ti outer shell. The idea for extending lifetime is to add the following three features: (i) an expendable water supply that is placed within the insulation or is contained in an additional vessel within the PMC tank; (ii) a thin spherical evaporator shell placed within the insulation a short radial distance from the outer shell; and (iii) a thin heat-intercepting liquid cooled shield placed inboard of the evaporator shell. These features lower the temperature of the insulation below what it would have been with the insulation alone, reducing the internal heat leak and lengthening lifetime. The use of phase change materials (PCMs) inside the PMC tank is also analyzed as a lifetime-extending design option. The paper describes: (1) analytical modeling to demonstrate reduced mass and extended life; (2) thermal conductivity testing of high performance insulation as a function of temperature and pressure; (3) a bench-top ambient pressure thermal test of the evaporation system; and (4) a higher fidelity test, to be conducted in a high pressure, high temperature inert gas test chamber, of a small-scale Venus lander prototype (made from two hemispherical interconnecting halves) that includes all of the aforesaid features. 22 CFR 125.4(b)(13) applicable

  8. Novel Architecture for a Long-Life, Lightweight Venus Lander

    International Nuclear Information System (INIS)

    This paper describes a novel concept for an extended lifetime, lightweight Venus lander. Historically, to operate in the 480 deg. C, 90 atm, corrosive, mostly CO2 Venus surface environment, previous landers have relied on thick Ti spherical outer shells and thick layers of internal insulation. But even the most resilient of these landers operated for only about 2 hours before succumbing to the environment. The goal on this project is to develop an architecture that extends lander lifetime to 20-25 hours and also reduces mass compared to the Pioneer Venus mission architecture. The idea for reducing mass is to: (a) contain the science instruments within a spherical high strength lightweight polymer matrix composite (PMC) tank; (b) surround the PMC tank with an annular shell of high performance insulation pre-pressurized to a level that (after landing) will exceed the external Venus surface pressure; and (c) surround the insulation with a thin Ti outer shell that contains only a net internal pressure, eliminating buckling overdesign mass. The combination of the PMC inner tank and thin Ti outer shell is lighter than a single thick Ti outer shell. The idea for extending lifetime is to add the following three features: (i) an expendable water supply that is placed within the insulation or is contained in an additional vessel within the PMC tank; (ii) a thin spherical evaporator shell placed within the insulation a short radial distance from the outer shell; and (adial distance from the outer shell; and (iii) a thin heat-intercepting liquid cooled shield placed inboard of the evaporator shell. These features lower the temperature of the insulation below what it would have been with the insulation alone, reducing the internal heat leak and lengthening lifetime. The use of phase change materials (PCMs) inside the PMC tank is also analyzed as a lifetime-extending design option. The paper describes: (1) analytical modeling to demonstrate reduced mass and extended life; (2) thermal conductivity testing of high performance insulation as a function of temperature and pressure; (3) a bench-top ambient pressure thermal test of the evaporation system; and (4) a higher fidelity test, to be conducted in a high pressure, high temperature inert gas test chamber, of a small-scale Venus lander prototype (made from two hemispherical interconnecting halves) that includes all of the aforesaid features.22 CFR 125.4(b)(13) applicable

  9. Venus - Multiple-Floored, Irregular Impact Crater

    Science.gov (United States)

    1991-01-01

    Magellan imaged this multiple-floored, irregular impact crater at latitude 16.4 degrees north, longitude 352.1 degrees east, during orbits 481 and 482 on 27 September 1990. This crater, about 9.2 kilometers in maximum diameter, was formed on what appears to be a slightly fractured, radar-dark (smooth) plain. The abundant, low viscosity flows associated with this cratering event have, however, filled local, fault-controlled troughs (called graben). These shallow graben are well portrayed on this Magellan image but would be unrecognizable but for their coincidental infilling by the radar-bright crater flows. This fortuitous enhancement by the crater flows of fault structures that are below the resolution of the Magellan synthetic aperture radar is providing the Magellan Science Team with valuable geologic information. The flow deposits from the craters are thought to consist primarily of shock melted rock and fragmented debris resulting from the nearly simultaneous impacts of two projectile fragments into the hot (800 degrees Fahrenheit) surface rocks of Venus. The presence of the various floors of this irregular crater is interpreted to be the result of crushing, fragmentation, and eventual aerodynamic dispersion of a single entry projectile during passage through the dense Venusian atmosphere.

  10. The Rarest Eclipse: Transit of Venus

    Science.gov (United States)

    The transit of Venus across the disk of the sun is a rare astronomical event that has transfixed astronomers for centuries. June 8, 2004 marked the last occurrence of this event. Due to its extreme rarity (occurring only twice a century) this past transit has been heavily documented and researched by scientists across the globe. This site from the Exploratorium contains educational webcasts and RealMedia streaming coverage of the event. The last instance of the transit of Venus in 1882 is also well documented on this site with an interview from Tony Misch of Lick Observatory and a Quicktime animation made with glass plate negatives. The site provides background information about the planet Venus and the importance of its transit across the sun, as well as information on how to view the event. Educators's will find the "Teacher's Guide" especially useful for lesson and activity plans revolving around Venus.

  11. Sapphire Viewports for a Venus Probe Project

    National Aeronautics and Space Administration — The proposed Phase 1 program will demonstrate that sapphire viewports are feasible for use in Venus probes. TvU's commercial viewport products have demonstrated...

  12. A dynamic model of Venus's gravity field

    Science.gov (United States)

    Kiefer, W. S.; Richards, M. A.; Hager, B. H.; Bills, B. G.

    1986-01-01

    Unlike Earth, long wavelength gravity anomalies and topography correlate well on Venus. Venus's admittance curve from spherical harmonic degree 2 to 18 is inconsistent with either Airy or Pratt isostasy, but is consistent with dynamic support from mantle convection. A model using whole mantle flow and a high viscosity near surface layer overlying a constant viscosity mantle reproduces this admittance curve. On Earth, the effective viscosity deduced from geoid modeling increases by a factor of 300 from the asthenosphere to the lower mantle. These viscosity estimates may be biased by the neglect of lateral variations in mantle viscosity associated with hot plumes and cold subducted slabs. The different effective viscosity profiles for Earth and Venus may reflect their convective styles, with tectonism and mantle heat transport dominated by hot plumes on Venus and by subducted slabs on Earth. Convection at degree 2 appears much stronger on Earth than on Venus. A degree 2 convective structure may be unstable on Venus, but may have been stabilized on Earth by the insulating effects of the Pangean supercontinental assemblage.

  13. A dynamic model of Venus's gravity field

    Science.gov (United States)

    Kiefer, W. S.; Richards, M. A.; Hager, B. H.; Bills, B. G.

    1984-01-01

    Unlike Earth, long wavelength gravity anomalies and topography correlate well on Venus. Venus's admittance curve from spherical harmonic degree 2 to 18 is inconsistent with either Airy or Pratt isostasy, but is consistent with dynamic support from mantle convection. A model using whole mantle flow and a high viscosity near surface layer overlying a constant viscosity mantle reproduces this admittance curve. On Earth, the effective viscosity deduced from geoid modeling increases by a factor of 300 from the asthenosphere to the lower mantle. These viscosity estimates may be biased by the neglect of lateral variations in mantle viscosity associated with hot plumes and cold subducted slabs. The different effective viscosity profiles for Earth and Venus may reflect their convective styles, with tectonism and mantle heat transport dominated by hot plumes on Venus and by subducted slabs on Earth. Convection at degree 2 appears much stronger on Earth than on Venus. A degree 2 convective structure may be unstable on Venus, but may have been stabilized on Earth by the insulating effects of the Pangean supercontinental assemblage.

  14. Venus' thermospheric temperature field using a refraction model at terminator : comparison with 2012 transit observations using SDO/HMI and NSO/DST/FIRS

    Science.gov (United States)

    Widemann, Thomas; Tanga, Paolo; Père, Christophe; Jaeggli, Sarah; Reardon, Kevin; Pasachoff, Jay M.

    2014-05-01

    The transit of Venus in June 2012 provided a unique case study of an Earth-size planet's atmosphere transiting in front of its parent star at 0.7AU, while at the same time ESA's Venus Express orbiter observed the evening terminator at solar ingress and solar egress. We report on mesospheric temperature at Venus' morning terminator using SDO/HMI aureole photometry and comparison with Venus Express. Close to ingress and egress phases, we have shown that the aureole photometry reflects the local density scale height and the altitude of the refracting layer (Tanga et al. 2012). The lightcurve of each spatial resolution element of the aureole is compared to a two-parameter model to constrain the meridional temperature gradient along the terminator. Our measurements are in agreement with the VEx/SOIR temperatures obtained during orbit 2238 at evening terminator during solar ingress (46.75N - LST = 6.075PM) and solar egress (31.30N - LST = 6.047PM) captured from the Venus Express orbiter at the time Venus transited the Sun for Earth-based observers. We also performed spectroscopy and polarimetry during the transit of Venus focusing on extracting signatures of CO2 absorption. Observations were taken during the first half of the transit using the Facility InfraRed Spectropolarimeter on the Dunn Solar Telescope. Although the predicted CO2 transmission spectrum of Venus was not particularly strong at 1565 nm, this region of the H-band often used in magnetic field studies of the Sun's photosphere provides a particularly flat solar continuum with few atmospheric and molecular lines. Sun-subtracted Venus limb observations show intensity distribution of vibrational CO2 bands 221 2v + 2?2 + ?3 at 1.571um and 141 ?1 + 4?2 + ?3 at 1.606um. Data independently allow to constrain temperature as well as cross-terminator thermospheric winds.

  15. High Temperature Seismometer, Electronics, and Sensor Development for Venus Applications

    Science.gov (United States)

    Hunter, G. W.; Ponchak, G. E.; Beheim, G. M.; Neudeck, P. G.; Spry, D. J.; Scardelletti, M. C.; Meredith, R. D.; Taylor, B.; Beard, S.; Kiefer, W. S.

    2015-04-01

    This poster describes work to develop long-lived seismometry, high temperature electronics, and sensor technologies operational in Venus conditions with the potential to enable new Venus surface missions.

  16. Venus-2 MOX-fuelled reactor dosimetry calculations. Final report

    International Nuclear Information System (INIS)

    It is essential to calculate the structural integrity of reactor components with a high degree of accuracy to make correct decisions on design plant lifetime, safety margins and potential plant lifetime extension. The Nuclear Science Committee of the OECD Nuclear Energy Agency (NEA) is thus organizing a series of benchmarks on this subject to verify the current international level of accuracy in pressure vessel fluence calculations and to clarify the relative merits of various methodologies and hence the areas of possible improvements in various calculation schemes. The main finding from the previous UO2-fuelled VENUS-1 two-dimensional (2-D) and VENUS-3 three-dimensional (3-D) benchmarks was that the calculated results of the 3-D benchmark are in general much closer to the experimental values than those for the 2-D benchmark. Knowing that many of commercial power plants in Europe and in Japan use MOX fuel and that the use of MOX fuel in LWRs presents different neutron characteristics, the present benchmark was launched in 2004 to test the current state of the art computation methods of calculating neutron flux to reactor components against the measured data of the VENUS-2 MOX-fuelled critical experiments. The latest versions of nuclear data sets and of three-dimensional calculation methods (both deterministic and stochastic methods) were applied by the participants. The 3-D results of most of the calculations are within the desired accuracy of ±10% for dosthin the desired accuracy of ±10% for dosimetry calculations. It is demonstrated that some precise calculations can achieve, for most of the detector positions, an accuracy of ±5% when compared with the experimental values. (author)

  17. Near-infrared observations of Venus

    International Nuclear Information System (INIS)

    Ground-based near-infrared observations of the Venus night side reveal anomalous bright features at wavelengths near 1.7 and 2.3 micrometer (Allen and Crawford, 1984; Allen, 1987). These features are thought to be formed as thermal radiation from the hot lower atmosphere leaks through holes in the middle and/or lower sulfuric acid cloud decks. Because these holes allow radiation to escape from deep in the troposphere, they provide an opportunity to significantly improve our understanding of the composition, thermal structure, and dynamics of this region of the Venus atmosphere. New near-infrared observations of the Venus night side are needed to address these questions. During the first year of this program, researchers requested and received observing time at six sites and organized a highly-skilled team. The wide array of sites should allow researchers to collect the data needed to meet all of the proposed objectives. High resolution spectra of the Venus night side was obtained. Researchers are currently collecting the first images of Venus from Kitt Peak and Table Mountain. The state-of-the-art infrared array detectors that are being used at these sites are allowing researchers to collect hundreds of high-quality images during each observing day. These images show the expected bright features, but they have not yet begun to track these features

  18. Meeting Venus:A Collection of Papers Presented at the Venus Transit Conference Tromsø 2012

    OpenAIRE

    Aspaas, Per Pippin; Sterken, Christiaan

    2013-01-01

    On 2–3 June 2012, the University of Tromsø hosted a conference about the cultural and scientific history of the transits of Venus. The conference took place in Tromsø for two very specific reasons. First and foremost, the last transit of Venus of this century lent itself to be observed on the disc of the Midnight Sun in this part of Europe during the night of 5 to 6 June 2012. Second, several Venus transit expeditions in this region were central in the global enterprise of measuring th...

  19. Data acquisition for measuring the wind on Venus from Pioneer Venus

    Science.gov (United States)

    Smith, J. R.; Ramos, R.

    1980-01-01

    The Pioneer Venus Differential Long Baseline Interferometry experiment was designed to measure the motion in three dimensions of the Pioneer probes during their fall to the surface of Venus, using a combination of Doppler and long baseline ratio interferometric methods. The altitude profiles of wind speed and direction that may be deduced from these data are expected to contribute significantly to the understanding of the dynamics of the Venus atmosphere. The design of the experiment and the equipment and software techniques that were developed specially for this experiment are described.

  20. Aerial electromagnetic sounding of the lithosphere of Venus

    Science.gov (United States)

    Grimm, Robert E.; Barr, Amy C.; Harrison, Keith P.; Stillman, David E.; Neal, Kerry L.; Vincent, Michael A.; Delory, Gregory T.

    2012-02-01

    Electromagnetic (EM) investigation depths are larger on Venus than Earth due to the dearth of water in rocks, in spite of higher temperatures. Whistlers detected by Venus Express proved that lightning is present, so the Schumann resonances ˜10-40 Hz may provide a global source of electromagnetic energy that penetrates ˜10-100 km. Electrical conductivity will be sensitive at these depths to temperature structure and hence thermal lithospheric thickness. Using 1D analytic and 2D numerical models, we demonstrate that the Schumann resonances—transverse EM waves in the ground-ionosphere waveguide—remain sensitive at all altitudes to the properties of the boundaries. This is in marked contrast to other EM methods in which sensitivity to the ground falls off sharply with altitude. We develop a 1D analytical model for aerial EM sounding that treats the electrical properties of the subsurface (thermal gradient, water content, and presence of conductive crust) and ionosphere, and the effects of both random errors and biases that can influence the measurements. We initially consider specified 1D lithospheric thicknesses 100-500 km, but we turn to 2D convection models with Newtonian temperature-dependent viscosity to provide representative vertical and lateral temperature variations. We invert for the conductivity-depth structure and then temperature gradient. For a dry Venus, we find that the error on temperature gradient obtained from any single local measurement is ˜100%—perhaps enough to distinguish "thick" vs. "thin" lithospheres. When averaging over thousands of kilometers, however, the standard deviation of the recovered thermal gradient is within the natural variability of the convection models, Schumann resonances to Schumann penetration depths are significantly larger. We conclude that EM sounding of the interior of Venus is feasible from a 55-km high balloon. Lithospheric thickness can be measured if the upper-mantle water content is low. If H 2O at hundreds of ppm is present, the deeper, temperature-sensitive structure is screened, but the "wet" nature of the upper mantle, as well as structure of the upper crust, is revealed.

  1. Change over a service learning experience in science undergraduates' beliefs expressed about elementary school students' ability to learn science

    Science.gov (United States)

    Goebel, Camille A.

    This longitudinal investigation explores the change in four (3 female, 1 male) science undergraduates' beliefs expressed about low-income elementary school students' ability to learn science. The study sought to identify how the undergraduates in year-long public school science-teaching partnerships perceived the social, cultural, and economic factors affecting student learning. Previous service-learning research infrequently focused on science undergraduates relative to science and society or detailed expressions of their beliefs and field practices over the experience. Qualitative methodology was used to guide the implementation and analysis of this study. A sample of an additional 20 science undergraduates likewise involved in intensive reflection in the service learning in science teaching (SLST) course called Elementary Science Education Partners (ESEP) was used to examine the typicality of the case participants. The findings show two major changes in science undergraduates' belief expressions: (1) a reduction in statements of beliefs from a deficit thinking perspective about the elementary school students' ability to learn science, and (2) a shift in the attribution of students, underlying problems in science learning from individual-oriented to systemic-oriented influences. Additional findings reveal that the science undergraduates perceived they had personally and profoundly changed as a result of the SLST experience. Changes include: (1) the gain of a new understanding of others' situations different from their own; (2) the realization of and appreciation for their relative positions of privilege due to their educational background and family support; (3) the gain in ability to communicate, teach, and work with others; (4) the idea that they were more socially and culturally connected to their community outside the university and their college classrooms; and (5) a broadening of the way they understood or thought about science. Women participants stated that the experience validated their science and science-related career choices. Results imply that these changes have the potential to strengthen the undergraduate pursuit of science-related careers and will contribute positive influences to our education system and society at large.

  2. High-resolution gravity model of Venus

    Science.gov (United States)

    Reasenberg, R. D.; Goldberg, Z. M.

    1992-01-01

    The anomalous gravity field of Venus shows high correlation with surface features revealed by radar. We extract gravity models from the Doppler tracking data from the Pioneer Venus Orbiter by means of a two-step process. In the first step, we solve the nonlinear spacecraft state estimation problem using a Kalman filter-smoother. The Kalman filter has been evaluated through simulations. This evaluation and some unusual features of the filter are discussed. In the second step, we perform a geophysical inversion using a linear Bayesian estimator. To allow an unbiased comparison between gravity and topography, we use a simulation technique to smooth and distort the radar topographic data so as to yield maps having the same characteristics as our gravity maps. The maps presented cover 2/3 of the surface of Venus and display the strong topography-gravity correlation previously reported. The topography-gravity scatter plots show two distinct trends.

  3. Sapphire Viewports for a Venus Probe

    Science.gov (United States)

    Bates, Stephen

    2012-01-01

    A document discusses the creation of a viewport suitable for use on the surface of Venus. These viewports are rated for 500 C and 100 atm pressure with appropriate safety factors and reliability required for incorporation into a Venus Lander. Sapphire windows should easily withstand the chemical, pressure, and temperatures of the Venus surface. Novel fixture designs and seals appropriate to the environment are incorporated, as are materials compatible with exploration vessels. A test cell was fabricated, tested, and leak rate measured. The window features polish specification of the sides and corners, soft metal padding of the sapphire, and a metal C-ring seal. The system safety factor is greater than 2, and standard mechanical design theory was used to size the window, flange, and attachment bolts using available material property data. Maintenance involves simple cleaning of the window aperture surfaces. The only weakness of the system is its moderate rather than low leak rate for vacuum applications.

  4. Venus project : experimentation at ENEA`s pilot site

    Energy Technology Data Exchange (ETDEWEB)

    Bargellini, M.L.; Fontana, F. [ENEA, Centro Ricerche Casaccia, Rome (Italy). Dip. Innovazione; Bucci, C.; Ferrara, F.; Sottile, P.A. [GESI s.r.l., Rome (Italy); Niccolai, L.; Scavino, G. [Rome Univ. Sacro Cuore (Italy); Mancini, R.; Levialdi, S. [Rome Univ. La Sapienza (Italy). Dip. di Scienze dell`Informazione

    1996-12-01

    The document describes the ENEA`s (Italian Agency for New Technologies, Energy and the Environment) experience in the Venus Project (Esprit III ). Venus is an advanced visual interface based on icon representation that permits to end-user to inquiry databases. VENUS interfaces to ENEA`s databases: cometa materials Module, Cometa Laboratories Module and European Programs. This report contents the results of the experimentation and of the validation carried out in ENEA`s related to the Venus generations. Moreover, the description of the architecture, the user requirements syntesis and the validation methodology of the VENUS systems have been included.

  5. Lunar & Planetary Science, 11.

    Science.gov (United States)

    Geotimes, 1980

    1980-01-01

    Presents a summary of each paper presented at the Lunar and Planetary Science Conference at the Johnson Space Center, Houston in March 1980. Topics relate to Venus, Jupiter, Mars, asteroids, meteorites, regoliths, achondrites, remote sensing, and cratering studies. (SA)

  6. Venus transit, a new experiment for education and communication

    Science.gov (United States)

    Maris, G.; Stavinschi, M.; Rusu, M.

    Almost five years ago, the Romanian astronomers had to cope with a totally exceptional event: the '99 total solar eclipse, whose maximum was on the territory of our country. It was not only a scientific participation, but also an experiment of education and communication with the general public. It was followed by other occasions, when the experience gained, but especially our exchange of ideas with researchers, amateur astronomers, teachers, pupils, etc., from home and abroad, helped us draw certain conclusions on the best ways in which scientific information must be communicated in order to be understood, in general, and to retract the youth towards science, in particular. We would like to mention, for instance: Life in the Universe, Living with a Star, Sun-Earth Days 2003. The Venus transit on June 8, 2004 has many aspects similar with other events, but also its own characteristics, having a great impact on the public perception. Our participation as members in the International Consortium Venus-2004, initiated by ESO and other European high reputation institutions, has obliged us to find new ways of training and communication. We believe that we will have a lot to learn about the way in which the professional astronomers can contribute to the training of various categories of people of different ages, cultural levels, etc. We present the preliminary conclusions of this international campaign at a national level.

  7. Secreted major Venus flytrap chitinase enables digestion of Arthropod prey

    DEFF Research Database (Denmark)

    Paszota, Paulina; Escalante-Perez, Maria

    2014-01-01

    Predation plays a major role in energy and nutrient flow in the biological food chain. Plant carnivory has attracted much interest since Darwin's time, but many fundamental properties of the carnivorous lifestyle are largely unexplored. In particular, the chain of events leading from prey perception to its digestive utilization remains to be elucidated. One of the first steps after the capture of animal prey, i.e. the enzymatic breakup of the insects' chitin-based shell, is reflected by considerable chitinase activity in the secreted digestive fluid in the carnivorous plant Venus flytrap. This study addresses the molecular nature, function, and regulation of the underlying enzyme, VF chitinase I. Using mass spectrometry based de novo sequencing, VF chitinase I was identified in the secreted fluid. As anticipated for one of the most prominent proteins in the flytrap's "green stomach" during prey digestion, transcription of VF chitinase I is restricted to glands and enhanced by secretion-inducing stimuli. In their natural habitat, Venus flytrap is exposed to high temperatures. We expressed and purified recombinant VF chitinase I and show that the enzyme exhibits the hallmark properties expected from an enzyme active in the hot and acidic digestive fluid of Dionaea muscipula. Structural modeling revealed a relative compact globular form of VF chitinase I, which might contribute to its overall stability and resistance to proteolysis. These peculiar characteristics could well serve industrial purposes, especially because of the ability to hydrolyze both soluble and crystalline chitin substrates including the commercially important cleavage of ?-chitin.

  8. On the stability of the Venus ionopause

    International Nuclear Information System (INIS)

    One of previously suggested mechanisms of magnetic twist formation in the Venus ionosphere - destruction of ionopause as a result of the Kelvin-Helmholtz instability development - has been analyzed. Axial symmetry of plasma flow in transition region leads to stability of perturbations of the size exceeding 50 km (characteristic size of magnetic twists near the ionopause) in the range of zenith angles ? < or equivalent 10 deg. It is pointed out that the known data obtained using the ''Pioneer-Venus'' American apparatus are also indicative of ionopause stability at small dynamic pressure of the solar wind

  9. The Tectonics and Evolution of Venus

    Science.gov (United States)

    Kaula, William M.

    1997-01-01

    This shift corresponded to a focusing of research on Venus. Some work included comparison with other planets. Venus research is being continued. The research can be summarized under five headings: (1) Planet formation; (2) Thermal and Compositional Evolution; (3) Tectonic structures and processes; (4) Determination and interpretation of gravity; and (5) Analyses of Ishtar Terra. Thirty-four publications were produced. References to publications supporting the summary are by year and letter: e.g., (1990 c,d) for the emphasis on the terminal phases in formation studies.

  10. Pioneer Venus Multiprobe entry telemetry recovery

    Science.gov (United States)

    Miller, R. B.; Ramos, R.

    1980-01-01

    The Entry Phase of the Pioneer Venus Multiprobe Mission involved data transmission over only a two-hour span. The criticality of recovery of those two hours of data, coupled with the fact that there were no radio signals from the Probes until their arrival at Venus, dictated unique telemetry recovery approaches on the ground. The result was double redundancy, use of spectrum analyzers to aid in rapid acquisition of the signals, and development of a technique for recovery of telemetry data without the use of real-time coherent detection which is normally employed by all other NASA planetary missions.

  11. Science Express: Out-of-Home-Media to Communicate Climate Change (Invited)

    Science.gov (United States)

    Lustick, D. S.; Lohmeier, J.; Chen, R.

    2013-12-01

    Science Express is an initiative to explore, develop, and test various approaches to using Out-of-Home-Media (OHM) to engage adults riding mass transit. To date, three projects represent this work: 1) Carbon Smarts Conference, 2) Cool Science, and 3) ScienceToGo.org. While the aim of each project is different, together they serve an immediate need to understand how OHM can be leveraged as an informal science learning medium. Using Climate Change as the content focus, each project is a variation on the theme of understanding mass transit as a form of mobile classroom for riders. The basic idea behind these initiatives is to engage individuals who do not necessarily read the science magazines, listen to science radio shows, or watch science programming on television. Science Express is about bringing the science learning opportunity to the audience during their daily routines. Mass Transit provides an ideal opportunity for engaging the disengaged in science learning since they represent a ';captive' audience while waiting at the bus stop, standing on the platform, riding inside the bus or train. These ';downtimes' present informal science educators with the opportunity to foster some science learning. With the advent of smartphone technology and its explosion in popularity among consumers, OHM is poised to offer riders a new kind of real time learning experience. The Science Express projects aim to understand the strengths and weaknesses of this new model for informal science learning so as to refine and improve its effectiveness at achieving desired goals. While the Science Express model for informal science learning could be used to foster understanding about any relevant scientific content, the research team chose to use Climate Change as the focus. Climate Change seemed like an obvious because of its timeliness, complexity, robust scientific foundation, and presence in popular media. Nearly all our riders have heard of 'Climate Change' or 'Global Warming', but a much smaller percentage actually understand the underlying science. In addition, riders appear to be very curious and want to know more about these issues.

  12. A Cubesat Mission to Venus: A Low-Cost Approach to the Investigation of Venus Lightning

    Science.gov (United States)

    Majid, W.; Duncan, C.; Kuiper, T.; Russell, C. T.; Hart, R. A.; Lightsey, E.

    2013-12-01

    The occurrence of Venus lightning has been detected by atmospheric probes and landers on Venus; by ionospheric satellites; by an orbiting visible spectrometer; at radio frequencies by the Galileo spacecraft while flying by Venus; and by an Earth-based telescope. However, none of these detectors has enabled us to determine the global occurrence rate of lightning in the atmosphere of Venus, nor the altitude at which this lightning is generated. Such measurements are needed in order to determine the processes that generate Venus lightning and to establish the importance of Venus lightning in controlling the chemical composition of the Venus atmosphere. A simple and affordable mission to perform this mapping could be achieved with CubeSat technology. A mother spacecraft with at least three CubeSat partners using RF detection could map the occurrence of lightning globally and determine its altitude of origin, with triangulation of precisely timed RF event arrivals. Such a mission would provide space for complementary investigations and be affordable under the Discovery mission program. We are embarking on a program to develop CubeSat-based instrumentation for such a mission. The initial task is to develop a lightning detector in a CubeSat development kit using a software defined radio (SDR) operating at decameter wavelengths (5-50 MHz). This involves algorithm development as well as selecting or developing radio hardware for a CubeSat. Two units will be tested on the ground in a lightning zone such as New Mexico, where the Long Wavelength Array operates in the same frequency range. When the concept has been proven, flight subsystems such as solar panels, attitude sensing and communication radios will be added to the CubeSats to test performance in low Earth orbit. Experience gained from flight would enable a cluster of sensors to be proposed for a future Venus mission.

  13. Measuring Solar Diameter with 2012 Venus Transits

    Science.gov (United States)

    Sigismondi, Costantino

    The role of Venus and Mercury transits is crucial to know the past history of the solar diameter. Through the W parameter, the logarithmic derivative of the radius with respect to the luminosity, the past values of the solar luminosity can be recovered. The black drop phenomenon affects the evaluation of the instants of internal and external contacts between the planetary disk and the solar limb. With these observed instants compared with the ephemerides the value of the solar diameter is recovered. The black drop and seeing effects are overcome with two fitting circles, to Venus and to the Sun, drawn in the undistorted part of the image. The corrections of ephemerides due to the atmospheric refraction will also be taken into account. The forthcoming transit of Venus will allow an accuracy on the diameter of the Sun better than 0.01 arcsec, with good images of the ingress and of the egress taken each second. Chinese solar observatories are in the optimal conditions to obtain valuable data for the measurement of the solar diameter with the Venus transit of 5/6 June 2012 with an unprecedented accuracy, and with absolute calibration given by the ephemerides.

  14. Solar activity and conjunctions of Venus

    International Nuclear Information System (INIS)

    Between 1856 and 1954, i.e. during 9 solar cycles, the Wolf numbers were significantly higher at superior conjunctions of Venus than an inferior conjunctions. The role of small isolated spots could be of some importance, but no theoretical explanation for the observed differences has been proposed

  15. Solar Airplane Concept Developed for Venus Exploration

    Science.gov (United States)

    Landis, Geoffrey A.

    2004-01-01

    An airplane is the ideal vehicle for gathering atmospheric data over a wide range of locations and altitudes, while having the freedom to maneuver to regions of scientific interest. Solar energy is available in abundance on Venus. Venus has an exoatmospheric solar flux of 2600 W/m2, compared with Earth's 1370 W/m2. The solar intensity is 20 to 50 percent of the exoatmospheric intensity at the bottom of the cloud layer, and it increases to nearly 95 percent of the exoatmospheric intensity at 65 km. At these altitudes, the temperature of the atmosphere is moderate, in the range of 0 to 100 degrees Celsius, depending on the altitude. A Venus exploration aircraft, sized to fit in a small aeroshell for a "Discovery" class scientific mission, has been designed and analyzed at the NASA Glenn Research Center. For an exploratory aircraft to remain continually illuminated by sunlight, it would have to be capable of sustained flight at or above the wind speed, about 95 m/sec at the cloud-top level. The analysis concluded that, at typical flight altitudes above the cloud layer (65 to 75 km above the surface), a small aircraft powered by solar energy could fly continuously in the atmosphere of Venus. At this altitude, the atmospheric pressure is similar to pressure at terrestrial flight altitudes.

  16. Vesper - Venus Chemistry and Dynamics Orbiter - A NASA Discovery Mission Proposal: Submillimeter Investigation of Atmospheric Chemistry and Dynamics

    Science.gov (United States)

    Chin, Gordon

    2011-01-01

    Vesper conducts a focused investigation of the chemistry and dynamics of the middle atmosphere of our sister planet- from the base of the global cloud cover to the lower thermosphere. The middle atmosphere controls the stability of the Venus climate system. Vesper determines what processes maintain the atmospheric chemical stability, cause observed variability of chemical composition, control the escape of water, and drive the extreme super-rotation. The Vesper science investigation provides a unique perspective on the Earth environment due to the similarities in the middle atmosphere processes of both Venus and the Earth. Understanding key distinctions and similarities between Venus and Earth will increase our knowledge of how terrestrial planets evolve along different paths from nearly identical initial conditions.

  17. Remote Raman - laser induced breakdown spectroscopy (LIBS) geochemical investigation under Venus atmospheric conditions

    Energy Technology Data Exchange (ETDEWEB)

    Clegg, Sanuel M [Los Alamos National Laboratory; Barefield, James E [Los Alamos National Laboratory; Humphries, Seth D [Los Alamos National Laboratory; Wiens, Roger C [Los Alamos National Laboratory; Vaniman, D. T. [Los Alamos National Laboratory; Sharma, S. K. [UNIV OF HAWAII; Misra, A. K. [UNIV OF HAWAII; Dyar, M. D. [MT. HOLYOKE COLLEGE; Smrekar, S. E. [JET PROPULSION LAB.

    2010-12-13

    The extreme Venus surface temperatures ({approx}740 K) and atmospheric pressures ({approx}93 atm) create a challenging environment for surface missions. Scientific investigations capable of Venus geochemical observations must be completed within hours of landing before the lander will be overcome by the harsh atmosphere. A combined remote Raman - LIBS (Laser Induced Breakdown Spectroscopy) instrument is capable of accomplishing the geochemical science goals without the risks associated with collecting samples and bringing them into the lander. Wiens et al. and Sharma et al. demonstrated that both analytical techniques can be integrated into a single instrument capable of planetary missions. The focus of this paper is to explore the capability to probe geologic samples with Raman - LIBS and demonstrate quantitative analysis under Venus surface conditions. Raman and LIBS are highly complementary analytical techniques capable of detecting both the mineralogical and geochemical composition of Venus surface materials. These techniques have the potential to profoundly increase our knowledge of the Venus surface composition, which is currently limited to geochemical data from Soviet Venera and VEGA landers that collectively suggest a surface composition that is primarily tholeiitic basaltic with some potentially more evolved compositions and, in some locations, K-rich trachyandesite. These landers were not equipped to probe the surface mineralogy as can be accomplished with Raman spectroscopy. Based on the observed compositional differences and recognizing the imprecise nature of the existing data, 15 samples were chosen to constitute a Venus-analog suite for this study, including five basalts, two each of andesites, dacites, and sulfates, and single samples of a foidite, trachyandesite, rhyolite, and basaltic trachyandesite under Venus conditions. LIBS data reduction involved generating a partial least squares (PLS) model with a subset of the rock powder standards to quantitatively determine the major elemental abundance of the remaining samples. PLS analysis suggests that the major element compositions can be determined with root mean square errors ca. 5% (absolute) for SiO{sub 2}, Al{sub 2}O{sub 3}, Fe{sub 2}O{sub 3}(total), MgO, and CaO, and ca. 2% or less for TiO{sub 2}, Cr{sub 2}O{sub 3}, MnO, K{sub 2}O, and Na{sub 2}O. Finally, the Raman experiments have been conducted under supercritical CO{sub 2} involving single-mineral and mixed-mineral samples containing talc, olivine, pyroxenes, feldspars, anhydrite, barite, and siderite. The Raman data have shown that the individual minerals can easily be identified individually or in mixtures.

  18. Venus - False Color of Bereghinya Planitia

    Science.gov (United States)

    1992-01-01

    This false color Magellan image shows a portion of Bereghinya Planitia (plains) in the northern hemisphere of Venus, centered at 31 degrees north latitude, 43 degrees east longitude. The area is 260 kilometers (160 miles) wide and 330 kilometers (200 miles) long. This image was produced from Magellan radar data collected in Cycle 2 of the mission. Cycle 2 was completed January 15, 1992. The area was not imaged during the first cycle because of superior conjunction when the sun was between the Earth and Venus, preventing communication with the spacecraft. This image contains examples of several of the major geologic terrains on Venus and illustrates the basic stratigraphy or sequence of geologic events. The oldest terrains appear as bright, highly-fractured or chaotic highlands rising out of the plains. This is seen in the upper right and lower left quadrants of the image. The chaotic highlands, sometimes called tessera, may represent older and thicker crustal material and occupy about 15 percent of the surface of Venus. Plains surround and embay the fractured highland tessera. Plains are formed by fluid volcanic flows that may have once formed vast lava seas which covered all the low lying surfaces. Plains comprise more than 80 percent of the surface of Venus. The most recent activity in the region is volcanism that produced the radar bright flows best seen in the lower right quadrant of the image. The lava flows in this image are associated with the shield volcano Tepev Mons whose summit is near the lower left corner of the image. The flows are similar to the darker plains volcanics, but apparently have more rugged surfaces that more efficiently scatter the radar signal back to the spacecraft. The geologic sequence is early fracturing of the tessera, flooding by extensive plains lavas and scattered, less extensive individual flows on the plains surface. The simulated hues are based on color images recorded by the Soviet Venera 13 and 14 spacecraft.

  19. Venus - False Color of Eistla Regio

    Science.gov (United States)

    1992-01-01

    This false color Magellan image shows a portion of Eistla Regio (region) in the northern hemisphere of Venus, centered at 1 degrees south latitude, 37 degrees east longitude. The area is 440 kilometers (270 miles) wide and 350 kilometers (220 miles) long. This image was produced from Magellan radar data collected in Cycle 2 of the mission. Cycle 2 was completed January 15, 1992. The area was not imaged during the first cycle because of superior conjunction when the sun was between the Earth and Venus, preventing communication with the spacecraft. This image contains examples of several of the major geologic terrains on Venus and illustrates the basic stratigraphy or sequence of geologic events. The oldest terrain appears as bright, highly fractured or chaotic highlands rising out of the plains. This is seen in the right half of the image. The chaotic highlands, sometimes called tessera, may represent older and thicker crustal material and occupy about 15 percent of the surface of Venus. The fractured terrain in this region has a distinctly linear structure with a shear-like pattern. Plains surround and embay the fractured highland tessera. Plains are formed by fluid volcanic flows that may have once formed vast lava seas which covered all the low lying surfaces. Plains comprise more than 80 percent of the surface of Venus. The most recent activity in the region is volcanism that produced the radar bright flows best seen in the upper left quadrant of the image. The flows are similar, in their volcanic origin to the darker plains volcanics, but apparently have more rugged surfaces that more efficiently scatter the radar signal back to the spacecraft. The geologic sequence is early fracturing of the tessera, flooding by extensive plains lavas, and scattered less extensive individual flows on the plains surface. The simulated hues are based on color images recorded by the Soviet Venera 13 and 14 spacecraft.

  20. Communications Transceivers for Venus Surface Missions

    Science.gov (United States)

    Force, Dale A.

    2004-01-01

    The high temperature of the surface of Venus poses many difficulties. Previous Venus landers have only operated for short durations before succumbing to the heat. NASA Glenn Research Center conducted a study on communications for long duration Venus surface missions. I report the findings in this presentation. Current technology allows production of communications transceivers that can operate on the surface of Venus, at temperatures above 450 C and pressures of over 90 atmospheres. While these transceivers would have to be relatively simple, without much of the advanced signal processing often used in modern transceivers, since current and near future integrated circuits cannot operate at such high temperatures, the transceivers will be able to meet the requirements of proposed Venus Surface mission. The communication bands of interest are High Frequency or Very High Frequency (HFNHF) for communication between Venus surface and airborne probes (including surface to surface and air to air), and Ultra High Frequency (UHF) to Microwave bands for communication to orbiters. For HFNHF, transceivers could use existing vacuum tube technology. The packaging of the vacuum tubes may need modification, but the internal operating structure already operates at high temperatures. Using metal vacuum structures instead of glass, allows operation at high pressure. Wide bandgap transistors and diodes may be able to replace some of the thermionic components. VHF communications would be useful for line-of- sight operations, while HF would be useful for short-wave type communications using the Venusian ionosphere. UHF and microwave communications use magnetically focused thermionic devices, such as traveling wave tubes (TWTs), magnetron (M-type) amplifiers, and klystrons for high power amplifiers, and backward wave oscillators (BWOs) and reflex klystrons for oscillators. Permanent magnets are already in use in industry that can operate at 500 C. These magnets could focus electron beam tubes on the surface of Venus. While microwave windows will need to be designed for the high pressure, diamond windows have already been demonstrated, so high-pressure microwave windows can be designed and built. Thus, all of these devices could be useful for Venus surface missions. Current electronic power conditioners to supply the high voltages used in these microwave devices cannot operate at high temperatures, but earlier electronic power conditioners that used vacuum tubes can be modified to work at high temperature. Evaluating the various devices in this study, the M-type traveling wave tube (where a traveling wave structure is used in a crossed-field device, similar to the Amplitron used on the Apollo missions) stood out for the high power amplifier since it requires a single high voltage, simplifying the power supply design. Since the receiver amplifier is a low power amplifier, the loss of efficiency in linear beam devices without a depressed collector (and thus needing a single high voltage) is not important; a low noise TWT is a possible solution. Before solid-state microwave amplifiers were available, such TWTs were built with a 1-2 dB noise figure. A microwave triode or transistor made from a wide bandgap material may be preferable, if available. Much of the development work needed for Venusian communication devices will need to focus on the packaging of the devices, and their connections, but the technology is available to build transceivers that can operate on the surface of Venus indefinitely.

  1. Dynamic compensation of Venus's geoid: A comparison with Earth

    Science.gov (United States)

    Kiefer, W. S.; Hager, B. H.; Richards, M. A.

    1985-01-01

    Unlike Earth, on Venus long wavelength geoid anomalies correlate well with topography. Venus's admittance curve between harmonic degrees 3 and 18 is inconsistent with Airy isostasy but is consistent with dynamic support from convection being the dominant mechanism of compensation on Venus. We model dynamic compensation on Venus using simple flow models which assume a spherically symmetric Newtonian mantle viscosity profile. Preliminary models parameterize the viscosity variation with depth as a 2 layer model with a boundary at 720 km depth. A model in which viscosity in the lower mantle is a factor of 10 lower than in the upper mantle can explain Venus's observed admittance curve for degrees 3 through 18. Dynamic models which include a chemical boundary between the upper and lower mantle do not successfully explain the observed admittance curve, indicating that Venus does not have a chemically layered mantle.

  2. The Structure of the Upper Atmosphere of Venus - New Measurements and Models of the Northern Polar Region

    Science.gov (United States)

    Svedhem, H.; Mueller-Wodarg, I. C.; Rosenblatt, P.

    2011-12-01

    Until recently the only information on the structure of the polar upper atmosphere of Venus available has been based on the reference atmosphere models such as the VTS3 or VIRA models. These models extrapolate the values from low latitudes to high latitudes by using equivalent solar zenith angles. New measurements by Venus Express show that such extrapolations not always give correct results and that there is a general overestimate of the density at high latitudes. These new results have been reached by using two different but related techniques, both using an atmospheric drag effect on the spacecraft. By reducing the pericentre altitude the total mass density in the altitude range 150-200km can be measured in situ by monitoring the orbital decay caused by the drag on the spacecraft by the atmosphere via direct tracking of the Doppler signal on the telecommunication link. Such measurements have been performed with Venus Express several times during the last years as part of the Venus Express Atmospheric Drag Experiment (VExADE). The results indicate a large variability within only a few days and have led to questions if these variations are real or within the uncertainty of the measurements. A completely different and independent measurement is given by monitoring the torque asserted by the atmosphere on the spacecraft. This is done by monitoring the momentum accumulated in the reaction wheels during the pericentre pass and at the same time considering all other perturbing forces. This requires the spacecraft to fly in an asymmetric attitude with respect to the centre of gravity, centre of drag and the velocity vector. This technique has proven very sensitive, in particular if the geometric asymmetry is large, and offers an additional method of measuring atmospheric densities in-situ that previously had not been explored with the Venus Express spacecraft. Similar measurements have been done in the past by Magellan at Venus and by Cassini at Titan. Between 2009 and 2011 several campaigns, with altitudes going as low as 165 km, were held. The highest density measured was 7.7 10-12kg/m3 which is significantly less than earlier models predict. The results largely confirm the density measurements by the VExADE drag measurements and add to the confidence in the results from these measurements. By using these drag and torque results and assuming a hydrostatic diffusive equilibrium atmosphere a new model has been constructed. The model is fitted to the Venus Express remote sensing measurements in the upper mesosphere (VeRa radio occultation data) and lower thermosphere (SpicaV/SOIR data) to give a continuous transition across the different regions.

  3. Venus transit 2004: Illustrating the capability of exoplanet transmission spectroscopy

    OpenAIRE

    Hedelt, P.; Alonso, R.; Brown, T.; Vera, M. Collados; Rauer, H.; Schleicher, H.; W. Schmidt; F. Schreier; Titz, R.

    2011-01-01

    The transit of Venus in 2004 offered the rare possibility to remotely sense a well-known planetary atmosphere using ground-based observations for absorption spectroscopy. Transmission spectra of Venus' atmosphere were obtained in the near infrared using the Vacuum Tower Telescope (VTT) in Tenerife. Since the instrument was designed to measure the very bright photosphere of the Sun, extracting Venus' atmosphere was challenging. CO_2 absorption lines could be identified in the...

  4. Venus - Simulated Color of Leda Planitia

    Science.gov (United States)

    1992-01-01

    This false color Magellan image shows a portion of Leda Planitia (plains) in the northern hemisphere of Venus, centered at 41 degrees north latitude, 52 degrees east longitude. The area is 220 kilometers (135 miles) wide and 275 kilometers (170 miles) long. This image was produced from Magellan radar data collected in Cycle 2 of the mission. Cycle 2 was completed January 15, 1992. The area was not imaged during the first cycle because of superior conjunction when the sun was between the Earth and Venus, preventing communication with the spacecraft. This image contains examples of several of the major geologic terrains on Venus and illustrates the basic stratigraphy or sequence of geologic events. The oldest terrains appear as bright, highly-fractured or chaotic highlands rising out of the plains. This is seen in the upper left, or northwest, quadrant of the image. The chaotic highlands, sometimes called tessera, may represent older and thicker crustal material and occupy about 15 percent of the surface of Venus. The circular ring structure in the lower left of the image is probably an impact crater. This 40 kilometer (25 miles) diameter crater has been given a proposed name, Heloise, after the French physician who lived from about 1098 to 1164 A.D. The crater was formed by the impact of an asteroid sometime before the plains lavas embayed and covered the region. The plains surround and embay the fractured highland tessera. Plains are formed by fluid volcanic flows that may have once formed vast lava seas which covered all the low lying surfaces. Plains comprise more than 80 percent of the surface of Venus. The most recent activity in the region is volcanism that produced the radar bright flows best seen in the upper right quadrant of the image. Those flows are similar to the darker plains volcanics, but apparently have more rugged surfaces that more efficiently scatter the radar signal back to the spacecraft. Thus the geologic sequence is early fracturing of the tessera, flooding by extensive plains lavas and scattered, less extensive individual flows on the plains surface. Impact cratering occurs throughout geologic history and provides a rough estimate of the time scale. Craters larger than a few kilometers in diameter form on Venus, as they do on Earth, at the rate of about one per million years, with smaller impacts much more frequent than larger ones. The simulated hues are based on color images recorded by the Soviet Venera 13 and 14 spacecraft.

  5. Comparison of accelerated ion populations observed upstream of the bow shocks at Venus and Mars

    Directory of Open Access Journals (Sweden)

    M. Yamauchi

    2011-03-01

    Full Text Available Foreshock ions are compared between Venus and Mars at energies of 0.6~20 keV using the same ion instrument, the Ion Mass Analyser, on board both Venus Express and Mars Express. Venus Express often observes accelerated protons (2~6 times the solar wind energy that travel away from the Venus bow shock when the spacecraft location is magnetically connected to the bow shock. The observed ions have a large field-aligned velocity compared to the perpendicular velocity in the solar wind frame, and are similar to the field-aligned beams and intermediate gyrating component of the foreshock ions in the terrestrial upstream region. Mars Express does not observe similar foreshock ions as does Venus Express, indicating that the Martian foreshock does not possess the intermediate gyrating component in the upstream region on the dayside of the planet. Instead, two types of gyrating protons in the solar wind frame are observed very close to the Martian quasi-perpendicular bow shock within a proton gyroradius distance. The first type is observed only within the region which is about 400 km from the bow shock and flows tailward nearly along the bow shock with a similar velocity as the solar wind. The second type is observed up to about 700 km from the bow shock and has a bundled structure in the energy domain. A traversal on 12 July 2005, in which the energy-bunching came from bundling in the magnetic field direction, is further examined. The observed velocities of the latter population are consistent with multiple specular reflections of the solar wind at the bow shock, and the ions after the second reflection have a field-aligned velocity larger than that of the de Hoffman-Teller velocity frame, i.e., their guiding center has moved toward interplanetary space out from the bow shock. To account for the observed peculiarity of the Martian upstream region, finite gyroradius effects of the solar wind protons compared to the radius of the bow shock curvature and effects of cold ion abundance in the bow shock are discussed.

  6. First stage of cosmic expedition Vega: Venus investigations

    International Nuclear Information System (INIS)

    Main results of the first (Venus) stage of the international complex program ''Venus - Halley'' (''Vega'' for short) are presented. The program is aimed at transporting descent space vehicles to the Venus to explore its atmosphere and surface. Then automatic interplanetary stations (AIS) will be directed to the Halley's comet. In June 1985 the descent space vehicles AIS ''Vega-1'' and ''Vega-2'' have landed softly on the Venus surface, aerostat probes have been launched to the planet atmosphere. The design of the descent space vehicle, structure and chemical composition of the atmosphere, ground composition are briefly outlined

  7. Sensitivity of Venus surface emissivity retrieval to model variations of CO2 opacity, cloud features, and deep atmosphere temperature field

    Science.gov (United States)

    Kappel, David; Arnold, Gabriele; Haus, Rainer

    2012-07-01

    The Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) aboard ESA's Venus Express space probe has acquired a wealth of nightside emission spectra from Venus and provides the first global database for systematic atmospheric and surface studies in the IR. The infrared mapping channel (VIRTIS-M-IR) sounds the atmosphere and surface at high spatial and temporal resolution and coverage. Quantitative analyses of data call for a sophisticated radiative transfer simulation model of Venus' atmosphere to be used in atmospheric and surface parameter retrieval procedures that fit simulated spectra to the measured data. The surface emissivity can be retrieved from VIRTIS-M-IR measurements in the transparency windows around 1 ?m, but it is not easy to derive, since atmospheric influences strongly interfere with surface information. There are mainly three atmospheric model parameters that may affect quantitative results of surface emissivity retrievals: CO_2 opacity, cloud features, and deep atmosphere temperature field. The CO_2 opacity with respect to allowed transitions is usually computed by utilizing a suitable line data base and certain line shape models that consider collisional line mixing. Both line data bases and shape models are not well established from measurements under the environmental conditions in the deep atmosphere of Venus. Pressure-induced additional continuum absorption introduces further opacity uncertainties. The clouds of Venus are usually modeled by a four-modal distribution of spherical droplets of about 75% sulfuric acid, where each mode is characterized by a different mean and standard deviation of droplet size distribution and a different initial altitude abundance profile. The influence of possible cloud mode variations on surface emissivity retrieval results is investigated in the paper. Future retrieval procedures will aim at a separation of cloud mode and surface emissivity variations using different atmospheric windows sounded by VIRTIS-M-IR. Another potential source of emissivity uncertainties is due to the deep atmosphere temperature field. It is usually considered to be independent on latitude below 32 km as described by the Venus International Reference Atmosphere (VIRA) model. Remote sensing of temperature fields down to the surface of Venus was never performed till now, and in situ measurements were mainly restricted to low latitudes up to about 30 degrees. Altitudinal and latitudinal deviations from the VIRA deep atmospheric temperature field may occur, however, and are in fact suggested by General Circulation Models. The paper will discuss the impact of the recited atmospheric parameters on the retrieved surface emissivity both in terms of absolute values and uncertainties. We gratefully acknowledge the support from the VIRTIS/Venus Express Team and from DLR, ASI, CNES, CNRS.

  8. Venus-solar wind interaction in a hybrid plasma simulation model

    Science.gov (United States)

    Jarvinen, R.; Kallio, E.; Barabash, S.; Zhang, T. L.; Fedorov, A.; Sillanpää, I.; Janhunen, P.

    2007-08-01

    We present a study of the plasma interaction between Venus and the solar wind. In the study we use a computer simulation model to interpret recerently acquired insitu data by the Venus Express spacecraft. The numerical simulation is based on a 3-dimensional hybrid model, which consists of particle ions, a charge neutralizing massless electron fluid and non-radiative electrodynamics. This arrangement makes it possible to study self-consistently coupled ion kinetics and electromagnetism in a global planetary scale. In the model, the Venusian upper atmosphere and exosphere are modelled as a perfectly conducting ionospheric medium and hydrogen and oxygen photoion production. Given the upstream conditions and the spatial planetary ion distributions the model provides, for example, the escape rates of the atmospheric ion populations and the geometry of the interplanetary magnetic field draped around the planet. Here the model is used to study ion observations from the ASPERA-4 plasma instrument and magnetic field measurements from the MAG magnetometer on Venus Express.

  9. The Venus Transit, the Mayan Calendar and Astronomy Education in Guanajuato, Mexico

    Science.gov (United States)

    Bravo-Alfaro, H.; Caretta, C. A.; Brito, E. M. S.; Campos, P.; Macias, F.

    2015-03-01

    In this work we present two aspects of the Astronomy education activities carried out in 2012 by a multidisciplinary group at Universidad de Guanajuato, including specialists in Astronomy, Social Sciences and Environmental Engineering. The first program linked the Venus Transit, occurred in June 2012, with a national campaign of vulgarization of both modern and ancient (Mayan) Astronomy. Professional astronomers all around the country took advantage of the recent myth linked to the end of a large Mayan calendar cycle (13 baktuns, or some 5125 years) happening, after certain authors, in December 2012. In Guanajuato, the Astronomy Department organized live observations of the Venus Transit at two different locations, and complemented with conferences about astronomical events and the fake predictions of disasters linked to the ``end`` of the Mayan calendar. This program was very successful not only in Guanajuato but throughout the country, with several thousands of people attending live observations, conferences, expositions, etc.

  10. Hybrid modelling of the plasma interaction between Venus and the solar wind

    Science.gov (United States)

    Jarvinen, R.; Barabash, S.; Zhang, T. L.; Sillanpaa, I.; Kallio, E.; Janhunen, P.

    This is a status report of a numerical simulation project to study the plasma interaction between Venus and the solar wind. The 3-dimensional model consists of particle ions, a charge neutralizing massless electron fluid and non-radiative eletrodynamics. This arrangement makes it possible to study self-consistently coupled ion kinetics and electromagnetism in a global planetary scale. In the model, the Venusian upper atmosphere and exosphere are modelled as a perfectly conducting ionospheric medium and hydrogen and oxygen photoion production. Given the upstream conditions and the spatial planetary ion distributions, the model provides, for example, the escape rates of the atmospheric ion populations and the geometry of the interplanetary magnetic field draped around the planet. In this presentation, the model is used to interpret ion observations from the ASPERA-4 plasma instrument and magnetic field measurements from the MAG-magnetometer on Venus Express spacecraft.

  11. Hybrid Modelling Study of the Plasma Interaction Between Venus and the Solar Wind

    Science.gov (United States)

    Jarvinen, R.; Barabash, S.; Zhang, T.; Fedorov, A.; Kallio, E.; Sillanpää, I.; Janhunen, P.

    2006-12-01

    This is a status report of a numerical simulation project to study the plasma interaction between Venus and the solar wind using a quasineutral hybrid model. The 3-dimensional model consists of particle ions, a charge neutralizing massless electron fluid and non-radiative electrodynamics. This arrangement makes it possible to study self-consistently coupled ion kinetics and electromagnetism in a global planetary scale. In the model, the Venusian upper atmosphere and exosphere are modelled as a perfectly conducting ionospheric medium and hydrogen and oxygen photoion production. Given the upstream conditions and the spatial planetary ion distributions the model provides, for example, the escape rates of the atmospheric ion populations and the geometry of the interplanetary magnetic field draped around the planet. Here the model is used to study ion observations from the ASPERA-4 plasma instrument and magnetic field measurements from the MAG- magnetometer on Venus Express spacecraft.

  12. Experimental Reconstruction of Lomonosov's Discovery of Venus's Atmosphere with Antique Refractors During the 2012 Transit of Venus

    OpenAIRE

    Koukarine, Alexandre; Nesterenko, Igor; Petrunin, Yuri; Shiltsev, Vladimir

    2012-01-01

    In 1761, the Russian polymath Mikhail Vasilievich Lomonosov (1711-1765) discovered the atmosphere of Venus during its transit over the Sun's disc. In this paper we report on experimental reenactments of Lomonosov's discovery with antique refractors during the transit of Venus June 5-6, 2012. We conclude that Lomonosov's telescope was fully adequate to the task of detecting the arc of light around Venus off the Sun's disc during ingress or egress if proper experimental techni...

  13. Venus transit, aureole and solar diameter

    Science.gov (United States)

    Xie, Wenbin; Sigismondi, Costantino; Wang, Xiaofan; Tanga, Paolo

    2013-07-01

    The possibility to measure the solar diameter using the transits of Mercury has been exploited to investigate the past three centuries of its evolution and to calibrate these measurements made with satellites. This measurement basically consists to compare the ephemerides of the internal contact timings with the observed timings. The transits of Venus of 2004 and 2012 gave the possibility to apply this method, involving a planet with atmosphere, with the refraction of solar light through it creating a luminous arc all around the disk of the planet. The observations of the 2012 transit made to measure the solar diameter participate to the project Venus Twilight Experiment to study the aureole appearing around it near the ingress/egress phases.

  14. Venus transit, aureole and solar diameter

    CERN Document Server

    Xie, Wenbin; Wang, Xiaofan; Tanga, Paolo

    2012-01-01

    The possibility to measure the solar diameter using the transits of Mercury has been exploited to investigate the past three centuries of its evolution and to calibrate these measurements made with satellites. This measurement basically consists to compare the ephemerides of the internal contact timings with the observed timings. The transits of Venus of 2004 and 2012 gave the possibility to apply this method, involving a planet with atmosphere, with the refraction of solar light through it creating a luminous arc all around the disk of the planet. The observations of the 2012 transit made to measure the solar diameter participate to the project Venus Twilight Experiment to study the aureole appearing around it near the ingress/egress phases.

  15. Venus gravity - A high-resolution map

    Science.gov (United States)

    Reasenberg, R. D.; Goldberg, Z. M.; Macneil, P. E.; Shapiro, I. I.

    1981-01-01

    The Doppler data from the radio tracking of the Pioneer Venus Orbiter (PVO) have been used in a two-stage analysis to develop a high-resolution map of the gravitational potential of Venus, represented by a central mass and a surface mass density. The two-stage procedure invokes a Kalman filter-smoother to determine the orbit of the spacecraft, and a stabilized linear inverter to estimate the surface mass density. The resultant gravity map is highly correlated with the topographic map derived from the PVO radar altimeter data. However, the magnitudes of the gravity variations are smaller than would be expected if the topography were uncompensated, indicating that at least partial compensation has taken place.

  16. La Hieroglyphica y el Nacimiento de Venus

    Directory of Open Access Journals (Sweden)

    González de Zarate, Jesús maría

    2003-09-01

    Full Text Available Sin duda a Botticelli se le debe el honor de ser el primero en pintar cuadros mitológicos monumentales que en tamaño competían con el arte religioso de la época. Entre sus argumentos, los más afamados vienen a ser las dos pinturas (hacia 1478 hoy custodiadas en los Uffizi y que conocemos como La Primavera y el Nacimiento de Venus, fábulas que proceden muy probablemente de la Villa di Castello de la que era propietario Lorenzo de Pierfrancesco, primo de Lorenzo de Médici y mecenas del maestro pintor. Las dos pinturas, como analizan importantes historiadores como Gombrich y Panofsky parecen responder a un concreto programa argumentai de claro sentido platónico y que explican la idea del Amor a través de la Venus Humanitas y la Celestis, es decir, el sentimiento humano y el contemplativo, comportamientos generados por Dios y por lo tanto, buenos en sí mismos…

  17. Changes in Latitude, Changes in Attitude: U. S. Naval Observatory Observations of the Transit of Venus 1874-2012

    Science.gov (United States)

    Bartlett, Jennifer L.; Chester, G.; Bosken, S.; Barron, E. G.

    2013-01-01

    Of the seven transits of Venus for which unambiguous observations exist, four have occurred since the U.S. Naval Observatory (USNO) was established in 1844. With the Transit of Venus Commission, the USNO was heavily involved in observing the December 8, 1874, and December 6, 1882, events to establish an accurate value for the astronomical unit. In the 1960s, radar measurements began providing reliable Solar System distances. Scientific interest in these transits has now moved towards studies of the Venusian atmosphere and understanding transiting extrasolar planets, subjects in which the USNO is less active. In 1874, American Transit of Venus expeditions to Siberia, China, Japan, Tasmania, New Zealand, and the Kerguelen and Chatham Islands returned with 350 photographic plates. The 1882 missions collected 1,487 plates from Washington, DC; Florida; Texas; New Mexico; South Africa; Patagonia; Chile; and New Zealand. From the 1882 photographs, Harkness determined the astronomical unit to be 92,455,000 ± 123,400 miles (148,790,000 ± 198,600 km). On June 8, 2004, and June 5, 2012, the USNO hosted friends and family interested in seeing the transits of Venus. Both events were partially visible from Washington, DC while the Flagstaff station was only able to watch a portion of 2012 transit. The surviving 19th century equipment was returned to service to view this scientific curiosity. In 2012, one 5-inch (0.1-m) Alvan Clark refractor (#856) was able to observe its fourth transit of Venus from Washington despite clouds. Between the two locations, approximately 570 people participated. Other USNO astronomers made personal trips west to Hawaii and Alaska to share the event with the public. In 1882, Harkness mused on the scientific advances that had and would occur between transits of Venus. Like him, we can only wonder “What will be the state of science when the next transit season arrives” on December 11, 2117.

  18. The photogeologic mapping of Northern Venus

    Science.gov (United States)

    Basilevsky, Alexander T.; Burba, G. A.; Ivanov, M. A.; Kryuchkov, V. P.; Pronin, A. A.; Bobina, N. N.; Shashkina, V. P.; Head, J. W.

    1997-03-01

    The present geologic mapping results for Venus at 1:10,000,000 scale have their basis in a photogeological analysis of the images obtained by Magellan. Attention is given to tessera terrian materials, mountain belt materials, materials of densely factured terrains of plains, material of fractured and ridged plains and ridge belts, materials of plains with wrinkle ridges, material of shield as well as smooth and lobate plains, and crater materials.

  19. Solar diameter with 2012 Venus transit

    OpenAIRE

    Sigismondi, Costantino

    2012-01-01

    The role of Venus and Mercury transits is crucial to know the past history of the solar diameter. Through the W parameter, the logarithmic derivative of the radius with respect to the luminosity, the past values of the solar luminosity can be recovered. The black drop phenomenon affects the evaluation of the instants of internal and external contacts between the planetary disk and the solar limb. With these observed instants compared with the ephemerides the value of the sol...

  20. Venus transit, aureole and solar diameter

    OpenAIRE

    Xie, Wenbin; Sigismondi, Costantino; Wang, Xiaofan; Tanga, Paolo

    2012-01-01

    The possibility to measure the solar diameter using the transits of Mercury has been exploited to investigate the past three centuries of its evolution and to calibrate these measurements made with satellites. This measurement basically consists to compare the ephemerides of the internal contact timings with the observed timings. The transits of Venus of 2004 and 2012 gave the possibility to apply this method, involving a planet with atmosphere, with the refraction of solar ...

  1. Electron identification with an upgraded VENUS detector

    International Nuclear Information System (INIS)

    We describe a new method of electron identification using a large cylindrical transition radiation detector together with the central drift chamber and lead glass calorimeter in the VENUS detector system. With this method we have obtained pion suppression factor of 3600 and an electron efficiency of about 70% for isolated tracks. For pions in hadronic jets the suppression factor is 135-700 with an electron efficiency of about 60%. (orig.)

  2. Venus clouds - A dirty hydrochloric acid model.

    Science.gov (United States)

    Hapke, B.

    1972-01-01

    The spectral and polarization data for Venus are consistent with micrometer-sized aerosol cloud particles of hydrochloric acid with soluble and insoluble iron compounds, whose source could be volcanic or crustal dust. The yellow color of the clouds could be due to absorption bands in the near UV involving ferric iron and chlorine complexes. It is pointed out that the UV features could arise from variations in the concentrations of iron and hydrochloric acid in the cloud particles.

  3. Venus tectonics: initial analysis from magellan.

    OpenAIRE

    Solomon, SC; Head, JW; Kaula, WM; D. McKenzie; Parsons, B; Phillips, RJ; Schubert, G.; Talwani, M

    1991-01-01

    Radar imaging and altimetry data from the Magellan mission have revealed a diversity of deformational features at a variety of spatial scales on the Venus surface. The plains record a superposition of different episodes of deformation and volcanism; strain is both areally distributed and concentrated into zones of extension and shortening. The common coherence of strain patterns over hundreds of kilometers implies that many features in the plains reflect a crustal response to mantle dynamic p...

  4. Science-Relevant Curiosity Expression and Interest in Science: An Exploratory Study

    Science.gov (United States)

    Luce, Megan R.; Hsi, Sherry

    2015-01-01

    In efforts to understand and promote long-term interest in science, much work has focused on measuring students' interest in topics of science, typically with surveys. This approach has challenges, as interest in a topic may not necessarily indicate interest in scientific practices and pursuits. An underexplored and perhaps productive way to…

  5. Solar diameter with 2012 Venus transit

    CERN Document Server

    Sigismondi, Costantino

    2012-01-01

    The role of Venus and Mercury transits is crucial to know the past history of the solar diameter. Through the W parameter, the logarithmic derivative of the radius with respect to the luminosity, the past values of the solar luminosity can be recovered. The black drop phenomenon affects the evaluation of the instants of internal and external contacts between the planetary disk and the solar limb. With these observed instants compared with the ephemerides the value of the solar diameter is recovered. The black drop and seeing effects are overcome with two fitting circles, to Venus and to the Sun, drawn in the undistorted part of the image. The corrections of ephemerides due to the atmospheric refraction will also be taken into account. The forthcoming transit of Venus will allow an accuracy on the diameter of the Sun better than 0.01 arcsec, with good images of the ingress and of the egress taken each second. Chinese solar observatories are in the optimal conditions to obtain valuable data for the measurement ...

  6. Venus tectonics: initial analysis from magellan.

    Science.gov (United States)

    Solomon, S C; Head, J W; Kaula, W M; McKenzie, D; Parsons, B; Phillips, R J; Schubert, G; Talwani, M

    1991-04-12

    Radar imaging and altimetry data from the Magellan mission have revealed a diversity of deformational features at a variety of spatial scales on the Venus surface. The plains record a superposition of different episodes of deformation and volcanism; strain is both areally distributed and concentrated into zones of extension and shortening. The common coherence of strain patterns over hundreds of kilometers implies that many features in the plains reflect a crustal response to mantle dynamic processes. Ridge belts and mountain belts represent successive degrees of lithospheric shortening and crustal thickening; the mountain belts also show widespread evidence for extension and collapse both during and following crustal compression. Venus displays two geometrical patterns of concentrated lithospheric extension: quasi-circular coronae and broad rises with linear rift zones; both are sites of significant volcanism. No long, large-offset strike-slip faults have been observed, although limited local horizontal shear is accommodated across many zones of crustal shortening. In general, tectonic features on Venus are unlike those in Earth's oceanic regions in that strain typically is distributed across broad zones that are one to a few hundred kilometers wide, and separated by stronger and less deformed blocks hundreds of kilometers in width, as in actively deforming continental regions on Earth. PMID:17769277

  7. Schumann Resonances Seen in the Venus Ionosphere: Possible Probes of Venus Interior

    Science.gov (United States)

    Russell, C. T.; Hart, R.; Strangeway, R. J.; Zhang, T. L.

    2012-09-01

    Schumann resonances are wave paths that circle the globe bouncing between the conducting surface or interior of a planet and its ionosphere. On Earth, these resonances start at about 7 Hz. We see apparent resonance bands in the Venus ionosphere but at these frequencies are not clearly at the Schumann resonant frequencies. This could be due to the different reflection depth of the Venus interior, but we do not yet have sufficient events to determine if this is the cause of the frequency shift. We will continue to search for new events.

  8. Infrared radiometer for the Pioneer Venus orbiter. 1: Instrument description

    International Nuclear Information System (INIS)

    An IR remote sensing instrument, similar in principle to some of those on terrestrial meteorological satellites, was flown to Venus on board the Pioneer Venus orbiter. Observations of the atmosphere were made from 5 December 1978 until 14 February 1979, during seventy-two orbits of the planet. The optical techniques employed and the design and implementation of the instrument are described

  9. Critical experiments: Recent and future international programmes in VENUS

    International Nuclear Information System (INIS)

    This paper outlines the outstanding measurement capabilities of the VENUS critical facility, by giving examples of validation calculations against the two experimental databases VIPEX and VIPO. Then, the two future programmes, called REBUS-BWR and VIPOX, are investigated by calculation. The paper ends by prospecting other possible projects with VENUS. (author)

  10. Giant radiating dyke swarms on Earth and Venus

    Science.gov (United States)

    Ernst, R. E.; Head, J. W.; Parfitt, E.; Grosfils, E.; Wilson, L.

    1995-09-01

    Concentrations of dykes of basic composition emplaced in the same igneous episode or along similar trends are known as mafic dyke swarms and they occur in a wide variety of environments and over a wide range of scales on Earth. Recent radar mapping of Venus has revealed families of linear features interpreted to be the surface expression of near-surface dyke swarms. The lack of significant erosion on Venus provides a view of the surface manifestation of dyke swarm emplacement, one which complements the terrestrial perspective of erosion to deeper levels. The goal of this review is to synthesize the information available on both planets in order to use the complementary and synergistic record of mafic dyke swarm emplacement to build toward a better understanding of this important phenomenon in planetary history. We focus on the formation and evolution of giant dyke swarms which cover tens to hundreds of thousands of square kilometres on both Earth and Venus. Mafic dyke swarms on Earth occur in a wide range of modes and are observed in environments ranging from volcanic edifices (e.g., Hawaii), to central complexes (e.g., Spanish Peaks Complex, USA; Ramon Swarm, Israel), spreading centres and ophiolite complexes, compressional plate boundaries in back-arc settings (Columbia River Basalts, USA) and in continent-continent collisions. One of the most impressive modes of occurrence is that linked to the formation and evolution of mantle plumes. Terrestrial examples include a giant radiating swarm covering 100° of azimuth (the Mackenzie swarm, Canada), a 360° giant radiating swarm (the Central Atlantic reconstructed swarm), deformed giant radiating swarms (the Matachewan swarm, Canada), rift-arm associated swarms (e.g., Grenville swarm, Canada; Yakutsk swarm, Siberia), and one consisting of widely separated dykes (e.g., the Abitibi swarm, Canada). We summarize the geometric, chemical and isotopic characteristics of terrestrial dyke swarms, including their size and geometry, ages, presence and absence of subswarms, and the relation between swarms of different ages. We also summarize the characteristics of individual dykes, examining dyke length and continuity, en echelon offsets, dyke bifurcation, dyke height, width and depth, dyke intrusion and cooling history, and evidence for flow directions. On Venus at least 163 large radiating lineament systems (radius generally > 100 km) composed of graben, fissure and fracture elements have been identified. On the basis of their structure, plan view geometry and volcanic associations, the radial elements of more than 70% of these are interpreted to have formed primarily through subsurface dyke swarm emplacement, with the remainder forming through uplift or some combination of these two mechanisms. These systems are essentially uneroded and provide a view of the surface characteristics of giant radial swarms prior to the erosion which commonly occurs on Earth. The individual graben, fissures and fractures of which the systems are composed are typically less than several kilometres in width and cluster near the centre, with fissures grading smoothly into fractures at greater distances to define the overall radial pattern. While the largest systems, like those on Earth, are thousands of kilometres in radius, the population average is about 325 km, and they generally do not extend to equal lengths in all directions. In their distal regions, however, the elements in 72% of the systems continue along a purely radial trend, while distal elements in the remaining 28% curve gradually into unidirectional, sub-parallel geometries, generally interpreted to be related to regional stress patterns. The radial systems have a strong association with volcanism; all but seven display some form of volcanic signature. A review of models of the emplacement of lateral dykes from magma chambers under constant (buffered) driving pressure conditions and declining (unbuffered) driving pressure conditions indicates that the two pressure scenarios lead to distinctly different styles of dyke emplacement. Emplac

  11. Possible chemical impact of planetary lightning in the atmospheres of Venus and Mars

    International Nuclear Information System (INIS)

    The implications for atmospheric chemistry of lightning on Venus and Mars are discussed. It is found that lightning, if present, may produce CO, O2, NO and O in the atmospheres of Venus and Mars. Calculations for lightning on Venus indicate that this process could conceivably influence the atmospheric nitrogen budget and the sulphur chemistry that maintains the Venus cloud layers. (U.K.)

  12. Venus transit 2004: Illustrating the capability of exoplanet transmission spectroscopy

    Science.gov (United States)

    Hedelt, P.; Alonso, R.; Brown, T.; Collados Vera, M.; Rauer, H.; Schleicher, H.; Schmidt, W.; Schreier, F.; Titz, R.

    2011-09-01

    The transit of Venus in 2004 offered the rare possibility to remotely sense a well-known planetary atmosphere using ground-based absorption spectroscopy. Transmission spectra of Venus' atmosphere were obtained in the near infrared using the Vacuum Tower Telescope (VTT) in Tenerife. Since the instrument was designed to measure the very bright photosphere of the Sun, extracting Venus' atmosphere was challenging. We were able to identify CO2 absorption lines in the upper Venus atmosphere. Moreover, the relative abundance of the three most abundant CO2 isotopologues could be determined. The observations resolved Venus' limb, showing Doppler-shifted absorption lines that are probably caused by high-altitude winds. We demonstrate the utility of ground-based measurements in analyzing the atmospheric constituents of a terrestrial planet atmosphere using methods that might be applied in future to terrestrial extrasolar planets.

  13. Venus transit 2004: Illustrating the capability of exoplanet transmission spectroscopy

    CERN Document Server

    Hedelt, P; Brown, T; Vera, M Collados; Rauer, H; Schleicher, H; Schmidt, W; Schreier, F; Titz, R

    2011-01-01

    The transit of Venus in 2004 offered the rare possibility to remotely sense a well-known planetary atmosphere using ground-based observations for absorption spectroscopy. Transmission spectra of Venus' atmosphere were obtained in the near infrared using the Vacuum Tower Telescope (VTT) in Tenerife. Since the instrument was designed to measure the very bright photosphere of the Sun, extracting Venus' atmosphere was challenging. CO_2 absorption lines could be identified in the upper Venus atmosphere. Moreover, the relative abundance of the three most abundant CO_2 isotopologues could be determined. The observations resolved Venus' limb, showing Doppler-shifted absorption lines that are probably caused by high-altitude winds. This paper illustrates the ability of ground-based measurements to examine atmospheric constituents of a terrestrial planet atmosphere which might be applied in future to terrestrial extrasolar planets.

  14. Venus, Mars, and the ices on Mercury and the moon: astrobiological implications and proposed mission designs.

    Science.gov (United States)

    Schulze-Makuch, Dirk; Dohm, James M; Fairén, Alberto G; Baker, Victor R; Fink, Wolfgang; Strom, Robert G

    2005-12-01

    Venus and Mars likely had liquid water bodies on their surface early in the Solar System history. The surfaces of Venus and Mars are presently not a suitable habitat for life, but reservoirs of liquid water remain in the atmosphere of Venus and the subsurface of Mars, and with it also the possibility of microbial life. Microbial organisms may have adapted to live in these ecological niches by the evolutionary force of directional selection. Missions to our neighboring planets should therefore be planned to explore these potentially life-containing refuges and return samples for analysis. Sample return missions should also include ice samples from Mercury and the Moon, which may contain information about the biogenic material that catalyzed the early evolution of life on Earth (or elsewhere). To obtain such information, science-driven exploration is necessary through varying degrees of mission operation autonomy. A hierarchical mission design is envisioned that includes spaceborne (orbital), atmosphere (airborne), surface (mobile such as rover and stationary such as lander or sensor), and subsurface (e.g., ground-penetrating radar, drilling, etc.) agents working in concert to allow for sufficient mission safety and redundancy, to perform extensive and challenging reconnaissance, and to lead to a thorough search for evidence of life and habitability. PMID:16379531

  15. Advanced Stirling Duplex Materials Assessment for Potential Venus Mission Heater Head Application

    Science.gov (United States)

    Ritzert, Frank; Nathal, Michael V.; Salem, Jonathan; Jacobson, Nathan; Nesbitt, James

    2011-01-01

    This report will address materials selection for components in a proposed Venus lander system. The lander would use active refrigeration to allow Space Science instrumentation to survive the extreme environment that exists on the surface of Venus. The refrigeration system would be powered by a Stirling engine-based system and is termed the Advanced Stirling Duplex (ASD) concept. Stirling engine power conversion in its simplest definition converts heat from radioactive decay into electricity. Detailed design decisions will require iterations between component geometries, materials selection, system output, and tolerable risk. This study reviews potential component requirements against known materials performance. A lower risk, evolutionary advance in heater head materials could be offered by nickel-base superalloy single crystals, with expected capability of approximately 1100C. However, the high temperature requirements of the Venus mission may force the selection of ceramics or refractory metals, which are more developmental in nature and may not have a well-developed database or a mature supporting technology base such as fabrication and joining methods.

  16. Venus high temperature atmospheric dropsonde and extreme-environment seismometer (HADES)

    Science.gov (United States)

    Boll, Nathan J.; Salazar, Denise; Stelter, Christopher J.; Landis, Geoffrey A.; Colozza, Anthony J.

    2015-06-01

    The atmospheric composition and geologic structure of Venus have been identified by the US National Research Council's Decadal Survey for Planetary Science as priority targets for scientific exploration; however, the high temperature and pressure at the surface, along with the highly corrosive chemistry of the Venus atmosphere, present significant obstacles to spacecraft design that have severely limited past and proposed landed missions. Following the methodology of the NASA Innovative Advanced Concepts (NIAC) proposal regime and the Collaborative Modeling and Parametric Assessment of Space Systems (COMPASS) design protocol, this paper presents a conceptual study and initial feasibility analysis for a Discovery-class Venus lander capable of an extended-duration mission at ambient temperature and pressure, incorporating emerging technologies within the field of high temperature electronics in combination with novel configurations of proven, high Technology Readiness Level (TRL) systems. Radioisotope Thermal Power (RTG) systems and silicon carbide (SiC) communications and data handling are examined in detail, and various high-temperature instruments are proposed, including a seismometer and an advanced photodiode imager. The study combines this technological analysis with proposals for a descent instrument package and a relay orbiter to demonstrate the viability of an integrated atmospheric and in-situ geologic exploratory mission that differs from previous proposals by greatly reducing the mass, power requirements, and cost, while achieving important scientific goals.

  17. Venus High Temperature Atmospheric Dropsonde and Extreme-Environment Seismometer (HADES)

    Science.gov (United States)

    Boll, Nathan J.; Salazar, Denise; Stelter, Christopher J.; Landis, Geoffrey A.; Colozza, Anthony J.

    2014-01-01

    The atmospheric composition and geologic structure of Venus have been identified by the US National Research Council's Decadal Survey for Planetary Science as priority targets for scientific exploration, however the high temperature and pressure at the surface, along with the highly corrosive chemistry of the Venus atmosphere, present significant obstacles to spacecraft design that have severely limited past and proposed landed missions. Following the methodology of the NASA Innovative Advanced Concepts (NIAC) proposal regime and the Collaborative Modeling and Parametric Assessment of Space Systems (COMPASS) design protocol, this paper presents a conceptual study and initial feasibility analysis for a Discovery-class Venus lander capable of an extended-duration mission at ambient temperature and pressure, incorporating emerging technologies within the field of high temperature electronics in combination with novel configurations of proven, high Technology Readiness Level (TRL) systems. Radioisotope Thermal Power (RTG) systems and silicon carbide (SiC) communications and data handling are examined in detail, and various high-temperature instruments are proposed, including a seismometer and an advanced photodiode imager. The study combines this technological analysis with proposals for a descent instrument package and a relay orbiter to demonstrate the viability of an integrated atmospheric and in-situ geologic exploratory mission that differs from previous proposals by greatly reducing the mass, power requirements, and cost, while achieving important scientific goals.

  18. Local and Global Waters on Venus and Earth: Poor Planetary Supply on Venus

    Science.gov (United States)

    Miura, Y.; Tanosaki, T.

    2015-04-01

    Global materials of rock, air and water can found in the inner solar system. Local water can be formed by mixing to the rocks, whereas global water found only Earth is required huge supply from two planets. Venus has no mixed source of global water.

  19. Counting Gene Expression in Single Cells to Identify Stem Cells | Physical Sciences in Oncology

    Science.gov (United States)

    Using a technique that can track the expression of multiple genes in a single cell, a team of investigators from the Massachusetts Institute of Technology (MIT) and the Royal Netherlands Academy of Arts and Sciences have demonstrated that they can identify and track individual stem cells from fixed samples of intestinal tissues. The researchers believe that this approach will be useful for studying the role of stem cells in the development of cancer.

  20. HIGH-RESOLUTION SATELLITE IMAGING OF THE 2004 TRANSIT OF VENUS AND ASYMMETRIES IN THE CYTHEREAN ATMOSPHERE

    International Nuclear Information System (INIS)

    This paper presents the only space-borne optical-imaging observations of the 2004 June 8 transit of Venus, the first such transit visible from Earth since AD 1882. The high-resolution, high-cadence satellite images we arranged from NASA's Transition Region and Coronal Explorer (TRACE) reveal the onset of visibility of Venus's atmosphere and give further information about the black-drop effect, whose causes we previously demonstrated from TRACE observations of a transit of Mercury. The atmosphere is gradually revealed before second contact and after third contact, resulting from the changing depth of atmospheric layers refracting the photospheric surface into the observer's direction. We use Venus Express observations to relate the atmospheric arcs seen during the transit to the atmospheric structure of Venus. Finally, we relate the transit images to current and future exoplanet observations, providing a sort of ground truth showing an analog in our solar system to effects observable only with light curves in other solar systems with the Kepler and CoRoT missions and ground-based exoplanet-transit observations.

  1. The Ideal Science Lesson (Views Expressed by Pupils Participating in a Science Extension Course).

    Science.gov (United States)

    Endean, Lou; George, David

    1983-01-01

    The article summarizes methodology and results of tests given to 30 13-year-old students who were nominated by their six schools as scientifically talented, for a summer science enrichment course at Nene College, England. Reported are children's ideas about the "ideal" classroom, the "ideal" teacher, and the "ideal" school. (Author/MC)

  2. Analysis of VENUS-3 benchmark experiment

    International Nuclear Information System (INIS)

    The paper presents the revision and the analysis of VENUS-3 benchmark experiment performed at CEN/SCK, Mol (Belgium). This benchmark was found to be particularly suitable for validation of current calculation tools like 3-D neutron transport codes, and in particular of the 3D sensitivity and uncertainty analysis code developed within the EFF project. The compilation of the integral experiment was integrated into the SINBAD electronic data base for storing and retrieving information about the shielding experiments for nuclear systems. SINBAD now includes 33 reviewed benchmark descriptions and several compilations waiting for the review, among them many benchmarks relevant for pressure vessel dosimetry system validation.(author)

  3. Venus - Multi-Floor Irregular Crater

    Science.gov (United States)

    1991-01-01

    This Magellan image shows an irregular crater of approximately 14- kilometer (8.7-mile) mean diameter. The crater is actually a cluster of four separate craters that are in rim contact. The noncircular rims and multiple, hummocky floors are probably the result of the breakup and dispersion of an incoming meteoroid during passage through the dense Venusian atmosphere. After breaking up, the meteoroid fragments impacted nearly simultaneously, creating the crater cluster. The area shown is 40 kilometers (25 miles) in width and 76 kilometers (47 miles) in length, it is centered at -21.4 degrees latitude, 335.2 degrees longitude in the northern Lavinia Region of Venus.

  4. On the induced magnetosphere of the Venus

    International Nuclear Information System (INIS)

    Numerical simulation of solar wind interaction with the Venus ionosphere is carried out. The calculation of distributing concentration and plasma current lines of the solar wind in the transition part and ionosphere in equatorial and meridional planes is given. Data on distributing magnetic field modulus in the equatorial plane and magnetic power line configuration in the meridional plane are presented. A substantial magnetic field is shown to be excited on the ionopause while the ionosphere is flowed about by the solar wind. The magnetic field amplitude on the ionopause surpasses interplanetary magnetic field amplitude by 2-10 times. Solar wind ions penetrate into the ionosphere at the depth of the gyroradius order

  5. Mars, Venus and Gray: Gender Communication

    OpenAIRE

    Kamarul Zaman Ahmad; Kalaiselvee Rethinam

    2010-01-01

    This research tests the propositions relating to gender communication by Gray (1992) in his book titled “Men are from Mars, Women are from Venus” This book has been the source of gender-related controversy since its publication. The sample consisted of 182 executives and non-executives (73 males and 109 females). T-test results show that out of 23 statements made by Gray (1992), only 8 were supported, 10 were not supported and 5 were actually true for the opposite gender. This research is...

  6. Venus - Stereoscopic Images of Volcanic Domes

    Science.gov (United States)

    1991-01-01

    This Magellan image depicts a stereoscopic pair of an area on Venus with small volcanic domes. Stereoscopic images of Venus offer exciting new possibilities for scientific analysis of Venusian landforms, such as the domes shown here, impact craters, graben -- long rifts bounded by faults -- and other geologic features. Stereopsis, or a three-dimensional view of this scene, may be obtained by viewing with a stereoscope. One may also cut this photograph into two parts and look at the left image with the left eye and the right image with the right eye; conjugate images (the same features) should be about 5 centimeters (2 inches) apart when viewing. This area is located at 38.4 degrees south latitude and 78.3 degrees east longitude. The incidence, or look, angle of the left image is 28.5 degrees and that of the right image is 15.6 degrees. Radar illumination for both images comes from the left. A small dome at left center is about 140 meters (464 feet) high and 6 kilometers (3.7 miles) wide. Other domes with smaller relief can be perceived in three dimensions. At the smaller incidence angle used to acquire the image on the right, radar brightness is more sensitive to small changes in topography. This enhances the visibility of many of the domes in this scene.

  7. Comparative plasma tails of Venus and comets

    International Nuclear Information System (INIS)

    A review of current models of solar wind flow in the plasma tails of weakly magnetized bodies is presented. Measurements conducted by the Mariner 5 spacecraft, the Veneras 9 and 10, and the PVO orbiters, in the Venus tail, and with the ICE spacecraft in the tail of Comet Giacobini-Zinner, reveal common plasma properties which suggest that similar physical processes are operative. Most notable is the observation of decreased flow velocities and enhanced plasma temperatures in the vicinity of their plasma tails. In Venus, the measured velocity and temperature fields are consistent with the effects of frictional forces between the mass-loaded ionosheath flow and the ionosphere along the (magnetic) polar regions of the ionopause. It is argued that similar conditions exist at a cometary ionopause and that the distribution of magnetic fluxes in a cometary tail is controlled by the entry of plasma fluxes from the (magnetic) polar regions of the comet's ionospheric obstacle. This question is further addressed in connection with the two-step shape of the magnetic profile measured across the tail of the comet. It is suggested that the low intensity outer increases of the magnetic lobes are associated with the draping of the interplanetary magnetic field lines around the comet's ionospheric obstacle, and that the higher intensity increases seen in the inner regions of the magnetic lobes are due to an additional compression of magnetic fluxes produced by the entry of plasma partiuxes produced by the entry of plasma particles into the tail

  8. Comparing Characteristics of Polygonal Impact Craters on Mercury and Venus

    International Nuclear Information System (INIS)

    Full text: Polygonal impact craters (PICs) are defined as craters, which rims are composed of at least two straight segments. These PICs are often found on terrestrial planets like Mercury, Venus, and Mars and on the Moon. In our current study we compare characteristics of PICs: the numbers, the mean diameters, and the PICs' ages on Mercury and Venus. The surfaces of both planets show significant differences in age - Mercury’s surface is about 4.5 Gyr, but Venus' not more than 1 Gyr old. The age of polygonal impact craters correspond to this difference. (author)

  9. Croconic acid - An absorber in the Venus clouds?

    International Nuclear Information System (INIS)

    The absorbing species responsible for the UV cloud features and pale yellow hue of the Venus clouds is presently suggested to be the carbon monoxide-polymer croconic acid, which strongly absorbs in the blue and near-UV. Laboratory absorption-coefficient measurements of a dilute solution of croconic acid in sulfuric acid are used as the bases of cloud-scattering models; the Venus planetary albedo's observed behavior in the blue and near-UV are noted to be qualitatively reproduced. Attention is given to a plausible croconic acid-production mechanism for the Venus cloudtop region. 34 references

  10. Geology of the Venus equatorial region from Pioneer Venus radar imaging

    International Nuclear Information System (INIS)

    The surface characteristics and morphology of the equatorial region of Venus were first described by Masursky et al. who showed this part of the planet to be characterized by two topographic provinces, rolling plains and highlands, and more recently by Schaber who described and interpreted tectonic zones in the highlands. Using Pioneer Venus (PV) radar image data (15 deg S to 45 deg N), Senske and Head examined the distribution, characteristics, and deposits of individual volcanic features in the equatorial region, and in addition classified major equatorial physiographic and tectonic units on the basis of morphology, topographic signature, and radar properties derived from the PV data. Included in this classification are: plains (undivided), inter-highland tectonic zones, tectonically segmented linear highlands, upland rises, tectonic junctions, dark halo plains, and upland plateaus. In addition to the physiographic units, features interpreted as coronae and volcanic mountains have also been mapped. The latter four of the physiographic units along with features interpreted to be coronae

  11. Position and shape of the Venus bow shock: Pioneer Venus Orbiter observations

    International Nuclear Information System (INIS)

    In this study magnetometer data from the Poineer Venus Orbiter is used to examine the position and shape of this planet's bow shock. Utilizing crossings identified on 86 occasions during the first 65 orbits a mean shock surface is defined for sun-Venus-satellite angles of 60--110 0. Both the shock shape and variance in location are found to be very similar to the terrestrial case for the range in SVS angle considered. However, while the spread in shock positions at the earth is due predominantly to the magnetopause location varying in response to solar wind dynamic pressure, ionopause altitude variations can have little effect on total obstacle radius. Thus, the Cytherean shock is sometimes observed much closer to or farther from the planet than previously predicted by gasdynamic theory applied to the deflection of flow about a blunt body which acts neither as source nor sink for any portion of the flow

  12. Experimental reconstruction of Lomonosov's discovery of Venus's atmosphere with antique refractors during the 2012 transit of Venus

    Science.gov (United States)

    Koukarine, A.; Nesterenko, I.; Petrunin, Yu.; Shiltsev, V.

    2013-11-01

    In 1761, the Russian polymath Mikhail Vasilievich Lomonosov (1711-1765) discovered the atmosphere of Venus during its transit over the Sun's disc. In this paper we report on experimental reenactments of Lomonosov's discovery with antique refractors during the transit of Venus June 5-6, 2012. We conclude that Lomonosov's telescope was fully adequate to the task of detecting the arc of light around Venus off the Sun's disc during ingress or egress provided proper experimental techniques as described by Lomonosov in his 1761 report are employed.

  13. Experimental Reconstruction of Lomonosov's Discovery of Venus's Atmosphere with Antique Refractors During the 2012 Transit of Venus

    CERN Document Server

    Koukarine, Alexandre; Petrunin, Yuri; Shiltsev, Vladimir

    2012-01-01

    In 1761, the Russian polymath Mikhail Vasilievich Lomonosov (1711-1765) discovered the atmosphere of Venus during its transit over the Sun's disc. In this paper we report on experimental reenactments of Lomonosov's discovery with antique refractors during the transit of Venus June 5-6, 2012. We conclude that Lomonosov's telescope was fully adequate to the task of detecting the arc of light around Venus off the Sun's disc during ingress or egress if proper experimental techniques as described by Lomonosov in his 1761 report are employed.

  14. Chinese records of the 1874 transit of Venus

    Science.gov (United States)

    Lu, Lingfeng; Li, Huifang

    2013-03-01

    Before the advent of radar, transits of Venus were very important for measuring the distance between the Earth and the Sun. A transit occurred in 1874, and was visible from China, other parts of east and southeast Asia and from India, Australia and New Zealand and certain islands in the Indian and Pacific Oceans. As a result, many astronomers from Western countries came to China to observe it. According to traditional Chinese astrology, the Sun represented the Emperor, and if the Sun was invaded by other astronomical bodies it meant that the Emperor and the country faced some ominous disaster. In the late nineteenth century, Western astronomical knowledge was widely translated into Chinese and spread among Chinese intellectuals, so the 1874 transit supposedly was easily understood by Chinese intellectuals. Before the transit took place, various Chinese publications introduced this kind of celestial event as science news, but at the same time other influential newspapers and journals discussed the astrological connection between the transit and the fortunes of the nation. In this paper we review these interesting Chinese records and discuss the different attitudes towards the transit exhibited by Chinese intellectuals and officials, during a period when Western learning was being widely disseminated throughout China.

  15. DRAGON analysis of the Venus-2 Mox benchmark

    International Nuclear Information System (INIS)

    Before large quantities of plutonium can be used in a systematic way in power reactors, there is a need to assess the quality of the basic nuclear data and of the calculation methods that are used for the safety analysis of reactors under such operating conditions. In order to achieve this goal the NEA Nuclear Science Committee has proposed a 2-dimensional (2-D) and a 3-dimensional (3-D) MOX benchmarks, based on VENUS-2 core measurements. This benchmark has been analyzed with various codes using deterministic (method of characteristics and collision probability method) or Monte Carlo methods. Here, we report the results of our analysis using the code DRAGON with an ENDF/B-V based cross section library. We show that in general DRAGON performs as well as most codes for the 2-D transport calculations. As expected, much larger errors are observed for the 3-D core calculations due to the fact that DRAGON can only perform coarse mesh calculations in these cases. (authors)

  16. Using the Glenn Extreme Environments Rig (GEER) for Venus Research

    Science.gov (United States)

    Vento, D. M.; Kremic, T.; Nakley, L. M.

    2015-04-01

    The Glenn Extreme Environments Rig (GEER) has the capability to simulate the Venus atmosphere chemistry, temperature and pressure anywhere from the surface to about 70 km. GEER can provide a CO2/N2 with six trace gasses plus water.

  17. Thermal Management System for Long-Lived Venus Landers Project

    National Aeronautics and Space Administration — Long-lived Venus landers require power and cooling. Heat from the roughly 64 General Purpose Heat Source (GPHS) modules must be delivered to the convertor with...

  18. Venus Nomenclature 2002: New Names and the Website's Changed Look

    Science.gov (United States)

    Burba, G. A.; Blue, J.; Marov, M. Ya.; Stofan, E. R.; Soltesz, T.

    2003-03-01

    34 new names of 10 generic types have been introduced for the features on the planet Venus in 2002. The list of the new names is provided. The advanced features of the renewed online Gazetteer of Planetary Nomenclature are described.

  19. Rift Stability and Localization in Devana Chasma, Venus

    Science.gov (United States)

    Martone, A. A.; Montési, L. G. J.

    2015-05-01

    The rift zone of Devana Chasma greatly resembles Earth's rift zones, especially the East African Rift, despite the lack of global plate tectonics. The stability of rifts on Venus will be characterized, and will include lithosphere weakening processes.

  20. Rheology, tectonics, and the structure of the Venus lithosphere

    Science.gov (United States)

    Zuber, M. T.

    1994-01-01

    Given the absence of ground truth information on seismic structure, heat flow, and rock strength, or short wavelength gravity or magnetic data for Venus, information on the thermal, mechanical and compositional nature of the shallow interior must be obtained by indirect methods. Using pre-Magellan data, theoretical models constrained by the depths of impact craters and the length scales of tectonic features yielded estimates on the thickness of Venus' brittle-elastic lithosphere and the allowable range of crustal thickness and surface thermal gradient. The purpose of this study is to revisit the question of the shallow structure of Venus based on Magellan observations of the surface and recent experiments that address Venus' crustal rheology.

  1. VISAR: A Next Generation Inteferometric Radar for Venus Exploration

    Science.gov (United States)

    Hensley, S.; Smrekar, S.; Shaffer, S.; Paller, M.; Figueroa, H.; Freeman, A.; Hodges, R.; Walkemayer, P.

    2015-04-01

    The VERITAS Mission is a proposed mission to Venus designed to obtain high resolution imagery and topography of the surface using an X-band radar configured as a single pass radar interferometer coupled with a multispectral NIR mapping capability.

  2. Harsh Environment Gas Sensor Array for Venus Atmospheric Measurements Project

    National Aeronautics and Space Administration — Makel Engineering and the Ohio State University propose to develop a harsh environment tolerant gas sensor array for atmospheric analysis in future Venus missions....

  3. Thermoacoustic Duplex Technology for Cooling and Powering a Venus Lander

    Science.gov (United States)

    Walker, A. R.; Haberbusch, M. S.; Sasson, J.

    2015-04-01

    A Thermoacoustic Stirling Heat Engine (TASHE) is directly coupled to a Pulse Tube Refrigerator (PTR) in a duplex configuration, providing simultaneous cooling and electrical power, thereby suiting the needs of a long-lived Venus lander.

  4. VENUS-7 plutonium recycling benchmark, results of AREVA NP

    International Nuclear Information System (INIS)

    Solutions for the NBA VENUS-7 plutonium recycling benchmark are presented in this paper. Various few-group 3D transport calculations were performed with pin cell homogenized cross sections, mostly generated by CASMO-4 ('L-Lib' based on ENDF/B data). In addition, also 2D solutions with a finer energy group structure are presented. In general the calculated reactivity effects agree well with the measured ones. A comparison with other VENUS configurations indicates that the reactivity of the MOX pins with Inconel 800 cladding seems to be slightly under-estimated. The calculated fission rates in the VENUS-7/1 configurations show good agreement with the measured fission rate traverses. This is also confirmed by a VENUS-9/0 analysis where preliminary measured fission rate data were available also at the water reflector, displaying the strong peaking at this reflector boundary. (authors)

  5. The evolution of hotspots on Earth and Venus

    International Nuclear Information System (INIS)

    Full text: Selected hotspots on Earth and Venus, sister planet to Earth due to similarities in size, gravity and bulk composition, are analyzed. Despite those similarities, several differences, such as the lack of water, the absence of plate tectonics, and a low degree of erosion affect Venusian mantle plumes with respect to their structure and dimension, their surface manifestation and their role in the heat budget of the planet Venus. Special attention will be paid to the magmatic output over the time. (author)

  6. The multistring model VENUS for ultrarelativistic heavy ion collisions

    International Nuclear Information System (INIS)

    The event generator VENUS is based on a multistring model for heavy ion collisions at ultrarelativistic energies. The model is a straightforward extension of a successful model for soft proton-proton scattering, the latter one being consistent with e/sup /plus//e/sup /minus// annihilation and deep inelastic lepton scattering. Comparisons of VENUS results with pA and recent AA data alow some statements about intranuclear cascading. 18 refs., 7 figs

  7. The 'Venus' of Laussel in the Light of Ethnomusicology

    OpenAIRE

    Huyge, D.

    1991-01-01

    De Venus of "Dame ? la corne" van Laussel werd in 1911 gevonden door G. Lalanne in de "Grand Abri de Laussel" (Dordogne, Fr.). Dit bas-relief wordt aanzien als een van de belangrijke voorbeelden van jong-paleolithische kunst uit het Perigordiaan. Dit artikel handelt over gebruik en symboliek van de hoorn in de hand van de Venus en de vergelijking met recentere etno-archeologische muziekinstrumenten.

  8. Transmission spectrum of Venus as a transiting exoplanet

    OpenAIRE

    Ehrenreich, David; Vidal-Madjar, Alfred; Widemann, Thomas; Gronoff, Guillaume; Tanga, Paolo; Barthélemy, Mathieu; Lilensten, Jean; Etangs, Alain Lecavelier des; Arnold, Luc

    2011-01-01

    On 5-6 June 2012, Venus will be transiting the Sun for the last time before 2117. This event is an unique opportunity to assess the feasibility of the atmospheric characterisation of Earth-size exoplanets near the habitable zone with the transmission spectroscopy technique and provide an invaluable proxy for the atmosphere of such a planet. In this letter, we provide a theoretical transmission spectrum of the atmosphere of Venus that could be tested with spectroscopic observ...

  9. Rotation of rigid Venus: a complete precession-nutation model

    OpenAIRE

    Cottereau, L.; Souchay, J.

    2010-01-01

    Context: With the increasing knowledge of the terrestrial planets due to recent space probes it is possible to model their rotation with increasing accuracy. Despite that fact, an accurate determination of Venus precession and nutation is lacking. Aims : Although Venus rotation has been studied in several aspects, a full and precise analytical model of its precession-nutation motion remains to be constructed. We propose to determine this motion with up-to-date physical ...

  10. Fast trigger processor for VENUS detector of Tristan experiment

    International Nuclear Information System (INIS)

    Fast look-up table processors of track finding and of the first level trigger decision have been developed for the VENUS detector. Both of them are key components of the VENUS trigger to achieve deadtimeless trigger. Even for the SSC experiment, the fast look-up table processor could be a quite powerful tool for the first and the second level trigger. It will be indispensable particularly for prompt track recognition

  11. Discovery of X-rays from Venus with Chandra

    OpenAIRE

    Dennerl, K.; Burwitz, V.; Englhauser, J.; Lisse, C.; Wolk, S

    2002-01-01

    On January 10 and 13, 2001, Venus was observed for the first time with an X-ray astronomy satellite. The observation, performed with the ACIS-I and LETG/ACIS-S instruments on Chandra, yielded data of high spatial, spectral, and temporal resolution. Venus is clearly detected as a half-lit crescent, with considerable brightening on the sunward limb. The morphology agrees well with that expected from fluorescent scattering of solar X-rays in the planetary atmosphere. The radiat...

  12. The discovery of X-rays from Venus with Chandra

    OpenAIRE

    Dennerl, K.; Burwitz, V.; Englhauser, J.; Lisse, C.; Wolk, S

    2002-01-01

    On January 10 and 13, 2001, Venus was observed for the first time with an X-ray astronomy satellite. The observation, performed with the ACIS-I and LETG/ACIS-S instruments on Chandra, yielded data of high spatial, spectral, and temporal resolution. Venus is clearly detected as a half-lit crescent, with considerable brightening on the sunward limb. The morphology agrees well with that expected from fluorescent scattering of solar X-rays in the planetary atmosphere. The radiat...

  13. Asteroid 2012 XE133, a transient companion to Venus

    CERN Document Server

    Marcos, C de la Fuente

    2013-01-01

    Apart from Mercury that has no known co-orbital companions, Venus remains as the inner planet that hosts the smallest number of known co-orbitals, 2: (322756) 2001 CK32 and 2002 VE68. Both objects have absolute magnitudes 18 < H < 21 and were identified as Venus co-orbitals in 2004. Here, we analyze the orbit of the recently discovered asteroid 2012 XE133 with H = 23.5 mag to conclude that it is a new Venus co-orbital currently following a transitional trajectory between Venus' Lagrangian points L5 and L3. The object could have been a 1:1 librator for several thousand years and it may leave the resonance with Venus within the next few hundred years, after a close encounter with the Earth. Our calculations show that its dynamical status as co-orbital, as well as that of the 2 previously known Venus co-orbitals, is controlled by the Earth-Moon system with Mercury playing a secondary role. The 3 temporary co-orbitals follow rather chaotic but similar trajectories with e-folding times of order of 100 yr. Ou...

  14. Can Venus and Mars Be Made Habitable?

    Science.gov (United States)

    This activity is about planetary climate. Once familiar with the factors that determine a planet's surface temperature, learners will use an interactive spreadsheet model of a planet's atmosphere to determine if greenhouse gases, luminosity of the source, the distance of the planet from the source and the albedo of the planet can be manipulated so that the average surface temperature on Mars or Venus could support human life. Learners will then be asked to make some conclusions about these methods and suggest improvements for the spreadsheet model (see related resources for link to this model). The activity requires use of Microsoft Excel software. This is Activity D in the fourth module, titled "How do Atmospheres Affect Planetary Temperatures?," of "Earth Climate Course: What Determines a Planet's Climate?."

  15. Analysis of the VENUS-3 experiments

    International Nuclear Information System (INIS)

    The results of applying a hybrid superposition-synthesis calculational method to a mockup of a three-dimensional geometry involving a partial length shield assembly (PLSA) at the VENUS-3 facility in Mol, Belgium, are described. Comparisons of transport calculations using the method and many measurements involving nickel, indium, and aluminum dosimeters indicate agreement generally to within five percent if effects of inaccuracies in the dosimeter cross sections are minimized and proper orientation of the coordinate system used in the synthesis procedure is observed. These conclusions bode well for the success of this method in solving neutron transport problems involving the use of PLSAs in light water reactors to reduce core leakage in pressurized thermal shock programs. A second report describing the experimental details of the measurements will serve as companion documentation to this one and will be furnished by the Studiecentrum voor Kernenergie/Centre d'Etude de l'Energie Nucleaire, Mol, Belgium. 12 refs., 4 figs., 22 tabs

  16. Analysis of the VENUS-3 experiments

    International Nuclear Information System (INIS)

    The results of applying a hybrid superposition-synthesis calculational method to a mockup of a three-dimensional geometry involving a partial length shield assembly at the VENUS-3 facility in Mol, Belgium, are described. Comparisons of transport calculations using the method and many measurements involving nickel, indium, and aluminum dosimeters indicate agreement usually to within measurement uncertainties estimated at around 5%, if effects of inaccuracies in the dosimeter cross sections are minimized and proper orientation of the coordinate system used in the synthesis procedure is observed. These conclusions suggest a solution to the problem of predicting pressure vessel fluence in reactors modified by these partial-length shield assemblies may already exist. 7 refs., 2 figs., 1 tab

  17. An Encounter between the Sun and Venus

    CERN Multimedia

    2004-01-01

    The astronomical event of the year will take place on Tuesday, 8 June, when Venus transits across the disk of the sun. In the framework of CERN's 50th anniversary celebrations, the CERN Astronomy Club and the Orion Club invite you to attend their observation of the event on the car park of the Val-Thoiry shopping centre (France) between 7.15 a.m. and 1.30 p.m. Various instruments will be set up in a special tent so that the event can be observed without any risk of damage to the eyes. As the observation of this astronomical event will depend on the weather forecast, confirmation of the above arrangements will be given on the 50th anniversary website the day before.

  18. Mars, Venus and Gray: Gender Communication

    Directory of Open Access Journals (Sweden)

    Kamarul Zaman Ahmad

    2010-03-01

    Full Text Available This research tests the propositions relating to gender communication by Gray (1992 in his book titled “Men are from Mars, Women are from Venus” This book has been the source of gender-related controversy since its publication. The sample consisted of 182 executives and non-executives (73 males and 109 females. T-test results show that out of 23 statements made by Gray (1992, only 8 were supported, 10 were not supported and 5 were actually true for the opposite gender. This research is indeed timely in that it addresses the long disservice to women. So the way forward into the future would be to train people on how to communicate better by making them aware that different people have different preferences and styles of communication, rather than essentializing and gender-stereotyping.

  19. Venus radar mapper attitude reference quaternion

    Science.gov (United States)

    Lyons, D. T.

    1986-01-01

    Polynomial functions of time are used to specify the components of the quaternion which represents the nominal attitude of the Venus Radar mapper spacecraft during mapping. The following constraints must be satisfied in order to obtain acceptable synthetic array radar data: the nominal attitude function must have a large dynamic range, the sensor orientation must be known very accurately, the attitude reference function must use as little memory as possible, and the spacecraft must operate autonomously. Fitting polynomials to the components of the desired quaternion function is a straightforward method for providing a very dynamic nominal attitude using a minimum amount of on-board computer resources. Although the attitude from the polynomials may not be exactly the one requested by the radar designers, the polynomial coefficients are known, so they do not contribute to the attitude uncertainty. Frequent coefficient updates are not required, so the spacecraft can operate autonomously.

  20. Venus - Maxwell Montes and Cleopatra Crater

    Science.gov (United States)

    1991-01-01

    This Magellan full-resolution image shows Maxwell Montes, and is centered at 65 degrees north latitude and 6 degrees east longitude. Maxwell is the highest mountain on Venus, rising almost 11 kilometers (6.8 miles) above mean planetary radius. The western slopes (on the left) are very steep, whereas the eastern slopes descend gradually into Fortuna Tessera. The broad ridges and valleys making up Maxwell and Fortuna suggest that the topography resulted from compression. Most of Maxwell Montes has a very bright radar return; such bright returns are common on Venus at high altitudes. This phenomenon is thought to result from the presence of a radar reflective mineral such as pyrite. Interestingly, the highest area on Maxwell is less bright than the surrounding slopes, suggesting that the phenomenon is limited to a particular elevation range. The pressure, temperature, and chemistry of the atmosphere vary with altitude; the material responsible for the bright return probably is only stable in a particular range of atmospheric conditions and therefore a particular elevation range. The prominent circular feature in eastern Maxwell is Cleopatra. Cleopatra is a double-ring impact basin about 100 kilometers (62 miles) in diameter and 2.5 kilometers (1.5 miles) deep. A steep-walled, winding channel a few kilometers wide breaks through the rough terrain surrounding the crater rim. A large amount of lava originating in Cleopatra flowed through this channel and filled valleys in Fortuna Tessera. Cleopatra is superimposed on the structures of Maxwell Montes and appears to be undeformed, indicating that Cleopatra is relatively young.

  1. Corona-related volcanism on Venus

    Science.gov (United States)

    Grindrod, Peter Martin

    This thesis reports the results of a study of volcanic processes at coronae on Venus. The Aglaonice F-Map region has been mapped, and its geological history interpreted, at the full-resolution of Magellan SAR data. Volcanism at coronae is shown to have occurred repeatedly over a protracted period of time, supporting a non-directional style of resurfacing in the F-Map region, and suggesting that corona-related flows may be an important resurfacing mechanism on Venus. It is likely that the magma storage system varies between each corona, with eruption dependent on local conditions such as location of magma body and local stress regime. Numerous flows which can be sourced to coronae, and were previously mapped as plains units, have also been identified. A global survey has revealed 29 volcano/corona 'hybrids', features which resemble both coronae and large volcanoes. Age, magma supply, stress state, thermal gradient and eruption duration are all important factors in determining gross hybrid morphology. It is likely that not all hybrids follow a similar evolutionary path. A detailed study of four selected hybrids is presented and suggests that processes typical of both large volcanoes and coronae have occurred throughout their history, and does not imply evolution from one type of feature into another. The presence of large central depressions and/or topographic rims at the hybrids support the theory that some large volcanoes undergo a sagging process similar to coronae. Study of the depth and extension at large radial graben at four centres of radial fractures is also reported. The inferred levels of hoop strain are too large to be explained by previous models of plume uplift, and a newly applied magma chamber inflation model concludes that dike formation is responsible for the strain at the large radial graben, and that intrusion is an important process at early-phase coronae.

  2. Transits of Venus and Colonial India

    Science.gov (United States)

    Kochhar, Rajesh

    2012-09-01

    Astronomical expeditions during the colonial period had a political and national significance also. Measuring the earth and mapping the sky were activities worthy of powerful and power- seeking nations. Such was the sanctity of global astronomical activity that many other agendas could be hidden under it. An early astronomy-related expedition turned out to be extremely beneficial, to botany. The expedition sent by the French Government in 1735 to South America under the leadership of Charles Marie de la Condamine (1701--1774) ostensibly for the measurement of an arc of the meridian at Quito in Ecuador surreptitiously collected data that enabled Linnaeus to describe the genus cinchona in 1742. When the pair of transits of Venus occurred in 1761 and 1769, France and England were engaged in a bitter rivalry for control of India. The observation of the transits became a part of the rivalry. A telescope presented by the British to a South Indian King as a decorative toy was borrowed back for actual use. Scientifically the transit observations were a wash out, but the exercise introduced Europe to details of living Indian tradition of eclipse calculations. More significantly, it led to the institutionalization of modern astronomy in India under the auspices of the English East India Company (1787). The transits of Venus of 1874 and 1882 were important not so much for the study of the events as for initiating systematic photography of the Sun. By this, Britain owned most of the world's sunshine, and was expected to help European solar physicists get data from its vast Empire on a regular basis. This and the then genuinely held belief that a study of the sun would help predict failure of monsoons led to the institutionalization of solar physics studies in India (1899). Of course, when the solar physicists learnt that solar activity did not quite determine rainfall in India, they forgot to inform the Government.

  3. Atmospheric Entry Studies for Venus Missions: 45 Sphere-Cone Rigid Aeroshells and Ballistic Entries

    Science.gov (United States)

    Prabhu, Dinesh K.; Spilker, Thomas R.; Allen, Gary A., Jr.; Hwang, Helen H.; Cappuccio, Gelsomina; Moses, Robert W.

    2013-01-01

    The present study considers direct ballistic entries into the atmosphere of Venus using a 45deg sphere-cone rigid aeroshell, a legacy shape that has been used successfully in the past in the Pioneer Venus Multiprobe Mission. For a number of entry mass and heatshield diameter combinations (i.e., various ballistic coefficients) and entry velocities, the trajectory space in terms of entry flight path angles between skip out and -30deg is explored with a 3DoF trajectory code, TRAJ. From these trajectories, the viable entry flight path angle space is determined through the use of mechanical and thermal performance limits on the thermal protection material and science payload; the thermal protection material of choice is entry-grade carbon phenolic, for which a material thermal response model is available. For mechanical performance, a 200 g limit is placed on the peak deceleration load experienced by the science instruments, and 10 bar is assumed as the pressure limit for entry-grade carbon-phenolic material. For thermal performance, inflection points in the total heat load distribution are used as cut off criteria. Analysis of the results shows the existence of a range of critical ballistic coefficients beyond which the steepest possible entries are determined by the pressure limit of the material rather than the deceleration load limit.

  4. Direct and Indirect Measurement of Rock and Soil Physical Properties on Venus

    Science.gov (United States)

    Wilson, J.; Bartlett, P.; Zacny, K.; Gorevan, S.; Roopnarine, R.

    2005-12-01

    Acquiring and analyzing samples from the Venusian surface is a primary goal of future Venus exploration. In addition to supplying in situ instruments with pristine samples, the data acquired during drilling operations (and any other material processing operations) can provide important information about the physical properties of the material encountered at the drilled sites. Data such as motor current draw, penetration rate, weight-on-bit, etc., can be used to indirectly infer physical properties about the medium being drilled via comparison to other materials drilled under the same conditions. Direct physical properties measurements may also be made, from dedicated tools such as imbedded shear strength test devices, provided that adequate space inside the drill string is available. Inferring physical properties from drill data is not a trivial matter but its benefit to science return is great. Honeybee Robotics is involved in several efforts that are attempting to directly and indirectly assess rock and soil physical properties based on drill data, which includes the Mars Exploration Rover mission Rock Abrasion Tool data set, though much more work is still required in this area. Lessons learned from these efforts so far have demonstrated the importance of co-developing the physical properties assessment techniques along with the drill system itself from the start of the design process. An overview of this process and how it relates to Venus exploration and science data return will be discussed.

  5. Ground-based Observations of Venus in the Ultraviolet and Infrared Light

    Science.gov (United States)

    Kowollik, S.; Gährken, B.; Gerstheimer, R.; Fiedler, M.; Fischer, D.; Sohl, F.

    2007-08-01

    Parallel to the Venus Express mission, ESA has initiated an observing campaign that incorporates a number of professional and amateur observers. Since the cameras onboard Venus Express have only a small field of view, ground based observations can provide important context information on Venus's dense atmosphere as a whole. Permanent observations by professional and amateur telescopes are therefore useful, e.g., to monitor daily changes occurring in the very dynamic upper part of the Venusian atmosphere. Typically, apertures of amateur telescopes vary between 8 and 16 inches, but occasionally Newton- and Cassegrain-type telescopes with apertures from 24 up to even 47 inches are in use at large public observatories. During the last couple of years, engaged amateur astronomers have benefited from the rapid development in the field of video-astronomy. By selecting and adding thousands of only shortly-exposed video-frames, it is possible to freeze atmospheric turbulence, thereby circumventing problems commonly attributed to devastating atmospheric seeing conditions. With that method of "Lucky Imaging", it is possible to nearly achieve the theoretical limit of telescopic resolution. Furthermore, cheaper and more efficient UV-filters in association with increasingly sensitive optical systems put amateur astronomers in a position to resolve weak atmospheric details better than one arc second in apparent diameter. The most preferred UV-filter, made by the manufacturer Schueler/USA, has a distinct transmission window between a wavelength of 330 and 400 nm. We present images that show typical V- and Y-shaped structures of the Venusian atmosphere that are generally attributed to an unknown UV-absorber; some images also reveal white and dark streaks and bright polar regions. First observations using a RG1000 filter have been performed in the infrared spectral range. Preliminary analyses suggest that structures visible in the infrared have an extremely weak contrast and appear to be much smaller than those seen in ultraviolet light. Several observers in Germany are engaged in the Planetary Section of the Association of Amateur Astronomers (VdS). A number of those have gained considerable experience in image processing, and were able to contribute to scrutinize and sort incoming data from current observing and remote sensing campaigns. Therefore, we are very interested to access additional images obtained during parallel observations with other telescopes, thereby optimizing observational techniques and improving the international coordination of future Venus observation campaigns.

  6. The June 2012 transit of Venus. Framework for interpretation of observations

    OpenAIRE

    Muñoz, A. García; Mills, F. P.

    2012-01-01

    Ground based observers have on 5/6th June 2012 the last opportunity of the century to watch the passage of Venus across the solar disk from Earth. Venus transits have traditionally provided unique insight into the Venus atmosphere through the refraction halo that appears at the planet outer terminator near ingress/egress. Much more recently, Venus transits have attracted renewed interest because the technique of transits is being successfully applied to the characterization ...

  7. Pissible Habitats in the Venusian Environment? How Can the Venus Payload Contribute?

    Science.gov (United States)

    Muller, C. L.; Schulze-Makuch, D.

    2005-12-01

    The Venusian conditions are unique in the solar system. Venus has a dense CO2 atmosphere, is volcanically active, and has plenty of energy sources such as light, UV radiation, volcanic activity, and chemical energy from atmospheric disequilibria conditions. Its surface conditions are sufficiently hot for sterilization and volcanism injects highly toxic gases which in the absence of unbound water can accumulate in the atmosphere. The Venusian surface is constantly regenerated by volcanism and any possible fossil record from early Venus history in which oceans existed on its surface is almost certainly destroyed. Its upper atmosphere lays bare to solar radiation with only carbon dioxide to act as a confirmed EUV filter. Any possibility of life was considered irrational before extremophile bacteria were discovered in dark undersea hot sulphur rich volcanic vents on Earth. However, some regions of the Venusian clouds might show conditions similar to the earth surface and could be a habitat of thermophilic microbial life similar to the one observed on Earth. A synergy between different instruments of the VENUS-Express payload, the SPICAV spectrometer and the VMC camera in a first step, and the spectrometers VIRTIS and PFS in a second step, will probe the actual environmental conditions of the cloud region. The SPICAV spectrometer, in particular, has three channels including, two infrared AOTF channels and could give access to organic signatures in both the UV and infrared. Given these observations we will be able to analyze whether the environmental conditions of the cloud layer would make it a possible habitat for extant microbial life. The instruments will shed answers to the availability of nutrients, water, types of energy sources, atmospheric dynamics, and organic chemistry.

  8. Sunlight refraction in the mesosphere of Venus during the transit on June 8th, 2004

    Science.gov (United States)

    Tanga, P.; Widemann, T.; Sicardy, B.; Pasachoff, J. M.; Arnaud, J.; Comolli, L.; Rondi, A.; Rondi, S.; Sütterlin, P.

    2012-03-01

    Many observers in the past gave detailed descriptions of the telescopic aspect of Venus during its extremely rare transits across the Solar disk. In particular, at the ingress and egress, the portion of the planet’s disk outside the Solar photosphere has been repeatedly perceived as outlined by a thin, bright arc (“aureole”). Those historical visual observations allowed inferring the existence of Venus’ atmosphere, the bright arc being correctly ascribed to the refraction of light by the outer layers of a dense atmosphere. On June 8th, 2004, fast photometry based on electronic imaging devices allowed the first quantitative analysis of the phenomenon. Several observers used a variety of acquisition systems to image the event - ranging from amateur-sized to professional telescopes and cameras - thus collecting for the first time a large amount of quantitative information on this atmospheric phenomenon. In this paper, after reviewing some elements brought by the historical records, we give a detailed report of the ground based observations of the 2004 transit. Besides confirming the historical descriptions, we perform the first photometric analysis of the aureole using various acquisition systems. The spatially resolved data provide measurements of the aureole flux as a function of the planetocentric latitude along the limb. A new differential refraction model of solar disk through the upper atmosphere allows us to relate the variable photometry to the latitudinal dependency of scale-height with temperature in the South polar region, as well as the latitudinal variation of the cloud-top layer altitude. We compare our measurements to recent analysis of the Venus Express VIRTIS-M, VMC and SPICAV/SOIR thermal field and aerosol distribution. Our results can be used a starting point for new, more optimized experiments during the 2012 transit event.

  9. Crater production on Venus and Earth by asteroid and comet impact

    International Nuclear Information System (INIS)

    New calculations of the collision probabilities of asteroids and comets with Venus were carried out based on the orbits of the known Venus-crossing asteroids and comets. For comparison, asteroid and comet collision probabilities and cratering rates on the Earth and Moon were recalculated and the estimated cratering rates on Venus were normalized to those of the Earth

  10. Giant radiating dyke swarms on Earth and Venus

    Science.gov (United States)

    Ernst, Richard E.; Head, James W.; Parfitt, Elisabeth; Wilson, Lionel; Grosfils, Eric

    1993-01-01

    On Earth, giant radiating dyke swarms are usually preserved as fan-shaped fragments which have been dismembered from their original configuration by subsequent plate tectonic rifting events. Analysis of the largest fragments and consideration of their original configuration has led to the idea that many swarms are plume related, and that dyke swarms radiate away from plume centers. Magellan radar data reveal abundant intact giant radiating swarms on Venus which are similar in scale and pattern to those on Earth. The absence of intense weathering and plate tectonic processes on Venus accounts for the preservation of the primary radiating patterns. It is characteristic of both Earth and Venus that giant radiating dikes are emplaced laterally for distances of at least 2000 km away from plume centers. At distances beyond the influence of the plume on both Earth and Venus, the radiating dyke pattern is often swept into a linear pattern aligned with the regional stress field. There is tremendous potential synergism between the characterization and analysis of terrestrial dyke swarms (where significant erosion has revealed their structure and emplacement directions at depth) and the giant swarms of Venus (where the complete circumferential structure is preserved, and the surface fracture systems above near surface dikes and the nature of the central source regions are revealed). In this study, we report on the characteristics of radial dyke swarms on Earth and Venus and draw some preliminary comparisons from the two perspectives. In summary, on both planets there is evidence for plume-related magmatic centers associated with vertical and lateral injection of magma over considerable distances (up to at least 2000 km). The abundance of very broadly radiating swarms on Venus supports the notion that the swarms on Earth were radiating over broad sectors at the time of intrusion but were dissected by later events. The Venus data show that a swarm can change from radiating (proximal) to regional (distal) subparallel orientations. An implication for Earth is that many regional linear swarms which do not have a radiating pattern may be due to fragmentation of the swarm during later plate tectonic rifting. Completion of the global classification and census of Venus features, comparison to the terrestrial synthesis, and documentation of the mode of emplacement of dikes in these environments (buffered and unbuffered conditions) should lead to additional general insight into mechanisms of formation and evolution and their relation to plumes.

  11. The case for a deep-atmospheric in situ mission to address the highest priority Decadal Survey questions for Venus (Invited)

    Science.gov (United States)

    Atreya, S. K.; Garvin, J. B.; Glaze, L. S.; Campbell, B. A.; Fisher, M. E.; Flores, A.; Gilmore, M. S.; Johnson, N.; Kiefer, W. S.; Lorenz, R. D.; Mahaffy, P. R.; Ravine, M. A.; Webster, C. R.; Zolotov, M. Y.

    2013-12-01

    Current understanding of Venus lags behind that for Mars, with a major disparity of information concerning noble and trace gases and the small scale surface processes needed for comparative studies of terrestrial planet evolution. Despite global surface mapping by Magellan, discoveries by Venera landers, and ongoing atmospheric observations by the Venus Express (VEx) orbiter, significant questions about Venus remain unanswered. To place Venus into its proper context with respect to Mars and Earth, it is necessary to obtain new measurements that address top issues identified in the National Research Council (NRC) Solar System Decadal Survey: (1) evolution of the atmosphere, history of climate, and evidence of past hydrologic cycles; (2) history of volatiles and sedimentary cycles; and (3) planetary surface evolution. To answer these questions, new measurements are needed. First and foremost, in situ noble gas measurements are needed to constrain solar system formation and Venus evolution. In particular, the isotopic ratios of Xe and Kr can provide unique insights into planetary accretion. Isotopic measurements of nitrogen (15N/14N) will place important constraints on atmospheric loss processes. Current knowledge of this ratio has a substantial uncertainty of ×20%. VEx observations of hydrogen isotopes indicate the D/H ratio above the clouds is substantially greater than measured by Pioneer Venus, and varies with height. High precision measurements of the vertical distribution of the D/H isotopic ratio below the cloud layers will provide constraints on models of the climate history of water on Venus. The majority of atmospheric mass is located below the clouds. Current data suggest intense interaction among atmospheric gases down to the surface. The haze within the cloud region of unknown composition plays a central role in the radiative balance. Photochemically-derived species (H2SO4, OCS, CO, Sn) are subjected to thermochemical reactions below the clouds, especially within 30 km of the surface. Competing temperature-pressure dependent reactions and atmospheric circulation may cause vertical and latitudinal gradients of chemically-active trace gases (e.g., SO2, H2S, OCS, CO). Measurements of the chemical composition of the near-surface atmosphere can be used to evaluate the stability of primary and secondary minerals and can help to understand chemistry of atmosphere-surface interactions. However, concentrations of many trace species have never been measured below ~30 km, and multiple in situ measurements are required to evaluate chemical processes and cycles of volatiles, which can only be accomplished with deep entry probes. Current lack of understanding about Venus not only limits our understanding of evolutionary pathways Earth could experience, but also suggests that we are ill-equipped to understand the evolution of star systems with similar-sized planets.

  12. Columbus State University Global Observation and Outreach for the 2012 Transit of Venus

    Science.gov (United States)

    Perry, Matthew; McCarty, C.; Bartow, M.; Hood, J. C.; Lodder, K.; Johnson, M.; Cruzen, S. T.; Williams, R. N.

    2013-01-01

    Faculty, staff and students from Columbus State University’s (CSU’s) Coca-Cola Space Science Center presented a webcast of the 2012 Transit of Venus from three continents to a global audience of 1.4 million unique viewers. Team members imaged the transit with telescopes using white-light, hydrogen-alpha, and calcium filters, from Alice Springs, Australia; the Gobi Desert, Mongolia; Bryce Canyon, UT; and Columbus, GA. Images were webcast live during the transit in partnership with NASA’s Sun-Earth Day program, and Science Center staff members were featured on NASA TV. Local members of the public were brought in for a series of outreach initiatives, in both Georgia and Australia, before and during the transit. The data recorded from the various locations have been archived for use in demonstrating principles such as the historical measurement of the astronomical unit.

  13. Venus's Mysterious Oxygen Green Line: An Auroral Process?

    Science.gov (United States)

    Gray, Candace L.; Chanover, Nancy; Slanger, Tom; Molaverdikhani, Karan; Hausler, Bernd; Tellmann, Silvia; Peter, Kerstin; Witasse, Olivier; Blelly, Pierre-Louise; Garcia-Munoz, Antonio

    2014-11-01

    Observations of nightglow (upper atmospheric emission from atoms and molecules on the nightside of a planet) allow for a multifaceted study of planetary atmospheres. Information on winds, chemistry, and solar effects is gained by observing temporal and spacial variation in nightglow intensity. One of the brightest nightglow features on Earth is the OI (1S) 557.7 nm line (oxygen green line). This emission is primarily due to photodissociation/transport but is also seen in the aurora as electron precipitation.Unlike Earth, the Venusian green line is highly temporally variable. The chemistry and mechanisms responsible are still unknown. We observe the Venusian nightglow before and after solar flares, which produce large amounts of EUV emission, and coronal mass ejections (CMEs) impacts, which inject a large number of higher energy charged particles in the the Venusian atmosphere. We consistently detect green line emission after large charged particles injections from CMEs. However we do not detectthe OI (1D) red line at 630.0 nm, which is quenched below 150 km. We propose that the Venusian green line is an auroral-type emission due to electron precipitation and is occurring deep in the atmosphere, near 125 km.To investigate how CMEs and solar flares effect the electron energy, flux, and density in the Venusian nightside atmosphere, we compare data taken by ASPERA and ELS onboard Venus Express (VEX) before and after solar storms. We find that both electron energy and flux increase after CMEs, but onlyflux increases after solar flares. Additionally, the V1 ionospheric layer at 125 km increases in electron density while the V2 at 150 km decreases in density after CMEs but not after solar flares. We model the nightside Venusian ionosphere using the observed electron energy and fluxes from VEX in an effort to constrain the chemical processes and mechanisms responsible for green line emission. We will present the results of our ground-based observations and modeling.

  14. The 28 GHZ, 10 KW, CW Gyrotron Generator for the VENUS ECR Ion Source at LBNL

    International Nuclear Information System (INIS)

    The VIA-301 HeatwaveTM gyrotron generator was specifically designed to meet the requirements of the Venus ECR Ion Source at the Lawrence Berkeley National Laboratory (LBNL). VENUS (Versatile ECR ion source for NUclear Science) is a next generation superconducting ECR ion source, designed to produce high current, high charge state ions for the 88-Inch Cyclotron at the Lawrence Berkeley National Laboratory. VENUS also serves as the prototype ion source for the RIA (Rare Isotope Accelerator) front end].This VIA-301 HeatwaveTM gyrotron system provides 100 watts to 10 kW continuous wave (CW) RF output at 28 GHz. The RF output level is smoothly controllable throughout this entire range. The power can be set and maintained to within 10 watts at the higher power end of the power range and to within 30 watts at the lower power end of the power range. A dual directional coupler, analog conditioning circuitry, and a 12-bit analog input to the embedded controller are used to provide a power measurement accurate to within 2%. The embedded controller completes a feedback loop using an external command set point for desired power output. Typical control-loop-time is on the order of 500 mS. Hard-wired interlocks are provided for personnel safety and for protection of the generator system. In addition, there are software controlled interlocks for protection of the generator from high ambient temperature, high water temperature, and other conditions that would affature, and other conditions that would affect the performance of the generator or reduce the lifetime of the gyrotron. Cooling of the gyrotron and power supply is achieved using both water and forced circulation of ambient air. Water-cooling provides about 80% of the cooling requirement. Input power to the generator from the prime power line is less than 60 kW at full power. The HeatwaveTM may be operated locally via its front panel or remotely via either RS-232 and/or Ethernet connections. Through the RS-232 the forward power, the reflected power, the interlock status and crucial operating parameters are transmitted and tied into the VENUS PLC control system.The paper describes the gyrotron system, control software, the user interface, the main system parameter, and performance in respect to output power stability

  15. Doppler Lidar for Wind Measurements on Venus

    Science.gov (United States)

    Singh, Upendra N.; Emmitt, George D.; Yu, Jirong; Kavaya, Michael J.

    2010-01-01

    NASA Langley Research Center has a long history of developing 2-micron laser transmitter for wind sensing. With support from NASA Laser Risk Reduction Program (LRRP) and Instrument Incubator Program (IIP), NASA Langley Research Center has developed a state-of-the-art compact lidar transceiver for a pulsed coherent Doppler lidar system for wind measurement. The transmitter portion of the transceiver employs the high-pulse-energy, Ho:Tm:LuLiF, partially conductively cooled laser technology developed at NASA Langley. The transceiver is capable of 250 mJ pulses at 10 Hz. It is very similar to the technology envisioned for coherent Doppler lidar wind measurements from Earth and Mars orbit. The transceiver is coupled to the large optics and data acquisition system in the NASA Langley VALIDAR mobile trailer. The large optics consists of a 15-cm off-axis beam expanding telescope, and a full-hemispheric scanner. Vertical and horizontal vector winds are measured, as well as relative backscatter. The data acquisition system employs frequency domain velocity estimation and pulse accumulation. It permits real-time display of the processed winds and archival of all data. This lidar system was recently deployed at Howard University facility in Beltsville, Mary-land, along with other wind lidar systems. Coherent Doppler wind lidar ground-based wind measurements and comparisons with other sensors will be presented. A simulation and data product for wind measurement at Venus will be presented.

  16. RAVEN - High-resolution Mapping of Venus within a Discovery Mission Budget

    Science.gov (United States)

    Sharpton, V. L.; Herrick, R. R.; Rogers, F.; Waterman, S.

    2009-12-01

    It has been more than 15 years since the Magellan mission mapped Venus with S-band synthetic aperture radar (SAR) images at ~100-m resolution. Advances in radar technology are such that current Earth-orbiting SAR instruments are capable of providing images at meter-scale resolution. RAVEN (RAdar at VENus) is a mission concept that utilizes the instrument developed for the RADARSAT Constellation Mission (RCM) to map Venus in an economical, highly capable, and reliable way. RCM relies on a C-band SAR that can be tuned to generate images at a wide variety of resolutions and swath widths, ranging from ScanSAR mode (broad swaths at 30-m resolution) to strip-map mode (resolutions as fine as 3 m), as well as a spotlight mode that can image patches at 1-m resolution. In particular, the high-resolution modes allow the landing sites of previous missions to be pinpointed and characterized. Repeat-pass interferometric SAR (InSAR) and stereo radargrammetry provide options for constraining topography to better than 100-m horizontal and 10-m vertical resolution. InSAR also provides the potential for detecting surface deformation at centimeter precision. Performing InSAR requires precise knowledge and control of the orbital geometry, and for this reason a 600-km circular polar orbit is favored. This configuration causes the equatorial nadir point to move ~9 km per orbit. Considering both ascending and descending passes, the spacecraft will pass over every point on the planet in half a Venus day (~4 Earth months). The ability to transmit data back to Earth via the Deep Space Network is the primary limiting factor on the volume of data that can be collected. Our current estimates indicate that within an imaging cycle of one Venus day we can image 20-30 percent of the planet at 20-30-m resolution and several percent at 3-5 m resolution. These figures compare favorably to the coverage provided by recent imaging systems orbiting Mars. Our strategy calls for the first cycle of coverage to be devoted to imaging large geographic areas (e.g., Thetis Regio) at 20-30-m resolution with interleaved observation of pre-selected targets at high resolution. The second cycle will include additional imaging, but the focus will be repeat-pass coverage to obtain topography for a significant fraction of the first-cycle targets. A focus of the third cycle will be InSAR-based deformation studies of selected areas. All components of the spacecraft are expected to remain operational well beyond the nominal mission time, so global mapping at 10 m or better resolution during an extended mission is conceivable. RAVEN will allow us to determine both the broad framework of the planet’s geologic history (e.g, uniformitarian versus catastrophic evolution) and the nature of current geologic activity. It will substantially advance our understanding of Venus and reveal details, issues, and further questions that will benefit future site-specific missions such as probes and landers. Current RAVEN science team members are Buck Sharpton (PI), Rudi Gens, Rebecca Ghent, Martha Gilmore, Robert Grimm, Robert Herrick, Catherine Johnson, Patrick McGovern, Franz Meyer, Peter Mouginis-Mark, Jeff Plaut, David Sandwell, Mark Simons, and Sean Solomon.

  17. VIRTIS emissivity of Alpha Regio, Venus, with implications for tessera composition

    Science.gov (United States)

    Gilmore, Martha S.; Mueller, Nils; Helbert, Jörn

    2015-07-01

    The composition of Venus tessera terrain is unknown. The Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) aboard Venus Express (VEx) collects data that yields the surface emissivity at ?1 ?m, which contains information convolving a number of surface properties, including composition. We examine the variation of emissivity in the vicinity of Alpha Regio, which is the largest exposure of tessera terrain imaged by VIRTIS. We find that the emissivity of Alpha Regio tessera is lower than adjacent plains materials and the deposits and flows of Eve corona, both of which have previously been interpreted to be basaltic. The emissivity of the bulk of Alpha is also lower than its western boundary, which is interpreted to comprise plains structurally deformed to the same degree as tessera terrain. This suggests that the lower emissivity of Alpha is independent of structural elements, macroscale roughness, or local sedimentation processes, and is due to material properties like composition or grain size. The deviation of the emissivity of Alpha from that of the plains for which a bulk basaltic composition is well supported corresponds to a significant difference in rock type or surface mineral assemblage. The 1 ?m emissivity of Alpha is consistent with rocks with low ferrous iron content. This includes felsic igneous rocks like granitoids that form under either water-rich or water-poor conditions. A water-rich origin would require both a hydrosphere and a plate recycling mechanism and thus be limited to the lifetime of surface water on Venus. Alternatively, granitoids could form via the differentiation of basaltic melts. The production of all tessera terrain by this mechanism would require the accumulation and preservation of felsic melts from a volume of mafic magma that exceeds what is preserved in the currently observed plains. Both mechanisms of granitoid formation would require that tessera terrain be formed prior to the emplacement of the plains, consistent with their stratigraphic position. Anorthosites also satisfy the emissivity signature and can form from copious amounts of partial melting of a mafic source. Low emissivity values are also consistent with carbonates, sulfates, phyllosilicates and their dehydration products, which may have formed via weathering of basalts under conditions of higher atmospheric PH2O. All of these hypotheses suggest the mineralogy of Alpha tessera records an extinct era of Venus history and is a key target for future exploration.

  18. Status of Radiative Transfer Model (RTM) development for the Northrop Grumman Venus Atmospheric Maneuverable Platform (VAMP) Technology Development Program

    Science.gov (United States)

    Wong, Eric

    2014-11-01

    In support of the Northrop Grumman/L-Garde Venus Atmospheric Maneuverable Platform (VAMP) development, we are developing a multi-purpose radiative transfer model (RTM) for the applications of the Venus atmosphere. For the solar array sizing, spectral solar radiance calculations are needed and a Correlated-k method of spectral integration will be used. This method is relatively fast computationally and typical error of the method is within a few percent, sufficiently accurate for solar array sizing analyses. For sensor characterization or sensor performance study, details of an absorption line, e.g. the near-IR “atmospheric window” absorption lines, must be used and an equivalent line-by-line calculation will be performed. At the completion of the model a large data base of radiance profiles of different atmospheric conditions will be created. The database can also be used to support thermal radiation analysis for other sub-systems. In this poster, we present our current state of the RTM development and model validation development. Additionally, we will present some preliminary comparison of top-of-atmosphere solar radiance with Venus Express VIRTIS measurements.

  19. Impact craters on Venus - Initial analysis from Magellan

    Science.gov (United States)

    Phillips, Roger J.; Arvidson, Raymond E.; Boyce, Joseph M.; Campbell, Donald B.; Guest, John E.

    1991-01-01

    The general features of impact craters are described emphasizing two aspects: the effect of the atmosphere on crater and ejecta morphology and the implications of the distribution and appearance of the craters for the volcanic and tectonic resurfacing history of Venus. Magellan radar images reveal 135 craters about 15 km in diameter containing central peaks, multiple central peaks, and peak rings. Craters smaller than 15 km exhibit multiple floors or appear in clusters. Surface flows of material initially entrained in the atmosphere are characterized. Zones of low radar albedo originated from deformation of the surface by the shock or pressure wave associated with the incoming meteoroid surround many craters. A spectrum of surface ages on Venus ranging from 0 to 800 million years indicates that Venus must be a geologically active planet.

  20. HARPS Observations of the 2012 Transit of Venus

    Science.gov (United States)

    Molaro, P.; Monaco, L.; Barbieri, M.; Zaggia, S.

    2013-09-01

    On 6 June 2012 the black disc of Venus passed across the Solar disc, taking nearly eight hours to complete the transit. The event was followed by millions of people worldwide. The transit of Venus is one of the rarest astronomical events, occurring approximately every 120 years. By means of HARPS spectroscopic observations, and using the Moon as a mirror, we detected the Rossiter-McLaughlin effect due to the eclipse by Venus of the Solar disc with a precision of few cm s-1. The observation demonstrates that this effect can be measured even for transits of exoplanets of Earth size, or even smaller, provided enough photons can be collected by a very high resolution and extremely stable spectrograph, such as the planned HIRES instrument for the E-ELT.

  1. Steady-state plasma transition in the Venus ionosheath

    International Nuclear Information System (INIS)

    The results of an extended analysis of the plasma and electric field data of the Pioneer Venus Orbiter (PVO) are presented. The authors report the persistent presence of a plasma transition embedded in the flanks of the Venus ionosheath between the bow shock and the ionopause. This transition is identified by the repeated presence of characteristic bursts in the 30 kHz channel of the electric field detector of the PVO. The observed electric field signals coincide with the onset of different plasma conditions in the inner ionosheat where more rarified plasma fluxes are measured. The repeated identification of this intermediate ionosheath transition in the PVO data indicates that it is present as a steady state feature of the Venus plasma environment. This distribution of PVO orbits in which the transition is observed suggests that it is more favourably detected in the vicinity of and downstream from the terminator

  2. Initial performance of the VENUS transition radiation detector

    International Nuclear Information System (INIS)

    The VENUS-TRD is a cylindrical transition radiation detector, extending from 127 cm to 157.7 cm radially and 296 cm axially. It is designed to improve the e/? separation capability of the VENUS detector by a factor of 10 in order to complement the lead glass calorimeter. It covers an angular region of vertical strokecos?vertical stroke+e- storage ring in June, 1991. The pion rejection power (R?=1/??) at an electron efficiency of 90% is R?=10±1 and 15±2 for isolated tracks with a momentum range of 1?=7±1 for tracks with P>1 GeV/c in hadronic events due to overlap of the tracks in the chamber cells of the TRD. The VENUS-TRD is the largest TRD to perform in colliding beam experiments. (orig.)

  3. Day and night models of the Venus thermosphere

    Science.gov (United States)

    Massie, S. T.; Hunten, D. M.; Sowell, D. R.

    1983-01-01

    A model atmosphere of Venus for altitudes between 100 and 178 km is presented for the dayside and nightside. Densities of CO2, CO, O, N2, He, and O2 on the dayside, for 0800 and 1600 hours local time, are obtained by simultaneous solution of continuity equations. These equations couple ionospheric and neutral chemistry and the transport processes of molecular and eddy diffusion. Photodissociation and photoionization J coefficients are presented to facilitate the incorporation of chemistry into circulation models of the Venus atmosphere. Midnight densities of CO2 CO, O, N2, He, and N are derived from integration of the continuity equations, subject to specified fluxes. The nightside densities and fluxes are consistent with the observed airglow of NO and O2(1 Delta). The homopause of Venus is located near 133 km on both the dayside and nightside.

  4. Geoid, topography, and convection-driven crustal deformation on Venus

    Science.gov (United States)

    Simons, Mark; Hager, Bradford H.; Solomon, Sean C.

    1993-01-01

    High-resolution Magellan images and altimetry of Venus reveal a wide range of styles and scales of surface deformation that cannot readily be explained within the classical terrestrial plate tectonic paradigm. The high correlation of long-wavelength topography and gravity and the large apparent depths of compensation suggest that Venus lacks an upper-mantle low-viscosity zone. A key difference between Earth and Venus may be the degree of coupling between the convecting mantle and the overlying lithosphere. Mantle flow should then have recognizable signatures in the relationships between the observed surface topography, crustal deformation, and the gravity field. Therefore, comparison of model results with observational data can help to constrain such parameters as crustal and thermal boundary layer thicknesses as well as the character of mantle flow below different Venusian features. We explore in this paper the effects of this coupling by means of a finite element modelling technique.

  5. Venus, Earth's Structural Sister: Investigations Using Radar Imagery

    Science.gov (United States)

    Let's face it: It's pretty difficult to get to Venus to do hands-on fieldwork. This helpful teaching resource from Vicki Hansen at the University of Minnesota-Duluth overcomes some of those difficulties by allowing students the opportunity to do just that, in a manner of speaking. Using data from NASA, students will learn how to construct of geologic map of a region of Venus' surface. The concepts covered by this activity include basic mapping principles, remote data set interpretation, and structure morphology. The activity is intended for students in a variety of educational settings, including high school geology classes and introductory college level geology courses. Visitors to this site will find important supporting online resources (such as geologic maps of Venus) and a complete description on how to conduct this activity.

  6. Grid Convergence of the HYB-Venus Hybrid Simulation

    Science.gov (United States)

    Jarvinen, R.; Kallio, E.; Janhunen, P.; Pohjola, V.; Sillanpää, I.

    2010-09-01

    We study the spatial grid convergence of a Venus-solar wind interaction simulation. HYB-Venus, a 3-D hybrid simulation, models the interaction in global scale including the ion kinetic effects. The selection of the spatial resolution is an important factor and can affect the physics in the simulation. Here we show that solutions of the nominal Venus run with cell sizes RV/10, RV/15 and RV/20 (RV is the planet's radius) share similar general characteristics. Especially, the planetary oxygen ion escape rate is not sensitive to the cell size. More quantitatively, the higher resolution, which also means smaller particle noise per physical volume unit, was found to introduce finer structures which could be important and useful in detailed studies of the properties of the Venusian plasma environment.

  7. Laboratory simulation of the induced magnetospheres of comets and Venus

    International Nuclear Information System (INIS)

    The comparison of data obtained in laboratory experiments on the solar wind interaction with a body endowed with a plasma shell, the observations of comet type I tails and the direct measurements near Venus show that an induced magnetosphere is formed with an extended magnetic tail. This magnetosphere appears due to currents associated with unipolar induction. The distribution of electrodynamical forces associated with the formation of the induced magnetosphere makes it possible to explain the acceleration of matter towards the tail as in the motion across the tail observed in comets and Venus. The analysis of the condensation motion in Halley's comet yields an estimate of tail magnetic field of 30 to 50 ?. A three-dimensional model of the induced magnetospheres of Venus and comets is developed. (Auth.)

  8. Venus lower atmospheric composition - Analysis by gas chromatography

    Science.gov (United States)

    Oyama, V. I.; Carle, G. C.; Woeller, F.; Pollack, J. B.

    1979-01-01

    The first gas chromatographic analysis of the lower atmosphere of Venus is reported. Three atmospheric samples were analyzed. The third of these samples showed carbon dioxide (96.4 percent), molecular nitrogen (3.41 percent), water vapor (0.135 percent), molecular oxygen (69.3 ppm), argon (18.6 ppm), neon (4.31 ppm), and sulfur dioxide (186 ppm). The amounts of water vapor and sulfur dioxide detected are roughly compatible with the requirements of greenhouse models of the high surface temperature of Venus. The large positive gradient of sulfur dioxide, molecular oxygen, and water vapor from the cloud tops to their bottoms, as implied by Earth-based observations and these results, gives added support for the presence of major quantities of aqueous sulfuric acid in the clouds. A comparison of the inventory of inert gases found in the atmospheres of Venus, Earth, and Mars suggests that these components are due to outgassing from the planetary interiors.

  9. Thermal structure at the Venus terminator: Comparison of SOIR/Vex profiles with a radiative transfer model

    Science.gov (United States)

    Mahieux, Arnaud; Erwin, Justin T.; Chamberlain, Sarah; Funke, Bernd; López Puertas, Manuel; López Valverde, Miguel; Robert, Séverine; Vandaele, Ann Carine; Wilquet, Valérie; Yelle, Roger V.; Bertaux, Jean-Loup

    2014-11-01

    The wavelength range probed by the SOIR instrument on board Venus Express - 2.2 to 4.3 µm - allows a detailed chemical inventory of the Venus atmosphere [Bertaux et al., 2006; Vandaele et al., 2007]. The measurements all occur at the Venus terminator, on both the morning and evening sides, covering all latitudes from the North Pole to the South Pole. In particular CO2 number density vertical profiles are obtained from 70 to 160 km. Temperature profiles are deduced from the CO2 density profiles, using two different and independent techniques. The first one considers the hydrostatic law applied on the retrieved CO2 density profiles, assuming a CO2 mixing ratio vertical profile [Mahieux et al., 2010; 2012; 2014a]. The second one uses the ro-vibrational structure of the CO2 lines [Mahieux et al., 2014b]. Results of both methods are in agreement within their error bars; the uncertainties are larger with the ro-vibrational method. These temperature measurements show a striking permanent temperature minimum (at 125 km) and a weaker temperature maximum (over 100-115 km). The time variability of the CO2 density profiles spans over two orders of magnitude, and a clear trend is seen with latitude. The temperature variations are also important, up to 80 K for a given pressure level, but the latitude variation are small [Mahieux et al., 2014a].A 1D radiative transfer model has been developed to reproduce the SOIR terminator profiles, derived from the Mars thermosphere code used to simulate the atmospheric effects of Siding Springs coma on Mars atmosphere [Yelle et al., 2014]. This model has been improved to better account for the CO2 and CO radiative heating and cooling processes which have to be considered in the dense atmosphere of Venus. Atmospheric diffusion of CO2, CO and O is also considered. The preliminary results of the model and its comparison with the SOIR observations will be presented and discussed.

  10. High resolution non-hydrostatic GCM simulations of Venus polar vortices

    Science.gov (United States)

    Rodin, Alexander V.; Orlov, Konstantin; Mingalev, Igor

    Non-hydrostatic general circulation model of the Venus atmosphere is capable of reproducing both superrotatoin and subsolar-antisolar circulation, providing proper parameterization of the peculiar heat balance. Using high resolution (0.7 (o) in longitude and latitude, 250 m in height) simulations from the bottom to 120 km, we explore the response of the circulation system to perturbation of heating and cooling rates in the polar regions. It is shown that diurnal tide results in off-axis displacement of the polar vortex external part at the upper cloud level, consistent with the patterns retrieved from cloud tracking observations. On the other hand, minor (3 (o) -7 (o) ) displacement of the polar vortex central part constrains the diurnal variations of the heating/cooling rates within main cloud deck. Based on the recently developed radiative transfer code, we simulate heat balance in the polar Venus atmosphere, that results in realistic circulation pattern. It is shown that Hadley cell circulation provides extra heating above the clouds, resulting in the effective damping of superrotation and development of subsolar-antisolar circulation at higher altitudes. In turin high slant opacity of the polar atmosphere within the clouds provides the effective cooling near the pole, that causes non-hydrostatic downwelling flow, manifested as a core of the observed polar vortex. The work has been supported by the Ministry of Education and Science of Russian Federation grant #11.G34.31.0074

  11. A novel cell-cycle-indicator, mVenus-p27K-, identifies quiescent cells and visualizes G0-G1 transition

    Science.gov (United States)

    Oki, Toshihiko; Nishimura, Koutarou; Kitaura, Jiro; Togami, Katsuhiro; Maehara, Akie; Izawa, Kumi; Sakaue-Sawano, Asako; Niida, Atsushi; Miyano, Satoru; Aburatani, Hiroyuki; Kiyonari, Hiroshi; Miyawaki, Atsushi; Kitamura, Toshio

    2014-02-01

    The quiescent (G0) phase of the cell cycle is the reversible phase from which the cells exit from the cell cycle. Due to the difficulty of defining the G0 phase, quiescent cells have not been well characterized. In this study, a fusion protein consisting of mVenus and a defective mutant of CDK inhibitor, p27 (p27K-) was shown to be able to identify and isolate a population of quiescent cells and to effectively visualize the G0 to G1 transition. By comparing the expression profiles of the G0 and G1 cells defined by mVenus-p27K-, we have identified molecular features of quiescent cells. Quiescence is also an important feature of many types of stem cells, and mVenus-p27K--transgenic mice enabled the detection of the quiescent cells with muscle stem cell markers in muscle in vivo. The mVenus-p27K- probe could be useful in investigating stem cells as well as quiescent cells.

  12. Photoelectron reflection and scattering at Venus: an upper limit on the "polar wind" ambipolar electric field, and a new source of top-side ionospheric heating

    Science.gov (United States)

    Collinson, Glyn; Glocer, Alex; Grebowsky, Joe; Peterson, William; Frahm, Rudy; Moore, Thomas; Gilbert, Lin; Coates, Andrew

    2015-04-01

    An important mechanism in the generation of Earth's polar wind is the ambipolar potential generated by the outflow along open field lines of superthermal electrons. This ?20V electric potential assists ions in overcoming the gravitational potential, and is a key mechanism for Terrestrial ionospheric escape. At Venus, except in rare circumstances, every field line is open, and a similar outflow of ionospheric electrons is observed. It is thus hypothesized that a similar electric potential may be present at Venus, contributing to global ionospheric loss. However, a very sensitive electric field instrument would be required to directly measure this potential, and no such instrument has yet been flown to Venus. In this pilot study, we examine photoelectron spectra measured by the ASPERA-ELS instrument on the Venus Express to put an initial upper bound on the total potential drop above 350km of ? electric field may not be as important a mechanism for atmospheric escape as previously suspected. Additionally, we find our spectra are consistent with the scattering of photoelectrons, the heating from which which we hypothesize may act as a source of top-side ionospheric heating, and may play a role in influencing the scale height of the ionosphere.

  13. A novel cell-cycle-indicator, mVenus-p27K-, identifies quiescent cells and visualizes G0-G1 transition.

    Science.gov (United States)

    Oki, Toshihiko; Nishimura, Koutarou; Kitaura, Jiro; Togami, Katsuhiro; Maehara, Akie; Izawa, Kumi; Sakaue-Sawano, Asako; Niida, Atsushi; Miyano, Satoru; Aburatani, Hiroyuki; Kiyonari, Hiroshi; Miyawaki, Atsushi; Kitamura, Toshio

    2014-01-01

    The quiescent (G0) phase of the cell cycle is the reversible phase from which the cells exit from the cell cycle. Due to the difficulty of defining the G0 phase, quiescent cells have not been well characterized. In this study, a fusion protein consisting of mVenus and a defective mutant of CDK inhibitor, p27 (p27K(-)) was shown to be able to identify and isolate a population of quiescent cells and to effectively visualize the G0 to G1 transition. By comparing the expression profiles of the G0 and G1 cells defined by mVenus-p27K(-), we have identified molecular features of quiescent cells. Quiescence is also an important feature of many types of stem cells, and mVenus-p27K(-)-transgenic mice enabled the detection of the quiescent cells with muscle stem cell markers in muscle in vivo. The mVenus-p27K(-) probe could be useful in investigating stem cells as well as quiescent cells. PMID:24500246

  14. A novel cell-cycle-indicator, mVenus-p27K?, identifies quiescent cells and visualizes G0–G1 transition

    Science.gov (United States)

    Oki, Toshihiko; Nishimura, Koutarou; Kitaura, Jiro; Togami, Katsuhiro; Maehara, Akie; Izawa, Kumi; Sakaue-Sawano, Asako; Niida, Atsushi; Miyano, Satoru; Aburatani, Hiroyuki; Kiyonari, Hiroshi; Miyawaki, Atsushi; Kitamura, Toshio

    2014-01-01

    The quiescent (G0) phase of the cell cycle is the reversible phase from which the cells exit from the cell cycle. Due to the difficulty of defining the G0 phase, quiescent cells have not been well characterized. In this study, a fusion protein consisting of mVenus and a defective mutant of CDK inhibitor, p27 (p27K?) was shown to be able to identify and isolate a population of quiescent cells and to effectively visualize the G0 to G1 transition. By comparing the expression profiles of the G0 and G1 cells defined by mVenus-p27K?, we have identified molecular features of quiescent cells. Quiescence is also an important feature of many types of stem cells, and mVenus-p27K?-transgenic mice enabled the detection of the quiescent cells with muscle stem cell markers in muscle in vivo. The mVenus-p27K? probe could be useful in investigating stem cells as well as quiescent cells. PMID:24500246

  15. Fundamental issues in the geology and geophysics of venus.

    Science.gov (United States)

    Solomon, S C; Head, J W

    1991-04-12

    A number of important and currently unresolved issues in the global geology and geophysics of Venus will be addressable with the radar imaging, altimetry, and gravity measurements now forthcoming from the Magellan mission. Among these are the global volcanic flux and the rate of formation of new crust; the global heat flux and its regional variations; the relative importance of localized hot spots and linear centers of crustal spreading to crustal formation and tectonics; and the planform of mantle convection on Venus and the nature of the interactions among interior convective flow, near-surface deformation and magmatism. PMID:17769271

  16. Propagation of the trip behavior in the VENUS vertex chamber

    International Nuclear Information System (INIS)

    The high voltage system of the VENUS vertex chamber occasionally trips by a discharge somewhere among cathode electrodes during data taking. This trip behavior induces often additional trips at other electrodes such as the skin and the grid electrodes in the vertex chamber. This propagation mechanism of trips is so complicated in this system related with multi-electrodes. Although the vertex chamber is already installed inside the VENUS detector and consequently the discharge is not able to observe directly, a trial to estimate the propagation has been done using only the information which appears around the trip circuits and the power supply of the vertex chamber. (author)

  17. Diffusion theory calculations for the pin-wise power distribution in VENUS-I and VENUS-II

    International Nuclear Information System (INIS)

    ''Standard'' pressurized water reactor (PWR) calculation procedures based on two-group diffusion theory are used to compute the relative pin-power distribution in the VENUS-I and VENUS-II benchmark configurations. These two critical lattices simulate PWR cores which have fresh (UO2) and burned (MO2) pins on the core periphery, respectively. The purpose of the study is to establish the accuracy of these methods which are used to obtain the core source distribution for RPV fluence calculations, by comparing with the experimentally determined relative power variation. Special consideration is given to the core periphery region, which contributes most heavily to the RPV fluence

  18. Observations of D/H ratios in H2O, HCl, and HF on Venus and new DCl and DF line strengths

    Science.gov (United States)

    Krasnopolsky, V. A.; Belyaev, D. A.; Gordon, I. E.; Li, G.; Rothman, L. S.

    2013-05-01

    Intensities of the spectral lines in the fundamental bands of D35Cl and DF were calculated using the semi-empirical dipole moment functions derived from the most accurate and precise measurements of intensities of the ro-vibrational lines of H35Cl and HF. Values obtained in this way for the deuterated species are superior to any available measured or calculated data to date. Our study of the D/H ratios in H2O, HCl, and HF on Venus is based on spatially-resolved high-resolution spectroscopy using the CSHELL spectrograph at NASA IRTF. Search for DF on Venus using its R5 (1-0) line at 3024.054 cm-1 results in a DF mixing ratio of 0.23 ± 0.11 ppb that corresponds to (D/H)HF = 420 ± 200 times that in the Standard Mean Ocean Water (SMOW). H2O abundances on Venus were retrieved using lines at 3022.366 and 3025.761 cm-1 that were observed at an exceptionally low overhead telluric water abundance of 0.3 pr. mm. The measured H2O mixing ratios at 74 km vary insignificantly between 55°S and 55°N with a mean value of 3.2 ppm. When compared with simultaneous observations of HDO near 2722 cm-1, this results in (D/H)H2O = 95 ± 15 times SMOW. Reanalysis of the observation of the D35Cl R4 (1-0) line at 2141.540 cm-1 (Krasnopolsky, V.A. [2012b]. Icarus 219, 244-249) using the improved line strength and more thorough averaging of the spectra gives (D/H)HCl = 190 ± 50 times SMOW. The similarity of the measured (D/H)H2O = 95 ± 15 at 74 km with 120 ± 40 observed by De Bergh et al. (De Bergh, C., Bezard, B., Owen, T., Crisp, D., Maillard, J.P., Lutz, B.L. [1991]. Science 251, 547-549) below the clouds favors the constant (D/H)H2O from the surface to the mesosphere, in accord with the prediction by theory. D/H ? 100 removes a difference of a factor of 2 between H2O abundances in the observations by Krasnopolsky (Krasnopolsky, V.A. [2010b]. Icarus 209, 314-322) and the Venus Express nadir observations (Cottini, V., Ignatiev, N.I., Piccioni, G., Drossart, P., Grassi, D., Markiewicz, W.J. [2012]. Icarus 217, 561-569). Equivalent widths of the HDO and H2O lines are similar in our observations; therefore some errors cancel out in their ratios. Photochemistry of HCl in the mesosphere tends to enrich D in HCl and deplete it in H2O. This may be an explanation of the twofold difference between the observed D/H in HCl and H2O. An alternative explanation is based on (D/H)H2O ? 200 observed in the mesosphere by Bjoraker et al. (Bjoraker, G.L., Larson, H.P., Mumma, M.J., Timmermann, R., Montani, J.L. [1992]. Bull. Am. Astron. Soc. 24, 995) and Fedorova et al. (Fedorova, A. et al. J. Geophys. Res. 113, E00B22). This means an effective exchange of D between H2O and HCl and almost equal D/H in both species. However, this requires a twofold increase in D/H from the lower atmosphere to the mesosphere. This increase is not supported by theory; furthermore, condensation processes usually deplete D/H above the clouds. Photochemistry of HF has not been studied; it proceeds mostly in the lower thermosphere, and D/H in HF may be very different from that in H2O. Overall, the observational data on D/H in all hydrogen-bearing species on Venus are helpful to solve the problem of deuterium fractionation on Venus.

  19. Teaching Planetary Sciences at the Universidad del País Vasco in Spain: The Aula Espazio Gela and its Master in Space Science and Technology

    Science.gov (United States)

    Hueso, R.; Sanchez-Lavega, A.; Pérez-Hoyos, S.

    2011-12-01

    Planetary science is a highly multidisciplinary field traditionally associated to Astronomy, Physics or Earth Sciences Departments. Spanish universities do not generally offer planetary sciences courses but some departments give courses associated to studies on Astronomy or Geology. We show a different perspective obtained at the Engeneering School at the Universidad del País Vasco in Bilbao, Spain, which offers a Master in Space Science and Technology to graduates in Engineering or Physics. Here we detail the experience acquired in two years of this master which offers several planetary science courses: Solar System Physics, Astronomy, Planetary Atmospheres & Space Weather together with more technical courses. The university also owns an urban observatory in the Engineering School which is used for practical exercises and student projects. The planetary science courses have also resulted in motivating part of the students to do their master thesis in scientific subjects in planetary sciences. Since the students have very different backgrounds their master theses have been quite different: From writing open software tools to detect bolides in video observations of Jupiter atmosphere to the photometric calibration and scientific use or their own Jupiter and Saturn images or the study of atmospheric motions of the Venus' South Polar Vortex using data from the Venus Express spacecraft. As a result of this interaction with the students some of them have been engaged to initiate Ph.D.s in planetary sciences enlarging a relative small field in Spain. Acknowledgements: The Master in Space Science and Technology is offered by the Aula Espazio Gela at the Universidad del País Vasco Engineer School in Bilbao, Spain and is funded by Diputación Foral de Bizkaia.

  20. Venus Nomenclature Progress Report: The New Names Introduced in 1998

    Science.gov (United States)

    Burba, G. A.; Blue, J.; Campbell, D. B.; Dollfus, A.; Gaddis, L.; Jurgens, R. F.; Marov, M. Ya.; Pettengill, G. H.; Stofan, E. R.

    1999-03-01

    19 new names were added on Venus in 1998 (6 craters, 5 fluctus, 1 patera, 3 tholi, 4 valles). All features, but craters, are at Aino Planitia area within 22o-46oS, 67o-105oE. The names are provisional until their final approval in 2000.

  1. Out of ecliptic missions using Venus or earth gravity assists

    Science.gov (United States)

    Bender, D. F.

    1976-01-01

    Multiple Venus or earth gravity-assist flybys are investigated as a means of producing trajectories that are inclined to the solar equator at low cost in total delta V. There are three phases to such trajectories: (1) production of a high flyby speed at the planet encounter, (2) attainment of one-to-one resonance by orbit pumping, and (3) deflection to high inclination by orbit cranking. Flybys are restricted to occur at the node of the planet orbit and the solar equator so as to take advantage of the natural inclination of the solar equator. For Venus flybys, the high approach speed is inherent in the earth to Venus trajectory. For earth flybys, the production of high approach speed can be accomplished by a VEGA (Venus-earth-gravity assist) trajectory or by a delta V-EGA trajectory. The general result is that moderate inclinations to the solar equator can be obtained at moderate total delta V cost, but at flight times which rise to five years for an inclination of 37 deg and to 13 years for an inclination of 54 deg.

  2. Using manufacturing message specification for monitor and control at Venus

    Science.gov (United States)

    Heuser, W. Randy; Chen, Richard L.; Stockett, Michael H.

    1993-01-01

    The flexibility and robustness of a monitor and control (M&C) system are a direct result of the underlying interprocessor communications architecture. A new architecture for M&C at the Deep Space Communications Complexes (DSCC's) has been developed based on the Manufacturing Message Specification (MMS) process control standard of the Open System Interconnection (OSI) suite of protocols. This architecture has been tested both in a laboratory environment and under operational conditions at the Deep Space Network (DSN) experimental Venus station (DSS-13). The Venus experience in the application of OSI standards to support M&C has been extremely successful. MMS meets the functional needs of the station and provides a level of flexibility and responsiveness previously unknown in that environment. The architecture is robust enough to meet current operational needs and flexible enough to provide a migration path for new subsystems. This paper will describe the architecture of the Venus M&C system, discuss how MMS was used and the requirements this imposed on other parts of the system, and provide results from systems and operational testing at the Venus site.

  3. Venus and Mercury, and how to observe them

    CERN Document Server

    Grego, Peter

    2007-01-01

    Venus and Mercury have long been regarded as difficult targets for amateur observers, but advances in commercially-made telescopes have brought them within the skills of observers of only moderate experience. This book presents description of the history and geology of the so-called inferior planets.

  4. Exploring the interior structure of Venus with balloons and satellites

    Science.gov (United States)

    Mimoun, David; Cutts, Jim; Stevenson, Dave

    2015-04-01

    Although present daily in our sky as the brightest object at dusk and dawn, many characteristics of Venus remains a mystery. Its dense atmosphere hides the surface from orbital viewing, and the extreme conditions experienced at its surface (460°C, almost 100 bar of pressure at the surface) pose a formidable challenge to the sustained survival and operation of planetary landers. Despite their sharply contrasting atmospheres, Venus is not very different from Earth in size, its composition should be very similar, its orbit is very close to be circular and it is only a little closer to the Sun ( 0.7 A.U). So what are the processes that turned the twin sister of our planet into such a different object? And how can we better understand the processes that have shaped the terrestrial planets, and to understand their formation history? With its harsh surface environment, conventional seismology on Venus, requiring seismometers to be deployed at the surface for months or even years seems impractical. In June 2014, the Keck Institute for Space Studies (KISS) at the California Institute of Technology sponsored a one-week workshop with 30 specialists in the key techniques and technologies relevant to investigating Venus's interior structure focusing on alternative approaches to seismology . As the vertical component of surface motion on Venus is very efficiently coupled into the atmosphere as infrasonic waves, especially at low frequency, several alternative approaches to detecting seismic events can be considered. Seismo-acoustic waves propagate upwards producing pressure fluctuations in the middle atmosphere of Venus and the seismic wave energy is ultimately dissipated by local heating, ionospheric perturbation, or airglow. These atmospheric perturbations can therefore be recorded either in-situ (with a barometer network, deployed on balloons floating in the cloud layer near 55 km) or remotely via optical imaging or electromagnetic sounding deployed on a spacecraft. A report, describing the findings of a workshop, sponsored by the Keck Institute of Space Studies (KISS), concludes that seismic investigations can be successfully conducted from all three vantage points - surface, middle atmosphere and space; these three vantage points being complementary in the information they provide. These novel techniques open a new window for the exploration of the interior structure of Venus, and enables a roadmap leading to a dedicated geophysical mission to our sister planet.

  5. Making the Venus Concept Watch 1.0

    Science.gov (United States)

    Balint, Tibor S.; Melchiorri, Julian P.

    2014-08-01

    Over the past year we have celebrated the 50th anniversary of planetary exploration, which started with the Venus flyby of Mariner-2; and the 35th anniversary of the Pioneer-Venus multi-probe mission where one large and three small probes descended to the surface of Venus, encountering extreme environmental conditions. At the surface of Venus the temperature is about 460 °C, and the pressure is 92 bar, with a highly corrosive super-critical CO2 atmosphere. At a Venusian altitude of 50 km the pressure and temperature conditions are near Earth-like, but the clouds carry sulfuric acid droplets. Deep probe missions to Jupiter and Saturn, targeting the 100 bar pressure depth encounter similar pressure and temperature conditions as the Pioneer-Venus probes did. Mitigating these environments is highly challenging and requires special considerations for designs and materials. While assessing such space mission concepts, we have found that there is an overlap between the extreme environments in planetary atmospheres and the environments experienced by deep-sea explorers back on Earth. Consequently, the mitigation approaches could be also similar between planetary probes and diver watches. For example, both need to tolerate about 100 bar of pressure-although high temperatures are not factors on Earth. Mitigating these environments, the potential materials are: titanium for the probe and the watch housing; sapphire for the window and glass; resin impregnated woven carbon fiber for the aeroshell's thermal protection system and for the face of the watch; and nylon ribbon for the parachute and for the watch band. Planetary probes also utilize precision watches; thus there is yet another crosscutting functionality with diver watches. Our team, from the Innovation Design Engineering Program of the Royal College of Art, has designed and built a concept watch to commemorate these historical events, while highlighting advances in manufacturing processes over the past three to five decades, relevant to both future planetary mission designs and can be used to produce deep diver watches. In this paper we describe our design considerations; give a brief overview of the extreme environments these components would experience on both Venus and Earth; the manufacturing techniques and materials we used to build the Venus Watch; and its outreach potential to bring a distant concept of planetary exploration closer to Earth. We will also address lessons learned from this project and new ideas forward, for the next generation of this concept design.

  6. Mariner 10 magnetic field observations of the venus wake

    International Nuclear Information System (INIS)

    Magnetic field measurements made over a 21-hour interval during the Mariner 10 encounter with Venus were used to study the downstream region of the solar wind--Venus interaction over a distance of approx. =100R/sub g/ (Venus radii). Mariner 10 encountered Venus on February 5, 1974, with closest approach at 1702 UT. For most of the day before closest approach the spacecraft was located in sheathlike region which was apparently bounded by the planet's bow shock on the outer side and either a planetary 'wake boundary' or a transient boundarylike feature on the inner side. The spacecraft made multiple encounters with the wakelike boundary during the 21-hour interval with an increasing frequency as it approached the planet. Each pass into the wake boundary from the sheath region was consistently characterized by a slight decrease in magnetic field magnitude, a marked increase in the frequency and amplitude of field fluctuations, and a systematic clockwise rotation of the field direction when viewed from above the plane of Venus' orbit. These boundary crossings were not accompanied strictly by hydromagnetic directional discontinuities, however, but occasionally (approx.1/3 of the crossings) such a discontinuity was sufficiently close to the crossing zone to be considered part of the boundary transition. There were a significantly larger number of discontinuities in the overall 21-hour period than were observed on average during other comparable periods both before and afterr comparable periods both before and after encounter. A simple large-scale draped field model in the sense of a magnetic 'comet tail' was found not to hold for the downstream region. The sporadic observation of the wake during the near-encounter period may have been controlled by changes in the direction of the interplanetary field

  7. Magellan Science Briefing from NASA Headquarters

    Science.gov (United States)

    1991-01-01

    This video presents a Magellan Science update on the most recent findings from the Magellan Mission to Venus. Brian Dunbar, NASA Public Affairs, introduces Dr. Wes Huntress, Division Director Solar System and Exploration Division. Dr. Huntress explains the Magellan Mission to Venus, which tested the temperature and emissivity of Venus, and collected high resolution radar imagery of 92% of the surface of the planet. Dr. Steve Saunders, Magellan Project Scientist, Jet Propulsion Lab, presents a visual global view of the North Pole of Venus. He also presents planet wide patterns of fracture on Venus. Dr. Saunders showed a video presentation of radio mapping results from Artemis. Dr. Wood, Radar Investigator, Smithsonian Astrophysical Observatory explains Mat Mons, which is the second highest mountain on Venus. Dr. John Wood also presents a video presentation of his findings. Dr. Gordon Pettengill, Principle Investigator, Massachusetts Institute of Technology, presents a video on the Topography of the Magellan Mission, which is able to give resolution ten times finer and further into the South and into the North than was possible earlier. The video of the Magellan Science update ends with a question and answer period.

  8. Calcium sensor kinase activates potassium uptake systems in gland cells of Venus flytraps.

    Science.gov (United States)

    Scherzer, Sönke; Böhm, Jennifer; Krol, Elzbieta; Shabala, Lana; Kreuzer, Ines; Larisch, Christina; Bemm, Felix; Al-Rasheid, Khaled A S; Shabala, Sergey; Rennenberg, Heinz; Neher, Erwin; Hedrich, Rainer

    2015-06-01

    The Darwin plant Dionaea muscipula is able to grow on mineral-poor soil, because it gains essential nutrients from captured animal prey. Given that no nutrients remain in the trap when it opens after the consumption of an animal meal, we here asked the question of how Dionaea sequesters prey-derived potassium. We show that prey capture triggers expression of a K(+) uptake system in the Venus flytrap. In search of K(+) transporters endowed with adequate properties for this role, we screened a Dionaea expressed sequence tag (EST) database and identified DmKT1 and DmHAK5 as candidates. On insect and touch hormone stimulation, the number of transcripts of these transporters increased in flytraps. After cRNA injection of K(+)-transporter genes into Xenopus oocytes, however, both putative K(+) transporters remained silent. Assuming that calcium sensor kinases are regulating Arabidopsis K(+) transporter 1 (AKT1), we coexpressed the putative K(+) transporters with a large set of kinases and identified the CBL9-CIPK23 pair as the major activating complex for both transporters in Dionaea K(+) uptake. DmKT1 was found to be a K(+)-selective channel of voltage-dependent high capacity and low affinity, whereas DmHAK5 was identified as the first, to our knowledge, proton-driven, high-affinity potassium transporter with weak selectivity. When the Venus flytrap is processing its prey, the gland cell membrane potential is maintained around -120 mV, and the apoplast is acidified to pH 3. These conditions in the green stomach formed by the closed flytrap allow DmKT1 and DmHAK5 to acquire prey-derived K(+), reducing its concentration from millimolar levels down to trace levels. PMID:25997445

  9. The VENUS/NWChem software package. Tight coupling between chemical dynamics simulations and electronic structure theory

    Science.gov (United States)

    Lourderaj, Upakarasamy; Sun, Rui; Kohale, Swapnil C.; Barnes, George L.; de Jong, Wibe A.; Windus, Theresa L.; Hase, William L.

    2014-03-01

    The interface for VENUS and NWChem, and the resulting software package for direct dynamics simulations are described. The coupling of the two codes is considered to be a tight coupling since the two codes are compiled and linked together and act as one executable with data being passed between the two codes through routine calls. The advantages of this type of coupling are discussed. The interface has been designed to have as little interference as possible with the core codes of both VENUS and NWChem. VENUS is the code that propagates the direct dynamics trajectories and, therefore, is the program that drives the overall execution of VENUS/NWChem. VENUS has remained an essentially sequential code, which uses the highly parallel structure of NWChem. Subroutines of the interface that accomplish the data transmission and communication between the two computer programs are described. Recent examples of the use of VENUS/NWChem for direct dynamics simulations are summarized.

  10. Charge-exchange in the magnetosheaths of Venus and Mars - A comparison

    Science.gov (United States)

    Russell, C. T.; Gombosi, T. I.; Horanyi, M.; Cravens, T. E.; Nagy, A. F.

    1983-01-01

    The amount of solar wind absorption due to charge-exchange in the Martian magnetosheath is evaluated and found to be about an order of magnitude less than that in the Venus magnetosheath. This difference might explain the observed difference in the scaled position and shape between the shocks at Venus and Mars. The lower solar wind absorption for Mars is attributable to the less dense hot oxygen corona of Mars compared to Venus.

  11. VENUS (Virtual ExploratioN of Underwater Sites) Two years of interdisciplinary collaboration

    OpenAIRE

    Alcala, F.; Alcocer, A.; Alves, F.; Bale, Kim; Bateman, J.; Caiti, A.; Casenove, M.; Chambelland, J. C.; Chapman, Giuseppe; Cure?, Olivier; Drap, Pierre; Durand, A.; Edmundson, K.; Gambella, L.; Gambogi, Pamela

    2008-01-01

    This article describes on-going developments of the VENUS European Project (Virtual ExploratioN of Underwater Sites, http://www.venus-project.eu) over its first two years of activity. The VENUS project is a collaborative venture which aims to bring together archaeological and scientific methodologies with technological tools for virtual exploration of deep underwater archaeological sites. The breadth of results produced by the project mean that we can only give an overview of the key project ...

  12. Venus-Earth-Mars: Comparative Climatology and the Search for Life in the Solar System

    OpenAIRE

    Launius, Roger D.

    2012-01-01

    Both Venus and Mars have captured the human imagination during the twentieth century as possible abodes of life. Venus had long enchanted humans—all the more so after astronomers realized it was shrouded in a mysterious cloak of clouds permanently hiding the surface from view. It was also the closest planet to Earth, with nearly the same size and surface gravity. These attributes brought myriad speculations about the nature of Venus, its climate, and the possibility of life existing there in ...

  13. Kinetics of Thermochemical Reactions Important in the Venus Atmospheric Sulfur Cycle

    Science.gov (United States)

    Fegley, Bruce, Jr.

    1997-01-01

    The purpose of this project was to experimentally measure the rates of several thermochemical gas-solid reactions between sulfur gases in the Venus atmosphere and reactive minerals on the hot Venus surface. Despite the great importance of these reactions for the maintenance of significant amounts of sulfur gases (and thus for the maintenance of the global cloud cover) in the atmosphere of Venus, essentially no kinetic data are currently available for them.

  14. Pioneer Venus 1978 Deep Space Network telecommunications compatibility test program status

    Science.gov (United States)

    Bryan, A. I.; Kemp, R. P.

    1978-01-01

    The Pioneer Venus 1978 flight project Deep Space Network telecommunications compatibility test program is discussed. Subsystem design tests performed during April 1977 and November 1977 are described.

  15. Instantaneous three-dimensional thermal structure of the South Polar Vortex of Venus

    Science.gov (United States)

    Garate-Lopez, I.; García Muñoz, A.; Hueso, R.; Sánchez-Lavega, A.

    2015-01-01

    The Venus thermal radiation spectrum exhibits the signature of CO2 absorption bands. By means of inversion techniques, those bands enable the retrieval of atmospheric temperature profiles. We have analyzed VIRTIS-M-IR night-side data obtaining high-resolution thermal maps of the Venus south polar region between 55 and 85 km altitudes. This analysis is specific to three Venus Express orbits where the vortex presents different dynamical configurations. The cold collar is clearly distinguishable centered at ?62 km (?100 mbar) altitude level. On average, the cold collar is more than 15 K colder than the pole, but its specific temperature varies with time. In the three orbits under investigation the South Polar Vortex appears as a vertically extended hot region close to the pole and squeezed by the cold collar between altitudes 55 and 67 km but spreading equatorwards at about 74 km. Both the instantaneous temperature maps and their zonal averages show that the top altitude limit of the thermal signature from the vortex is at ?80 km altitude, at least on the night-side of the planet. The upper part of the atmosphere (67-85 km) is more homogeneous and has long-scale horizontal temperature differences of about 25 K over horizontal distances of ?2000 km. The lower part (55-67 km) shows more fine-scale structure, creating the vortex morphology, with thermal differences of up to about 50 K over the same altitude range and ?500 km horizontal distances. This lower part of the atmosphere is highly affected by the upper cloud deck, leading to stronger local temperature variations and larger uncertainties in the retrieval. From the temperature maps, we also study the vertical stability of different atmospheric layers for the three vortex configurations. The static stability is always positive (ST > 0) in the considered altitude range (55-85 km) and in the whole polar vortex. The cold collar is the most vertically stable structure at polar latitudes, while the vortex and sub-polar latitudes show lower stability values. Furthermore, the hot filaments present within the vortex exhibit lower stability values than their surroundings. The layer between 62 and 67 km resulted to be the most stable. These results are in good agreement with conclusions from previous radio occultation analyses.

  16. Venus - Improved spin vector from Goldstone radar observations

    International Nuclear Information System (INIS)

    Twenty-one radar images of the surface of Venus obtained between 1972 and 1982 have been compared to follow the motion of 28 distinct features. The delays and Doppler shifts of these features with respect to the subradar points on the various days were used in a nonlinear least-squares parameter estimation algorithm to refine the period and pole orientation of Venus. The period is found to be -243.022 + or - 0.003 days; the right ascension and declination of the pole are: alpha = 272.816 + or - 0.14 deg; beta = 67.218 + or - 0.05 deg (B1950). These standard error estimates attempt to include effects of systematic errors. 14 refs

  17. Hot-spot evolution and the global tectonics of venus.

    Science.gov (United States)

    Phillips, R J; Grimm, R E; Malin, M C

    1991-05-01

    The global tectonics of Venus may be dominated by plumes rising from the mantle and impinging on the lithosphere, giving rise to hot spots. Global sea-floor spreading does not take place, but direct convective coupling of mantle flow fields to the lithosphere leads to regional-scale deformation and may allow lithospheric transport on a limited scale. A hot-spot evolutionary sequence comprises (i) a broad domal uplift resulting from a rising mantle plume, (ii) massive partial melting in the plume head and generation of a thickened crust or crustal plateau, (iii) collapse of dynamic topography, and (iv) creep spreading of the crustal plateau. Crust on Venus is produced by gradual vertical differentiation with little recycling rather than by the rapid horizontal creation and consumption characteristic of terrestrial sea-floor spreading. PMID:17746665

  18. Volcanic processes and landforms on Venus - Theory, predictions, and observations

    Science.gov (United States)

    Head, James W., III; Wilson, Lionel

    1986-01-01

    The ascent and eruption of magma on Venus in the current Venusian environment is modeled, taking into account the influence of extreme surface temperatures and pressures. Comparison of present predictions with observations obtained from Pioneer Venus, Arecibo, and Venera data support a picture of regional pyroclastic deposits being very rare, magma contents not usually exceeding about 4 wt pct, and the atmospheric pressure having been about the same as the present value over a time period equivalent to the average age of the northern areas of the northern hemisphere. Data suggest that numerous eruptions had effusion rates exceeding common terrestrial rates, and that shield volcanoes are often wide, but are low relative to those on Mars and earth. Implications of the proposed Venusian reduction of the driving density contrast include dike intrusion being very common, and large minimum magma volumes being required to ensure surface eruptions.

  19. Venus spherical harmonic gravity model to degree and order 60

    Science.gov (United States)

    Konopliv, Alex S.; Sjogren, William L.

    1994-01-01

    The Magellan and Pioneer Venus Orbiter radiometric tracking data sets have been combined to produce a 60th degree and order spherical harmonic gravity field. The Magellan data include the high-precision X-band gravity tracking from September 1992 to May 1993 and post-aerobraking data up to January 5, 1994. Gravity models are presented from the application of Kaula's power rule for Venus and an alternative a priori method using surface accelerations. Results are given as vertical gravity acceleration at the reference surface, geoid, vertical Bouguer, and vertical isostatic maps with errors for the vertical gravity and geoid maps included. Correlation of the gravity with topography for the different models is also discussed.

  20. Retrograde rotation of the upper atmosphere of Venus.

    Science.gov (United States)

    Caldwell, J.

    1972-01-01

    From June through September 1970, ultraviolet photographs of Venus were obtained by the International Planetary Patrol Program. A study of these photographs, together with some from other observatories, confirms previous reports that there is a retrograde circulation of the upper atmosphere of Venus. The sense of the rotation and its approximate period are determined from the motions of well-defined cloud features on five occasions over intervals of several hours. A distinctive feature similar to the 'Y' described by Boyer and Guerin (1969, 1971) is seen many times over a forty-day interval (June 21 to August 1) and allows a good determination of the rotation period: 4.41 plus or minus 0.02 days retrograde (synodic) or 4.50 days (sidereal). This value differs significantly from other estimates, but applies only to this particular forty-day interval.

  1. Magma Reservoirs Feeding Giant Radiating Dike Swarms: Insights from Venus

    Science.gov (United States)

    Grosfils, E. B.; Ernst, R. E.

    2003-01-01

    Evidence of lateral dike propagation from shallow magma reservoirs is quite common on the terrestrial planets, and examination of the giant radiating dike swarm population on Venus continues to provide new insight into the way these complex magmatic systems form and evolve. For example, it is becoming clear that many swarms are an amalgamation of multiple discrete phases of dike intrusion. This is not surprising in and of itself, as on Earth there is clear evidence that formation of both magma reservoirs and individual giant radiating dikes often involves periodic magma injection. Similarly, giant radiating swarms on Earth can contain temporally discrete subswarms defined on the basis of geometry, crosscutting relationships, and geochemical or paleomagnetic signatures. The Venus data are important, however, because erosion, sedimentation, plate tectonic disruption, etc. on Earth have destroyed most giant radiating dike swarm's source regions, and thus we remain uncertain about the geometry and temporal evolution of the magma sources from which the dikes are fed. Are the reservoirs which feed the dikes large or small, and what are the implications for how the dikes themselves form? Does each subswarm originate from a single, periodically reactivated reservoir, or do subswarms emerge from multiple discrete geographic foci? If the latter, are these discrete foci located at the margins of a single large magma body, or do multiple smaller reservoirs define the character of the magmatic center as a whole? Similarly, does the locus of magmatic activity change with time, or are all the foci active simultaneously? Careful study of giant radiating dike swarms on Venus is yielding the data necessary to address these questions and constrain future modeling efforts. Here, using giant radiating dike swarms from the Nemesis Tessera (V14) and Carson (V43) quadrangles as examples, we illustrate some of the dike swarm focal region diversity observed on Venus and briefly explore some key implications for the questions framed above.

  2. On the origin of Venus' unusual gravity spectrum

    Science.gov (United States)

    Rolf, Tobias; Werner, Stephanie; Steinberger, Bernhard

    2015-04-01

    Despite obvious differences in the present state of the terrestrial planets and the Earth's Moon, e.g. in their tectonic mode (plate tectonics, episodic resurfacing, stagnant lid, ...), al these bodies feature a gravity spectrum that is dominated by the spherical harmonic degree 2. The only exception is Venus, which features a degree 3-dominance and a much stronger correlation between geoid and topography at long wavelength than e.g. Earth. Taking this as motivation, we analyze Venus' gravity spectrum in more detail. We use a dynamic model to predict synthetic gravity spectra for a Venus-like planet and compare them to the observed spectrum provided from satellite missions in sufficient detail. It is known that the viscosity structure of a planetary mantle has a strong impact on the spectrum, such that we can in turn use the misfit between observed and predicted spectrum as a constraint for the viscosity profile, which also shapes the structure of mantle flow. First, we test different prescribed viscosity structures inferred from mineral physics. While the match between observed and predicted spectrum is a matter of improvement, these models reproduce Venus' strong geoid-topography correlation. Furthermore, these models support the idea of no, respectively, a small viscosity contrast between upper and lower mantle - in contrast to Earth. Second, we test self-consistently calculated viscosity structures based on an Arrhenius law, which include lateral viscosity variations. These cases lead to a stable degree 3-structure as observed, if convective vigor is sufficiently high. However, comparison of viscosity structures with and without lateral variation indicates that the long-wavelength components of the spectrum are basically insensitive to the lateral variations, which do not improve the fit between observed and predicted spectra. In order to further address this discrepancy, we test models that include a crustal layer and spatial variations in its thickness in the next step.

  3. Solar diameter with 2012 Venus transit: history and opportunities

    OpenAIRE

    Sigismondi, Costantino

    2012-01-01

    The role of Venus and Mercury transits is crucial to know the past history of the solar diameter. Through the W parameter, the logarithmic derivative of the radius with respect to the luminosity, the past values of the solar luminosity can be recovered. The black drop phenomenon affects the evaluation of the instants of internal and external contacts between the planetary disk and the solar limb. With these observed instants compared with the ephemerides the value of the sol...

  4. Initial Pioneer Venus magnetic field results - Dayside observations

    Science.gov (United States)

    Russell, C. T.; Elphic, R. C.; Slavin, J. A.

    1979-01-01

    Pioneer Venus magnetometer observations in the sunlit ionosphere indicate that the ionosphere is dynamic and very responsive to external solar wind conditions. Bow shock location, ionosphere location, the strength of the magnetic field just outside the ionopause, and the field strength in the ionosphere are found to be variable, and the properties of flux ropes in the ionospheric magnetic field are considered. Data on magnetic energy density and on magnetic field strength are presented.

  5. Parabolic features and the erosion rate on Venus

    Science.gov (United States)

    Strom, Robert G.

    1993-01-01

    The impact cratering record on Venus consists of 919 craters covering 98 percent of the surface. These craters are remarkably well preserved, and most show pristine structures including fresh ejecta blankets. Only 35 craters (3.8 percent) have had their ejecta blankets embayed by lava and most of these occur in the Atla-Beta Regio region; an area thought to be recently active. parabolic features are associated with 66 of the 919 craters. These craters range in size from 6 to 105 km diameter. The parabolic features are thought to be the result of the deposition of fine-grained ejecta by winds in the dense venusian atmosphere. The deposits cover about 9 percent of the surface and none appear to be embayed by younger volcanic materials. However, there appears to be a paucity of these deposits in the Atla-Beta Regio region, and this may be due to the more recent volcanism in this area of Venus. Since parabolic features are probably fine-grain, wind-deposited ejecta, then all impact craters on Venus probably had these deposits at some time in the past. The older deposits have probably been either eroded or buried by eolian processes. Therefore, the present population of these features is probably associated with the most recent impact craters on the planet. Furthermore, the size/frequency distribution of craters with parabolic features is virtually identical to that of the total crater population. This suggests that there has been little loss of small parabolic features compared to large ones, otherwise there should be a significant and systematic paucity of craters with parabolic features with decreasing size compared to the total crater population. Whatever is erasing the parabolic features apparently does so uniformly regardless of the areal extent of the deposit. The lifetime of parabolic features and the eolian erosion rate on Venus can be estimated from the average age of the surface and the present population of parabolic features.

  6. Accurate free and forced rotational motions of rigid Venus

    OpenAIRE

    Cottereau, L.; Souchay, J.; Aljbaae, S.

    2010-01-01

    % context :The precise and accurate modelling of a terrestrial planet like Venus is an exciting and challenging topic, all the more interesting since it can be compared with that of the Earth for which such a modelling has already been achieved at the milliarcsecond level % aims: We want to complete a previous study (Cottereau and Souchay, 2009), by determining at the milliarcsecond level the polhody, i.e. the torque-free motion of the axis of angular momentum of a rigid Ven...

  7. Plasma clouds above the ionopause of Venus and their implications

    International Nuclear Information System (INIS)

    Early Pioneer Venus orbiter measurements by the Electron Temperature Probe have revealed wavelike structures at the ionopause and clouds of plasma above the ionopause, features which may represent ionospheric plasma at different stages in its removal by solar wind-ionosphere interaction processes. Continuing operation of the orbiter through three Venus years has now provided enough additional examples of these features to permit their morphologies to be examined in some detail. The global distribution of the clouds suggests that they originate at the dayside ionopause as wavelike structures which may become detached and swept downstream in the ionosheath flow. Alternatively the clouds may actually be attached streamers analogous to cometary structure. Estimates of the total ion escape rate from Venus by this process yields values up to 7 x 1026 ions s-1, based on their measured transit times, their probability of occurrence, their statistical distribution and their average electron density. Preliminary analysis shows that such an escape flux could be supplied by the upward diffusion limited flow of O+ from the entire dayside ionosphere. Observed distortions of dayside ionosphere height profiles suggest that such flows may be present much of the time. (author)

  8. A high resolution gravity model for Venus - GVM-1

    Science.gov (United States)

    Nerem, R. S.; Bills, B. G.; Mcnamee, J. B.

    1993-01-01

    A spherical harmonic model of the gravitational field of Venus complete to degree and order 50 has been developed using the S-band Doppler tracking data of the Pioneer Venus Orbiter (PVO) collected between 1979 and 1982. The short wavelengths of this model could only be resolved near the PVO periapse location (about 14 deg N latitude), therefore a priori constraints were applied to the model to bias poorly observed coefficients towards zero. The resulting model has a half-wavelength resolution of 400 km near the PVO periapse location, but the resolution degrades to greater than 1000 km near the poles. This gravity model correlates well with a degree 50 spherical harmonic expansion of the Venus topography derived from a combination of Magellan and PVO data. New tracking data from Magellan's gravity mission should provide some improvement to this model, although a complete model of the Venusian gravity field will depend on tracking of Magellan after the circularization of its orbit using aerobraking.

  9. Solar diameter with 2012 Venus transit: history and opportunities

    CERN Document Server

    Sigismondi, Costantino

    2012-01-01

    The role of Venus and Mercury transits is crucial to know the past history of the solar diameter. Through the W parameter, the logarithmic derivative of the radius with respect to the luminosity, the past values of the solar luminosity can be recovered. The black drop phenomenon affects the evaluation of the instants of internal and external contacts between the planetary disk and the solar limb. With these observed instants compared with the ephemerides the value of the solar diameter is recovered. The black drop and seeing effects are overcome with two fitting circles, to Venus and to the Sun, drawn in the undistorted part of the image. The corrections of ephemerides due to the atmospheric refraction will also be taken into account. The forthcoming transit of Venus will allow an accuracy on the diameter of the Sun better than 0.01 arcsec, with good images of the ingress and of the egress taken each second. Chinese solar observatories are in the optimal conditions to obtain valuable data for the measurement ...

  10. A discussion of CO and O on Venus and Mars

    Science.gov (United States)

    Shimizu, M.

    1972-01-01

    The absorption of solar ultraviolet radiation in the wavelength range 2000 to 2200 A by CO2 strongly reduces the dissociation rate of HCl on Venus. The Cl catalytic reaction for the rapid recombination of O and CO and the yellow coloration of the Venus haze by OCl(-) and Cl3(-) appears to be unlikely. At the time of the Martian dust storm, the dissociation of H2O in the vicinity of the surface may vanish. The increase of dissociation at high altitudes, however, can be the source of H atoms in the upper atmosphere. The H atoms from the dissociation of hydrides may catalyze the recombination of CO and O in the lower atmospheres of these planets according to the following scheme: H + CO + M yields HCO + M, and HCO + O yields H + CO2. In the case of Venus, there may be other kinds of sinks for the photodissociation products, and its chemical environment might be more complex than that of Mars.

  11. Venera-D: Russian mission for complex investigation of Venus

    Science.gov (United States)

    Korablev, O.; Zasova, L.; Perminov, V.; Ekonomov, A.; Basilevsky, A.; Gerasimov, M.; Linkin, V.; Rodin, A.; Skalsky, A.

    Russian Federal Space program for 2006-2015 includes a mission "Venera-D" for complex investigation of Venus. It is planned to be launched around 2016, by rocket Soyuz-2. According to preliminary investigation in Babakin Center mass of 1900 kg may be delivered to Venus. This mass may include orbiter, balloon(s), lander(s) with long living station on the surface of Venus. Scientific goals: investigation of structure, composition and dynamics of the atmosphere, structure and chemical composition of the clouds and nature of the hazes, investigation of the composition and properties of the surface, search for the volcanic activity, interaction between atmosphere and the surface, search for the electric and acoustic activity in the atmosphere, search for seismic activity, investigations of ionosphere and magnetosphere. A conception of the mission is under development now: new elements, like balloons, flying at different levels in the atmosphere may be down to 10 km altitude with landing and working on the surface, and descend module with long living station on the surface are considered. With existing electronics working at around 300C and corresponding insulation the life of station on the surface may be provided for a month We acknowledge IKI RAS for financial support, grant "Perspectiva"

  12. The monopropellant hydrazine propulsion subsystem for the Pioneer Venus spacecraft

    Science.gov (United States)

    Barker, F. C.

    1979-01-01

    The Pioneer Venus Orbiter and the Multiprobe spacecraft propulsion subsystems and their performance are presented. Monopropellant hydrazine subsystems on each spacecraft provided the capability to spin up the spacecraft after separation and perform all spin rate, velocity, and attitude changes required by the control subsystem to satisfy mission objectives. The propulsion subsystem provides thrust on demand by supplying anhydrous hydrazine from the propellant tanks through manifolds, filters and valves to the thrust chamber assemblies where the hydrazine is catalytically decomposed and expanded in a conical nozzle. The subsystems consist of seven 1 lbf thrusters for the Orbiter and six 1 lbf thrusters for the multiprobe which are isolated by two latch valves from the two propellant tanks so that two redundant thruster clusters are provided to ensure mission completion in the event of a single point failure. The propellant feed system is of all-welded construction to minimize weight and leakage and titanium is used as the primary material of construction. The multiprobe burned up on entering the Venus atmosphere with enough propellant left for the mission and the Orbiter was inserted into Venus orbit with enough propellant remaining for more than 2 earth years of orbital operations.

  13. The effects of Venus' thermal structure on buoyant magma ascent

    Science.gov (United States)

    Sakimoto, S. E. H.; Zuber, M. T.

    1992-01-01

    The recent Magellan images have revealed a broad spatial distribution of surface volcanism on Venus. Previous work in modeling the ascent of magma on both Venus and Earth has indicated that the planetary thermal structure significantly influences the magmatic cooling rates and thus the amount of magma that can be transported to the surface before solidification. In order to understand which aspects of the thermal structure have the greatest influence on the cooling of ascending magma, we have constructed magma cooling curves for both plutonic and crack buoyant ascent mechanisms, and evaluated the curves for variations in the planetary mantle temperature, thermal gradient curvature with depth, surface temperature gradient, and surface temperature. The planetary thermal structure is modeled as T/T(sub 0) = 1-tau(1-Z/Z(sub 0)(exp n), where T is the temperature, T(sub 0) is the source depth temperature, tau = 1-(T(sub s)/T(sub 0)) where T(sub s) is the planetary surface temperature, Z is the depth, Z(sub 0) is the source depth, and n is a constant that controls thermal gradient curvature with depth. The equation is used both for mathematical convenience and flexibility, as well as its fit to the thermal gradients predicted by the cooling half-space models. We assume a constant velocity buoyant ascent, body-averaged magma temperatures and properties, an initially crystal-free magma, and the same liquidus and solidus for both Venus and Earth.

  14. Glory revealed in disk-integrated photometry of Venus

    CERN Document Server

    Muñoz, A García; Sánchez-Lavega, A

    2014-01-01

    Context. Reflected light from a spatially unresolved planet yields unique insight into the overall optical properties of the planet cover. Glories are optical phenomena caused by light that is backscattered within spherical droplets following a narrow distribution of sizes; they are well known on Earth as localised features above liquid clouds. Aims. Here we report the first evidence for a glory in the disk-integrated photometry of Venus and, in turn, of any planet. Methods. We used previously published phase curves of the planet that were reproduced over the full range of phase angles with model predictions based on a realistic description of the Venus atmosphere. We assumed that the optical properties of the planet as a whole can be described by a uniform and stable cloud cover, an assumption that agrees well with observational evidence. Results. We specifically show that the measured phase curves mimic the scattering properties of the Venus upper-cloud micron-sized aerosols, also at the small phase angles ...

  15. The split fate of the early Earth, Mars, Venus, and Moon

    Science.gov (United States)

    Albarède, Francis; Blichert-Toft, Janne

    2007-11-01

    Plate tectonics shaped the Earth, whereas the Moon is a dry and inactive desert, Mars probably came to rest within the first billion years of its history, and Venus, although internally very active, has a dry inferno for its surface. Here we review the parameters that determined the fates of each of these planets and their geochemical expressions. The strong gravity field of a large planet allows for an enormous amount of gravitational energy to be released, causing the outer part of the planetary body to melt (magma ocean), helps retain water on the planet, and increases the pressure gradient. The weak gravity field and anhydrous conditions prevailing on the Moon stabilized, on top of its magma ocean, a thick buoyant plagioclase lithosphere, which insulated the molten interior. On Earth, the buoyant hydrous phases (serpentines) produced by reactions between the terrestrial magma ocean and the wet impactors received from the outer solar system isolated the magma and kept it molten for some few tens of million years. The planets from the inner solar system accreted dry: foundering of wet surface material softened the terrestrial mantle and set the scene for the onset of plate tectonics. This very same process also may have removed all the water from the surface of Venus and added enough water to its mantle to make its internal dynamics very strong and keep the surface very young. Because of a radius smaller than that of the Earth, not enough water could be drawn into the Martian mantle before it was lost to space and Martian plate tectonics never began. The radius of a planet is therefore the key parameter controlling most of its evolutional features.

  16. Venus Kinase Receptors: prospects in signalling and biological functions of these invertebrate receptors

    Directory of Open Access Journals (Sweden)

    ColetteDissous

    2014-05-01

    Full Text Available Venus Kinase Receptors (VKRs form a family of invertebrate receptor tyrosine kinases (RTKs initially discovered in the parasitic platyhelminth Schistosoma mansoni. VKRs are single transmembrane receptors which contain an extracellular Venus Flytrap (VFT structure similar to the ligand binding domain of G Protein Coupled Receptors of class C, and an intracellular Tyrosine Kinase domain close to that of Insulin Receptors. VKRs are found in a large variety of invertebrates from cnidarians to echinoderms, and are highly expressed in larval stages and in gonads, suggesting a role of these proteins in embryonic and larval development as well as in reproduction. Vkr gene silencing could demonstrate the function of these receptors in oogenesis as well as in spermatogenesis in Schistosoma .mansoni. VKRs are activated by amino-acids, and highly responsive to arginine. As many other RTKs, they form dimers when activated by ligands and induce intracellular pathways involved in protein synthesis and cellular growth, such as MAPK and PI3K/Akt/S6K pathways. VKRs are not present in vertebrates, nor in some invertebrate species. Questions remain open about the origin of this little-known RTK family in evolution and its role in emergence and specialization of Metazoa. What is the meaning of maintenance or loss of VKR in some phyla or species in terms of development and physiological functions? The presence of VKRs in invertebrates of economical and medical importance, such as pests, vectors of pathogens and platyhelminth parasites, and the implication of these RTKs in gametogenesis and reproduction processes are valuable reasons to consider VKRs as interesting targets in new programs for eradication/ control of pests and infectious diseases, with the main advantage in the case of parasite targeting that VKR counterparts are absent from the vertebrate host kinase panel.

  17. Sequencing Medicago truncatula expressed sequenced tags using 454 Life Sciences technology

    Directory of Open Access Journals (Sweden)

    Xiao Yongli

    2006-10-01

    Full Text Available Abstract Background In this study, we addressed whether a single 454 Life Science GS20 sequencing run provides new gene discovery from a normalized cDNA library, and whether the short reads produced via this technology are of value in gene structure annotation. Results A single 454 GS20 sequencing run on adapter-ligated cDNA, from a normalized cDNA library, generated 292,465 reads that were reduced to 252,384 reads with an average read length of 92 nucleotides after cleaning. After clustering and assembly, a total of 184,599 unique sequences were generated containing over 400 SSRs. The 454 sequences generated hits to more genes than a comparable amount of sequence from MtGI. Although short, the 454 reads are of sufficient length to map to a unique genome location as effectively as longer ESTs produced by conventional sequencing. Functional interpretation of the sequences was carried out by Gene Ontology assignments from matches to Arabidopsis and was shown to cover a broad range of GO categories. 53,796 assemblies and singletons (29% had no match in the existing MtGI. Within the previously unobserved Medicago transcripts, thousands had matches in a comprehensive protein database and one or more of the TIGR Plant Gene Indices. Approximately 20% of these novel sequences could be found in the Medicago genome sequence. A total of 70,026 reads generated by the 454 technology were mapped to 785 Medicago finished BACs using PASA and over 1,000 gene models required modification. In parallel to 454 sequencing, 4,445 5'-prime reads were generated by conventional sequencing using the same library and from the assembled sequences it was shown to contain about 52% full length cDNAs encoding proteins from 50 to over 500 amino acids in length. Conclusion Due to the large number of reads afforded by the 454 DNA sequencing technology, it is effective in revealing the expression of transcripts from a broad range of GO categories and contains many rare transcripts in normalized cDNA libraries, although only a limited portion of their sequence is uncovered. As with longer ESTs, 454 reads can be mapped uniquely onto genomic sequence to provide support for, and modifications of, gene predictions.

  18. Comparison of modern lattice codes, MCNP and other transport codes for the VENUS-1 and VENUS-2 cores

    International Nuclear Information System (INIS)

    Regarding fission rate distributions, the modern lattice codes CASMO-4 and APOLLO2-A show good agreement with both MCNP solutions and with experimental data, the quality being comparable to MCNP; with the codes MOCA, VARIANT, and THREEDANT, which use pin cell homogenized few group cross sections with 5 or 18 energy groups, the C/E ratio in the fission rate distributions exhibits a slightly higher tilt from the core centre to the periphery. The overestimation of the fission rates in the MOX zone in VENUS-2 seems to be to a large extent a MOX effect, since the overestimation in the outer rows of the VENUS-1 UOX core is substantially lower. This effect is seen more or less in all solutions. Although this may be attributed to nuclear library data, the transition from JEF2.2 to JEFF3.1 does not change the results significantly. (orig.)

  19. MSR, a multi-spectrum retrieval technique for spatially-temporally correlated or common Venus surface and atmosphere parameters

    Science.gov (United States)

    Kappel, David

    2014-01-01

    A common way to regularize mathematical ill-posed retrieval problems in atmospheric remote sensing is the incorporation of single-spectrum Bayesian a priori mean values and standard deviations for the parameters to be retrieved, along with measurement and simulation error information. This decreases the probability to obtain unlikely parameter values. For a reliable evaluation of measurements with sparse spectral information content like Venus' nightside emissions in the infrared as acquired by the VIRTIS-M-IR instrument aboard ESA's Venus Express spacecraft, it can help to consider further a priori knowledge. A new multi-spectrum retrieval technique (MSR) is presented that allows one to incorporate expected correlation lengths and times for the retrieval parameters used to describe several spectra. It is demonstrated by examples that this decreases the probability to retrieve spatial-temporal state vector distributions that are incompatible with these a priori spatial-temporal correlations. Also, a priori correlations between the parameters used to describe a single spectrum and exhibiting similar a priori spatial-temporal behavior, act to rule out unlikely single-spectrum state vectors. Parameters with infinite correlation length or time and identic single-spectrum a priori data are spatially or temporally constant and can be retrieved as parameters that are common to a certain selection of measurements. This is shown to be especially useful to retrieve surface emissivity in the infrared as a parameter that is common to several measurements that repeatedly cover the same target, and to determine deep atmospheric CO2 opacity corrections, which are common to all Venus nightside spectra. Also this way, all considered measurements can be parameterized by a fully consistent set of atmospheric, surface, and instrumental parameters that respects all available a priori data as well as the measurement and simulation error distributions and that does not neglect the context between adjacent measurements. MSR is demonstrated to enhance the retrieval reliability and accuracy and pushes the VIRTIS-M-IR data evaluation to its limits.

  20. Relief and geology of the northern polar region of the planet Venus

    Energy Technology Data Exchange (ETDEWEB)

    Kuz' min, R.O.; Burba, G.A.; Shashkina, V.P.; Bogomolov, A.F.; Zherikhin, N.V.; Skrypnik, G.I.; Kudrin, L.V.; Berman, M.Yu.; Rzhiga, O.N.; Sidorenko, A.I.; Aleksandrov, Yu.N.

    1987-01-01

    A description is given of the topographic features of the relief of the northern polar region of the planet Venus. The main morphological types of terrains and also their geological relations are characterized. The relative age sequence of the geological subdivisions in the northern polar region of Venus is discussed.

  1. Relief and geology of the northern polar region of the planet Venus

    International Nuclear Information System (INIS)

    A description is given of the topographic features of the relief of the northern polar region of the planet Venus. The main morphological types of terrains and also their geological relations are characterized. The relative age sequence of the geological subdivisions in the northern polar region of Venus is discussed

  2. Relief and geology of the North polar region of the Venus planet

    International Nuclear Information System (INIS)

    Description of topographic features is given for the North polar region of the Venus planet. Principal morphological and geomorphic types of terrain are characterized as well as their geologic relations. Relative ages of geologic units in Venus North polar region are discussed

  3. The June 2012 transit of Venus. Framework for interpretation of observations

    CERN Document Server

    Muñoz, A García

    2012-01-01

    Ground based observers have on 5/6th June 2012 the last opportunity of the century to watch the passage of Venus across the solar disk from Earth. Venus transits have traditionally provided unique insight into the Venus atmosphere through the refraction halo that appears at the planet outer terminator near ingress/egress. Much more recently, Venus transits have attracted renewed interest because the technique of transits is being successfully applied to the characterization of extrasolar planet atmospheres. The current work investigates theoretically the interaction of sunlight and the Venus atmosphere through the full range of transit phases, as observed from Earth and from a remote distance. Our model predictions quantify the relevant atmospheric phenomena, thereby assisting the observers of the event in the interpretation of measurements and the extrapolation to the exoplanet case. Our approach relies on the numerical integration of the radiative transfer equation, and includes refraction, multiple scatter...

  4. El pedido de armas de Venus a Vulcano (En. 8. 370-406): algunos intertextos / Venus' request of armours from Vulcan (Aen. 8. 370-406): some intertexts

    Scientific Electronic Library Online (English)

    María Emilia, Cairo.

    2010-06-01

    Full Text Available El objetivo de este artículo es estudiar el episodio de Eneida 8 en el cual Venus le solicita a Vulcano la elaboración de armas para Eneas. En particular, nos interesa indagar las relaciones de intertextualidad que establece con cuatro pasajes de la tradición épica: Ilíada 18, Ilíada 14, Odisea 8 y [...] el proemio de De rerum natura de Lucrecio. El análisis de la imitatio virgiliana contribuye al estudio de la complejidad del personaje de Venus. Abstract in english The aim of this paper is to study the episode of Aeneid 8 in which Venus asks Vulcan to make an armour for Aeneas. In particular, we are interested in investigating the intertextual relationships which it bears to four passages of the epic tradition: Iliad 18, Iliad 14, Odyssey 8 and Lucretius' proe [...] m to De rerum natura. The analysis of Virgilian imitatio contributes to the study of the complexity of Venus' character.

  5. Venus' clouds as inferred from the phase curves acquired by IR1 and IR2 on board Akatsuki

    Science.gov (United States)

    Satoh, Takehiko; Ohtsuki, Shoko; Iwagami, Naomoto; Ueno, Munetaka; Uemizu, Kazunori; Suzuki, Makoto; Hashimoto, George L.; Sakanoi, Takeshi; Kasaba, Yasumasa; Nakamura, Ryosuke; Imamura, Takeshi; Nakamura, Masato; Fukuhara, Tetsuya; Yamazaki, Atsushi; Yamada, Manabu

    2015-03-01

    We present phase curves for Venus in the 1-2 ?m wavelength region, acquired with IR1 and IR2 on board Akatsuki (February-March 2011). A substantial discrepancy with the previously-published curves was found in the small phase angle range (0-30°). Through analysis by radiative-transfer computation, it was found that the visibility of larger (?1 ?m or larger) cloud particles was significantly higher than in the standard cloud model. Although the cause is unknown, this may be related to the recently reported increase in the abundance of SO2 in the upper atmosphere. It was also found that the cloud top is located at ?75 km and that 1-?m particles exist above the cloud, both of these results being consistent with recent studies based on the Venus Express observations in 2006-2008. Further monitoring, including photometry for phase curves, polarimetry for aerosol properties, spectroscopy for SO2 abundance, and cloud opacity measurements in the near-infrared windows, is required in order to understand the mechanism of this large-scale change.

  6. Impact craters on Venus: An overview from Magellan observations

    Science.gov (United States)

    Schaber, G. G.; Strom, R. G.; Moore, H. J.; Soderblom, L. A.; Kirk, R. L.; Chadwick, D. J.; Dawson, D. D.; Gaddis, L. R.; Boyce, J. M.; Russell, J.

    1992-01-01

    Magellan has revealed an ensemble of impact craters on Venus that is unique in many important ways. We have compiled a database describing 842 craters on 89 percent of the planet's surface mapped through orbit 2578 (the craters range in diameter from 1.5 to 280 km). We have studied the distribution, size-frequency, morphology, and geology of these craters both in aggregate and, for some craters, in more detail. We have found the following: (1) the spatial distribution of craters is highly uniform; (2) the size-density distribution of craters with diameters greater than or equal to 35 km is consistent with a 'production' population having a surprisingly young age of about 0.5 Ga (based on the estimated population of Venus-crossing asteroids); (3) the spectrum of crater modification differs greatly from that on other planets--62 percent of all craters are pristine, only 4 percent volcanically embayed, and the remainder affected by tectonism, but none are severely and progressively depleted based on size-density distribution extrapolated from larger craters; (4) large craters have a progression of morphologies generally similar to those on other planets, but small craters are typically irregular or multiple rather than bowl shaped; (5) diffuse radar-bright or -dark features surround some craters, and about 370 similar diffuse 'splotches' with no central crater are observed whose size-density distribution is similar to that of small craters; and (6) other features unique to Venus include radar-bright or -dark parabolic arcs opening westward and extensive outflows originating in crater ejecta.

  7. Possible Signs of Life on the Planet Venus

    OpenAIRE

    Ksanfomality, Leonid V.

    2013-01-01

    It is possible, the question on the existence of extraterrestrial life will be answered not as a result of its search for in other worlds removed by distances of dozens of parsecs but on the surface of Venus, i.e., of the nearest planet of the Solar system. The search for “habitable zones” in extrasolar planetary systems is based on the postulate on “normal” physical conditions, i.e., the pressure, temperature, and maybe atmospheric composition similar to those on Earth. But could no...

  8. Galileo orbit determination for the Venus and Earth-1 flybys

    Science.gov (United States)

    Kallemeyn, P. H.; Haw, R. J.; Pollmeier, V. M.; Nicholson, F. T.; Murrow, D. W.

    1992-01-01

    This paper presents the orbit determination strategy and results in navigating the Galileo spacecraft from launch through its Venus and first earth flybys. Many nongravitational effects were estimated, including solar radiation pressure, small velocity impulses from attitude changes and eight trajectory correction maneuvers. Tracking data consisted of S-Band Doppler and range. The fitting of Doppler was difficult since one of the cpacecraft's two antennas was offset from the spin axis, thus producing the sinusoidal velocity fluctuation seen in the data. Finally, Delta Differential One-way Range data was used during the last three months of the earth approach to help deliver the spacecraft to within desired accuracy.

  9. Venus Atmosphere Profile from a Maximum Entropy Principle

    CERN Document Server

    Epele, L N; Canal-Garcia, C A; Pacheco, A F; Sañudo, J; Epele, Luis N.; Fanchiotti, Huner; Canal, Carlos A. Garc\\'{\\i}a; Pacheco, Amalio F.; Sa\\~nudo, Jaime

    2006-01-01

    The variational method with constraints recently developed by Verkley and Gerkema to describe maximum-entropy atmospheric profiles is generalized to ideal gases but with temperature-dependent specific heats. In so doing, an extended and non standard potential temperature is introduced that is well suited for tackling the problem under consideration. This new formalism is successfully applied to the atmosphere of Venus. Three well defined regions emerge in this atmosphere up to a height of $100 km$ from the surface: the lowest one up to about $35 km$ is adiabatic, a transition layer located at the height of the cloud deck and finally a third region which is practically isothermal.

  10. The 1882 Transit of Venus: Observations from Wellington, South Africa

    Science.gov (United States)

    Koorts, W.P.

    The transit of Venus is a rare astronomical event that has been well documented throughout history. The most recent transit occurred in June of 2004, and the one before that took place more than 100 years earlier in 1882. This site from the South African Astronomical Observatory provides information and first-hand observations of the 1882 event from Wellington, South Africa. Just prior to the event, an observatory was erected at the Huguenot Seminary for girls, and some of the historical observations made from that site in 1882 are provided here for your perusal.

  11. Venus gravity and topography: 60th degree and order model

    Science.gov (United States)

    Konopliv, A. S.; Borderies, N. J.; Chodas, P. W.; Christensen, E. J.; Sjogren, W. L.; Williams, B. G.; Balmino, G.; Barriot, J. P.

    1993-01-01

    We have combined the most recent Pioneer Venus Orbiter (PVO) and Magellan (MGN) data with the earlier 1978-1982 PVO data set to obtain a new 60th degree and order spherical harmonic gravity model and a 120th degree and order spherical harmonic topography model. Free-air gravity maps are shown over regions where the most marked improvement has been obtained (Ishtar-Terra, Alpha, Bell and Artemis). Gravity versus topography relationships are presented as correlations per degree and axes orientation.

  12. The resurfacing history of Venus: Constraints from buffered crater densities

    Science.gov (United States)

    Kreslavsky, Mikhail A.; Ivanov, Mikhail A.; Head, James W.

    2015-04-01

    Because of atmospheric shielding and endogenic resurfacing, the population of impact craters on Venus is small (about a thousand) and consists of large craters. This population has been used in numerous studies with the goal of deciphering the geologic and geodynamic history of Venus, but the nearly spatially random nature of the crater population has complicated efforts to understand this history. Here we utilize the recent 1:15 M-scale global geological map of Venus (Ivanov, M.A., Head, J.W. [2011]. Planet. Space Sci. 59, 1559-1600) to help address this problem. The global geological map provides a stratigraphic sequence of units, and known areas where each unit is exposed on the planet. For each crater on Venus we identify the specific geological units predating and postdating the crater. We perform a statistical analysis of this set of observations with a buffered crater density approach, which rigorously and consistently takes into account the large size of craters and the fact that many craters are known to predate and/or postdate more than one unit. In this analysis we consider crater emplacement as random and resurfacing history as determined (although unknown). We obtain formal confidence intervals for the mean ages of geological units and the mean age differences between the pairs of units at the unit boundaries. We find that (1) size-frequency distributions of craters superposed on each unit are consistent with each other; (2) regional plains and stratigraphically older units have similar crater retention ages; (3) stratigraphically younger units have a mean crater retention age significantly younger than the regional plains. These findings are readily and consistently explained by global resurfacing scenarios and are difficult to reconcile with equilibrium resurfacing scenarios. Our analysis also shows that the latest recorded part of intensive resurfacing period lasted on the order of 10% of the mean surface age (tens of millions of years). The termination of intensive resurfacing may or may not be synchronous over the planet. Our results also indicate that there are extended deposits associated with large craters that are almost indiscernible in the radar images, but obscure radar contrasts between predating lava flows. We do not see evidence for any significant and prolonged change of atmospheric pressure following the termination of the intensive resurfacing epoch.

  13. Project ExPreSS: Social studies and science remediation program for the Georgia High School Graduation Test

    Science.gov (United States)

    Shearouse, Randy

    Over half of the states now require students to pass a high stakes exit exam before being allowed to graduate from high school. No Child Left Behind requires that standardized testing be included to determine whether or not a school makes Adequate Yearly Progress (AYP). The purpose of this study is to examine the results of the Georgia High School Graduation Test (GHSGT) of students who participated in the remedial program Project ExPreSS with those students who did not participate. Using a quantitative research design, the question that will be answered is whether Project ExPreSS makes a difference in passing the GHSGT in science and social studies among three groups: all Georgia students, African American students in one Georgia school system, and all students in one Georgia school system. A chi-square test was conducted and a determination was made that there is a statistically significant relationship between project participation and pass-fail status in all but one area. The majority of students in this study were 17--18 years of age and were taking the science or social studies section of the GHSGT for the second time. The findings of this study will be important not only for Georgia and the school system examined, but also for other states and systems that give High Stakes Exit Exams (HSEEs). The results indicate that highly focused remedial programs like Project ExPreSS make a difference for students who may not be successful on their first attempt at passing a HSEE.

  14. Long-term variations in abundance and distribution of sulfuric acid vapor in the Venus atmosphere inferred from Pioneer Venus and Magellan radio occultation studies

    Science.gov (United States)

    Jenkins, J. M.; Steffes, P. G.

    1992-01-01

    Radio occultation experiments have been used to study various properties of planetary atmospheres, including pressure and temperature profiles, and the abundance profiles of absorbing constituents in those planetary atmospheres. However, the reduction of amplitude data from such experiments to determine abundance profiles requires the application of the inverse Abel transform (IAT) and numerical differentiation of experimental data. These two operations preferentially amplify measurement errors above the true signal underlying the data. A new technique for processing radio occultation data has been developed that greatly reduces the errors in the derived absorptivity and abundance profiles. This technique has been applied to datasets acquired from Pioneer Venus Orbiter radio occultation studies and more recently to experiments conducted with the Magellan spacecraft. While primarily designed for radar studies of the Venus surface, the high radiated power (EIRP) from the Magellan spacecraft makes it an ideal transmitter for measuring the refractivity and absorptivity of the Venus atmosphere by such experiments. The longevity of the Pioneer Venus Orbiter has made it possible to study long-term changes in the abundance and distribution of sulfuric acid vapor, H2SO4(g), in the Venus atmosphere between 1979 and 1992. The abundance of H2SO4(g) can be inferred from vertical profiles of 13-cm absorptivity profiles retrieved from radio occultation experiments. Data from 1979 and 1986-87 suggest that the abundance of H2SO4(g) at latitudes northward of 70 deg decreased over this time period. This change may be due to a period of active volcanism in the late 1970s followed by a relative quiescent period, or some other dynamic process in the Venus atmosphere. While the cause is not certain, such changes must be incorporated into dynamic models of the Venus atmosphere. Potentially, the Magellan spacecraft will extend the results of Pioneer Venus Orbiter and allow the continued monitoring of the abundance of distribution of H2SO4(g) in the Venus atmosphere, as well as other interesting atmospheric properties. Without such measurements it will be difficult to address other issues such as the short-term spatial variability of the abundance of H2SO4(g) at similar latitudes in Venus atmosphere, and the identities of particles responsible for large-scale variations observed in NIR images.

  15. Venus-Earth-Mars: Comparative Climatology and the Search for Life in the Solar System

    Directory of Open Access Journals (Sweden)

    Roger D. Launius

    2012-09-01

    Full Text Available Both Venus and Mars have captured the human imagination during the twentieth century as possible abodes of life. Venus had long enchanted humans—all the more so after astronomers realized it was shrouded in a mysterious cloak of clouds permanently hiding the surface from view. It was also the closest planet to Earth, with nearly the same size and surface gravity. These attributes brought myriad speculations about the nature of Venus, its climate, and the possibility of life existing there in some form. Mars also harbored interest as a place where life had or might still exist. Seasonal changes on Mars were interpreted as due to the possible spread and retreat of ice caps and lichen-like vegetation. A core element of this belief rested with the climatology of these two planets, as observed by astronomers, but these ideas were significantly altered, if not dashed during the space age. Missions to Venus and Mars revealed strikingly different worlds. The high temperatures and pressures found on Venus supported a “runaway greenhouse theory,” and Mars harbored an apparently lifeless landscape similar to the surface of the Moon. While hopes for Venus as an abode of life ended, the search for evidence of past life on Mars, possibly microbial, remains a central theme in space exploration. This survey explores the evolution of thinking about the climates of Venus and Mars as life-support systems, in comparison to Earth.

  16. A 10 km-resolution synthetic Venus gravity field model based on topography

    Science.gov (United States)

    Li, Fei; Yan, Jianguo; Xu, Luyuan; Jin, Shuanggen; Rodriguez, J. Alexis P.; Dohm, James H.

    2015-02-01

    A high resolution gravity field model is extremely important in the exploration of Venus. In this paper, we present a 3-dimensional Venus gravity field VGM2014 constructed by using the latest gravity and topography models, residual terrain model (RTM) and the Airy-Heiskanen isostatic compensation model. The VGM2014 is the first 10 km scale Venus gravity field model; the final results are representations of the 3-dimensional surface gravity accelerations and gravity disturbances for Venus. We found that the optimal global compensation depth of Venus is about 60 km, and the crustal density is potentially less than the commonly accepted value of 2700-2900 kg m-3. This model will be potentially beneficial for the precise orbit determination and landing navigation of spacecraft around Venus, and may be utilized as a priori model for Venus gravity field simulation and inversion studies. The VGM2014 does not incorporate direct gravity information beyond degree 70 and it is not recommended for small-scale geophysical interpretation.

  17. A Low-Cost Approach to the Investigation of Venus Lightning

    Science.gov (United States)

    Majid, Walid

    2015-04-01

    The occurrence of Venus lightning has been detected by atmospheric probes and landers on Venus; by ionospheric satellites; by an orbiting visible spectrometer; at radio frequencies by the Galileo spacecraft while flying by Venus; and by an Earth-based telescope. However, none of these detectors has enabled us to determine the global occurrence rate of lightning in the atmosphere of Venus, nor the altitude at which this lightning is generated. Such measurements are needed in order to determine the processes that generate Venus lightning and to establish the importance of Venus lightning in controlling the chemical composition of the Venus atmosphere. A simple and affordable mission to perform this mapping can be achieved with CubeSat technology. A mother spacecraft with at least three CubeSat partners using RF detection could map the occurrence of lightning globally and determine its altitude of origin, with triangulation of precisely timed RF event arrivals. Such a mission will provide space for complementary investigations and be affordable under future Discovery mission programs.

  18. Volatile transport on Venus and implications for surface geochemistry and geology

    Science.gov (United States)

    Brackett, Robert A.; Fegley, Bruce; Arvidson, Raymond E.

    1995-01-01

    The high vapor pressure of volatile metal halides and chalcogenides (e.g., of Cu, Zn, Sn, Pb, As, Sb, Bi) at typical Venus surface temperatures, coupled with the altitude-dependent temperature gradient of approximately 8.5 K/km, is calculated to transport volatile metal vapors to the highlands of Venus, where condensation and accumulation will occur. The predicted geochemistry of volatile metals on Venus is supported by observations of CuCl in volcanic gases at Kilauea and Nyiragongo, and large enrichments of these and other volatile elements in terrestrial volcanic aerosols. A one-dimensional finite difference vapor transport model shows the diffusive migration of a thickness of 0.01 to greater than 10 microns/yr of moderately to highly volatile phases (e.g., metal halides and chalcogenides) from the hot lowlands (740 K) to the cold highlands (660 K) on Venus. The diffusive transport of volatile phases on Venus may explain the observed low emissivity of the Venusian highlands, hazes at 6-km altitude observed by two Pioneer Venus entry probes, and the Pioneer Venus entry probe anomalies at 12.5 km.

  19. The June 6 2012 transit of Venus: Imaging and spectroscopic analysis of the upper atmosphere emission

    Science.gov (United States)

    Bazin, C.; Zhi, X.; Valls-Gabaud, D.; Koutchmy, S.; Rocher, P.; Zin, Z. Y.; Fu, Y.; Yang, L.; Liu, G. Q.; Liu, Z.; Ji, K.; Goodarzi, H.

    2014-12-01

    In the context of transiting exoplanets, the last June 6, 2012 Venus transit was a unique opportunity to address important questions regarding its atmosphere. The transit of Venus is indeed a particular case of an Earth-like planet transit, and the inference one can make about the upper layers of its atmosphere can be applied to other exoplanets. To this aim, we designed a small spectrograph that we placed at the focus of the New Vacuum Solar Telescope of Yunnan Observatory in China (45 m focus and 1 m of aperture), coupled to a 4K×2K 14 bit CCD detector, to measure low-resolution optical spectra of the refracted, scattered and transmitted solar radiation in the upper layers of the planet. It covered the 385-780 nm range when Venus was over the disc, and 540-680 nm (including the O_2 terrestrial bands) during the 18 minutes-long egress. The H? and He I D3 lines were recorded repeatedly. The atmospheric Lomonossov arc of Venus was simultaneously imaged using H? and TiO filters, allowing us to check the slit position on the images of Venus and to locate the spectroscopic features on its disc. The spectra show the signature of the Northern Pole horn part; a second part was evidenced on the spectra taken near but outside the limb. We studied the O_2, H_2O and H? line profiles searching for signatures arising from Venus and we compared the observed spectra with synthetic models. The spectroscopic dataset can now be used by a large community for discussing the properties of the upper atmosphere of Venus and the future detection of Venus-like exoplanets. Finally, the study is completed using a unique very high resolution deconvolved image of the arc and Venus silhouetted at the limb of the Sun, from the SOT of the Hinode space mission.

  20. A POTENTIAL SUPER-VENUS IN THE KEPLER-69 SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    Kane, Stephen R.; Gelino, Dawn M. [NASA Exoplanet Science Institute, Caltech, MS 100-22, 770 South Wilson Avenue, Pasadena, CA 91125 (United States); Barclay, Thomas, E-mail: skane@ipac.caltech.edu [NASA Ames Research Center, M/S 244-30, Moffett Field, CA 94035 (United States)

    2013-06-20

    Transiting planets have greatly expanded and diversified the exoplanet field. These planets provide greater access to characterization of exoplanet atmospheres and structure. The Kepler mission has been particularly successful in expanding the exoplanet inventory, even to planets smaller than the Earth. The orbital period sensitivity of the Kepler data is now extending into the habitable zones of their host stars, and several planets larger than the Earth have been found to lie therein. Here we examine one such proposed planet, Kepler-69c. We provide new orbital parameters for this planet and an in-depth analysis of the habitable zone. We find that, even under optimistic conditions, this 1.7 R{sub Circled-Plus} planet is unlikely to be within the habitable zone of Kepler-69. Furthermore, the planet receives an incident flux of 1.91 times the solar constant, which is similar to that received by Venus. We thus suggest that this planet is likely a super-Venus rather than a super-Earth in terms of atmospheric properties and habitability, and we propose follow-up observations to disentangle the ambiguity.

  1. Impact craters on venus: initial analysis from magellan.

    Science.gov (United States)

    Phillips, R J; Arvidson, R E; Boyce, J M; Campbell, D B; Guest, J E; Schaber, G G; Soderblom, L A

    1991-04-12

    Magellan radar images of 15 percent of the planet show 135 craters of probable impact origin. Craters more than 15 km across tend to contain central peaks, multiple central peaks, and peak rings. Many craters smaller than 15 km exhibit multiple floors or appear in clusters; these phenomena are attributed to atmospheric breakup of incoming meteoroids. Additionally, the atmosphere appears to have prevented the formation of primary impact craters smaller than about 3 km and produced a deficiency in the number of craters smaller than about 25 km across. Ejecta is found at greater distances than that predicted by simple ballistic emplacement, and the distal ends of some ejecta deposits are lobate. These characteristics may represent surface flows of material initially entrained in the atmosphere. Many craters are surrounded by zones of low radar albedo whose origin may have been deformation of the surface by the shock or pressure wave associated with the incoming meteoroid. Craters are absent from several large areas such as a 5 million square kilometer region around Sappho Patera, where the most likely explanation for the dearth of craters is volcanic resurfacing. There is apparently a spectrum of surface ages on Venus ranging approximately from 0 to 800 million years, and therefore Venus must be a geologically active planet. PMID:17769276

  2. Possible Signs of Life on the Planet Venus

    Directory of Open Access Journals (Sweden)

    Leonid V. Ksanfomality

    2013-03-01

    Full Text Available It is possible, the question on the existence of extraterrestrial life will be answered not as a result of its search for in other worlds removed by distances of dozens of parsecs but on the surface of Venus, i.e., of the nearest planet of the Solar system. The search for “habitable zones” in extrasolar planetary systems is based on the postulate on “normal” physical conditions, i.e., the pressure, temperature, and maybe atmospheric composition similar to those on Earth. But could not such an approach be a kind of “terrestrial chauvinism”? Considering the conditions on Venus as a possible analogue of physical conditions on low-orbiting exoplanets of the “super-Earths” type, a new analysis of Venusian surface panoramas’ details has been made. These images were produced by the VENERA landers in 1975 and 1982. A few relatively large objects were found with size ranging from a decimeter to half meter and with unusual morphology. The objects were observed in some images, but were absent in the other or altered their shape. The article presents the obtained results and analyzes the evidence of reality of these objects.

  3. Venus exospheric structure: the role of solar radiation pressure

    International Nuclear Information System (INIS)

    The existence of a ''hot'' population of hydrogen atoms in the Venus exosphere is well known. In the outer coronal region where it is dominant (r>? 2.0Rv), hydrogen atoms are also subject to a relatively strong radiation pressure exerted by resonant scattering of solar Lyman-? photons. Collisionless models illustrating the consequent structure are discussed, with the nonthermal population mimicked by a dual Maxwellian exobase kinetic distribution. In these models, a considerable fraction of the ''hot'' atoms outside 2.0Rv belongs to the quasi-satellite component, this fraction exceeding 1/2 for 4.0Rvv. Quasi-satellites also raise the kinetic temperature near 2.0Rv by ? 150 K. Solar ionization of bound atoms occurs mainly outside the ionopause, yielding a partial escape flux >?2 x 106 cm-2s-1 over the dayside exobase for assumed solar conditions. The inclusion of a cold exobase prescribed by Pioneer Venus observations has little influence on the outer region (in particular, the quasi-satellite component is unaltered) except that the transition to ''hot'' kinetic character occurs closer to the exobase on the nightside due to the colder main exobase temperatures there. Lastly, a ''tail'' of bound atoms is formed as in the terrestrial situation. (author)

  4. A Potential Super-Venus in the Kepler-69 System

    CERN Document Server

    Kane, Stephen R; Gelino, Dawn M

    2013-01-01

    Transiting planets have greatly expanded and diversified the exoplanet field. These planets provide greater access to characterization of exoplanet atmospheres and structure. The Kepler mission has been particularly successful in expanding the exoplanet inventory, even to planets smaller than the Earth. The orbital period sensitivity of the Kepler data is now extending into the Habitable Zones of their host stars, and several planets larger than the Earth have been found to lie therein. Here we examine one such proposed planet, Kepler-69c. We provide new orbital parameters for this planet and an in-depth analysis of the Habitable Zone. We find that, even under optimistic conditions, this 1.7 R$_\\oplus$ planet is unlikely to be within the Habitable Zone of Kepler-69. Furthermore, the planet receives an incident flux of 1.91 times the solar constant, which is similar to that received by Venus. We thus suggest that this planet is likely a super-Venus rather than a super-Earth in terms of atmospheric properties a...

  5. The discovery of X-rays from Venus with Chandra

    CERN Document Server

    Dennerl, K; Englhauser, J; Lisse, C M; Wolk, S

    2002-01-01

    On January 10 and 13, 2001, Venus was observed for the first time with an X-ray astronomy satellite. The observation, performed with the ACIS-I and LETG/ACIS-S instruments on Chandra, yielded data of high spatial, spectral, and temporal resolution. Venus is clearly detected as a half-lit crescent, with considerable brightening on the sunward limb. The morphology agrees well with that expected from fluorescent scattering of solar X-rays in the planetary atmosphere. The radiation is observed at discrete energies, mainly at the O-K_alpha energy of 0.53 keV. Fluorescence radiation is also detected from C-K_alpha at 0.28 keV and, marginally, from N-K_alpha at 0.40 keV. An additional emission line is indicated at 0.29 keV, which might be the signature of the C 1s --> pi* transition in CO2 and CO. Evidence for temporal variability of the X-ray flux was found at the 2.6 sigma level, with fluctuations by factors of a few times indicated on time scales of minutes. All these findings are fully consistent with fluorescen...

  6. Discovery of X-rays from Venus with Chandra

    CERN Document Server

    Dennerl, K; Englhauser, J; Lisse, C M; Wolk, S

    2001-01-01

    On January 10 and 13, 2001, Venus was observed for the first time with an X-ray astronomy satellite. The observation, performed with the ACIS-I and LETG/ACIS-S instruments on Chandra, yielded data of high spatial, spectral, and temporal resolution. Venus is clearly detected as a half-lit crescent, with considerable brightening on the sunward limb. The morphology agrees well with that expected from fluorescent scattering of solar X-rays in the planetary atmosphere. The radiation is observed at discrete energies, mainly at the O-K_alpha energy of 0.53 keV. Fluorescent radiation is also detected from C-K_alpha at 0.28 keV and, marginally, from N-K_alpha at 0.40 keV. An additional emission line is indicated at 0.29 keV, which might be the signature of the C 1s --> pi* transition in CO_2 and CO. Evidence for temporal variability of the X-ray flux was found at the 2.6 sigma level, with fluctuations by factors of a few times indicated on time scales of minutes. All these findings are fully consistent with fluorescen...

  7. Rotation of rigid Venus: a complete precession-nutation model

    CERN Document Server

    Cottereau, L

    2010-01-01

    Context: With the increasing knowledge of the terrestrial planets due to recent space probes it is possible to model their rotation with increasing accuracy. Despite that fact, an accurate determination of Venus precession and nutation is lacking. Aims : Although Venus rotation has been studied in several aspects, a full and precise analytical model of its precession-nutation motion remains to be constructed. We propose to determine this motion with up-to-date physical parameters of the planet Methods: We adopt a theoritical framework already used for a precise precession-nutation model of the Earth, based on a Hamiltonian formulation, canonical equations and an accurate development of the perturbing function due to the Sun. Results: After integrating the disturbing function and applying the canonical equations, we can evaluate the precession constant $\\dot{\\Psi}$ and the coefficients of nutation, both in longitude and in obliquity. We get $\\dot{\\Psi}=4474".35/Jcy \\pm 66.5 $, corresponding to a precession per...

  8. Small domes on Venus: Probable analogs of Icelandic lava shields

    International Nuclear Information System (INIS)

    On the basis of observed shapes and volumetric estimates, the authors interpret small, dome-like features on radar images of Venus to be analogs of Icelandic lava-shield volcanoes. Using morphometric data for venusian domes in Aubele and Slyuta, as well as their own measurements of representative dome volumes and areas from Tethus Regio, they demonstrate that the characteristic aspect ratios and flank slopes of these features are consistent with a subclass of low Icelandic lava-shield volcanoes (LILS). LILS are slightly convex in cross-section with typical flank slopes of ?3 degree. Plausible lava-shield-production rates for the venusian plains suggest formation of ?53 million shields over the past 0.25 Ga. The cumulative global volume of lava that would be associated with this predicted number of lava shields is only a factor of 3-4 times that of a single oceanic composite shield volcano such as Mauna Loa. The global volume of all venusian lava shields in the 0.5-20-km size range would only contribute a meter of resurfacing over geologically significant time scales. Thus, venusian analogs to LILS may represent the most abundant landform on the globally dominant plains of Venus, but would be insignificant with regard to the global volume of lava extruded. As in Iceland, associated lavas from fissure eruptions probably dominate plains volcanism and should be evident on the higher resolution Magellan radar images

  9. Radiative heat transfer and water content in atmosphere of Venus

    International Nuclear Information System (INIS)

    The authors present the procedure for calculating optical characteristics of the main components and the effective fluxes in the atmosphere of Venus, and concrete results of the calculations. They are compared to the results of other authors and to the experimantal data. Integration was carried out by the Simpson method with automatic selection of the step or interval for a given relative integrating accuracy delta. The calculations were done with a BESM-6 computer. Using this procedure and data on absorbtion coefficients, calculations of the spectrum of effective flux were carried out for a pure carbon dioxide atmosphere and for an atmosphere containing water vapor at various relative admixtures, for different altitude profiles of temperature and cloudiness albedo. Thus, the comparisons made, enable the authors to judge about the degree of agreement of the F(z) altitude profile, in some regions of the planet where measurements have been made, rather than about the absolute values of the heat fluxes. In conclusion, the authors point out that the task of calculating in detail the radiation balance in Venus' lower atmosphere, as also the problem of a more reliable interpretation of the experimantal data, is coupled with the necessity of elaborating reliable models of the atmospheric components' optical characteristics, which determine the radiative transfer of heat

  10. High resolution cloud feature tracking on Venus by Galileo

    Science.gov (United States)

    Toigo, Anthony; Gierasch, Peter J.; Smith, Michael D.

    1994-01-01

    The Venus cloud deck was monitored in February 1990 for 16 hours at 400 nanometers wavelength by the Galileo imaging system, with a spatial resolution of about 15 km and with image time separations as small as 10 minutes. Velocities are deduced by following the motion of small cloud features. In spite of the high temporal frequence is capable of being detected, no dynamical phenomena are apparent in the velocity data except the already well-known solar tides, possibly altered by the slow 4-day wave and the Hadley circulation. There is no evidence, to a level of approximately 4 m/s, of eddy or wavelike activity. The dominant size of sub-global scale albedo features is 200-500 km, and their contrast is approximately 5%. At low altitudes there are patches of blotchy, cell-like structures but at most locations the markings are streaky. The patterns are similar to those discovered by Mariner 10 and Pioneer Venus (M. J. S. Belton et al., 1976, W. B. Rossow et al., 1980). Scaling arguments are presented to argue that the mesoscale blotchy cell-like cloud patterns are caused by local dynamics driven in a shallow layer by differential absorption of sunlight. It is also argued that mesoscale albedo features are either streaky or cell-like simply depending on whether the horizontal shear of the large scale flow exceeds a certain critical value.

  11. Asymmetries in the location of the Venus ionopause

    International Nuclear Information System (INIS)

    Four large data sets of Venus ionopause observations, based on different definitions and observations by Pioneer Venus orbiter field and particle instruments, are compared. Regardless of the definition chosen, the ionopause is observed to be higher on average at dawn than at dusk. The results of an empirical ionosphere model and a data analysis technique which minimizes orbital bias are combined to show that most or all of this asymmetry results from the effects of orbital bias and uneven sampling of solar wind conditions. However, an additional asymmetry is found in which the ionopause is displaced in the direction opposite to the motional electric field of the solar wind. This effect is attributed to asymmetric pickup of exospheric ions by the electric and magnetic fields in the magnetosheath. This ion pickup interpretation can be understood in terms of a previously observed magnetosheath magnetic field asymmetry. Quantitative analysis indicates that the transverse momentum imparted by the solar plasma to pickup particles in their initial gyration is transmitted by the magnetosheath magnetic field to the ionosphere boundary. copyright American Geophysical Union 1988

  12. Blonde Venus y el género cinematográfico de la mujer caída

    Scientific Electronic Library Online (English)

    María Paula, Noval Morgan.

    2011-12-01

    Full Text Available Este artículo analiza algunos problemas relacionados con la representación de la mujer caída en la película Blonde Venus, ya que su tratamiento poco convencional provocó muchos contratiempos con la censura, conflicto que permite observar de cerca los mecanismos de representación del cine clásico de [...] Hollywood. Aunque la película retoma la dicotomía presente en la representación occidental entre la imagen de la madre y de la prostituta (entre María y Eva), el personaje de Marlene Dietrich encarna ambos papeles al mismo tiempo, generando ambigüedades y contradicciones que desestabilizan los discursos moralistas tanto de la mujer caída como del ama de casa. Dichos discursos cobraron auge a fines del siglo XIX y posteriormente fueron retomados por el cine. Abstract in english This article analyzes some problems related to the representation of the fallen woman in the Blonde Venus film, regarding to the fact that its unconventional treatment caused many setbacks with censorship, and this conflict allows to observe closely the representation mechanisms in the Hollywood's c [...] lassic cinema. In spite of the film reassumed the western dichotomy between the images of the mother and the prostitute (Mary versus Eve), Marlene Dietrich's character incarnates both roles at once, generating ambiguities and contradictions that de-stabilize the moralist discourses on the fallen woman and on the housewife; such discourses meet a peak by the end of the nineteenth century, to be later reassumed by the cinema.

  13. A POTENTIAL SUPER-VENUS IN THE KEPLER-69 SYSTEM

    International Nuclear Information System (INIS)

    Transiting planets have greatly expanded and diversified the exoplanet field. These planets provide greater access to characterization of exoplanet atmospheres and structure. The Kepler mission has been particularly successful in expanding the exoplanet inventory, even to planets smaller than the Earth. The orbital period sensitivity of the Kepler data is now extending into the habitable zones of their host stars, and several planets larger than the Earth have been found to lie therein. Here we examine one such proposed planet, Kepler-69c. We provide new orbital parameters for this planet and an in-depth analysis of the habitable zone. We find that, even under optimistic conditions, this 1.7 R? planet is unlikely to be within the habitable zone of Kepler-69. Furthermore, the planet receives an incident flux of 1.91 times the solar constant, which is similar to that received by Venus. We thus suggest that this planet is likely a super-Venus rather than a super-Earth in terms of atmospheric properties and habitability, and we propose follow-up observations to disentangle the ambiguity.

  14. The Effect of Recent Venus Transit on Earth?s Atmosphere

    OpenAIRE

    H. P. Sardar; Mandal, S. K.; Mandal, P K; A. Guha; S. K. SARKAR; Sarkar, B. K.; Adhikari, S K; De, B. K.; S. S.; Ray, M.

    2006-01-01

    Some experiments on June 8, 2004, the day of transit of Venus across the Sun, were undertaken at Kolkata (latitude: 23034? N) to observe effect, if any, of transit of Venus on FWF, ELF and VLF amplitudes. The result shows good correlation between their temporal variations during the transit. The observation was unbelievable as the Venus subtends only 1/32th of the cone subtended by Sun on Earth. This anomaly may be explained on the assumption that the height of Venusian atmosphere with high c...

  15. The effect of recent Venus transit on Earth?s atmosphere

    OpenAIRE

    H. P. Sardar; Mandal, S. K.; Mandal, P K; A. Guha; S. K. SARKAR; Sarkar, B. K.; Adhikari, S K; De, B. K.; S. S.; Ray, M.

    2006-01-01

    Some experiments on June 8, 2004, the day of transit of Venus across the Sun, were undertaken at Kolkata (latitude: 22°34lN) to observe the effect, if any, of transit of Venus on FWF, ELF and VLF amplitudes. The result shows a good correlation between their temporal variations during the transit. The observation was unbelievable as the Venus subtends only 1/32th of the cone subtended by Sun on Earth. This anomaly may be explained on the assumption that the height of Venusian atmosphere with h...

  16. Can a time-stratigraphic classification system be developed for Venus?

    Science.gov (United States)

    Tanaka, K. L.; Schaber, G. G.

    1992-01-01

    Magellan radar images reveal that Venus' exposed geologic record covers a relatively short and recent time span, as indicated by the low density of impact craters across the planet. Therefore, because impact cratering in itself will not be a useful tool to define geologic ages on Venus, it was questioned whether a useful stratigraphic scheme can be developed for the planet. We believe that a venusian stratigraphy is possible and that it can be based on the following: (1) an examination of the rationale and methods that have been used to develop such schemes for the other planets; and (2) what can be gleaned from Magellan and other datasets of Venus.

  17. Oxygen ionization rates at Mars and Venus - Relative contributions of impact ionization and charge exchange

    Science.gov (United States)

    Zhang, M. H. G.; Luhmann, J. G.; Nagy, A. F.; Spreiter, J. R.; Stahara, S. S.

    1993-01-01

    Oxygen ion production rates above the ionopauses of Venus and Mars are calculated for photoionization, charge exchange, and solar wind electron impact ionization processes. The latter two require the use of the Spreiter and Stahara (1980) gas dynamic model to estimate magnetosheath velocities, densities, and temperatures. The results indicate that impact ionization is the dominant mechanism for the production of O(+) ions at both Venus and Mars. This finding might explain both the high ion escape rates measured by Phobos 2 and the greater mass loading rate inferred for Venus from the bow shock positions.

  18. In-core and ex-core calculations of the VENUS simulated PWR benchmark experiment

    International Nuclear Information System (INIS)

    The VENUS PWR engineering mockup experiment was established to simulate a beginning-of-life, generic PWR configuration at the zero-power VENUS critical facility located at CEN/SCK, Mol, Belgium. The experimental measurement program consists of (1) gamma scans to determine the core power distribution, (2) in-core and ex-core foil activations, (3) neutron spectrometer measurements, and (4) gamma heating measurements with TLD's. Analysis of the VENUS benchmark has been performed with two-dimensional discrete ordinates transport theory, using the DOT-IV code

  19. Corona Formation and Heat Loss on Venus by Coupled Upwelling and Delamination

    Science.gov (United States)

    Smrekar, Suzanne E.; Stofan, Ellen R.

    1997-01-01

    Coronae are volcanotectonic features that are unique to Venus and are interpreted to be small-scale upwellings. A model in which upwelling causes delamination at the edge of the plume head, along with deformation of a pre-existing depleted mantel Layer, can produce the full range of topographic forms of coronae. If half of the coronae are active, delamination of the lower lithosphere could account for about 10% of venus's heat loss, with another 15% due to upwelling. Delamination may occur in other geologic enviroment and could help account for 'Venus' heat loss 'deficit'.

  20. A novel cell-cycle-indicator, mVenus-p27K?, identifies quiescent cells and visualizes G0–G1 transition

    OpenAIRE

    Oki, Toshihiko; Nishimura, Koutarou; Kitaura, Jiro; Togami, Katsuhiro; Maehara, Akie; Izawa, Kumi; Sakaue-sawano, Asako; Niida, Atsushi; Miyano, Satoru; Aburatani, Hiroyuki; Kiyonari, Hiroshi; Miyawaki, Atsushi; Kitamura, Toshio

    2014-01-01

    The quiescent (G0) phase of the cell cycle is the reversible phase from which the cells exit from the cell cycle. Due to the difficulty of defining the G0 phase, quiescent cells have not been well characterized. In this study, a fusion protein consisting of mVenus and a defective mutant of CDK inhibitor, p27 (p27K?) was shown to be able to identify and isolate a population of quiescent cells and to effectively visualize the G0 to G1 transition. By comparing the expression profiles of the G0...

  1. Organization for Economic Cooperation and Development/Nuclear Energy Agency International Benchmark on the VENUS-2 MOX Core Measurements

    International Nuclear Information System (INIS)

    Within the framework of the Nuclear Energy Agency Nuclear Science Committee, theoretical physics benchmarks and multiple recycling issues related to various mixed-oxide (MOX)-fueled systems have been studied. Many improvements and clarifications in nuclear data libraries and calculation methods have been achieved from the results of the theoretical benchmarks performed. However, it was felt that there was also a need to link these findings to data from experiments. Hence, a blind international benchmark exercise based on the two-dimensional VENUS-2 MOX core measurement data was carried out. Twelve participants from ten countries participated in the benchmark. Both the deterministic and the Monte Carlo methods were applied with different nuclear data sets. This technical note provides a comparative analysis between calculated and measured results. Comparison with experimental results identified the origins of discrepancies between calculations and measurements and enabled the quantitative comparison of the relative merits of the different calculation methods

  2. Autonomous Aerobraking Development Software: Phase One Performance Analysis at Mars, Venus, and Titan

    Science.gov (United States)

    Maddock, Robert W.; Bowes, Angela; Powell, Richard W.; Prince, Jill L. H.; Cianciolo, Alicia Dwyer

    2012-01-01

    When entering orbit about a planet or moon with an appreciable atmosphere, instead of using only the propulsion system to insert the spacecraft into its desired orbit, aerodynamic drag can be used after the initial orbit insertion to further decelerate the spacecraft. Several past NASA missions have used this aerobraking technique to reduce the fuel required to deliver a spacecraft into a desired orbit. Aerobraking was first demonstrated at Venus with Magellan in 1993 and then was used to achieve the science orbit of three Mars orbiters: Mars Global Surveyor in 1997, Mars Odyssey in 2001, and Mars Reconnaissance Orbiter in 2006. Although aerobraking itself reduces the propellant required to reach a final low period orbit, it does so at the expense of additional mission time to accommodate the aerobraking operations phase (typically 3-6 months), a large mission operations staff, and significant Deep Space Network (DSN) coverage. By automating ground based tasks and analyses associated with aerobraking and moving these onboard the spacecraft, a flight project could save millions of dollars in operations staffing and DSN costs (Ref. 1).

  3. Ionization efficiency studies for xenon ions with the superconducting ECR ion source VENUS

    International Nuclear Information System (INIS)

    Ionization efficiency studies for high charge state xenon ions using a calibrated gas leak are presented. A 75% enriched 129Xe gas leak with a gas flow equivalent to 5.11 p?A was used in all the measurements. The experiments were performed at the VENUS (Versatile ECR ion source for Nuclear Science) ion source for 18 GHz, 28 GHz and double frequency operation. Overall, total ionization efficiencies close to 100% and ionization efficiencies into a single charge state up to 22% were measured. The influence of the biased disk on the ionization efficiency was studied and the results were somewhat surprising. When the biased disk was removed from the plasma chamber, the ionization efficiency was dramatically reduced for single frequency operation. However, using double frequency heating the ionization efficiencies achieved without the biased disk almost matched the ionization efficiencies achieved with the biased probe. In addition, we have studied the influence of the support gas on the charge state distribution of the xenon ions. Either pure oxygen or a mixture of oxygen and helium were used as support gases. The addition of a small amount of helium can increase the ionization efficiency into a single charge state by narrowing the charge state distribution. Furthermore by varying the helium flow the most efficient charge state can be shifted over a wide range without compromising the ionization efficiency. This is not possible using only oxygen as support gas.ossible using only oxygen as support gas. Results from these studies are presented and discussed

  4. Astronomy Behind Enemy Lines in Colonial North America: John Winthrop's Observations of the Transits of Venus

    Science.gov (United States)

    Schechner, S. J.

    2005-12-01

    In May 1761, John Winthrop packed up two students, an excellent clock, an octant, and two telescopes, and embarked for Newfoundland to observe the Transit of Venus. Winthrop's departure was hasty. Only days before had the President and Fellows of Harvard College approved Professor Winthrop's request to take the college apparatus behind enemy lines to serve the cause of science, and Winthrop knew he had no time to waste if he were to reach Newfoundland and properly calibrate his equipment before the Transit. Winthrop's expedition to St. John's, Newfoundland was nothing short of remarkable. His goal was to help determine the distance from the Earth to the Sun, and he was the only North American astronomer fit for this project. His expedition was financed by the General Court of Massachusetts, which also secured him safe passage across enemy lines during the French and Indian War. Winthrop's trip to St. John's was a major achievement for colonial astronomy, but he was unhappy with his observations and so looked forward to a second chance to observe a transit in 1769. Benjamin Franklin urged him to go to Lake Superior. Planning for that transit was thwarted, however, by two events: (1) the loss of nearly all of Harvard's apparatus in a fire of 1764; and (2) pre-Revolutionary politics in the American colonies. In the end, Winthrop was forced to content himself with first-class observations with new instruments in Cambridge.

  5. Names on the maps of Venus - A pre-Magellan review

    Science.gov (United States)

    Burba, G. A.

    1990-12-01

    As Venus is the only planet which has a female name, the Working Group on Planetary System Nomenclature of the International Astronomical Union has designated that only female names shall be used for topographic features on Venus. Craters and paterae have the names of famous women as well as female first names, noncrater features have names of mythological characters. The first 80 names appeared on the maps after the Pioneer Venus mission. About 300 more names were added after the Venera 15 and 16 missions. It is noted that a large number of new names will be needed after the Magellan mission, when detailed maps will be produced for nearly the whole surface of Venus. A list is provided of the 376 features of 17 types which are now named.

  6. Topographic Distribution of Geologic Units in Northern Venus and in the 30N Geotraverse

    Science.gov (United States)

    Ivanov, M. A.; Head, J. W., III; Basilevsky, A. T.; Bobina, N. N.; Burba, G. A.; Kryuchkov, V. P.; Pronin, A. A.; Shashkina, V. P.

    1999-03-01

    The topographic distribution of the same geologic units in two large areas on Venus (around N. Pole and in the 30N geotraverse) is essentially the same, suggesting similar evolution of large-scale topography in both areas.

  7. Detection from Space of Active Volcanism on Earth and, Potentially, on Venus and Rocky Exoplanets

    Science.gov (United States)

    Mouginis-Mark, P. J.

    2015-05-01

    Volcanic eruptions (lava flows, lava lakes, and explosive activity) on Earth have been monitored from space for >3 decades. Such observations are extrapolated to understand how volcanic activity on Venus and rocky exoplanets may be detected.

  8. Sprite discharges on Venus and Jupiter-like planets: a laboratory investigation

    CERN Document Server

    Dubrovin, Daria; van Veldhuizen, Eddie; Ebert, Ute; Yair, Yoav; Price, Colin; 10.1029/2009JA014851

    2010-01-01

    Large sprite discharges at high atmospheric altitudes have been found to be physically similar to small streamer discharges in air at sea level density. Based on this understanding, we investigate possible sprite discharges on Venus or Jupiter-like planets through laboratory experiments on streamers in appropriate CO2-N2 and H2-He mixtures. First, the scaling laws are experimentally confirmed by varying the density of the planetary gasses. Then streamer diameters, velocities and overall morphology are investigated for sprites on Venus and Jupiter; they are quite similar to those on earth, but light emissions in the visible range are fainter by two orders of magnitude. The discharge spectra are measured; they are dominated by the minority species N2 on Venus, while signatures of both species are found on Jupiter-like planets. The spectrum of a fully developed spark on Venus is measured. We show that this spectrum is significantly different from the expected sprite spectrum.

  9. Solar wind mass-loading at Halley comet: a lesson from Venus

    International Nuclear Information System (INIS)

    Direct investigations of the Halley comet interaction with solar wind have shown, that near the comet there is an area of magnetized comet plasma, which was not observed experimentally before, and the existance of which was not predicted by most part of theoretical researches. This area, however, has similarity features with the area of magnetized planet plasma, observed in Venus daytime ionosphere under the conditions, when dynamic pressure of solar wind inleaking flow exceeds ionospheric plasma maximal pressure. Despite the fact, that these phenomena details are different for Venus and the Halley comet, the penetration of magnetic field through ionopause at Venus and cometpause of the Halley comet is apparently the result of similar processes of recharging and photoionization. For Venus this effect appears when under the effect ''power'' with planetary-origin ions comes to be comparable with the comet one

  10. Possible Plume-Initiated Subduction on Venus: Results from Laboratory Experiments and Corona Examples

    Science.gov (United States)

    Smrekar, S. E.; Davaille, A.

    2015-05-01

    We propose that possible subduction zones on Venus are initiated via plume activity based on the formation of analogous features in the laboratory. We assess gravity and topography and radar image data for agreement with this model.

  11. Thermo-Chemical Plumes Generated by Core Formation Processes in Venus and Earth Interior Differentiation

    Science.gov (United States)

    Weeraratne, D. S.; Fleck, J.; Rains, C.; Brand, D.

    2015-05-01

    We study thermo-chemical plumes generated during core formation using liquid gallium in fluid experiments. These plumes produce magmatic events which can form Venus highlands and pretectonic proto-continents on Earth which lack high crater density.

  12. A photochemical model for the Venus atmosphere at 47-112 km

    Science.gov (United States)

    Krasnopolsky, Vladimir A.

    2012-03-01

    The model is intended to respond to the recent findings in the Venus atmosphere from the Venus Express and ground-based submillimeter and infrared observations. It extends down to 47 km for comparison with the kinetic model for the lower atmosphere (Krasnopolsky, V.A. [2007]. Icarus 191, 25-37) and to use its results as the boundary conditions. The model numerical accuracy is significantly improved by reduction of the altitude step from 2 km in the previous models to 0.5 km. Effects of the NUV absorber are approximated using the detailed photometric observations at 365 nm from Venera 14. The H2O profile is not fixed but calculated in the model. The model involves odd nitrogen and OCS chemistries based on the detected NO and OCS abundances. The number of the reactions is significantly reduced by removing of unimportant processes. Column rates for all reactions are given, and balances of production and loss may be analyzed in detail for each species. The calculated vertical profiles of CO, H2O, HCl, SO2, SO, OCS and of the O2 dayglow at 1.27 ?m generally agree with the existing observational data; some differences are briefly discussed. The OH dayglow is ?30 kR, brighter than the OH nightglow by a factor of 4. The H + O3 process dominates in the nightglow excitation and O + HO2 in the dayglow, because of the reduction of ozone by photolysis. A key feature of Venus’ photochemistry is the formation of sulfuric acid in a narrow layer near the cloud tops that greatly reduces abundances of SO2 and H2O above the clouds. Delivery of SO2 and H2O through this bottleneck determines the chemistry and its variations above the clouds. Small variations of eddy diffusion near 60 km result in variations of SO2, SO, and OCS at and above 70 km within a factor of ?30. Variations of the SO2/H2O ratio at the lower boundary have similar but weaker effect: the variations within a factor of ?4 are induced by changes of SO2/H2O by ±5%. Therefore the observed variations of the mesospheric composition originate from minor variations of the atmospheric dynamics near the cloud layer and do not require volcanism. NO cycles are responsible for production of a quarter of O2, SO2, and Cl2 in the atmosphere. A net effect of photochemistry in the middle atmosphere is the consumption of CO2, SO2, and HCl from and return of CO, H2SO4, and SO2Cl2 to the lower atmosphere. These processes may be balanced by thermochemistry in the lower atmosphere even without outgassing from the interior, though the latter is not ruled out by our models. Some differences between the model and observations and the previous models are briefly discussed.

  13. Modelling the thermo-chemical evolution of the interiors of Venus, Mars and Mercury

    Science.gov (United States)

    Tackley, P. J.; Keller, T.; Armann, M.; Aurnou, J. M.

    2009-04-01

    The latest generation of the global 3-D spherical convection model StagYY [Tackley, PEPI 2008] allows the direct computation of a planet's thermo-chemical evolution, including self-consistent lithospheric behavior (e.g., rigid lid, plate tectonics, or episodic plate tectonics [van Heck and Tackley, GRL 2008]), chemical differentiation induced by melting, large viscosity variations, a parameterized core heat balance, and a realistic treatment of phase diagrams and material properties. The latter has recently been added using free energy minimization to compute stable phases as a function of temperature, pressure, and composition as expressed by ratios of the five main oxides, and thus avoids the need for increasingly complicated and ad hoc parameterizations of phase transitions. Global models allow the computation of planetary secular cooling including prediction of how the core heat flux varies with time hence the evolution of the geodynamo, and possible transitions in plate tectonic mode. Modern supercomputers and clusters allow increasingly higher resolution, with up to 1.2 billion unknowns possible on only 32 dual-processor nodes of an opteron cluster. In ongoing research, this tool is being applied to understand the evolution of Earth, Mars, Venus, and Mercury. Our Mars models [T. Keller and P.J. Tackley, submitted] show that with an appropriate viscosity profile, convection rapidly develops a 'one ridge' planform consisting of a single ridge-like upwelling and small-scale downwellings below a stagnant lid, and that this produces a dichotomous crustal distribution that bears a striking first-order resemblance to the crustal distribution on Mars. The actual boundary of the crustal dichotomy on Mars is not hemispherical but rather like the seam on a tennis ball, and this is reproduced by our models, with the highland region being located above the upwelling. Furthermore, the elevation difference between the highland and lowland regions is very similar to that on Mars, although the average crustal thickness is higher than thought to be appropriate for Mars. In some calculations, the location of the upwelling subsequently migrates to the edge of the highland region, providing an explanation for Tharsis. Melting is found to have a dramatic influence on thermal evolution particularly during the early stages. With our Venus models we are studing the modes of heat loss, the origin of the inferred surface age and understanding the admittance (gravity/topography) ratio. Of particular interest is whether a smooth evolution can satisfy the various observational constraints, or whether episodic or catastrophic behaviour is needed, as has been hypothesised by some authors. Simulations in which the lithosphere remains stagnant over the entire history indicate that over time, the crust becomes at least as thick as the mechanical lithosphere, and delamination occurs from its base. The dominant heat transport mechanism is magmatic. A thick crust is a quite robust feature of these calculations. Higher mantle viscosity results in larger topographic variations, thicker crust and lithosphere and higher admittance ratios; to match those of Venus, the upper mantle reference viscosity is about 1020 Pa s and internal convection is quite vigorous. The most successful results in matching observations are those in which the evolution is episodic, being in stagnant lid mode for most of the evolution but with 2-3 bursts of activity caused by lithospheric overturn. If the last burst of activity occurs ~1 Ga before present, then the present day tends to display low magmatic rates and mostly conductive heat transport, consistent with observations. In ongoing work we are examining the effect of crustal rheology and a more accurate melting treatment. Due to the absence of an atmosphere and proximity to the Sun, Mercury's surface temperature varies laterally by several 100s K, even when averaged over long time periods. The dominant variation in time-averaged surface T occurs from pole to equator (~225 K). Here we demonstrate, using models of mantle conv

  14. Venusians: the Planet Venus in the 18th-Century Extraterrestrial Life Debate

    Science.gov (United States)

    Duner, David

    2013-05-01

    In the seventeenth and eighteenth centuries it became possible to believe in the existence of life on other planets on scientific grounds. Once the Earth was no longer the center of the universe according to Copernicus, once Galileo had aimed his telescope at the Moon and found it a rough globe with mountains and seas, the assumption of life on other planets became much less far-fetched. In general there were no actual differences between Earth and Venus, since both planets orbited the Sun, were of similar size, and possessed mountains and an atmosphere. If there is life on Earth, one may ponder why it could not also exist on Venus. In the extraterrestrial life debate of the seventeenth and eighteenth centuries, the Moon, our closest celestial body, was the prime candidate for life on other worlds, although a number of scientists and scholars also speculated about life on Venus and on other planets, both within our solar system and beyond its frontiers. This chapter discusses the arguments for life on Venus and those scientific findings that were used to support them, which were based in particular on assumptions and claims that both mountains and an atmosphere had been found on Venus. The transits of Venus in the 1760s became especially important for the notion that life could thrive on Venus. Here, I detect two significant cognitive processes that were at work in the search for life on Venus, i.e., analogical reasoning and epistemic perception, while analogies and interpretations of sensory impressions based on prior knowledge played an important role in astrobiological theories.

  15. Sunlight refraction in the mesosphere of Venus during the transit on June 8th, 2004

    OpenAIRE

    Tanga, P.; Widemann, Th.; Sicardy, B.; Pasachoff, J. M.; Arnaud, J.; Comolli, L.; Rondi, A.; Rondi, S.; Suetterlin, P.

    2011-01-01

    Many observers in the past gave detailed descriptions of the telescopic aspect of Venus during its extremely rare transits across the Solar disk. In particular, at the ingress and egress, the portion of the planet's disk outside the Solar photosphere has been repeatedly perceived as outlined by a thin, bright arc ("aureole"). Those historical visual observations allowed inferring the existence of Venus' atmosphere, the bright arc being correctly ascribed to the refraction of...

  16. Photogenic Venus: The "Cinematographic Turn" and Its Alternatives in Nineteenth-Century France

    OpenAIRE

    Canales, Jimena

    2002-01-01

    During the late nineteenth century, scientists around the world disagreed as to the types of instruments and methods that should be used for determining the most important constant of celestial mechanics: the solar parallax. Venus's 1874 transit across the sun was seen as the best opportunity for ending decades of debate. However, a mysterious "black drop" that appeared between Venus and the sun and individual differences in observations of the phenomenon brought traditional methods into disr...

  17. Models of the Venus planet thermal evolution in parametrized convection approximation

    International Nuclear Information System (INIS)

    The thermal evolution of Venus in a parametrized convection approximation is examined. It is supposed that on Venus as on the Earth a double-layered convection takes place. The model is composed of four layers: the lithosphere (which includes the crust), the upper mantle, the lower mantle and the core (which may have a solid internal core). With help of the boundary conditions these four zones are connected in the whole evolution model. The thermal evolution of Venus is divided in three periods: 1) matching the upper mantle to the thermal regime of the lower mantle ? (0,5-1)109 y; 2) transition to a quasistationary regime ? (1-2)-109 y and 3) the quasi-stationary regime, at last ? (1-2)x109 y. The surface heat flow of Venus is not excess of 60 erg cm-2 s-1. The crust growing, thickness of lithospere and evolution of the core of Venus are also under consideration. The conclusion is made about the presence at Venus of a thick basalt crust ? (70-30) km and an explanation of the lack of the intrinsic magnetic field is proposed

  18. 1565 nm Observations of the transit of Venus, Proxy for a Transiting Exoplanet

    Science.gov (United States)

    Jaeggli, Sarah A.; Reardon, K. P.; Pasachoff, J. M.; Schneider, G.; Widemann, T.; Tanga, P.

    2013-07-01

    The transit of Venus in June 2012 provided a unique chance to view its atmosphere as we might see that of a transiting Cytherean exoplanet, through scattered and refracted illumination from its parent star. We performed spectroscopy and polarimetry during the transit of Venus focusing on extracting signatures of CO2 absorption of Venus from the solar spectrum. Although the predicted CO2 transmission spectrum of Venus was not particularly strong at 1565 nm, this region of the H-band often used in magnetic-field studies of the Sun's photosphere provides a particularly flat solar continuum with few atmospheric and molecular lines. Observations of Venus were taken throughout first contact and on the solar disk using the Facility InfraRed Spectropolarimeter on the Dunn Solar Telescope at the National Solar Observatory. The transit also provided a unique opportunity to investigate instrumental effects. In this poster we discuss initial results from the transit, including estimates for an exoplanet detection of this kind, preliminary comparison with atmospheric models, and the stray light properties of the instrument. This work was performed in collaboration with the Williams College Venus transit expedition, which was sponsored by Natl Geog/Comm for Research and Exploration.

  19. On the status of the rotation of Venus

    Science.gov (United States)

    Lyttleton, R. A.

    1974-01-01

    Owing to its extremely slow rotation, Venus must be regarded as a triaxial body with differences of all three principal moments of inertia comparable in magnitude, thus rendering it a body essentially different from a rapidly rotating planet. The dynamical problem then arises of how such a body, with a rotation-period comparable with its orbital period, would be affected by couples exerted upon it by the gravitational action of the sun. Equations for the rotatory motion are set up in a form suitable for numerical solution by machine-calculations, but the problem so presented can be adequately investigated only for a hypothetical planet. Results obtained on this limited basis nevertheless suggest that for the actual planet the direction of the rotation axis may move almost randomly between the two hemispheres defined by the orbital plane and thus that the present direction near the south celestial pole of the orbit may be only a temporary situation.

  20. Readout electronics for the Venus TRD at TRISTAN

    International Nuclear Information System (INIS)

    A large cylindrical transition radiation detector has been constructed as a part of the Venus detector for the TRISTAN e+e- collider. It was designed to supplement the e/? separation capability of the lead glass calorimeter. It is one of the largest transition radiation detector in the world at present. The detector has a total of 2,688 channels of readout electronics. The electronics employs the method of charge sensitive preamplifier-trapezoidal shaping. Each TKO board contains 32 channels of shaper-gated integrators and a 12bit ADC. This paper describes full details of the readout electronics, the electronics for wire-gain control and the performance of the detector

  1. Tidal Venuses: Triggering a Climate Catastrophe via Tidal Heating

    CERN Document Server

    Barnes, Rory; Goldblatt, Colin; Meadows, Victoria S; Kasting, James F; Heller, Rene

    2012-01-01

    Traditionally stellar radiation has been the only heat source considered capable of determining global climate on long timescales. Here we show that terrestrial exoplanets orbiting low-mass stars may be tidally heated at high enough levels to induce a runaway greenhouse for a long enough duration for all the hydrogen to escape. Without hydrogen, the planet no longer has water and cannot support life. We call these planets "Tidal Venuses," and the phenomenon a "tidal greenhouse." Tidal effects also circularize the orbit, which decreases tidal heating. Hence, some planets may form with large eccentricity, with its accompanying large tidal heating, and lose their water, but eventually settle into nearly circular orbits in the habitable zone (HZ). However, these planets are not habitable as past tidal heating desiccated them, and hence should not be ranked highly for detailed follow-up observations aimed at detecting biosignatures. We simulate the evolution of hypothetical planetary systems in a quasi-continuous ...

  2. Venus atmosphere profile from a maximum entropy principle

    Directory of Open Access Journals (Sweden)

    L. N. Epele

    2007-10-01

    Full Text Available The variational method with constraints recently developed by Verkley and Gerkema to describe maximum-entropy atmospheric profiles is generalized to ideal gases but with temperature-dependent specific heats. In so doing, an extended and non standard potential temperature is introduced that is well suited for tackling the problem under consideration. This new formalism is successfully applied to the atmosphere of Venus. Three well defined regions emerge in this atmosphere up to a height of 100 km from the surface: the lowest one up to about 35 km is adiabatic, a transition layer located at the height of the cloud deck and finally a third region which is practically isothermal.

  3. Application of Transputers to second level trigger at VENUS

    International Nuclear Information System (INIS)

    A second level trigger system, based on microprocessors working in parallel, has been installed into VENUS experiment. The purpose of the system is to find particle tracks in Central Drift Chamber on-line during A/D conversion time, in about 10 milliseconds. Based on the transverse momentum values calculated by the system, a more precise event selection that the present one is possible. Potentially even as much as around 90% of the low transverse momentum event background remaining after first level trigger could be rejected by this trigger. This has also been demonstrated in tests with real event data. To realize sufficient computing power for the task, the task must be divided and distributed to processors as evenly as possible and a good balance between computation and communication load must be achieved. Sufficient performance has been realized, with an average triggering time of 9.8 milliseconds. (author)

  4. Ballistic Mercury orbiter mission via Venus and Mercury gravity assists

    Science.gov (United States)

    Yen, Chen-Wan Liu

    1989-01-01

    This paper shows that it is possible to deliver a payload of 600 to 2000 kg to a 300-km circular orbit at Mercury, using the presently available NASA STS and a single-stage bipropellant chemical rocket. This superior payload performance is attained by swingbys of Venus, plus more importantly, the use of the reverse Delta-V/EGA process. In contrast to the familiar Delta-V/EGA process used to boost the launch energy by returning to earth for a gravity assist, the reverse process reduces the Mercury approach energy each time a spacecraft makes a near-resonant return to Mercury for a gravity assist and reduces the orbit-capture Delta-V requirement. The mission sequences for such high-performance missions are described, and example mission opportunities for the years 1990 to 2010 are presented.

  5. Uplifts on Venus and Earth: A Principal Component Analysis

    Science.gov (United States)

    Stoddard, P. R.; Jurdy, D. M.

    2014-12-01

    Principal component analysis (PCA) offers a quantitative approach for comparison of topographic profiles. We have previously compared simple shapes of topographic profiles of rifts and uplifts on Venus and Earth. Although yielding some interesting results, these studies were more qualitative than quantitative. We address this by applying PCA to sets of topographic profiles on the two planets. Doing so yields not only groupings of like features in what we call "PC-space," but also the actual shapes of principal component profiles. PC-space consists of a modified ternary diagram showing the relative contributions of the three strongest principal components derived from a particular data set. The first PC profile generally shows a simple broad uplift, while profiles 2 and 3 display more complexity, which we attribute to lithospheric response to loading. Regardless of size of data set, the top three components account for about 95% of the shape of a feature's profile, so we concentrate our analysis on these three components. We first look at a data set with several forms of uplift - mid-ocean ridges and continental rifts, and continental and oceanic hotspots on Earth, and chasmata and regiones from Venus. Subsets based on the groupings from this original data set are examined. Specifically, the hotspot data set is tested looking at potential differences between oceanic and continental, and Types 1, 2, and 3 as defined by Courtillot. We look for correlations between terrestrial features and venusian chasmata and regiones. The effect of spreading rate on mid-ocean ridge topography is examined and compared to chasmata.

  6. The connection between Venus' free obliquity and its CMB oblateness

    Science.gov (United States)

    Yoder, C. F.

    1993-01-01

    The most striking feature of Venus rotational state is its slow retrograde rotation which is apparently maintained by a balance between solid tidal friction and thermal tidal torques. Solid tides tend to drive the spin toward synchronous rotation while thermal tides drive it away. A balance is achieved at a specific rate because of the inverse frequency dependence of the thermal tide to the semi-diurnal heating. Atmospheric models have been constructed to estimate the thermal tidal torque based on ground heating. The solid friction dissipation factor Q approximately equal to 50 can be deduced assuming rotation has achieved steady state. The most perplexing feature of Venus orientation is its non-zero free obliquity epsilon approximately equal to 1.5 deg relative to its orbit. Although solid tides and perhaps atmospheric tides tend to increase the free obliquity on a time 1/K(sub t) approximately equal to 1 x 10(exp 8) yr, viscous friction (CMF) at a core-mantle boundary (CMB) resulting from the differential angular orientation Delta-epsilon of the core and mantle spin axes should have damped the free obliquity on a time scale as short as 10(exp 6) yr. One means of achieving a balance similar to that controlling rotation is to introduce a comparatively large CMB ellipticity e(sub c) to reduce Delta-epsilon such that there is a balance between solid-thermal tides and CMF. The balance depends not so much on the potential frequency dependence on the tides as on the quadratic dependence of CMF on Delta-epsilon if the layer is turbulent.

  7. Radio Science Observations of the Mars Express December 2013 Phobos Flyby and Implications for the Satellite's Gravity Field

    Science.gov (United States)

    Andert, T.; Paetzold, M.; Rosenblatt, P.; Lainey, V.; Pasewaldt, A.; Oberst, J.; Jaumann, R.; Thuillot, W.; Remus, S.; Gurvits, L.; Pogrebenko, S.; Bocanegra Bahamon, T.; Cimo, G.; Duev, D.; Molera Calves, G.

    2014-12-01

    On 29th December 2013, the European spacecraft Mars Express performed a very close flyby at the Martian moon Phobos dedicated to the radio science experiment MaRS. The flyby distance was 58 km, the closest ever. Almost 32 hours of continuous tracking data were collected by ESTRACK (35 m) and DSN (70 m) ground station antennas. 31 VLBI antennas worldwide also recorded the radio signal. The tracking data were interrupted by occultations of approximately 1 hour duration in each orbit revolution, when the spacecraft in Mars orbit disappeared behind the planet as seen from the ground station. Images were taken with the Super Resolution Channel (SRC) of the High Resolution Stereo Camera (HRSC) onboard Mars Express before and after the flyby in order to improve the ephemeris of Phobos. The gravity field of Phobos was estimated from a close MEX flyby in 2010 at a distance of 77 km. The derived second degree and order gravity coefficients, however, showed large errors and could not resolve the interior structure of Phobos. Hence, the close flyby in 2013 was the opportunity to estimate the gravity field of Phobos at a higher precision because of the closer flyby distance, improved Phobos ephemeris obtained from the HRSC/SRC camera, and longer observation times with the ground station antennas. We aim at measurements of the gravity coefficients C20 and C22, which are linked with the main moments of inertia of the body. By comparison with the Phobos shape model and assuming a homogeneous mass distribution these can help in interpretations of the internal structure of Phobos. The main contribution to the error budget of the gravity field is caused by the uncertainty of the Phobos ephemeris, which potentially can be improved by HRSC/SRC observations.

  8. Linked Plume-Related Rifting and Regional Lateral Displacements and Indentation Tectonics on Venus Interpreted from Bouguer Gravity and Radar — Implications for an Archean Earth Without Plate Tectonics

    Science.gov (United States)

    Harris, L. B.; Bédard, J. H.

    2015-05-01

    Rifts and regional shears on Venus are interpreted from Bouguer gravity and radar. Structures resemble Archean terrains on Earth. Mantle flow on deep keels to plana (Venus) or cratons (Earth) provides an alternative to plate tectonics in the Archean.

  9. Formation and evolution of radial fracture systems on Venus

    Science.gov (United States)

    Parfitt, E. A.; Head, James W.

    1993-01-01

    A survey of approximately 90 percent of the surface of Venus using Magellan data has been carried out to locate all radial fracture systems and to assess their association with other features such as volcanic edifices and coronae. Squyres et al. and Stofan et al. have discussed the association of radial fracture features in relation to coronae features, our approach was to assess the associations of all of the fracture systems. These fracture systems have two broad types of form - some fracture systems are associated with updomed topography, radiate from a point and have relatively uniform fracture lengths while others have a wider range of fracture lengths and radiate from the outer edge of a central caldera. Squyres et al. and Stofan et al. have interpreted both types of feature as reflecting tectonic fracturing resulting from uplift of the surface as a mantle plume impinges upon the crust. While it is true that a number of features are related to uplift and that such uplift will induce stresses consistent with radial fracturing, we explore the possibility that these fractures are not exclusively of tectonic origin. Purely tectonic fracturing will tend to generate a few main fractures/faults along which most of the stresses due to uplift will be accommodated leading to the triple-junction form common for terrestrial updoming. Though this type of feature is observed on Venus (e.g., feature located at 34S86), the majority of radial fracture systems display much more intensive fracturing than this through a full 360 degrees; this is difficult to explain by purely tectonic processes. The association of many of the fractures with radial lava flows leads us to interpret these fractures as reflecting dike emplacement: the form of the fractures being consistent with primarily vertical propagation from the head of a mantle plume. In the case of the second type of fracture system (those radiating from a central caldera), an even stronger case can be made that the fractures are not of tectonic origin. These features are not as commonly associated with updoming of the surface and where they are, the fractures extend out well beyond the edge of the topographic rise - an observation which is not consistent with the fractures being of tectonic uplift origin. Furthermore the fractures have a distribution of lengths (many short, fewer long) which is characteristic of dike swarms, and show direct associations with calderas and lava flows consistent with a volcanic origin. In addition, the longest fractures have a radial pattern only close to the center of the system but bend with distance to align themselves with the regional stress field - this behavior is very difficult to explain on purely tectonic grounds but is a pattern commonly seen for terrestrial dikes. For these reasons, we argue that many, if not the majority, of radial fracture systems found on Venus are the surface reflection of dike swarms, those associated with positive topography reflecting vertical emplacement and those radiating from calderas reflecting lateral propagation.

  10. ESA's Planetary Science Archive: International collaborations towards transparent data access

    Science.gov (United States)

    Heather, David

    The European Space Agency's (ESA) Planetary Science Archive (PSA) is the central repository for science data returned by all ESA planetary missions. Current holdings include data from Giotto, SMART-1, Cassini-Huygens, Mars Express, Venus Express, and Rosetta. In addition to the basic management and distribution of these data to the community through our own interfaces, ESA has been working very closely with international partners to globalize the archiving standards used and the access to our data. Part of this ongoing effort is channelled through our participation in the International Planetary Data Alliance (IPDA), whose focus is on allowing transparent and interoperable access to data holdings from participating Agencies around the globe. One major focus of this work has been the development of the Planetary Data Access Protocol (PDAP) that will allow for the interoperability of archives and sharing of data. This is already used for transparent access to data from Venus Express, and ESA are currently working with ISRO and NASA to provide interoperable access to ISRO's Chandrayaan-1 data through our systems using this protocol. Close interactions are ongoing with NASA's Planetary Data System as the standards used for planetary data archiving evolve, and two of our upcoming missions are to be the first to implement the new 'PDS4' standards in ESA: BepiColombo and ExoMars. Projects have been established within the IPDA framework to guide these implementations to try and ensure interoperability and maximise the usability of the data by the community. BepiColombo and ExoMars are both international missions, in collaboration with JAXA and IKI respectively, and a strong focus has been placed on close interaction and collaboration throughout the development of each archive. For both of these missions there is a requirement to share data between the Agencies prior to public access, as well as providing complete open access globally once the proprietary periods have elapsed. This introduces a number of additional challenges in terms of managing different access rights to data throughout the mission lifetime. Both of these mission will have data pipelines running internally to our Science Ground Segment, in order to release the instrument teams to work more on science analyses. We have followed the IPDA recommendations of trying to start work on archiving with these missions very early in the life-cycle (especially on BepiColombo and now starting on JUICE), and endeavour to make sure that archiving requirements are clearly stated in official mission documentation at the time of selection. This has helped to ensure that adequate resources are available internally and within the instrument teams to support archive development. This year will also see major milestones for two of our operational missions. Venus Express will start an aerobraking phase in late spring / early summer, and will wind down science operations this year, while Rosetta will encounter the comet Churyamov-Gerasimenko, deploy the lander and start its main science phase. While these missions are at opposite ends of their science phases, many of the challenges from the archiving side are similar. Venus Express will have a full mission archive review this year and data pipelines will start to be updated / corrected where necessary in order to ensure long-term usability and interoperable access to the data. Rosetta will start to deliver science data in earnest towards the end of the year, and the focus will be on ensuring that data pipelines are ready and robust enough to maintain deliveries throughout the main science phase. For both missions, we aim to use the lessons learned and technologies developed through our international collaborations to maximise the availability and usability of the data delivered. In 2013, ESA established a Planetary Science Archive User Group (PSA-UG) to provide independent advice on ways to improve our services and our provision of data to the community. The PSA-UG will be a key link to the international planetary science community, pr

  11. Geologic Map of the Diana Chasma Quadrangle (V-37), Venus

    Science.gov (United States)

    Hansen, V.L.; DeShon, H.R.

    2002-01-01

    Introduction The Diana Chasma quadrangle (V-37), an equatorial region between 0? to 25? S. and 150? to 180? E. that encompasses ~8,400,000 km2, is broadly divided into southern Rusalka Planitia in the north, eastern Aphrodite Terra in the central region, and unnamed regions to the south. Geologic mapping constrains the temporal and spatial relations of the major features, which include a tessera inlier, Markham crater, six large coronae (300-675 km diameter), four smaller coronae (150-225 km diameter), Diana and Dali chasmata, a large fracture zone, and southern Rusalka Planitia. Eastern Aphrodite Terra, marked here by large coronae, deep chasmata, and an extensive northeast-trending fracture zone, extends from Atla Regio to Thetis Regio. The large coronae are part of a chain of such features that includes Inari Corona to the west-southwest and Zemina Corona to the northeast. V-37 quadrangle is bounded on the north by Rusalka Planitia and on the south by Zhibek Planitia. International Astronomical Union (IAU) approved and provisional nomenclature and positions for geographic features within Diana Chasma quadrangle are shown on the geologic map. [Note: Atahensik Corona was referred to as Latona Corona in much previously published literature.] Diana Chasma quadrangle hosts some of the steepest topography on Venus. Altimetry measurements range from -2.5 to 4.7 km (0.0 = mean planetary radius), with a surface mean of 0.6 km. Fractures and faults within the central fracture/rift zone create large blocks of down-dropped material, especially along the east-central edge of the map area. The Dali and Diana chasmata display slopes of >30?, the steepest and deepest trenches on Venus. Both chasmata host landslide deposits presumably sourced from the steep chasmata walls. The tessera inlier, coronae, and ridge belts sit topographically above Rusalka and Zhibek planitiae. Rusalka Planitia topography describes broad undulations having northwest-trending ridges spaced ~200 km apart. The most distinctive ridge, Vetsorgo Dorsum, centered at 6.5? S., 163? E., is a Class I ridge belt owing to its simple arch morphology. The central interior of Markham crater sits topographically lower than the surrounding region, which slopes downward to the east.

  12. Planning for VRM: Radar and sonar studies of volcanic terrains on Earth, Venus and Mars

    Science.gov (United States)

    Mouginis-Mark, P. J.; Gaddis, L. R.; Blake, P. L.; Fryer, P.; Ferrall, C.

    1985-01-01

    Venera 15 and 16 radar images of Venus, together with Earth based data from the Arecibo Observatory, indicate that volcanism has played an important role in the evolution of the Venusian landscape. At the end of this decade, NASA's Venus Radar Mapper (VRM) spacecraft will return near global information that will further constrain the planet's geologic history. Due to the diversity of volcano/tectonic features that have already been identified on Venus, and the intrinsic differences between radar images and conventional photography, additional expertise is being developed with which to interpret the VRM images of this unusual environment. Several attempts to better understand the physical characteristics of volcanic terrains are described here. Pioneer Venus radar altimeter measurements of topographic variability and surface roughness are compared with Goldstone radar measurements of volcanic terrains on Mars. Synthetic aperture radar images obtained by the SIR-B Space Shuttle experiment over Kilauea Volcano, Hawaii, are employed to investigate the differences in radar returns from pahoehoe, aa and sheet lava flows. Four polarization, multiple incidence angle, aircraft radar images of the Medicine Lake area of N. California are used to address the unusually high cross-polarization ratio of lobate flows around Beta Regio on Venus, as measured by the Arecibo radar.

  13. The Transit of Venus, 8 June 2004: A Teachers' Guide to Finding the Earth-Sun Distance

    Science.gov (United States)

    Catchpole, Robin

    2004-01-01

    Transits of Venus have been observed since the 17th century and were soon recognized as a way of determining the distance from the Earth to the Sun. But just how can this be done? There are in fact four methods and this article examines them in turn, making clear how Venus will appear to move, what observations are required, the calculations that…

  14. SPH modelling of energy partitioning during impacts on Venus

    Science.gov (United States)

    Takata, T.; Ahrens, T. J.

    1993-01-01

    Impact cratering of the Venusian planetary surface by meteorites was investigated numerically using the Smoothed Particle Hydrodynamics (SPH) method. Venus presently has a dense atmosphere. Vigorous transfer of energy between impacting meteorites, the planetary surface, and the atmosphere is expected during impact events. The investigation concentrated on the effects of the atmosphere on energy partitioning and the flow of ejecta and gas. The SPH method is particularly suitable for studying complex motion, especially because of its ability to be extended to three dimensions. In our simulations, particles representing impactors and targets are initially set to a uniform density, and those of atmosphere are set to be in hydrostatic equilibrium. Target, impactor, and atmosphere are represented by 9800, 80, and 4200 particles, respectively. A Tillotson equation of state for granite is assumed for the target and impactor, and an ideal gas with constant specific heat ratio is used for the atmosphere. Two dimensional axisymmetric geometry was assumed and normal impacts of 10km diameter projectiles with velocities of 5, 10, 20, and 40 km/s, both with and without an atmosphere present were modeled.

  15. Transcriptome and genome size analysis of the venus flytrap

    DEFF Research Database (Denmark)

    Jensen, Michael Krogh; Vogt, Josef Korbinian

    2015-01-01

    The insectivorous Venus flytrap (Dionaea muscipula) is renowned from Darwin's studies of plant carnivory and the origins of species. To provide tools to analyze the evolution and functional genomics of D. muscipula, we sequenced a normalized cDNA library synthesized from mRNA isolated from D. muscipula flowers and traps. Using the Oases transcriptome assembler 79,165,657 quality trimmed reads were assembled into 80,806 cDNA contigs, with an average length of 679 bp and an N50 length of 1,051 bp. A total of 17,047 unique proteins were identified, and assigned to Gene Ontology (GO) and classified into functional categories. A total of 15,547 full-length cDNA sequences were identified, from which open reading frames were detected in 10,941. Comparative GO analyses revealed that D. muscipula is highly represented in molecular functions related to catalytic, antioxidant, and electron carrier activities. Also, using a single copy sequence PCR-based method, we estimated that the genome size of D. muscipula is approx. 3 Gb. Our genome size estimate and transcriptome analyses will contribute to future research on this fascinating, monotypic species and its heterotrophic adaptations.

  16. Outcrops of plastic material on the surface of Venus

    Science.gov (United States)

    Ksanfomality, L. V.

    2015-05-01

    The archive data of the television experiment performed by the Venera-14 spacecraft on the surface of the planet Venus in March, 1982, were reprocessed, which significantly improved the image definition quality. An unusual geologic object located relatively near the camera was found, which allowed its details to be analyzed. The object is a low long bank in shape; it is formed by a relatively thin, jagged, almost vertical stratum. The bank contours the oval formation 1.5-2 m across that stands out against the layered surface. The location of the bank suggests that its material is extruded from under the layered plates surrounding the oval formation. A segment of the bank resembling a falling wave is inclined and partly covers the surface by forming the beddings. The object is likely formed by the rocks that remain semisoftened (plastic), when they appear on the surface at the temperature characteristic for the Venusian surface (about 740 K). It is suggested that, from the data on the physical and chemical conditions and the composition of the Venusian surface, the nature of the observed plastic medium can be hypothesized, and it can be even modeled under laboratory conditions.

  17. Readout electronics for the VENUS muon drift tubes at TRISTAN

    International Nuclear Information System (INIS)

    A simple and low-cost readout electronics system for the VENUS muon drift tubes was developed. The muon detector was constructed from about 900 extruded aluminum drift tubes. Each tube is composed of 2 layers of 4 isolated cells staggered by a half cell. Each set of the readout system consists of a memory board ( TKO module ), a main-address-generator board, 8 module-address-generator boards, and 64 front-end boards in tree structure. Thus each memory board can handle up to 512 channels of drift cell. The front-end board contains not only 8 channels of preamplifiers and comparators, but also 40MHz direct counting 6-bit TDCs. This board is located directly on an 8-cell drift tube. Relatively easy position resolution ( --1mm ) allowed us to use TTL/CMOS ICs for most of the readout electronics. The location of TDC and address generators near drift tubes helped us reduce the number of long signal cables. Therefore, total construction cost was reduced significantly. The system has been successfully operating for over a year

  18. The Important Role of the Two French Astronomers J.-N. Delisle and J.-J. Lalande in the Choice of Observing Places during the Transits of Venus in 1761 and 1769

    Science.gov (United States)

    Dumont, Simone; Gros, Monique

    2013-05-01

    Joseph-Nicolas Delisle, as a member of the Academie Royale des Sciences of Paris and professor at the College Royal de France, went to England in 1724 to visit Newton and Halley. The latter suggested observations of the transits of Mercury and of Venus in order to obtain the solar parallax. Delisle was also interested in the Mercury transits. After a stay of 22 years in Saint Petersburg, on his return to Paris, he distributed avertissements (information bulletins) encouraging all astronomers to observe the same phenomena, like the solar eclipse of 1748. Later, in 1760, Delisle presented an Adresse to the King and to the Academie in which he detailed his method to observe the 1761 transit of Venus. This was accompanied by a mappemonde showing the best places for observations. Copies of the text, together with 200 maps, were sent to his numerous correspondents in France and abroad. Following the advanced age and finally death of Delisle, his assistant and successor Joseph-Jerome Lalande presented a memoire related to the 1769 transit of Venus and an improved map of the best observing places. We detail the role of Delisle and Lalande in the preparation of the international collaboration related to these two transits.

  19. Proceedings of the 40th Lunar and Planetary Science Conference

    Science.gov (United States)

    2009-01-01

    The 40th Lunar and Planetary Science Conference included sessions on: Phoenix: Exploration of the Martian Arctic; Origin and Early Evolution of the Moon; Comet Wild 2: Mineralogy and More; Astrobiology: Meteorites, Microbes, Hydrous Habitats, and Irradiated Ices; Phoenix: Soil, Chemistry, and Habitability; Planetary Differentiation; Presolar Grains: Structures and Origins; SPECIAL SESSION: Venus Atmosphere: Venus Express and Future Missions; Mars Polar Caps: Past and Present; SPECIAL SESSION: Lunar Missions: Results from Kaguya, Chang'e-1, and Chandrayaan-1, Part I; 5 Early Nebula Processes and Models; SPECIAL SESSION: Icy Satellites of Jupiter and Saturn: Cosmic Gymnasts; Mars: Ground Ice and Climate Change; SPECIAL SESSION: Lunar Missions: Results from Kaguya, Chang'e-1, and Chandrayaan-1, Part II; Chondrite Parent-Body Processes; SPECIAL SESSION: Icy Satellites of Jupiter and Saturn: Salubrious Surfaces; SNC Meteorites; Ancient Martian Crust: Primary Mineralogy and Aqueous Alteration; SPECIAL SESSION: Messenger at Mercury: A Global Perspective on the Innermost Planet; CAIs and Chondrules: Records of Early Solar System Processes; Small Bodies: Shapes of Things to Come; Sulfur on Mars: Rocks, Soils, and Cycling Processes; Mercury: Evolution and Tectonics; Venus Geology, Volcanism, Tectonics, and Resurfacing; Asteroid-Meteorite Connections; Impacts I: Models and Experiments; Solar Wind and Genesis: Measurements and Interpretation; Mars: Aqueous Processes; Magmatic Volatiles and Eruptive Conditions of Lunar Basalts; Comparative Planetology; Interstellar Matter: Origins and Relationships; Impacts II: Craters and Ejecta Mars: Tectonics and Dynamics; Mars Analogs I: Geological; Exploring the Diversity of Lunar Lithologies with Sample Analyses and Remote Sensing; Chondrite Accretion and Early History; Science Instruments for the Mars Science Lander; . Martian Gullies: Morphology and Origins; Mars: Dunes, Dust, and Wind; Mars: Volcanism; Early Solar System Chronology; Seek Out and Explore: Upcoming and Future Missions; Mars: Early History and Impact Processes; Mars Analogs II: Chemical and Spectral; Achondrites and their Parent Bodies; and Planning for Future Exploration of the Moon The poster sessions were: Lunar Missions: Results from Kaguya, Chang'e-1, and Chandrayaan-1; LRO and LCROSS; Geophysical Analysis of the Lunar Surface and Interior; Remote Observation and Geologic Mapping of the Lunar Surface; Lunar Spectroscopy; Venus Geology, Geophysics, Mapping, and Sampling; Planetary Differentiation; Bunburra and Buzzard Coulee: Recent Meteorite Falls; Meteorites: Terrestrial History; CAIs and Chondrules: Records of Early Solar System Processes; Volatile and Organic Compounds in Chondrites; Crashing Chondrites: Impact, Shock, and Melting; Ureilite Studies; Petrology and Mineralogy of the SNC Meteorites; Martian Meteorites; Phoenix Landing Site: Perchlorate and Other Tasty Treats; Mars Polar Atmospheres and Climate Modeling; Mars Polar Investigations; Mars Near-Surface Ice; Mars: A Volatile-Rich Planet; Mars: Geochemistry and Alteration Processes; Martian Phyllosilicates: Identification, Formation, and Alteration; Astrobiology; Instrument Concepts, Systems, and Probes for Investigating Rocks and Regolith; Seeing is Believing: UV, VIS, IR, X- and Gamma-Ray Camera and Spectrometer Instruments; Up Close and Personal: In Situ Analysis with Laser-Induced Breakdown Spectroscopy and Mass Spectrometry; Jupiter and Inscrutable Io; Tantalizing Titan; Enigmatic Enceladus and Intriguing Iapetus; Icy Satellites: Cryptic Craters; Icy Satellites: Gelid Geology/Geophysics; Icy Satellites: Cool Chemistry and Spectacular Spectroscopy; Asteroids and Comets; Comet Wild 2: Mineralogy and More; Hypervelocity Impacts: Stardust Models, LDEF, and ISPE; Presolar Grains; Early Nebular Processes: Models and Isotopes; Solar Wind and Genesis: Measurements and Interpretation; Education and Public Outreach; Mercury; Pursuing Lunar Exploration; Sources and Eruptionf Lunar Basalts; Chemical and Physical Properties of the Lunar Regolith; Lunar Dust and Transient

  20. Comparison of gas dynamic model with steady solar wind flow around Venus

    International Nuclear Information System (INIS)

    A gas dynamic model for solar wind flow around Venus has been compared with Pioneer Venus orbiter plasma analyzer measurements for times when the solar wind flow seemed steadiest. The comparisions were made near the terminator. When the observed and model bow shock locations are matched, the model agrees fairly well with the observed parameters: the components of the flow velocity and magnetic field, and the proton number density and isotropic temperature. However, the Mach numbers required to fit the observed bow shock locations are less than 2/3 those estimated from the measured parameters of the free-stream flow, because the bow shock locations (near the terminator) are farther from Venus than expected. Sometimes the measured flow speeds appear to be retarded near the ionopause

  1. Role of the hot oxygen corona in the Venus-solar wind interaction

    International Nuclear Information System (INIS)

    Numerical MHD of the Venus-solar wind interaction taking into account solar wind loading with ions formed as a result of hot oxygen corona photoionization in transition region between the shock wave front and ionopause, is presented. The calculation was made for concrete characteristics of the solar wind measured when American spacecraft ''Pioneer-Venus'' (PVO) passed the orbit No. 582. Results of calculation of front position, solar wind properties beyond the front were compared with the ones measured on board PVO and calculation data of other gas dynamic models, which did not take into account the effect of loading. It is shown that the effect of loadig permits to explain unambiguously the main peculiarities of the Venus streamline pattern

  2. The Effect of Recent Venus Transit on Earth?s Atmosphere

    Directory of Open Access Journals (Sweden)

    H. P. Sardar

    2006-06-01

    Full Text Available Some experiments on June 8, 2004, the day of transit of Venus across the Sun, were undertaken at Kolkata (latitude: 23034? N to observe effect, if any, of transit of Venus on FWF, ELF and VLF amplitudes. The result shows good correlation between their temporal variations during the transit. The observation was unbelievable as the Venus subtends only 1/32th of the cone subtended by Sun on Earth. This anomaly may be explained on the assumption that the height of Venusian atmosphere with high content of CO2, and nitrogen which absorbs electromagnetic and corpuscular radiations from Sun, depleting the solar radiation reaching the Earth to a considerable extent. As a result, relevant parameters of Earth?s atmosphere are modulated and here we show how these changes are reflected in identical behaviour of fair weather field and ELF and VLF spectra.

  3. The effect of recent Venus transit on Earth?s atmosphere

    Directory of Open Access Journals (Sweden)

    H. P. Sardar

    2006-06-01

    Full Text Available Some experiments on June 8, 2004, the day of transit of Venus across the Sun, were undertaken at Kolkata (latitude: 22°34lN to observe the effect, if any, of transit of Venus on FWF, ELF and VLF amplitudes. The result shows a good correlation between their temporal variations during the transit. The observation was unbelievable as the Venus subtends only 1/32th of the cone subtended by Sun on Earth. This anomaly may be explained on the assumption that the height of Venusian atmosphere with high content of CO2, and nitrogen which absorbs electromagnetic and corpuscular radiations from Sun, depleting the solar radiation reaching the Earth to a considerable extent. As a result, relevant parameters of Earth?s atmosphere are modulated and here we show how these changes are reflected in identical behaviour of fair weather field and ELF and VLF spectra.

  4. Using the transit of Venus to probe the upper planetary atmosphere.

    Science.gov (United States)

    Reale, Fabio; Gambino, Angelo F; Micela, Giuseppina; Maggio, Antonio; Widemann, Thomas; Piccioni, Giuseppe

    2015-01-01

    During a planetary transit, atoms with high atomic number absorb short-wavelength radiation in the upper atmosphere, and the planet should appear larger during a primary transit observed in high-energy bands than in the optical band. Here we measure the radius of Venus with subpixel accuracy during the transit in 2012 observed in the optical, ultraviolet and soft X-rays with Hinode and Solar Dynamics Observatory missions. We find that, while Venus's optical radius is about 80?km larger than the solid body radius (the top of clouds and haze), the radius increases further by >70?km in the extreme ultraviolet and soft X-rays. This measures the altitude of the densest ion layers of Venus's ionosphere (CO2 and CO), useful for planning missions in situ, and a benchmark case for detecting transits of exoplanets in high-energy bands with future missions, such as the ESA Athena. PMID:26102562

  5. On the proper Mach number and ratio of specific heats for modeling the Venus bow shock

    Science.gov (United States)

    Tatrallyay, M.; Russell, C. T.; Luhmann, J. G.; Barnes, A.; Mihalov, J. D.

    1984-01-01

    Observational data from the Pioneer Venus Orbiter are used to investigate the physical characteristics of the Venus bow shock, and to explore some general issues in the numerical simulation of collisionless shocks. It is found that since equations from gas-dynamic (GD) models of the Venus shock cannot in general replace MHD equations, it is not immediately obvious what the optimum way is to describe the desired MHD situation with a GD code. Test case analysis shows that for quasi-perpendicular shocks it is safest to use the magnetospheric Mach number as an input to the GD code. It is also shown that when comparing GD predicted temperatures with MHD predicted temperatures total energy should be compared since the magnetic energy density provides a significant fraction of the internal energy of the MHD fluid for typical solar wind parameters. Some conclusions are also offered on the properties of the terrestrial shock.

  6. In-core and ex-core calculations of the VENUS simulated PWR benchmark experiment

    International Nuclear Information System (INIS)

    The VENUS pressurized water reactor (PWR) engineering mockup experiment was established to simulate a beginning-of-life, generic PWR configuration at the zero-power VENUS critical facility located at CEN/SCK in Mol, Belgium. The reactor contains Zircaloy-clad, low-enriched UO2 pins in a light water moderator. The size and pitch of the pins are consistent with modern PWR cores. The VENUS rectangular core region is surrounded by a steel baffle, followed by a water reflector, a simulated core barrel, a simulated thermal shield, and a simulated downcomer region, respectively. The US Nuclear Regulatory Commission has supported dosimetry measurements and calculations in this Belgium-sponsored benchmark experiment as part of its light water (LWR) reactor pressure vessel (RPV) surveillance dosimetry improvement program to determine the accuracy to which neutron and gamma responses can be calculated in a prototypic LWR environment

  7. Laboratory studies on the reactions between chlorine, sulfur dioxide, and oxygen - Implications for the Venus stratosphere

    Science.gov (United States)

    Demore, W. B.; Leu, M.-T.; Smith, R. H.; Yung, Y. L.

    1985-01-01

    Fourier transform IR spectrophotometry is used to monitor the reactants and products in a Venus stratosphere simulation study involving the photolysis of mixtures of Cl2 and SO2, with and without O2 present in an atmosphere of N2. When several speculative reactions inferred from these experiments are incorporated by the Yung and DeMore (1982) model of Venus stratospheric chemistry, it emerges that SO2Cl2 is a key reservoir species for chlorine, and that the reaction between Cl and SO2 furnishes an important cycle for the destruction of O2 and the conversion of SO2 to H2SO4, thereby providing a possible solution to the photochemistry of the Venus stratosphere.

  8. Laboratory studies on the reactions between chlorine, sulfur dioxide, and oxygen - Implications for the Venus stratosphere

    International Nuclear Information System (INIS)

    Fourier transform IR spectrophotometry is used to monitor the reactants and products in a Venus stratosphere simulation study involving the photolysis of mixtures of Cl2 and SO2, with and without O2 present in an atmosphere of N2. When several speculative reactions inferred from these experiments are incorporated by the Yung and DeMore (1982) model of Venus stratospheric chemistry, it emerges that SO2Cl2 is a key reservoir species for chlorine, and that the reaction between Cl and SO2 furnishes an important cycle for the destruction of O2 and the conversion of SO2 to H2SO4, thereby providing a possible solution to the photochemistry of the Venus stratosphere. 17 references

  9. The 2012 Transit of Venus: A Closer Look at the Cytherean Aureole

    Science.gov (United States)

    Edelman, Eric; Pasachoff, J. M.; Schneider, G.; Babcock, B. A.; Lu, M.; Reardon, K.; Widemann, T.; Tanga, P.; Dantowitz, R.

    2013-01-01

    The 2012 Transit of Venus provided a new opportunity to study the events that occur during the ingress and egress of transit in greater detail. The Venus Twilight Experiment is a group that was formed to analyze the twilight phenomena of Venus through close and careful observation of planet’s 21st century transits. One particular object of interest to this group is the Cytherean aureole, or the arc of light caused by refraction of the Sun’s light through Venus’s upper atmosphere. A goal associated with the study of this aureole is to measure how the brightness of the atmosphere changes over time and as a function of latitude on Venus with the use of the multitude of images taken of the planet near the beginning and end of the transit. In order to further along this goal, I was tasked with sorting, processing, and aligning the images taken by the coronagraph used on the 2012 Williams College Transit of Venus Expedition at Haleakala, Hawaii. Our observations through a B filter will be compared with observations through VRI-filter observations from other coronagraphs in the set. This was research was performed with the support of the Keck Northeast Astronomy Consortium, sponsored by the NSF and the Keck foundation. The expedition to Haleakala and Sac Peak was sponsored by the Committee for Research and Exploration/National Geographic Society. Some funds for the IBIS carbon-dioxide filter came from NASA/AAS's Small Research Grant Program. We thank Rob Ratkowski, Stan Truitt, Rob Lucas, Aram Friedman, and Eric Pilger '82 for assistance with Haleakala observing.

  10. Imaging and mapping the circumsolar dust ring near the orbit of Venus

    Science.gov (United States)

    Jones, M.; Bewsher, D.; Brown, D.

    2014-07-01

    Asteroids and comets are the dominant source of dust feeding the zodiacal cloud [1,2]. The orbits of grains of size 10--100 microns are expected to decay by Poynting-Robertson drag [3], but in the vicinity of planetary orbits dust may get trapped into exterior mean motion resonances [4] to form a circumsolar dust ring. It has long been known that such a ring exists close to the Earth's orbit [5], but even now, little is known about its detailed structure. No such ring or associated resonance feature has been detected at the orbits of Mars or Jupiter [6]. While re-analysis of photometry data from the Helios mission provided some evidence of a ring associated with Venus [7], the existence of such a ring could not be conclusively demonstrated. Here we report on recent work that confirms the existence of a circumsolar ring at Venus from sensitive optical photometry of the zodiacal cloud [8]. Our analysis uses synoptic images from the HI-2 instrument on STEREO [9]. We discuss the techniques that we have developed to extract images of the Venus ring, and describe the approach taken towards creating a simple parametric model of the ring. We note that the maximum over-density in the ring is about 10% that of the smooth zodiacal cloud, and we highlight other aspects of the ring structure that we have already determined. We demonstrate that the STEREO HI-2 data allow the density structure of the Venus ring to be mapped in much greater detail than the Earth ring. Thus the Venus ring has the potential to provide a stringent test of models of resonance ring formation. Not only is this relevant to understanding the structure of the zodiacal cloud, it is of importance in the context of exoplanetary systems which are also expected to display analogous circumstellar dust rings [10,11]. We conclude by discussing current progress in mapping the density distribution of the Venus circumsolar ring.

  11. Study on neutron amplification factor of fast-zone in VENUS 1# on unidirectional coupling mode

    International Nuclear Information System (INIS)

    VENUS 1# is the first fast-thermal coupled accelerator driven sub-critical experimental facility of the world built by China Atomic Energy Institute-CIAE. In this paper, the leakage and net neutron yield of fast zone and leakage neutron spectrum driven by 252Cf, Am-Be and D-T neutron sources with different loading layers was calculated based on VENUS 1# unidirectional coupling mode. The results show that, from the view of energy production and transmutation, there exists optimized fuel loadings of fast-zone, which will provide theoretical basis for designing 'fast-thermal' unidirectional coupling systems. (authors)

  12. Venus transits: history and opportunities for planetary, solar and gravitational physics

    OpenAIRE

    Sigismondi, Costantino; Wang, Xiaofan; Rocher, Patrick; Reis-Neto, Eugenio

    2013-01-01

    The data of 2012 transit of Venus are compared with the ones of 2004. The thickness of the atmosphere of Venus, its aureole and the effect of oblateness and other asphericities in the figure of the Sun are taken into consideration, as well as the black drop effect. A new extrapolation method for the contact times is presented. The next Mercury transit in 2016 will be fully visible from Europe, and the data will be gathered in view of this new method of analysis, to obtain th...

  13. Indian astronomy and the transits of Venus. 2: The 1874 event

    Science.gov (United States)

    Kapoor, R. C.

    2014-03-01

    This paper is about sightings and astronomical observations of the 1874 transit of Venus made from the Indian region. The sources of the information presented here range from some classic texts and historiographies, publications and records of institutions, and chronicles, to accounts by individuals. Of particular interest is the fact that the transits of 1761 and of 1874 both provided independent evidence of an atmosphere around Venus in observations made from India, and the transit of 1874 led to spectroscopic confirmation of the presence of this atmosphere.

  14. Venus transits: history and opportunities for planetary, solar and gravitational physics

    CERN Document Server

    Sigismondi, Costantino; Rocher, Patrick; Reis-Neto, Eugenio

    2013-01-01

    The data of 2012 transit of Venus are compared with the ones of 2004. The thickness of the atmosphere of Venus, its aureole and the effect of oblateness and other asphericities in the figure of the Sun are taken into consideration, as well as the black drop effect. A new extrapolation method for the contact times is presented. The next Mercury transit in 2016 will be fully visible from Europe, and the data will be gathered in view of this new method of analysis, to obtain the solar diameter.

  15. Venus imaged with the Hat Creek interferometer in the J = 1-0 CO line

    International Nuclear Information System (INIS)

    Venus 2.7-mm continuum emission and CO J = 1-0 transition observations conducted in January 1987, when Venus was at western elongation, indicate a 10 percent brightness temperature increase from the day to the nightside. It is suggested that this brightness temperature variation, which is greater than anticipated on the basis of physical variations in temperature, may be associated with potentially cloud-related atmospheric opacity variations. Model fits to the CO spectra suggest that, while the CO at altitudes greater than 90 km decreases from night to day, low altitude CO may exhibit a general enhancement. 36 refs

  16. Venus Transits: History and Opportunities for Planetary, Solar and Gravitational Physics

    Science.gov (United States)

    Sigismondi, C.; Wang, X.; Rocher, P.; Reis Neto, E.

    2015-01-01

    The data of 2012 transit of Venus are compared with the ones of 2004. The thickness of the atmosphere of Venus, its aureole and the effect of oblateness and other asphericities in the figure of the Sun are taken into consideration, as well as the black drop effect. A new extrapolation method for the contact times is presented. The next Mercury transit in 2016 will be fully visible from Europe, and the data will be gathered in view of this new method of analysis, to obtain the solar diameter.

  17. Radiowave attenuation and sulfuric acid vapor content in the Venus atmosphere

    International Nuclear Information System (INIS)

    The data of radiotranslucence on the change in the intensity of centimeter (?=5 cm) and decimeter (?=32 cm) radiosignal field have been used to study radiowave attenuation in the Venus atmosphere. An altitude profile of radiowave absorption coefficient for ?=5 cm is obtained. It is shown that absorption with sulfuric acid vapors is the most probable reason for the attenuation of centimeter range radiowaves at the altitudes below 50 km. The content of sulfuric acid vapors equalling 15 ppm at the altitude of 48 km and 19 ppm at the altitude of 47 km is determined which agrees with analogous measurements of the Pionere-Venus device obtained for radiowaves with ?=13 cm

  18. Trajectories to the outer planets using aero-gravity assist flybys of Venus and Mars

    Science.gov (United States)

    Bender, David F.

    1992-01-01

    The trajectory concept used here is to flyby Venus and then Mars with moderately high speeds expecting to use both gravity and aeroassisted (wave rider) turns in the atmospheres of the planets in order to form fast trajectories to the planets beyond Jupiter. The first part of the paper contains a description of the development of earth-Venus-Mars trajectories yielding the required speeds at Mars in the interval 2001 to 2015. The second part consists in identifying cases in which Mars is at the proper longitude for each target and obtaining trajectories. Trajectories to Saturn, Uranus, Neptune, and Pluto have been found.

  19. Multi-asteroid flyby trajectories using Venus-earth gravity assists

    Science.gov (United States)

    Bender, D. F.; Friedlander, A. L.

    1975-01-01

    The feasibility of using Venus and earth gravity assists for delivering spacecraft to the asteroid belt with a low launch energy but with the additional flight time from earth to Venus and back to earth. A numerical investigation for this kind of trajectory reveals a wide range of possibilities. Energy gain tables and synodic and resonance interval tables are presented for the gravity-assist trajectories. Tables are presented for the first twenty asteroids on the trajectories. These gravity-assist flybys are compared to direct launch multi-asteroid flybys, illustrating the advantage of the gravity-assist type in launch energy requirements.

  20. Literature and Mythology in Tennessee Williams's "Suddenly Last Summer": Fighting against Venus and Oedipus

    OpenAIRE

    Gilabert Barberà, Pau

    2006-01-01

    The aim of this article is to analyze accurately the role played by two classical references, Venus and Oedipus, in Tennessee Williams Suddenly Last Summer, in accordance with the usual nature of studies on Classical Tradition a Greek and Roman- and focusing in this case on the relationship between literature and mythology. It is thanks to Venus and Oedipus that the playwright succeeds in showing the magnitude of mens and womens tragedy, which from his point of view is simply that they have f...

  1. The twin sister planets Venus and Earth why are they so different?

    CERN Document Server

    Malcuit, Robert

    2014-01-01

    This book explains how it came to be that Venus and Earth, while very similar in chemical composition, zonation, size and heliocentric distance from the Sun, are very different in surface environmental conditions. It is argued here that these differences can be accounted for by planetoid capture processes and the subsequent evolution of the planet-satellite system. Venus captured a one-half moon-mass planetoid early in its history in the retrograde direction and underwent its "fatal attraction scenario" with its satellite (Adonis). Earth, on the other hand, captured a moon-mass planetoid (Lun

  2. A Photochemical Model for the Venus Atmosphere at 47-112 km

    Science.gov (United States)

    Krasnopolsky, V. A.

    2011-12-01

    The model is intended to respond to the recent findings in the Venus atmosphere from the Venus Express and ground-based submillimeter and infrared observations. It extends down to 47 km for comparison with the kinetic model for the lower atmosphere (Krasnopolsky, V.A., 2007, Icarus 191, 25-37) and to use its data as the boundary conditions. The model numerical accuracy is significantly improved by reduction of the altitude step from 2 km in the previous models to 0.5 km. Effects of the NUV absorber are approximated using the detailed photometric observations at 365 nm from Venera 14. The H2O profile is not fixed but calculated in the model. The model involves odd nitrogen and OCS chemistries based on the detected NO and OCS abundances. The number of the reactions is significantly reduced by removing of unimportant processes. Column rates for all reactions are given, and balances of production and loss may be analyzed in detail for each species. The calculated vertical profiles of CO, H2O, HCl, SO2, SO, OCS and of the O2 dayglow at 1.27 ?m generally agree with the existing observational data; some differences are briefly discussed. The OH dayglow is ~30 kR, brighter than the OH nightglow by a factor of 4. The H + O3 process dominates in the nightglow excitation and O + HO2 in the dayglow, because of the reduction of ozone by photolysis. The model is extremely sensitive to small variations of eddy diffusion near 60 km: the calculated variations of SO2, SO, and OCS at and above the cloud tops are within a factor of ~30. Variations of the SO2/H2O ratio at the lower boundary have similar but weaker effect: variations within a factor of ~4 are induced by changes of SO2/H2O by ±5%. Therefore the observed variations of sulfur species originate from minor variations of the atmospheric dynamics near the cloud layer and do not require volcanism. NO cycles are responsible for production of a quarter of O2, SO2, and Cl2 in the atmosphere. A net effect of photochemistry in the middle atmosphere is the consumption of CO2, SO2, and HCl from and return of CO, H2SO4, and SO2Cl2 to the lower atmosphere. These processes may be balanced by thermochemistry in the lower atmosphere even without outgassing from the interior, though the latter is not ruled out by our models.Variations of observable species induced by variations of eddy breakpoint he and SO2 at 47 kmsrc="/meetings/fm11/program/tables/P11G-06_T1.jpg">

  3. Preliminary Stratigraphic Basis for Geologic Mapping of Venus

    Science.gov (United States)

    Basilevsky, A. T.; Head, J. W.

    1993-01-01

    The age relations between geologic formations have been studied at 36 1000x1000 km areas centered at the dark paraboloid craters. The geologic setting in all these sites could be characterized using only 16 types of features and terrains (units). These units form a basic stratigraphic sequence (from older to younger: (1) Tessera (Tt); (2-3) Densely fractured terrains associated with coronae (COdf) and in the form of remnants among plains (Pdf); (4) Fractured and ridged plains (Pfr); (5) Plains with wrinkle ridges (Pwr); (6-7) Smooth and lobate plains (Ps/Pl); and (8) Rift-associated fractures (Fra). The stratigraphic position of the other units is determined by their relation with the units of the basic sequence: (9) Ridge bells (RB), contemporary with Pfr; (10-11) Ridges of coronae and arachnoids annuli (COar/Aar), contemporary with wrinkle ridges of Pwr; (12) Fractures of coronae annuli (COaf) disrupt Pwr and Ps/Pl; (13) Fractures (F) disrupt Pwr or younger units; (14) Craters with associated dark paraboloids (Cdp), which are on top of all volcanic and tectonic units except the youngest episodes of rift-associated fracturing and volcanism; (15-16) Surficial streaks (Ss) and surficial patches (Sp) are approximately contemporary with Cdp. These units may be used as a tentative basis for the geologic mapping of Venus including VMAP. This mapping should test the stratigraphy and answer the question of whether this stratigraphic sequence corresponds to geologic events which were generally synchronous all around the planet or whether the sequence is simply a typical sequence of events which occurred in different places at diffferent times.

  4. PERSPECTIVAS DA EDUCAÇÃO EM CIÊNCIAS EXPRESSAS NOS PERIÓDICOS SCIENCE E NATURE / PERSPECTIVES OF SCIENCE EDUCATION EXPRESSES IN THE PERIODICALS SCIENCE AND NATURE / PERSPECTIVAS DE LA EDUCACIÓN EN CIENCIAS EXPRESAS EN LOS PERIODICOS SCIENCE Y NATURE

    Scientific Electronic Library Online (English)

    Myriam, Krasilchik; Rosana Louro Ferreira, Silva; Paulo Fraga da, Silva.

    2015-04-01

    Full Text Available Os periódicos são essenciais para análise e compreensão dos movimentos científicos. O objetivo desta investigação foi identificar o que os dois mais influentes periódicos científicos, Science e Nature, publicam sobre a educação em ciências, em que segmentos da revista e sob qual(is) perspectiva(s). [...] Realizamos um levantamento no período de 2006-2010, identificando 31 textos publicados na Nature que traziam menção à educação em ciências e 163 na Science. Na Science notou-se um volume crescente de textos relacionados à educação em ciências no período analisado, além de uma maior concentração na categoria "políticas (investimentos/avaliação) na/da educação científica" seguida da categoria "ensino-aprendizagem, novos métodos/recursos". Na Nature, a categoria "relação entre ciência e religião" foi mais recorrente. A pesquisa se propôs a ampliar o diálogo e levantar projetos de interesse comum das áreas científicas básicas e da pesquisa em educação em ciências. A análise apontou a necessidade de aproximação dessas duas culturas. Abstract in spanish Los periódicos son esenciales para el análisis y la comprensión de los movimientos científicos. El objetivo de esta investigación fue identificar qué los dos más influyentes periódicos científicos, Science y Nature, publican acerca de la educación en ciencias, en que segmentos de la revista y por cu [...] al(es) perspectiva(s). Realizamos un levantamiento en el periodo de 2006-2010, identificando 31 textos publicados en Nature que hacían mención a la educación en ciencias y 163 en Science. En Science se nota un volumen creciente de textos relacionados a la educación en ciencias en el periodo analizado, además de una mayor concentración en la categoría "políticas (investimentos/evaluación) en la/de la educación científica", seguida de la categoría "enseñanza-aprendizaje, nuevos métodos/recursos". En Nature, la categoría "relación entre ciencia y religión" fue la más recurrente. La investigación se propuso a ampliar el diálogo y levantar proyectos de interés común de las áreas científicas másicas y de la investigación en educación en ciencias. El análisis apuntó la necesidad de aproximación de esas dos culturas. Abstract in english Periodicals are essential to the analysis and comprehension of the scientific trends. This investigation aimed at identifying what two of the most important periodicals about science publish on science education, under which perspectives and in which section of the periodical they are published. We [...] conducted a survey on the number of articles published between 2006 and 2010 and we were able to identify 31 texts in Nature magazine whereas Science published 163 articles on science education. Science magazine concentrated more on the politics (investments) on/from science education followed by the teaching and learning approach, new methods and resources. Nature magazine the category the relation between science and religion were more frequent. The proposal of the research is to enhance discussion and lead to common projects between basic scientific areas and research on science education.

  5. Large Ring Structure Around Colorado Plateau in North America Looks Similar to Coronae on Venus

    Science.gov (United States)

    Burba, G. A.

    2006-03-01

    Colorado Ring Structure is located between 33-41°N and 105-115°W. Its outer diameter is ~850 km, the rim width is ~170 km. The overall topographic shape is similar to the typical topography of the large circular features on Venus termed corona.

  6. Did Ibn Sina Observe the Transit of Venus of 1032 CE?

    Science.gov (United States)

    Kapoor, R. C.

    2012-09-01

    The Persian polymath Abu Ali ibn Sina (980--1037 CE), known to early Western sources as Avicenna, records that ``I say that I saw Venus as a spot on the surface of the sun''. This statement has been quoted, for example, by Nasir al Din al Tusi (1201--1274 CE). A Transit of Venus indeed took place during ibn Sina's life time, that is on 24 May 1032 CE. Did ibn Sina see this Transit or did he merely see a sunspot? The question was addressed by Bernard R. Goldstein in 1969 who concluded that ``this Transit may not have been visible where he lived''. Goldstein based his conclusion on the input provided by Brian G Marsden who in turn used mathematical tables prepared by J. Meeus in 1958. I have begun re-examination of the question by employing Fred Espenak's Transit predictions. Preliminary work shows that ibn Sina could indeed have obtained a glimpse of the Transit of Venus just before sunset from places like Isfahan or Hamadan. In other words, when ibn Sina said he saw Venus on the surface of the Sun, he probably meant it.

  7. Radioisotope Stirling Engine Powered Airship for Low Altitude Operation on Venus

    Science.gov (United States)

    Colozza, Anthony J.

    2012-01-01

    The feasibility of a Stirling engine powered airship for the near surface exploration of Venus was evaluated. The heat source for the Stirling engine was limited to 10 general purpose heat source (GPHS) blocks. The baseline airship utilized hydrogen as the lifting gas and the electronics and payload were enclosed in a cooled insulated pressure vessel to maintain the internal temperature at 320 K and 1 Bar pressure. The propulsion system consisted of an electric motor driving a propeller. An analysis was set up to size the airship that could operate near the Venus surface based on the available thermal power. The atmospheric conditions on Venus were modeled and used in the analysis. The analysis was an iterative process between sizing the airship to carry a specified payload and the power required to operate the electronics, payload and cooling system as well as provide power to the propulsion system to overcome the drag on the airship. A baseline configuration was determined that could meet the power requirements and operate near the Venus surface. From this baseline design additional trades were made to see how other factors affected the design such as the internal temperature of the payload chamber and the flight altitude. In addition other lifting methods were evaluated such as an evacuated chamber, heated atmospheric gas and augmented heated lifting gas. However none of these methods proved viable.

  8. Measuring the Solar Radius from Space during the 2012 Venus Transit

    Science.gov (United States)

    Emilio, M.; Couvidat, S.; Bush, R. I.; Kuhn, J. R.; Scholl, I. F.

    2015-01-01

    We report in this work the determination of the solar radius from observations by the Helioseismic and Magnetic Imager (HMI) and the Atmospheric Imaging Assembly (AIA) instruments on board the Solar Dynamics Observatory during the 2012 June Venus transit of the Sun. Two different methods were utilized to determine the solar radius using images of Sun taken by the HMI instrument. The first technique fit the measured trajectory of Venus in front of the Sun for seven wavelengths across the Fe I absorption line at 6173 Å. The solar radius determined from this method varies with the measurement wavelength, reflecting the variation in the height of line formation. The second method measured the area of the Sun obscured by Venus to determine the transit duration from which the solar radius was derived. This analysis focused on measurements taken in the continuum wing of the line, and applied a correction for the instrumental point spread function (PSF) of the HMI images. Measurements taken in the continuum wing of the 6173 Å line, resulted in a derived solar radius at 1 AU of 959.''57 ± 0.''02 (695, 946 ± 15 km). The AIA instrument observed the Venus transit at ultraviolet wavelengths. Using the solar disk obscuration technique, similar to that applied to the HMI images, analysis of the AIA data resulted in values of R ? = 963.''04 ± 0.''03 at 1600 Å and R ? = 961.''76 ± 0.''03 at 1700 Å.

  9. Observation of Venus and Mercury Transits from the Pic-du-Midi Observatory

    Science.gov (United States)

    Ratier, Guy; Rondi, Sylvain

    2013-05-01

    The Pic-du-Midi, on the French side of the Pyrenees, became a state observatory in the summer of 1882. The first major astronomical event to be observed was the Venus transit of 6 December 1882. Unfortunately this attempt by the well-known Henry brothers was unsuccessful due to bad weather conditions. During the twentieth century, the Pic-du-Midi became famous for the quality of its solar and planetary observations. In the sixties, Jean Rosch decided to use this experience to monitor the transits of Mercury. The objective was not to measure the parallax, but to determine the diameter of the planet in order to confirm its high density. Observations were made using a photometric method - the Hertzsprung method - during the transits of 1960, 1970 and 1973. The pioneer work of Ch. Boyer on the rotation of the Venus atmosphere as well as some experiments involving Lyot coronographs are also noteworthy. A Venus transit was finally observed on 8 June 2004 with a new CCD camera, providing a significant contribution to the model of the Venus mesosphere. This opened the field for new observations in 2012.

  10. Lomonosov's Discovery of Venus Atmosphere in 1761: English Translation of Original Publication with Commentaries

    CERN Document Server

    Shiltsev, Vladimir

    2012-01-01

    Key figure of Russian Enlightenment, polymath Mikhail Vasilievich Lomonosov (1711-1765) had discovered atmosphere of Venus during its transit over the Sun's disc in 1761. This paper contains the first full English translation of his report (originally published in Russian in July of 1761 and in German in August of the same year), commentaries and extensive bibliography.

  11. Analysis of blackdrop effect in the transit of Venus on June 6, 2012

    Science.gov (United States)

    Admiranto, A. Gunawan; Mumpuni, E. Sungging; Muhamad, Johan; Suryana, Nana

    2014-03-01

    Transit Venus was observed in LAPAN Biak using a portable telescope with a diameter of 103 mm and recorded using ImagingSource CCD video camera. The backdrop effect was observed during the beginning of transit. This work tries to analyze this backdrop effect observed during this expedition.

  12. Lidar Measurements of Wind and Cloud Around Venus from an Orbiting or Floating/Flying Platform

    Science.gov (United States)

    Singh, U. N.; Limaye, S.; Emmitt, G.; Refaat, T. F.; Kavaya, M. J.; Yu, J.; Petros, M.

    2015-04-01

    Given the presence of clouds and haze in the upper portion of the Venus atmosphere, it is reasonable to consider a Doppler Wind Lidar (DWL) for making remote measurements of the 3D winds within the tops of clouds and the overlying haze layer.

  13. A Wind-powered Rover for a Low-Cost Venus Mission

    Science.gov (United States)

    Benigno, Gina; Hoza, Kathleen; Motiwala, Samira; Landis, Geoffrey A.; Colozza, Anthony J.

    2013-01-01

    Venus, with a surface temperature of 450 C and an atmospheric pressure 90 times higher than that of the Earth, is a difficult target for exploration. However, high-temperature electronics and power systems now being developed make it possible that future missions may be able to operate in the Venus environment. Powering such a rover within the scope of a Discovery class mission will be difficult, but harnessing Venus' surface winds provides a possible way to keep a powered rover small and light. This project scopes out the feasibility of a wind-powered rover for Venus surface missions. Two rover concepts, a land-sailing rover and a wind-turbine-powered rover, were considered. The turbine-powered rover design is selected as being a low-risk and low-cost strategy. Turbine detailed analysis and design shows that the turbine can meet mission requirements across the desired range of wind speeds by utilizing three constant voltage generators at fixed gear ratios.

  14. A direct digital control of the temperature for the VENUS vertex chamber at TRISTAN

    International Nuclear Information System (INIS)

    A trial to introduce a DDC (direct digital control) system has been carried out in order to stabilize the temperature of the VENUS vertex chamber so as to obtain a spatial resolution of better than 50 ?m. The temperature is controlled to within 0.1 C in the gas near to the chamber endplates. ((orig.))

  15. Natural 10 ?m band CO2 laser in the atmospheres of Mars and Venus

    International Nuclear Information System (INIS)

    It is shown that in the daytime atmosphere of Mars a natural laser exists permanently, whereas in the daytime atmosphere of Venus it appears to arise only when internal gravity waves propagate through the atmosphere. The volume laser amplification coefficient and the amplification for a single passage are estimated

  16. An Overview of the 13:8 Mean Motion Resonance between Venus and Earth

    CERN Document Server

    Bazsó, Ákos; Dvorak, Rudolf; Pilat-Lohinger, Elke; Lhotka, Christoph

    2009-01-01

    It is known since the seminal study of Laskar (1989) that the inner planetary system is chaotic with respect to its orbits and even escapes are not impossible, although in time scales of billions of years. The aim of this investigation is to locate the orbits of Venus and Earth in phase space, respectively to see how close their orbits are to chaotic motion which would lead to unstable orbits for the inner planets on much shorter time scales. Therefore we did numerical experiments in different dynamical models with different initial conditions -- on one hand the couple Venus-Earth was set close to different mean motion resonances (MMR), and on the other hand Venus' orbital eccentricity (or inclination) was set to values as large as e = 0.36 (i = 40deg). The couple Venus-Earth is almost exactly in the 13:8 mean motion resonance. The stronger acting 8:5 MMR inside, and the 5:3 MMR outside the 13:8 resonance are within a small shift in the Earth's semimajor axis (only 1.5 percent). Especially Mercury is strongly...

  17. Venus-2 PWR engineering mock-up: core qualification and fast neutron field characterization

    International Nuclear Information System (INIS)

    VENUS-2 is the second stage of the VENUS PWR engineering Mock-up experiment which is part of the Belgian PWR-Pressure Vessel Surveillance Programme, sponsored by the Belgian utilities. Through a cooperation agreement it contributes also, as one of the benchmark fields, to the international LWR-Pressure Vessel-Surveillance Dosimetry Improvement Program supported by the U.S. Nuclear Regulatory Commission. The VENUS-2 Pressure Vessel Mock-up simulates a low-leakage core with the reflector geometry and the core boundary shape of a generic 3-loop power plant. The low leakage configuration is achieved by replacing the eight outer rows of the stainless steel cladded, 4 w/o U-235 enriched, UO2 fuel pins by mixed-oxide fuel pins having the same diameter and the same cladding but containing 2.7 w/o Pu and 2 w/o U-235 enriched fuel. The comparison of the experimental and the theoretical pin-to-pin power distributions is given in this paper as well as the comparison of computed and measured ex-core fast neutron responses of several threshold detectors. The paper gives also some information on the VENUS-3 programme which is designed to benchmark the PLSA (Partial Length Shielded Assembly) concept. This concept aimed to lower exposure to critical vessel sections, especially at the horizontal weld level

  18. Vega balloon experiment: small-scale turbulence in the middle cloud layer of Venus

    International Nuclear Information System (INIS)

    From measurements of variations of Doppler velocity of Vega balloons strong turbulence was found in a cloud layer on both dayside and nightside Venus cloud layer. The amplitude of Wind velocity variations with time scales of 30-100 s is up to 2 m/s

  19. Effects of Planetary Thermal Structure on the Ascent and Cooling of Magma on Venus

    Science.gov (United States)

    Sakimoto, Susan E. H.; Zuber, Maria T.

    1995-01-01

    Magellan radar images of the surface of Venus show a spatially broad distribution of volcanic features. Models of magmatic ascent processes to planetary surfaces indicate that the thermal structure of the interior significantly influences the rate of magmatic cooling and thus the amount of magma that can be transported to the surface before solidification. In order to understand which aspects of planetary thermal structure have the greatest influence on the cooling of buoyantly ascending magma, we have constructed magma cooling profiles for a plutonic ascent mechanism, and evaluated the profiles for variations in the surface and mantle temperature, surface temperature gradient, and thermal gradient curvature. Results show that, for a wide variety of thermal conditions, smaller and slower magma bodies are capable of reaching the surface on Venus compared to Earth, primarily due to the higher surface temperature of Venus. Little to no effect on the cooling and transport of magma are found to result from elevated mantle temperatures, elevation-dependent surface temperature variations, or details of the thermal gradient curvature. The enhanced tendency of magma to reach the surface on Venus may provide at least a partial explanation for the extensive spatial distribution of observed volcanism on the surface.

  20. Effect of Interplanetary Matter on the Spin Evolutions of Venus and Mercury

    Directory of Open Access Journals (Sweden)

    Chuan Li

    2011-03-01

    Full Text Available Differs from other planets in the Solar System, the Venus has a retrograde and long-period rotation. To ex-plain the special spin of the Venus, mechanisms such as core mantle friction inside planet[1], atmospheric tide[2-7], or twain effects together[8-11], and impact with a giant object[12,13] have been suggested. These mecha-nisms, however, need specific initial conditions with a remote probability [3,5]. The slow spin of Mercury cannot be explained very well. One viewpoint is that the unusual spins of Venus and Mercury might be naturally evolved from similar initial states by interaction with interplanetary matter during long-time evolu-tion. Based on the theory of planet formation and the orderliness of planetary distance, we discuss the possi-bility that the radial density distribution of interplanetary matter is undulated, and the wave function satisfies the formal Schrödinger equation. We calculate the evolution of planet spins under the effect of interplanetary matter during planets revolution and rotation. The results show that planets can naturally evolve to the cur-rent state (particularly the negative spin of the Venus given the similar initial quick and positive spins.

  1. Kinetics of thermochemical gas-solid reactions important in the Venus sulfur cycle

    Science.gov (United States)

    Fegley, Bruce, Jr.

    1988-01-01

    The thermochemical net reaction CaCO3 + SO2 yields CaSO4 + CO is predicted to be an important sink for incorporation of SO2 into the Venus crust. The reaction rate law was established to understand the dependence of rate on experimental variables such as temperature and partial pressure of SO2, CO2, and O2. The experimental approach was a variant of the thermogravimetric method often employed to study the kinetics of thermochemical gas-solid reactions. Clear calcite crystals were heated at constant temperature in SO2-bearing gas streams for varying time periods. Reaction rate was determined by three independent methods. A weighted linear least squares fit to all rate data yielded a rate equation. Based on the Venera 13, 14 and Vega 2 observations of CaO content of the Venus atmosphere, SO2 at the calculated rate would be removed from the Venus atmosphere in about 1,900,00 years. The most plausible endogenic source of the sulfur needed to replenish atmospheric SO2 is volcanism. The annual amount of erupted material needed for the replenishment depends on sulfur content; three ratios are used to calculate rates ranging from 0.4 to 11 cu km/year. This geochemically derived volcanism rate can be used to test if geophysically derived rates are correct. The work also suggests that Venus is less volcanically active than the Earth.

  2. Complex Permittivity Model of Venus Atmosphere and Implications for Design of Imaging Altimeter and INSAR Orbiters

    Science.gov (United States)

    Duan, X.; Moghaddam, M.; Smrekar, S.; Wenkert, D.; Jordan, R.

    2008-12-01

    To design altimeter and interferometric SAR (InSAR) systems for measuring Venus' topography, the effects of Venus' atmosphere on the signals need to be investigated. These radar systems are envisioned to operate at X-band, and therefore, a model of Venus atmosphere permittivity profile at X-band is required and has been developed in this work. The effect of signal propagation through this atmosphere and its implication in designing the altimeter and the InSAR instruments are also investigated. The model was constructed for the complex dielectric constant of the atmosphere. Using relations between permittivity and polarization of polar material, the real part of the atmosphere dielectric constant was obtained by calculating the total polarization of the mixture of known atmospheric components including CO2, N2, H2O, SO2, H2SO4, CO, and OCS. The contribution of each atmospheric component to the mixture polarization was calculated based on given temperatures and component densities in the mixture. For each atmospheric component, the polarization was modeled as a function of frequency, temperature, and pressure based on available information in literature. Imaginary part of the atmospheric dielectric constant was calculated by superposing the measured absorptions of mixture components. The temperature and pressure dependences of absorption of each component were modeled according to measurement data and published information. Hence, based on several datasets inferred or directly measured from previous explorations of Venus, the complex dielectric constant profile has been constructed. The validity of the atmosphere permittivity model has been verified by comparing simulation results with measurement data of Venus atmosphere, e.g., from nadir refractivity and absorption measured by the Magellan mission for a portion of the profile. Using this simulated dielectric constant profile, the X-band electromagnetic wave propagation in Venus atmosphere has been modeled, in particular for phase delay and ground pixel center shift of prospective altimeter and InSAR systems. Sensitivity of those quantities to perturbations in atmospheric profile has been investigated as well. The results indicate that radar signal processing and image formation schemes can tolerate at least up to 10% uncertainty in our knowledge of the atmospheric permittivity profile, therefore holding promise that such systems can be successful in producing accurate surface topography for Venus.

  3. Global circulation, thermal structure, and carbon monoxide distribution in Venus' mesosphere in 1991

    Science.gov (United States)

    Lellouch, Emmanuel; Goldstein, Jeffrey J.; Rosenqvist, Jan; Bougher, Stephen W.; Paubert, Gabriel

    1994-01-01

    Millimeter-wave observations of CO lines have provided a detailed picture of Venus' mesosphere dynamics in 1991 from simultaneous measurements of absolute wind velocities in two layers and of temperature and CO horizontal and vertical profiles at 75-115 km. Venus' circulation at 90-110 km was characterized in 1991 by the superposition of a zonal retrograde flow and a subsolar-to-antisolar flow of approximately equal velocities, increasing from about 40 +/- 15 m/sec at 95 km to 90 +/- 15 m/sec at 105 km altitude. The magnitude of the increase of the SS-AS flow is consistent with Venus thermosphere general circulation models (VTGCM). At 105 km, the data further indicate a cos(latitude) dependence of the zonal flow and marginally suggest the presence of a poleward meridional component of 35 +/- 30 m/sec. No obvious day-to-day variations of the circulation are evident in the data at the 20 m/sec level. Thermal profiles in the low-latitude region appear to be consistent with the Pioneer Venus nightside profile, except above 110 km, where they are somewhat colder. High-latitude warming is still found, but mid-latitudes appear to be colder than the equator. The atmosphere appears to be in cyclostrophic balance up to about 105 km. The horizontal distribution of CO on Venus' nightside is essentially uniform, both in latitude and in local time. This behavior agrees with VTGCM simulations in which the zonal flow velocity is prescribed to match the observations. Comparison with previous wind measurements indicates that the zonal flow experiences dramatic long-term variations. This variability, along with short-term fluctuations of the mesospheric zonal flow (evidenced by the variability in the O2 nightglow emissions), apparently controls the CO and O2 nightglow distributions. Gravity wave activity is a plausible mechanism that can drive these variations.

  4. Nature of the atmospheric dynamics on Venus from power spectrum analysis of Mariner 10 images

    International Nuclear Information System (INIS)

    Mariner 10 Venus images are analyzed into power spectra of the brightness field for planetary zonal wavenumbers n> or =3 and for latitudes from 55 0S--25 0N. These spectra are examined for significant features and latitudinal variation as well as compared with cloud brightness distribution spectra similarly determined for the Earth. The Venus image spectra are found to have a systematic variation as a function of latitude. In the equatorial region the average power spectrum has an approximately -2.7 power law behavior for n or =3. Although a flattening of the equatorial region spectrum for wavenumbers less than 5 is noted, no obvious peaks are superimposed on the general power law behavior of the Venus spectra. This is in contrast to the result for the Earth cloud brightness spectra, which exhibit a noticeable peak near wavenumber 5 or 6 for the midlatitude region.The Venus image spectra are further interpreted under the assumption that the UV cloud features serve as markers of large-scale dynamical processes and thus can reveal the characteristics of the eddy kinetic energy spectrum. Support for this assumption is provided by the results of a comparison of the cloud brightness spectra for the Earth with observed eddy kinetic energy spectra. The characteristics of the Venus spectra at low latitudes suggest that the observed clouds are in a region of higthe observed clouds are in a region of high static stability in which the large-scale turbulence is essentially two-dimensional, and that the important energy sources are at the largest scales (n<5), with the spectrum exhibiting a slope close to the theoretically expected -3 value for an inertial subrange at larger wavenumbers. It is concluded that the less steep slope observed for the mid-latitude spectrum is quite possibly the manifestation of the importance of barotropic eddy disturbances in that region

  5. Global Magellan-image map of Venus at full resolution

    Science.gov (United States)

    Kirk, R. L.; Edwards, K. B.; Morgan, H. F.; Soderblom, L. A.; Stoewe, T. L.

    1993-01-01

    During its first 243-day mapping cycle, the Magellan spacecraft succeeded in imaging 84 percent of the surface of Venus at resolutions on the order of 100 meters; subsequent cycles have increased the total coverage to over 97 percent and provided redundant coverage of much of the planet with differing viewing geometries. Unfortunately, this full-resolution global dataset is in the form of thousands of individual orbit tracks (F-BIDR's) whose length-to-width ratio of nearly 1000:1 makes them minimally useful unless mosaicked. The Magellan project produced full-resolution mosaics (F-MIDR's) only for selected regions on the planet, whereas a global set of mosaics was made only at threefold degraded resolution (C1-MIDR's). Furthermore, although the F-MIDR's, which are approximately equidimensional, are much better suited for scientific interpretation than the F-BIDR's, they are still an unwieldy dataset: over 1500 quadrangles, each showing a region only about 600 km on a side, would be required to cover the entire planet. The USGS has therefore undertaken to produce and distribute a global, full resolution set of mosaics of the Magellan image data in a format that will be efficient for both hardcopy and digital use. The initial motivation was that it would provide an efficient means of verifying the integrity of the F-BIDR's to be archived on computer-compatible tape at the USGS Flagstaff facility. However, the resulting product, known as the FMAP, should also serve as an important resource for future scientific interpretation. It will offer several advantages beyond global coverage at full resolution. The first, alluded to above, is its division of the planet's surface to minimize the number of quadrangles and maximize their area, subject to the limits on the number of pixels imposed by state-of-the-art digital recording media and hardcopy output devices. The second, the use of improved 'cosmetic' processing techniques, will greatly reduce tonal discontinuities between component F-BIDR's in the FMAP compared to the standard Magellan mosaic products. Finally, wherever possible, the FMAP will incorporate data that were unavailable (e.g., because of processing delays) when the standard MIDR products were created, as well as data that were reprocessed to improve their radiometric or geometric quality.

  6. ESA's Planetary Science Archive: Status and Plans

    Science.gov (United States)

    Heather, David; Barthelemy, Maud; Manaud, Nicolas; Martinez, Santa; Szumlas, Marek; Vazquez, Jose Luis; Arviset, Christophe; Osuna, Pedro; PSA Development Team

    2013-04-01

    Scientific and engineering data from ESA's planetary missions are made accessible to the world-wide scientific community via the Planetary Science Archive (PSA). The PSA consists of online services incorporating search, preview, download, notification and delivery basket functionality. The PSA currently holds data from Mars Express, Venus Express, SMART-1, Huygens, Rosetta and Giotto, as well as several ground-based cometary observations. It will be used for archiving on ExoMars, BepiColombo and for the European contributions to Chandrayaan-1. The focus of the PSA activities is on the long-term preservation of data and knowledge from ESA's planetary missions. Scientific users can access the data online using several interfaces: - The Advanced Search Interface allows complex parameter based queries, providing the end user with a facility to complete very specific searches on meta-data and geometrical parameters. - The Map-based Interface is currently operational only for Mars Express HRSC and OMEGA data. This interface allows an end-user to specify a region-of-interest by dragging a box onto a base map of Mars. From this interface, it is possible to directly visualize query results. The Map-based and Advanced interfaces are linked and cross-compatible. If a user defines a region-of-interest in the Map-based interface, the results can be refined by entering more detailed search parameters in the Advanced interface. - The FTP Browser Interface is designed for more experienced users, and allows for direct browsing and access of the data set content through ftp-tree search. Each dataset contains documentation and calibration information in addition to the scientific or engineering data. All PSA data are prepared by the corresponding instrument teams, and are made to comply with the internationally recognized PDS standards. PSA supports the instrument teams in the full archiving process, from the definition of the data products, meta-data and product labels through to validation and ingestion of the products into the archive. To ensure a common archiving approach for all of ESA's planetary missions as well as to provide a similar data quality and standard for end users, a tool has been developed supporting the instrument teams in syntactically validating their datasets before delivering to the PSA. This tool, and the overall archiving process is being streamlined in line with the re-development of the science ground segment for Rosetta. This will be very important for the efficient handling and release of data during Rosetta's encounter with the comet Churyamov-Gerasimenko. A major focus for the PSA in 2013 will be to establish a PSA User Group (PSA-UG) and host a first working meeting. The PSA-UG is comprised of 6-8 members chosen to ensure an appropriate range of expertise in disciplines important for the PSA. They shall be a major driver for the future development of the PSA and its data content, and will be a focus for the interests of the scientific community. PSA personnel are the ESA representatives on the committee of the International Planetary Data Alliance (IPDA), an international collaboration of space agencies with a mission of providing access to scientific data returned from Solar System missions archived at international data centers. Venus Express data are already made available internationally via the 'PDAP' protocol thanks to this collaboration. A key IPDA project for 2013 is the implementation of the emerging PDS4 data standards. The new Standards aim to provide a framework for capturing planetary science data results in international archives based on a homogeneous set of standards that can be extended as needed for international usage. PSA are co-leading this project, using the upcoming BepiColombo mission to develop our first PDS4 data models.

  7. Prelude to the Venus Express mission: a study of the atmosphere using infrared spectro-imaging

    International Nuclear Information System (INIS)

    This thesis deals with the search for and the study of young galactic supernova remnants using the observations performed by IBIS/ISGRI, one of the two main coded-mask instruments onboard the european gamma-ray satellite INTEGRAL. This research is based on i) the study of gamma-ray lines coming from the radioactive decay of 44Ti, a short-lived nucleus (?? 86 y) exclusively produced during the first stages of stellar explosions, and ii) the study of the nonthermal continuum mechanisms which take place inside the young supernova remnants. I separate the manuscript in four main parts. The first one presents an overview of supernovae from an observational and theoretical point of view. The second part describes the INTEGRAL satellite with its instruments, the techniques used for analyzing the data collected by IBIS/ISGRI, and my personal investigations concerning different developments such as: the spectral calibration of the IBIS/ISGRI instrument, the correction of noisy pixels on the camera, the creation of background maps, and the development of an alternative pipeline useful for dealing with a large amount of data. I also present a method for imaging extended sources with a coded-mask instrument such as IBIS/ISGRI, and its first application on the Coma Cluster. The results obtained on historical supernova remnants like Cas A, Tycho, RXJ0852-4622 (Vela Junior) are presented in the third part. The first chapter of the last part is devoted to the study of the detectability of supernovae in the optical domain with a model of the interstellar extinction. The second chapter reports on the search for missing and hidden young supernova remnants in the Milky Way with the IBIS/ISGRI galactic plane survey through the 44Sc gamma-ray lines as well as with a multi-wavelength approach, from the radio domain (VLA) to the new observational window at TeV energies (HESS). I also discuss the constraints on the supernova rate and the 44Ti production in core-collapse supernovae, based on these IBIS/ISGRI observations and the 44Ca solar abundance. (author)

  8. Venus Nomenclature 2001: Introduction of the New Names, Changes to the Earlier Approved Names, and Improvements at the Website

    Science.gov (United States)

    Burba, G. A.; Blue, J.; Campbell, D. B.; Dollfus, A.; Gaddis, L.; Jurgens, R. F.; Marov, M. Ya.; Pettengill, G. H.; Stofan, E. R.

    2002-03-01

    54 new names introduced for features on Venus. Parga Chasmata (term in plural) name is used for the broad zone of canyons. Prominent features within it obtained individual names. Web Gazetteer provides now name search along 9 parameters.

  9. Model of the spectral and high-altitude distributions of the scattered solar radiation fluxes in the Venus atmosphere

    International Nuclear Information System (INIS)

    With the help of the equation of the transition by the method of spherical harmonics calculated are the descending and ascending fluxes, and the radiant heat flow in the Venus atmosphere in the range of 0.3-3 ?m, as well. The calculation results are in an approximate agreement with the data of direct measurements on the ''Venus 9'' and ''Venus 10'' in the range of 0.5-1 ?m. It is found out that the fluxes of solar and heat irradiation near the Venus surface are comparable by the value as it must be at the hotbed effect. 80% of solar energy is absorped in the region of the main cloud layer

  10. Measurement of Trace Gases in the Atmosphere of Venus Project

    National Aeronautics and Space Administration — Southwest Sciences proposes to develop small, lightweight, low power instrumentation for the in situ balloon-borne measurement of several trace gases of importance...

  11. The Use of Euphemistic Expressions by Arab EFL Learners: Evidence from Al Ain University of Science and Technology

    Directory of Open Access Journals (Sweden)

    Abdel Rahman Mitib Altakhaineh

    2015-01-01

    Full Text Available This study measures the extent to which Arab EFL learners are aware of euphemistic expressions related to two areas, namely, courtesy and physical appearance and whether they are able to recognise them in context. The study also attempts to investigate whether the participants' gender and English proficiency level may play a role in their use of euphemism in their day-to-day lives. For the purposes of the study, we developed a multiple-choice test in which the participants were asked to choose the suitable answer out of four choices. The contextualized sentences used in the test were adapted from the Corpus of Contemporary American English (COCA to suit the participants’ English proficiency level. Results revealed that Arab EFL learners had little awareness of euphemistic expressions in English. Also, the participants' English proficiency level had little effect on their use of euphemistic expressions. However, the participants' gender played a significant role in their performance on the test. In particular, the female participants were significantly more aware of euphemistic expressions than the males. The study concluded with some pedagogical implications and recommendations for further research.

  12. Calculation of the neutron source distribution in the VENUS PWR Mockup Experiment

    International Nuclear Information System (INIS)

    The VENUS PWR Mockup Experiment is an important component of the Nuclear Regulatory Commission's program goal of benchmarking reactor pressure vessel (RPV) fluence calculations in order to determine the accuracy to which RPV fluence can be computed. Of particular concern in this experiment is the accuracy of the source calculation near the core-baffle interface, which is the important region for contributing to RPV fluence. Results indicate that the calculated neutron source distribution within the VENUS core agrees with the experimental measured values with an average error of less than 3%, except at the baffle corner, where the error is about 6%. Better agreement with the measured fission distribution was obtained with a detailed space-dependent cross-section weighting procedure for thermal cross sections near the core-baffle interface region. The maximum error introduced into the predicted RPV fluence due to source errors should be on the order of 5%

  13. The German transit of Venus expeditions of 1874 and 1882: organization, methods, stations, results

    Science.gov (United States)

    Duerbeck, Hilmar W.

    2004-06-01

    The first major Government-funded German scientific enterprise was triggered by a smaller one to observe the total solar eclipse of 1868. The photoheliograph built for this occasion was later used for transit of Venus observations, together with three similar instruments. Furthermore, five small Fraunhofer heliometers were used to visually measure the position of Venus on the solar disk. The 1874 expeditions went to Tschifu (China), Kerguelen, Auckland and Mauritius Islands, to Isfahan (Persia) and Luxor (Egypt). The low accuracy achieved from the photographic observations led to the abandonment of such studies in the next transit. The 1882 transit expeditions went to Hartford (Connecticut), Aiken (South Carolina), Bahia Blanca (Argentina), Punta Arenas (Chile) and Royal Sound (South Georgia Island). Meticulous calibrations of the heliometers were carried out before and after the transits, and final results of contact timings, photographic and heliometric observations were only published in 1896.

  14. Sunlight refraction in the mesosphere of Venus during the transit on June 8th, 2004

    CERN Document Server

    Tanga, P; Sicardy, B; Pasachoff, J M; Arnaud, J; Comolli, L; Rondi, A; Rondi, S; Suetterlin, P

    2011-01-01

    Many observers in the past gave detailed descriptions of the telescopic aspect of Venus during its extremely rare transits across the Solar disk. In particular, at the ingress and egress, the portion of the planet's disk outside the Solar photosphere has been repeatedly perceived as outlined by a thin, bright arc ("aureole"). Those historical visual observations allowed inferring the existence of Venus' atmosphere, the bright arc being correctly ascribed to the refraction of light by the outer layers of a dense atmosphere. On June 8th, 2004, fast photometry based on electronic imaging devices allowed the first quantitative analysis of the phenomenon. Several observers used a variety of acquisition systems to image the event -- ranging from amateur-sized to professional telescopes and cameras -- thus collecting for the first time a large amount of quantitative information on this atmospheric phenomenon. In this paper, after reviewing some elements brought by the historical records, we give a detailed report of...

  15. Indian astronomy and the transits of Venus. 1: The early observations

    Science.gov (United States)

    Kapoor, R. C.

    2013-11-01

    This paper, the first of two, is about sightings and astronomical observations of transits of Venus across the disk of the Sun made from the Indian region. The period covered in this first paper is from ancient times up to and including the 1769 transit. The sources of the information presented here range from some classical texts and historiographies to publications and records of institutions, and accounts by individuals. Of particular interest is the 1761 transit, which was observed from atop the Governor's house in Madras by the Reverend William Hirst, who made a significant observation. During ingress he noticed a nebulosity about the planet, which he attributed to the atmosphere of Venus, and this was duly recorded in his paper reporting the transit observation that appeared in the Philosophical Transactions of the Royal Society of London. However, in a recent analysis, Pasachoff and Sheehan (2012) have shown that it was not the Cytherian atmosphere that Hirst and other astronomers observed in 1761.

  16. Analysis of the atmosphere of Venus by mass-spectrometry and gas chromatography

    International Nuclear Information System (INIS)

    A brief description of the methods of mass spectrometry and gas chromatography and the corresponding apparatus used in analysis of the troposphere and cloud layer of Venus in the second stage of its study is given. As a result of the investigation performed using mass spectrometers and gas chromatographs installed on the space probes of the Venera and Pioneer-Venera series, the content of the basic components of the atmosphere of Venus and many peculiarities of the distribution of its minor components were determined. During these experiments, considerable experience was gained in creating and using on-board apparatus having high reliability, low weight and power consumption, capable of automatically performing measurements with rapidly changing parameters of the external medium. The possibilities and limitations of such apparatus were also established

  17. The brightness temperature of Venus and the absolute flux-density scale at 608 MHz.

    Science.gov (United States)

    Muhleman, D. O.; Berge, G. L.; Orton, G. S.

    1973-01-01

    The disk temperature of Venus was measured at 608 MHz near the inferior conjunction of 1972, and a value of 498 plus or minus 33 K was obtained using a nominal CKL flux-density scale. The result is consistent with earlier measurements, but has a much smaller uncertainty. Our theoretical model prediction is larger by a factor of 1.21 plus or minus 0.09. This discrepancy has been noticed previously for frequencies below 1400 MHz, but was generally disregarded because of the large observational uncertainties. No way could be found to change the model to produce agreement without causing a conflict with well-established properties of Venus. Thus it is suggested that the flux-density scale may require an upward revision, at least near this frequency, in excess of what has previously been considered likely.

  18. Installation of VENUS-2 code for the analysis of transition phase of LMR HCDA

    International Nuclear Information System (INIS)

    VENUS-2 is a two-dimensional coupled neutronics-hydrodynamics program that calculate the dynamic behavior of an LMFBR during a prompt-critical disassembly excursion. The code, was developed by the Argonne National Laboratory(ANL) in 1972, was originally written in FORTRAN-4 computer language to run on the CDC7600 or IBM3033 computer systems. A number of modifications were done on the code to make it work in the DIGITAL Fortran system of the MS-Windows. In particular, an effort has been made to revise I/O status system and graphical plotting routines using Excel and Origin 6.0. Test runs with the sample problem show that the modified VENUS-2 code provides the results in general agreement to sample outputs described in the manual

  19. Venus pancake dome formation: Morphologic effects of a cooling-induced variable viscosity during emplacement

    Science.gov (United States)

    Sakimoto, S. E. H.; Zuber, M. T.

    1993-01-01

    The distinctive steep-sided 'pancake' domes discovered in the Magellan images of Venus have morphologies that suggest formation by a single continuous emplacement of a high viscosity magma. A resemblance of the venusian domes to much smaller terrestrial rhyolite and dacite volcanic domes has prompted some authors to suggest that the domes on Venus also have high silica compositions and thus, high viscosities. However, viscosity is a function of crystallinity as well as silica content in a magma, and thus increases as a result of magmatic cooling. To investigate the effect of a cooling-induced viscosity increase on dome morphology, we have modeled the domes as radial viscous gravity currents that cool during emplacement. Various aspects of the investigation are discussed.

  20. O2/1 Delta/ emission in the day and night airglow of Venus

    Science.gov (United States)

    Connes, P.; Noxon, J. F.; Traub, W. A.; Carleton, N. P.

    1979-01-01

    An intense airglow from O2(1 Delta) at 1.27 microns on both the light and the dark sides of Venus has been detected by using a ground-based high-resolution Fourier-transform spectrometer. Both dayglow and nightglow are roughly 1,000 times brighter than the visible O2 nightglow found by Veneras 9 and 10 in 1975. The column emission rate of O2(1 Delta) from Venus is close to the rate at which fresh O atoms are produced from photolysis of CO2 on the day side. Formation of O2(1 Delta) is thus a major step in the removal of O atoms from the atmosphere, and dynamical processes must carry these atoms to the night side fast enough to yield a maximum density near 90 km, which is almost constant over the planet.

  1. O2(1?) emission in the day and night airglow of Venus

    International Nuclear Information System (INIS)

    We have detected an intense airglow from O2(1?) at 1.27 ?m on both the light and the dark sides of Venus, using a ground-based, high-resolution Fourier transform spectrometer. Both dayglow and nightglow are roughly 1,000 times brighter than the visible O2 nightglow found by Veneras 9 and 10 in 1975. The column emission rate of O2(1?) from Venus is close to the rate at which fresh O atoms are produced from photolysis of CO2 on the day side. Formation of O2(1?) is thus a major step in the removal of O atoms from the atmosphere, and dynamical processes must carry these atoms to the night side fast enough to yield a maximum density near 90 km, which is almost constant over the planet

  2. Progress Towards the Development of a Long-Lived Venus Lander Duplex System

    Science.gov (United States)

    Dyson, Rodger, W.; Bruder, Geoffrey A.

    2011-01-01

    NASA has begun the development of a combined Stirling cycle power and cooling system (duplex) to enable the long-lived surface exploration of Venus and other harsh environments in the solar system. The duplex system will operate from the heat provided by decaying radioisotope plutonium-238 or its substitute. Since the surface of Venus has a thick, hot, and corrosive atmosphere, it is a challenging proposition to maintain sensitive lander electronics under survivable conditions. This development effort requires the integration of: a radioisotope or fission heat source; heat pipes; high-temperature, corrosion-resistant material; multistage cooling; a novel free-displacer Stirling convertor for the lander; and a minimal vibration thermoacoustic Stirling convertor for the seismometer. The first year effort includes conceptual system design and control studies, materials development, and prototype hardware testing. A summary of these findings and test results is presented in this report.

  3. High-gain backup antenna design for Pioneer Venus Orbiter spacecraft

    Science.gov (United States)

    Glaser, J. I.

    1986-01-01

    The development and performance is described of a high-gain antenna designed to serve on the Pioneer Venus Orbiter spacecraft as a backup to the principal high-gain antenna unit in the unlikely event the mechanically despun antenna mechanism malfunctioned. The final design, a center-fed standing wave array of six sleeve dipoles enclosed in a fiber glass radome, performed successfully, as did all the antennas, on the Pioneer Orbiter spacecraft which was launched on May 20, 1978, as part of the Pioneer Venus mission. Photographs of experimental models giving details of design and construction are included, as well as graphs showing measured pattern and impedance matching characteristics of the subject antenna.

  4. Installation of VENUS-2 code for the analysis of transition phase of LMR HCDA

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Yong Joon; Suk, S. D.; Hahn, D. H

    2000-06-01

    VENUS-2 is a two-dimensional coupled neutronics-hydrodynamics program that calculate the dynamic behavior of an LMFBR during a prompt-critical disassembly excursion. The code, was developed by the Argonne National Laboratory(ANL) in 1972, was originally written in FORTRAN-4 computer language to run on the CDC7600 or IBM3033 computer systems. A number of modifications were done on the code to make it work in the DIGITAL Fortran system of the MS-Windows. In particular, an effort has been made to revise I/O status system and graphical plotting routines using Excel and Origin 6.0. Test runs with the sample problem show that the modified VENUS-2 code provides the results in general agreement to sample outputs described in the manual.

  5. Low energy trajectories to Mars via gravity assist from Venus to earth

    Science.gov (United States)

    Williams, S. N.; Longuski, J. M.

    1991-01-01

    The analytical determination of launch dates and proposed trajectories is reviewed with respect to the search for a low-energy trajectory to Mars with gravitational assist from Venus for the years 1995-2024. Both Ballistic and Venus-Earth gravity assist (VEGA) trajectories are calculated with an automated design tool by the authors (1990). The trajectories are modeled as conic sections from one gravitating body to the next, and gravity assist is considered to act impulsively. VEGA trajectories to Mars require similar launch energies for 6 years listed and have moderate arrival C3s, with the lowest C3 requirement in 2015. The flight time and arrival energies of the trajectories are found to be larger than those of ballistic trajectories, but the low-energy launch window makes them desirable for unmanned Mars missions, in particular.

  6. Solar-cycle changes in the thermal structure of the Venus dayside ionosphere

    Science.gov (United States)

    Kliore, Arvydas J.; Mullen, Luke F.

    1990-01-01

    Vertical profiles of electron density in the dayside ionosphere of Venus, measured by the Pioneer Venus radio occultation experiment, averaged in bins of solar zenith angle, have been used to examine the behavior of the ionospheric thermal structure with the solar cycle. It was found that the plasma scale height decreased by a factor ranging from 1.5 at 190 km to about 3.0 at 300 km altitude as the solar input went from maximum to minimum. If the assumption of diffusive equilibrium holds above h = 180 km for both the times of solar maximum and solar minimum, similar decreases in the plasma temperature and, consequently, the electron and ion temperatures, are inferred. If, however, diffusive equilibrium conditions do not apply at the time of solar activity minimum, perhaps due to the effects of enhanced solar wind interaction, no information on the plasma temperatures is contained in the data on the topside electron density structure.

  7. Electron cooling by carbon monoxide in the atmospheres of Mars and Venus

    Directory of Open Access Journals (Sweden)

    Campbell Laurence

    2008-02-01

    Full Text Available Abstract Electron cooling, in which free electrons lose energy to vibrational excitation of gases, has been identified as a significant process in the atmospheres of Mars and Venus for electron impact on CO2. This process does not appear to have been evaluated for CO, although the density of CO exceeds that of CO2 in the upper atmospheres of these planets. In this paper electron cooling rates for CO are calculated and compared with existing rates for CO2. It is found that electron cooling by CO becomes more significant than by CO2 above altitudes of about 300 km on Mars and about 168 km on Venus. The sensitivity of the calculated cooling rates to different measurements of the integral cross sections for electron-impact vibrational excitation of CO is also investigated. PACS Codes: 34.80.Gs, 96.12.Jt

  8. Harry Potter and the Upcoming Venus-Jupiter Conjunction: A Unique Outreach Opportunity

    Science.gov (United States)

    Larsen, K.

    2008-09-01

    As we prepare for the International Year of Astronomy 2009 (IYA2009), we should be on the lookout for celestial events which we can use not only to popularise the IYA2009 and practise our outreach skills, but which also have natural connections to popular culture. The Venus-Jupiter conjunction this autumn is such an opportunity, given several direct connections to the use of astronomy in J. K. Rowling's famous Harry Potter universe.

  9. Social Media Planning for the June 5, 2012 transit of Venus

    Science.gov (United States)

    Young, C.; Wawro, M.; Cline, T. D.; Schenk, L. C.; Durscher, R.

    2012-12-01

    On June 5, 2012 at sunset on the East Coast of North America and earlier for other parts of the U.S., the planet Venus made its final trek across the face of the sun as seen from Earth until the year 2117! The NASA Goddard Sun-Earth Day and Solar Dynamics Observatory EPO teams developed a social media strategy to support NASAs Transit of Venus event and webcast from Mauna Kea, Hawaii, on June 5, 2012. Our goal was to connect our contacts with a growing and vibrant social media community during all phases of this celestial event! We also wanted to help spread the word about the Transit of Venus by sharing content, facts, videos, images and links about the transit with our networks. Although social media events occurred throughout the world, our strategy was to provide an additional focus on NASA related events in key locations including those events happening in Hawaii, Alaska, and NASA Ames thereby amplifying our outreach efforts while ensuring that a strong connection existed across geographical and cultural borders. We also wanted to provide the public with information that would help them understand the importance of staying connected via social media even if viewing the transit was possible from their own locations. The social media strategy and the transit of Venus events were a great success and well as a learning experience for future social media events. We present the results of our plan as well as ways to improve and expand for future events. In addition, we present our social media template developed for the transit and now used by other heliophysics EPO teams.

  10. Hemispheric asymmetries of plasma environments of Venus and Mars in a hybrid model

    Science.gov (United States)

    Jarvinen, Riku; Dyadechkin, Sergey; Kallio, Esa

    2013-04-01

    We study the asymmetries of planetary plasma environments at Venus and Mars in the global HYB-Venus and HYB-Mars hybrid simulations. The hemispheric asymmetry in the direction of the solar wind electric field (the Esw asymmetry) and the asymmetry between the magnetic dawn and dusk hemispheres, defined by the plane perpendicular to the Esw vector (the dawn-dusk asymmetry), have both been observed by in situ spacecraft particle and magnetic measurements. In ideal, single-fluid MHD simulations of planetary-solar wind interactions no Esw asymmetry rises provided that the inner boundary conditions and planetary ion sources are axially symmetric (i.e. depend only on the solar-zenith angle). But, the Hall JxB term of the electric field can break the Esw symmetry in ideal MHD. Further, kinetic effects of planetary ions and solar wind protons, such as finite gyro radii, can depend on whether the solar wind electric field is pointing towards the planet (-Esw hemisphere) or away from the planet (+Esw hemisphere). Thus, ion kinetics can contribute to the Esw asymmetry. In literature the origin of the Esw asymmetry of the magnetic field is traditionally attributed to planetary ion pick-up by the solar wind flow. Further, the flow-aligned component of the interplanetary magnetic field results in large scale dawn-dusk asymmetry of an induced magnetosphere. In this presentation we study the hemispheric asymmetries in a global hybrid simulation for Venus and Mars. We consider why the asymmetries arise in a hybrid model and we also discuss the importance of the asymmetries for particle and magnetic observations at Venus and Mars.

  11. Analysis of the VENUS-1 Benchmark Using Tort and BUGLE-96

    Science.gov (United States)

    Fero, Arnold H.; Hayes, Eugene T.

    2003-06-01

    This paper describes the results of analyzing the VENUS-1 Benchmark in X, Y, Z and R, ?, Z geometry using TORT, the BUGLE-96 transport cross-section library, and the SNLRML neutron dosimetry cross-section library. The three-dimensional TORT calculations show significant improvement over prior two-dimensional calculations in comparison to measurements for both neutron dosimetry and gamma ray dose rates.

  12. Remote-Raman spectroscopic study of minerals under supercritical CO2 relevant to Venus exploration.

    Science.gov (United States)

    Sharma, Shiv K; Misra, Anupam K; Clegg, Samuel M; Barefield, James E; Wiens, Roger C; Acosta, Tayro E; Bates, David E

    2011-10-01

    The authors have utilized a recently developed compact Raman spectrometer equipped with an 85 mm focal length (f/1.8) Nikon camera lens and a custom mini-ICCD detector at the University of Hawaii for measuring remote Raman spectra of minerals under supercritical CO(2) (Venus chamber, ?102 atm pressure and 423 K) excited with a pulsed 532 nm laser beam of 6 mJ/pulse and 10 Hz. These experiments demonstrate that by focusing a frequency-doubled 532 nm Nd:YAG pulsed laser beam with a 10× beam expander to a 1mm spot on minerals located at 2m inside a Venus chamber, it is possible to measure the remote Raman spectra of anhydrous sulfates, carbonates, and silicate minerals relevant to Venus exploration during daytime or nighttime with 10s integration time. The remote Raman spectra of gypsum, anhydrite, barite, dolomite and siderite contain fingerprint Raman lines along with the Fermi resonance doublet of CO(2). Raman spectra of gypsum revealed dehydration of the mineral with time under supercritical CO(2) at 423 K. Fingerprint Raman lines of olivine, diopside, wollastonite and ?-quartz can easily be identified in the spectra of these respective minerals under supercritical CO(2). The results of the present study show that time-resolved remote Raman spectroscopy with a compact Raman spectrometer of moderate resolution equipped with a gated intensified CCD detector and low power laser source could be a potential tool for exploring Venus surface mineralogy both during daytime and nighttime from a lander. PMID:21333587

  13. The geologic mapping of Venus using C-1 format: Sheets 75N254, 60N263

    Science.gov (United States)

    Shalimov, I. V.

    1992-01-01

    The results of geologic mapping of Venus, produced on the base of Magellan images, are presented. We submit two C-1 format geologic maps with the appropriate legend. The mapping territory was taken from Venera 15 and 16 missions and geologic maps were composed. Magellan images allow us to divide some types of the plains units to determine the lava flow direction and to map with better accuracy.

  14. Bimodal Distribution of Sulfuric Acid Aerosols in the Upper Haze of Venus

    OpenAIRE

    Gao, Peter; Zhang, Xi; Crisp, David; Bardeen, Charles G.; Yung, Yuk L.

    2013-01-01

    The upper haze (UH) of Venus is variable on the order of days and it is populated by two particle modes. We use a 1D microphysics and vertical transport model based on the Community Aerosol and Radiation Model for Atmospheres to evaluate whether interaction of upwelled cloud particles and sulfuric acid particles nucleated in situ on meteoric dust are able to generate the two size modes and whether their observed variability are due to cloud top vertical transient winds. Nucl...

  15. Plasma near Venus from the Venera 9 and 10 wide-angle analyzer data

    International Nuclear Information System (INIS)

    Preliminary results of ion and electron plasma measurements near Venus are presented and discussed. The data were obtained with wide-angle plasma analyzers carried on the Venera 9 and 10 spacecraft. On the basis of 33 bow shock crossings the position of the shock is quite stable and agrees well with theoretical predictions of Spreiter et al. with H/r0=0.01 and a stagnation point altitude of approx.500 km. This observation lends strong support to the assumption that the solar wind interacts with the upper ionosphere of Venus and not with a planetary magnetic field. These spacecraft are the first to explore the optical umbra of Venus. Close to the planet a stable population of electrons and an ill-defined population of positive ions were found; this region is called the corpuscular umbra. The corpuscular umbra and the transition region are separated by a zone which contains both positive ions and electrons and is characterized by a flow velocity reduced in comparison with that of the transition region. This zone is called the corpuscular penumbra. The distribution of plasma density behind the bow shock (including the optical umbra of the planet) is given, and the existence of a Venusian plasma magnetic til is revealed

  16. Detection of the Rossiter-McLaughlin effect in the 2012 June 6 Venus transit

    Science.gov (United States)

    Molaro, P.; Monaco, L.; Barbieri, M.; Zaggia, S.

    2013-02-01

    Eclipsing bodies on stars produce radial velocity variations on the photospheric stellar lines known as the Rossiter-McLaughlin (RM) effect. The body occults a small area of the stellar disc and, due to the rotation of the star, the stellar line profiles are distorted according to the projected location of the body on to the stellar disc. The effect originally observed in eclipsing binaries was also shown to be produced by extrasolar planets transits. Here we report the detection of the RM effect in the Sun due to the Venus transit of 2012 June 6. We used the integrated sunlight as reflected by the Moon at night time to record part of the transit by means of the high-precision HARPS spectrograph at the 3.6-m La Silla European Southern Observatory (ESO) telescope. The observations show that the partial Venus eclipse of the solar disc in correspondence of the passage in front of the receding hemisphere produced a modulation in the radial velocity with a negative amplitude of ?-1 m s-1, in agreement with the theoretical model. The radial velocity change is comparable to the solar jitter and more than a factor of 2 smaller than previously detected in extrasolar hot Neptunes. This detection, facilitated by an amplification factor of 3.5 of the Venus radius due to proximity, anticipates the study of transits of Earth-size bodies in solar-type stars by means of a high-resolution spectrograph attached to a 40-m class telescope.

  17. Using the transit of Venus to probe the upper planetary atmosphere

    CERN Document Server

    Reale, Fabio; Micela, Giuseppina; Maggio, Antonio; Widemann, Thomas; Piccioni, Giuseppe

    2015-01-01

    The atmosphere of a transiting planet shields the stellar radiation providing us with a powerful method to estimate its size and density. In particular, because of their high ionization energy, atoms with high atomic number (Z) absorb short-wavelength radiation in the upper atmosphere, undetectable with observations in visible light. One implication is that the planet should appear larger during a primary transit observed in high energy bands than in the optical band. The last Venus transit in 2012 offered a unique opportunity to study this effect. The transit has been monitored by solar space observations from Hinode and Solar Dynamics Observatory (SDO). We measure the radius of Venus during the transit in three different bands with subpixel accuracy: optical (4500A), UV (1600A, 1700A), Extreme UltraViolet (EUV, 171-335A) and soft X-rays (about 10A). We find that, while the Venus optical radius is about 80 km larger than the solid body radius (the expected opacity mainly due to clouds and haze), the radius i...

  18. Touchdown on Venus: Analytic wind models and a heuristic approach to estimating landing dispersions

    Science.gov (United States)

    Lorenz, Ralph D.

    2015-04-01

    The 'landing ellipse' or region of uncertainty within which an unguided probe to Venus may be expected to land is calculated. The region can be usefully seen as the convolution of three different factors: an initial circular delivery uncertainty which is smeared at a grazing entry angle onto the planetary sphere, an along-track uncertainty due to atmospheric density and vehicle aerodynamic variations during hypersonic entry, and a descent dispersion due to uncertain and/or variable zonal and meridional winds. This decomposition allows the various contributions to be instructively exposed and conveniently traded-off, without conducting explicit entry and descent dynamics simulations. It is seen that for descent durations and delivery errors typical of past Venus missions, the zonal wind contribution (determined with an analytic fit to Pioneer Venus tracking data) generally dominates, causing a ~200 km E-W (99%) dispersion, with meridional dispersions being about 4 times smaller. However, when entry angles become shallower than about 8°, the along-track dispersions may dominate, with the resulting ellipse becoming longer or wider depending on the entry azimuth. The analytic wind descriptions presented here may be applied to scientific problems, such as the dispersal of volcanic plumes or impact ejecta.

  19. Sprites and lightning in Venus: constraints for observations by the Planet-C mission

    Science.gov (United States)

    Takahashi, Y.; Yair, Y.; Goto, Y.; Sentman, D.; Yoshida, J.; Sato, M.; Hoshino, N.

    2007-12-01

    Lightning activity in Venus has been mystery for long period, although many studies based on observations both by spacecrafts and by ground-based telescope have been carried out. This situation may be attributed to the ambiguity of these evidential measurements. In order to conclude this controversial subject, we are developing a new type of lightning detector, LAC (Lightning and Airglow Camera), which will be onboard Planet-C (Venus Climate Orbiter: VCO). PLanet-C will be launched in 2010 by JAXA. To distinguish optical lightning flash from other pulsing noises, high-speed sampling at 50kHz for each pixel, that enables us to investigate the time variation of each lightning flash phenomenon, is adopted. On the other hand, spatial resolution is not first priority. For this purpose we developed new type of APD (avalanche photo diode) array with a format of 8 x 8. Narrow band interference filter at wavelength of 777.4 nm (OI), which is expected lightning color based on laboratory discharge experiment, is chosen for lightning measurement. LAC detects lightning flash with an optical intensity of average of Earth's lightning or less at a distance of 3 Rv. We also present results of theoretical calculations of the expected occurrance heights and emissions of sprites above thunderstorms in the CO2 atmosphere of Venus and the Hydrogen-Helium atmospheres of Jupiter and Saturn. General detection methodology of sprites/lightning in planetary atmospheres by orbiting spacecraft will be discussed.

  20. Lightning Detection by LAC Onboard the Japanese Venus Climate Orbiter, Planet-C

    Science.gov (United States)

    Takahashi, Y.; Yoshida, J.; Yair, Y.; Imamura, T.; Nakamura, M.

    2008-06-01

    Lightning activity in Venus has been a mystery for a long period, although many studies based on observations both by spacecraft and by ground-based telescope have been carried out. This situation may be attributed to the ambiguity of these evidential measurements. In order to conclude this controversial subject, we are developing a new type of lightning detector, LAC (Lightning and Airglow Camera), which will be onboard Planet-C (Venus Climate Orbiter: VCO). Planet-C will be launched in 2010 by JAXA. To distinguish an optical lightning flash from other pulsing noises, high-speed sampling at 50 kHz for each pixel, that enables us to investigate the time variation of each lightning flash phenomenon, is adopted. On the other hand, spatial resolution is not the first priority. For this purpose we developed a new type of APD (avalanche photo diode) array with a format of 8×8. A narrow band interference filter at wavelength of 777.4 nm (OI), which is the expected lightning color based on laboratory discharge experiment, is chosen for lightning measurement. LAC detects lightning flash with an optical intensity of average of Earth’s lightning or less at a distance of 3 Rv. In this paper, firstly we describe the background of the Venus lightning study to locate our spacecraft project, and then introduce the mission details.

  1. A new, fast and flexible radiative transfer method for Venus general circulation models

    Science.gov (United States)

    Mendonça, J. M.; Read, P. L.; Wilson, C. F.; Lee, C.

    2015-01-01

    We present a new radiation scheme for the Oxford Planetary Unified Model System for Venus, suitable for the solar and thermal bands. This new and fast radiative parameterization uses a different approach in the two main radiative wavelength bands: solar radiation (0.1 - 5.5 ?m) and thermal radiation (1.7 - 260 ?m). The solar radiation calculation is based on the ?-Eddington approximation (two-stream-type) with an adding layer method. For the thermal radiation case, a code based on an absorptivity/emissivity formulation is used. The new radiative transfer formulation implemented is intended to be computationally light, to allow its incorporation in 3D global circulation models, but still allowing for the calculation of the effect of atmospheric conditions on radiative fluxes. This will allow us to investigate the dynamical-radiative-microphysical feedbacks. The model flexibility can be also used to explore the uncertainties in the Venus atmosphere such as the optical properties in the deep atmosphere or cloud amount. The results of radiative cooling and heating rates and the global-mean radiative-convective equilibrium temperature profiles for different atmospheric conditions are presented and discussed. This new scheme works in an atmospheric column and can be easily implemented in 3D Venus global circulation models.

  2. Comparison of Pioneer Venus and Venera bow shock observations: Evidence for a solar cycle variation

    International Nuclear Information System (INIS)

    Observations by the Venera 9 and 10 orbiters in 1975--1976 have been used in previous studies to determmine the mean location and shape of the Cytherean bow shock. In addition it has also been reported that the shock is found to be more distant from the planet above regions of the ionosheath where draped IMF field lines are oriented perpendicular to the flow as opposed to parallel. An examination of the dependence of shock altitude in the terminator plane on upstream IMF direction using 86 Pioneer Venus orbiter bow shock crossings in 1978--79 sets an upper limmit on this asymmetry of 12% or approximately half that derived earlier from the Venera data. More significantly, the mean distance to the bow shock observed by Pioneer Venus Orbiter is 35% greater than was the case in 1975--76 near solar minimum. As the growth in effective obstacle radius is an order of magnitude larger than can be accounted for in terms of varying ionopause altitude due to all causes, these results strongly suggest that Venus can absorb significantly more of the incident solar wind plasma diring solar minimum when EUV flux is low than during the current epoch in which maximum is approaching

  3. A two-dimensional model of the ionosphere of Venus - Thermal structure

    Science.gov (United States)

    Singhal, R. P.; Whitten, R. C.

    1986-01-01

    A spectral model is defined for the electron and ion temperature profiles of the Venus ionosphere. The model is developed using data collected with the retarding potential analyzer on the Pioneer Venus Orbiter, and account is taken of horizontal bulk heat transport and a heat flux saturation effect. Coupled ion and energy equations and thermal flux equations are defined. A finite difference algorithm is applied to solve the equations, assuming an ionopause at 740 km altitude. Horizontal plasma flow velocities of 2.5-5.6 km/sec are found necessary in order to account for a dip in the ion temperature around the terminator and a sharp rise at about 140 deg, i.e., far past the solar zenith angle. An external heat source of 0.0001-0.0002 ergs/sq cm per sec, uniformly distributed around Venus, is required to maintain observed dayside and nightside ion temperatures. The heat source may be the solar wind, which would be sufficient without shocks.

  4. Transit Observations as Means to Re-establish the Reputation of the Russian Academy of Sciences

    Science.gov (United States)

    Bucher, Gudrun

    2013-05-01

    This paper explores how Catherine II used the worldwide attention given to observations of the transit of Venus to bring back the Russian Academy of Sciences into international recognition. Starting from the planned observations of the transit of Venus at various locations of the Russian Empire, the expeditions became more complex because naturalists were added to the astronomical expeditions. As the naturalists got separate instructions, their expeditions became more and more independent of the astronomers and eventually became known as the famous Academic Expeditions with a tremendous output of publications. This was the second huge effort made by Russia during the eighteenth century to explore scientifically remote parts of its empire. As far as individual Venus transit expeditions are concerned, this paper focuses on those that visited places in the southern parts of the Ural Mountains and the northern shores of the Caspian Sea.

  5. Observations of the Black-Drop Effect at the 2012 Transit of Venus

    Science.gov (United States)

    Rogoszinski, Zeeve; Pasachoff, J. M.; Babcock, B. A.; Schneider, G.; Reardon, K. P.

    2014-01-01

    We observed the 2012 transit of Venus from several locations, including the Mees Solar Observatory of the University of Hawaii on Maui; the Dunn Solar Telescope at the Sacramento Peak Observatory of the National Solar Observatory in Sunspot, NM; and the Big Bear Solar Observatory of the New Jersey Institute of Technology in California. Our observations, mainly directed at the study of Venus's atmosphere, also included high-resolution views of the black-drop effect. Historically, the black-drop effect proved to be a daunting anomaly for measuring the path length of Venus across the Sun’s surface with sufficient time accuracy to allow satisfactory measurement of the astronomical unit. Therefore, this phenomenon set back the accurate calculations for centuries of the size and scale of the solar system. In this paper, we discuss data taken with the New Solar Telescope at the Big Bear Observatory and with the IBIS on the Dunn Solar Telescope. We show the evolution of isophotes as a function of time to demonstrate various limb effects during second and third contacts. Schneider, Pasachoff, and Golub (Icarus 168. 249-256, 2004) have shown that the black-drop effect as seen in a transit of Mercury resulted from both the point-spread function of the telescope and the extreme limb-darkening effect at the region of the solar limb where the black-drop effect is demonstrated, and the current paper extends the analysis to the recent transit of Venus. As they showed, and as is verified here, Venus's atmosphere plays no role in the black-drop effect. ZR (Vassar '14) was a Keck Northeast Astronomy Consortium Summer Fellow at Williams College, supported by an NSF/REU grant to the Keck Northeast Astronomy Consortium. This research used the following tools: IDL/IDP3, ImageJ, and DS9. For obtaining the data at the Big Bear Solar Observatory, we thank Vasyl Yurchyshyn. Special thanks goes to Dr. Steven Souza for his support. The 2012 observations were obtained with a grant from the Committee for Research and Exploration of the National Geographic Society.

  6. Expression image data of Drosophila GAL4 enhancer trap lines - GETDB | LSDB Archive [Life Science Database Archive metadata

    Lifescience Database Archive (English)

    Full Text Available [ Credits ] BLAST Search Image S earch Home About Archive Update History Contact us GETDB Express ... n image data by developmental stages of Drosophila Images ... are classified into the following four development ... o (e), larva (g), adult (a))""serial number of the images ... classified by developmental stages in the line".jp ... m.csv" in the ZIP file. Data file File name: getdb_images .zip File URL: ftp://ftp.biosciencedbc.jp/archive/g ... etdb/LATEST/getdb_images .zip File size: 247MB Simple search URL - Data acqu ...

  7. The Venus "Shell-over-Star" hieroglyph and Maya warfare: An examination of the interpretation of a Mayan symbol

    Science.gov (United States)

    Voit, Claudia Ann

    For decades, Maya scholars have associated the Mayan "Shell-Star" (also referred to as "Star-War") hieroglyph with Maya warfare. Put forward by scholars such as Floyd Lounsbury and David Kelley, and later advanced by Linda Schele, David Freidel, Ian Graham, Peter Matthews, Anthony Aveni and others, there are now dozens of published articles and chapters relating the hieroglyph to Venus and warfare. Venus is one of the most notable celestial objects outside of the Sun and Moon and was highly visible to the inhabitants of the Maya world. The Dresden Codex (an astronomical almanac) contains important information about the planet Venus, and the calendar section was deciphered by the librarian and mathematician, Ernst Förstemann in the late 1800s. In his decipherment, he deduced that the numbers contained in the tables must be connected to the orbital period of the planet. There is no other planet with the same orbital period 3 as Venus. Förstemann suggested that the decoded astronomy tables were used by the Maya to determine when to wage war. This interpretation, along with others, like Floyd Lounsbury`s study of Venus and the Long Count date at Bonampak were the seeds that have led to methodological errors that first began to take root in Maya research. The idea of the Venus association with warfare took hold and continues to propagate. Many scholars continue to assert that the "shell-star" glyph is related to warfare events. Others, like Gerardo Aldana, and Stanley Guenter, have recently come forward to reexamine and question the hieroglyph and its relationship, if any, to Maya warfare. I suggest, further, that methodological errors may have occurred along the way. I propose that these errors include data lost in translation, and inaccurate translations. In addition, the statistical analysis of Venus cycles has weak points. If this identification of the errors is correct, we need to re-evaluate the weakened foundation on which we are building our assertions about the role of Venus in Maya warfare. In this work, I examine the initial and subsequent interpretations of the Mayan "shell-star" hieroglyph, a symbol that has begun to generate an increasing amount of discussion among Mayan scholars over the last several years. In addition, I discuss new arguments (like that of Gerardo Aldana) regarding the role of Venus in Maya warfare. Finally, I would like to provide some suggestions for future research regarding this subject.

  8. Evidence for Regional Basin Formation in Early Post-Tessera Venus History: Geology of the Lavinia Planitia Area (V55)

    Science.gov (United States)

    Head, J. W.; Ivanov, M. A.

    1995-01-01

    On Venus, global topography shows the presence of highs and lows including regional highly deformed plateaus (tesserae), broad rifted volcanic rises, linear lows flanking uplands, and more equidimensional lowlands (e.g. Lavinia and Atalanta planitiae) Each of these terrain types on Venus has relatively distinctive characteristics, but origins are uncertain in terms of mode of formation, time of formation, and potential evolutionary links. There is a high level of uncertainty about the formation and evolution of lowlands on Venus. We have undertaken the mapping of a specific lowlands region of Venus to address several of these major questions. Using geologic mapping we have tried to establish: What is the sequence of events in the formation and evolution of large-scale equidimensional basins on Venus? When do the compressional features typical of basin interiors occur? What is the total volume of lava that occurs in the basins and is this similar to other non-basin areas? How much subsidence and downwarping has occurred after the last major plains units? WE have undertaken an analysis of the geology of the V55 Lavinia Planitia quadrangle in order to address many of these issues and we report on the results here.

  9. On the Frequency of Potential Venus Analogs from Kepler Data

    OpenAIRE

    Kane, Stephen R.; Kopparapu, Ravi kumar; Domagal-Goldman, Shawn D.

    2014-01-01

    The field of exoplanetary science has seen a dramatic improvement in sensitivity to terrestrial planets over recent years. Such discoveries have been a key feature of results from the {\\it Kepler} mission which utilizes the transit method to determine the size of the planet. These discoveries have resulted in a corresponding interest in the topic of the Habitable Zone (HZ) and the search for potential Earth analogs. Within the Solar System, there is a clear dichotomy between...

  10. Excitations From Impact: The Affect of CMEs on Venus' Mysterious Oxygen Green Line and Ionospheric Electrons. An Auroral Process?

    Science.gov (United States)

    Gray, C.; Chanover, N.; Slanger, T. G.; Molaverdikhani, K.; Häusler, B.; Tellmann, S.; Peter, K.

    2014-12-01

    Observations of nightglow (upper atmospheric emission from atoms and molecules on the nightside of a planet) allow for a multifaceted study of planetary atmospheres. Information on winds, chemistry, and solar effects is gained by observing temporal and spatial variation in nightglow intensity. One of the brightest nightglow features on Earth is the OI (1S-1D) 557.7 nm line (oxygen green line). This emission is primarily due to photodissociation/transport but is also seen in the aurora as electron precipitation. Unlike Earth, the Venusian green line is highly temporally variable. The chemistry and mechanisms responsible are still unknown. We observe the Venusian nightglow before and after solar flares, which produce large amounts of EUV emission, and coronal mass ejections (CMEs) impacts, which inject a large number of higher energy charged particles in the the Venusian atmosphere. We consistently detect green line emission after large charged particles injections from CMEs. However we do not detect the OI (1D) red line at 630.0 nm, which is quenched below 150 km. We propose that the Venusian green line is an auroral-type emission due to electron precipitation and is occurring deep in the atmosphere, near 125 km. To investigate how CMEs and solar flares affect the electron energy, flux, and density in the Venusian nightside atmosphere, we compare data taken by ASPERA and ELS onboard Venus Express (VEX) before and after solar storms. We find that both electron energy and flux increase after CMEs, but only flux increases after solar flares. Additionally, the V1 ionospheric layer at 125 km increases in electron density while the V2 at 150 km decreases in density after CMEs but not after solar flares. We model the nightside Venusian ionosphere using the observed electron energy and fluxes from VEX in an effort to constrain the chemical processes and mechanisms responsible for green line emission. We will present the results of our ground-based observations and modeling.

  11. Ciência e Tecnologia: expressões sutis da discriminação de gênero? (Science and Technology: subtle expressions of gender discrimination?

    Directory of Open Access Journals (Sweden)

    Vívian Matias dos Santos

    2010-01-01

    Full Text Available Resumo: O presente artigo pretende analisar como se manifesta a discriminação de gênero no cenário contemporâneo da Política de Ciência e Tecnologia Nacional. Para tanto, observa a participação de mulheres e homens na produção em C&T financiada pela Fundação Cearense de Apoio ao Desenvolvimento Científico e Tecnológico – FUNCAP. As discussões realizadas constituíram-se por meio de uma abordagem descritiva e de caráter quantitativo, tendo sido imprescindíveis o recurso à pesquisa bibliográfica e documental.Abstract: The present article analyses how gender discrimination takes place in the contemporary scenario of the Brazilian Science & Technology policies. In order to do so, the author has assessed the participation of male and female individuals in a research funded by the Fundação Cearense de Apoio ao Desenvolvimento Científico e Tecnológico – FUNCAP. The discussion was based on a descriptive and qualitative approach, along with a research of the relevant literature and documents, which proved to be essential to the work.

  12. Transits of Venus and Solar diameter measures from ground: method and results from Athens (2004) and Huairou (2012)

    CERN Document Server

    Sigismondi, Costantino; Wang, Xiaofan; Xie, Wenbin; Carinci, Massimo; Mimmo, Alessio

    2015-01-01

    The variation of the solar diameter in time and in position angle has implications in astrophysics and in general relativity, as the long series of studies attest. The Transits of Venus in 2004 and 2012 have been carefully studied because of the rarity of the phenomenon and its historical importance due the AU measure and to the discovery of Venus atmosphere. The characterization of Venus atmosphere and the measure of the solar diameter to the milliarcsecond level of precision have been studied also from satellite images. The results of the solar diameter measurements made with the observations in Athens (2004) and at the Huairou Solar Observing Station in China (2012) are presented. The topic of the oblateness of the Sun at sunset and its intrinsic value is drafted to introduce the general public to the relativistic relevance of measuring the solar figure, in the occasion of the International Year of Light 2015.

  13. Constraints on crustal rheology and age of deformation from models of gravitational spreading in Ishtar Terra, Venus

    Science.gov (United States)

    Smrekar, Suzanne E.; Soloman, Sean C.

    1992-01-01

    Gravitational spreading is expected to lead to rapid relaxation of high relief due to the high surface temperature and associated weak crust on Venus. In this study, we use new Magellan radar and altimetry data to determine the extent of gravitational relaxation in Ishtar Terra, which contains the highest relief on Venus as well as areas of extremely high topographic slope. Within Ishtar Terra the only mountain belts found on Venus, Akna, Danu, Freyja, and Maxwell Montes, nearly encircle the smooth, high (3-4 km) plateau of Lakshmi Planum. Finite-element models of this process give expected timescales for relaxation of relief and failure at the surface. From these modeling results we attempt to constrain the strength of the crust and timescales of deformation in Ishtar Terra. Below we discuss observational evidence for gravitational spreading in Ishtar Terra, results from the finite-element modeling, independent age constraints, and implications for the rheology and timing of deformation.

  14. The Atmospheres of the Terrestrial Planets:Clues to the Origins and Early Evolution of Venus, Earth, and Mars

    Science.gov (United States)

    Baines, Kevin H.; Atreya, Sushil K.; Bullock, Mark A.; Grinspoon, David H,; Mahaffy, Paul; Russell, Christopher T.; Schubert, Gerald; Zahnle, Kevin

    2015-01-01

    We review the current state of knowledge of the origin and early evolution of the three largest terrestrial planets - Venus, Earth, and Mars - setting the stage for the chapters on comparative climatological processes to follow. We summarize current models of planetary formation, as revealed by studies of solid materials from Earth and meteorites from Mars. For Venus, we emphasize the known differences and similarities in planetary bulk properties and composition with Earth and Mars, focusing on key properties indicative of planetary formation and early evolution, particularly of the atmospheres of all three planets. We review the need for future in situ measurements for improving our understanding of the origin and evolution of the atmospheres of our planetary neighbors and Earth, and suggest the accuracies required of such new in situ data. Finally, we discuss the role new measurements of Mars and Venus have in understanding the state and evolution of planets found in the habitable zones of other stars.

  15. Missing plate tectonics in Venus caused by rheological contrast at Moho

    Science.gov (United States)

    Azuma, S.; Katayama, I.; Nakakuki, T.

    2012-12-01

    Venus has been regarded as a twin planet to the Earth, because of density, mass, size and distance from the Sun (Taylor and McLennan, 2008). However, the Magellan mission revealed that plate tectonics is unlikely to work on the Venus (Turcotte et al., 1999). The plate tectonics is one of the most important mechanism of heat transport and material circulation of the Earth, consequently, its absence might cause the different tectonic evolution between Earth and Venus. Rheological structure is a key to inferring mantle structure and convection style of planet interiors because the rock rheology controls strength and viscosity. In previous study, the behavior of Venusian lithosphere has been inferred from the power-law type flow law of dry diabase (Mackwell et al., 1998). They indicated that lower crust can be weaker than upper mantle, which might result decoupling at the crust-mantle boundary (Moho depth) and mantle convection without crustal entrainment. However, the power-law creep may not be applicable to infer the rheological structure at Moho depths, because the dislocation-glide control creep (Peierls mechanism) is known to become dominant at relatively low temperatures in materials with a relatively strong chemical bonding such as silicates (Tsenn and Carter 1987). In this study, we conduct two-phase deformation experiments to directly investigate rheological contrast between plagioclase (crust) and olivine (mantle) using solid-medium deformation apparatus and discuss the difference between these planets in terms of rheological behaviors. Moreover, we conduct numerical simulation utilizing the results of deformation experiments to investigate the effect of the strength contrast between the crust and the mantle to the motion of planetary surface. In this study, we perform experiments to directly investigate the relative strength between plagioclase and olivine without any extrapolating of flow law; the crustal materials consist predominantly of plagioclase that largely control deformation of the crust, whereas deformation of the upper mantle is largely controlled by olivine. These samples are together sandwiched between alumina pistons in a simple shear geometry and we used the hot-pressed samples and perform deformation experiments using solid-medium deformation apparatus. The experimental conditions are ranging 1-2 GPa and 400-1000oC, corresponding conditions approximately to Moho of the Venus at dry and wet conditions. Under wet environments, olivine is weaker than plagioclase at temperature less than 400oC, whereas plagioclase becomes weaker at temperature higher than 600oC. In contrast, under dry conditions, olivine is still weaker than plagioclase at temperature as high as 600oC. Based on microstructures and mechanical data, we found that the deformation mechanism is dominated by Peierls mechanism (dislocation-glide) in each sample under experimental condition. The investigated strength contrast between plagioclase and olivine are applied for the Venus's Moho in numerical simulation, in which the strength contrast at Moho plays a key role on the activation of plate tectonics. In presentation, we will report additional results of deformation experiments, and hope to propose the rheological structure of Venus based on the experimental and numerical results.

  16. Reentry response of the lightweight radioisotope heater unit resulting from a Cassini Venus-Venus-Earth-Jupiter gravity assist maneuver accident

    International Nuclear Information System (INIS)

    Reentry analyses consisting of ablation response, thermal response and thermal stress response have been conducted on the Lightweight Radioisotope Heater Unit (LWRHU) for Cassini/Venus-Venus-Earth-Jupiter-Gravity-Assist (VVEJGA) reentry conditions. Sequential ablation analyses of the LWRHU aeroshell, and the fuel pellet have been conducted in reentry regimes where the aeroshell has been deemed to fail. The failure criterion for ablation is generally assumed to be recession corresponding to 75% and 100% of the wall thickness. The 75% recession failure criteria allows for uncertainties that result mainly because of the high energies involved in the VVEJGA reentries compared to orbital decay reentries. Risk evaluations should consider the fact that for shallow flight paths the unit may disassemble at high-altitude as a result of ablation or may remain intact with a clad that had been molten. Within the limitations of the methodologies and assumptions of the analyses, the results indicate that: (1) For a side-on stable LWRHU reentry, aeroshell ablation failures occur for all reentry angles. (2)For a side-on spinning LWRHU reentry, aeroshell ablation failures are minimal. (3) For the tumbling LWRHU reentry, the aeroshell survives for most angles. (4) For the thermostructural analyses, using both a 1% and 5% allowable strain, all reentry angles and orientations examined resulted in small localized failures, but aeroshell breach is not predicted for any case. The analyses included in this report concentrate on VVEJGA reentry scenarios. Analyses reported previously have demonstrated that the LWRHU has adequate design margin to survive reentry from orbital decay scenarios and most injection scenarios at speeds up to escape speeds. The exception is a narrow range of flight path angles that produce multiple skip trajectories which may have excessive ablation

  17. Reentry response of the lightweight radioisotope heater unit resulting from a Cassini Venus-Venus-Earth-Jupiter gravity assist maneuver accident

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-12-01

    Reentry analyses consisting of ablation response, thermal response and thermal stress response have been conducted on the Lightweight Radioisotope Heater Unit (LWRHU) for Cassini/Venus-Venus-Earth-Jupiter-Gravity-Assist (VVEJGA) reentry conditions. Sequential ablation analyses of the LWRHU aeroshell, and the fuel pellet have been conducted in reentry regimes where the aeroshell has been deemed to fail. The failure criterion for ablation is generally assumed to be recession corresponding to 75% and 100% of the wall thickness. The 75% recession failure criteria allows for uncertainties that result mainly because of the high energies involved in the VVEJGA reentries compared to orbital decay reentries. Risk evaluations should consider the fact that for shallow flight paths the unit may disassemble at high-altitude as a result of ablation or may remain intact with a clad that had been molten. Within the limitations of the methodologies and assumptions of the analyses, the results indicate that: (1) For a side-on stable LWRHU reentry, aeroshell ablation failures occur for all reentry angles. (2)For a side-on spinning LWRHU reentry, aeroshell ablation failures are minimal. (3) For the tumbling LWRHU reentry, the aeroshell survives for most angles. (4) For the thermostructural analyses, using both a 1% and 5% allowable strain, all reentry angles and orientations examined resulted in small localized failures, but aeroshell breach is not predicted for any case. The analyses included in this report concentrate on VVEJGA reentry scenarios. Analyses reported previously have demonstrated that the LWRHU has adequate design margin to survive reentry from orbital decay scenarios and most injection scenarios at speeds up to escape speeds. The exception is a narrow range of flight path angles that produce multiple skip trajectories which may have excessive ablation.

  18. The non-homogeneous accumulation model for terrestrial planet formation and the consequences for the atmosphere of Venus

    Science.gov (United States)

    Turekian, K. K.; Clark, S. P., Jr.

    1975-01-01

    The nonhomogeneous-accumulation model for the formation of the terrestrial planets is described, and its consequences for the formation of the Venusian atmosphere are assayed in the context of our knowledge of the composition of the earth and carbonaceous chondrites. The relative abundances of the low-temperature condensibles in the reservoirs at the earth's surface are applied to Venus. Although carbonaceous chondrites show similar properties for the chemically bound elements, they show large deficiencies for the rare gases. The major gases on Venus, by volume, are predicted to be 98.12% CO2, 1.86% N2 and 0.02% Ar-40.

  19. Remote Raman Spectroscopy of Minerals at Elevated Temperature Relevant to Venus Exploration

    Science.gov (United States)

    Sharma, Shiv K.; Misra, Anupam K.; Singh, Upendra N.

    2008-01-01

    We have used a remote time-resolved telescopic Raman system equipped with 532 nm pulsed laser excitation and a gated intensified CCD (ICCD) detector for measuring Raman spectra of a number of minerals at high temperature to 970 K. Remote Raman measurements were made with samples at 9-meter in side a high-temperature furnace by gating the ICCD detector with 2 micro-sec gate to minimize interference from blackbody emission from mineral surfaces at high temperature as well as interference from ambient light. A comparison of Raman spectra of gypsum (CaSO4.2H2O), dolomite (CaMg(CO3)2), and olivine (Mg2Fe2-xSiO4), as a function of temperature shows that the Raman lines remains sharp and well defined even in the high-temperature spectra. In the case of gypsum, Raman spectral fingerprints of CaSO4.H2O at 518 K were observed due to dehydration of gypsum. In the case of dolomite, partial mineral dissociation was observed at 973 K at ambient pressure indicating that some of the dolomite might survive on Venus surface that is at approximately 750 K and 92 atmospheric pressure. Time-resolved Raman spectra of low clino-enstatite (MgSiO3) measured at 75 mm from the sample in side the high-temperature furnace also show that the Raman lines remains sharp and well defined in the high temperature spectra. These high-temperature remote Raman spectra of minerals show that time-resolved Raman spectroscopy can be used as a potential tool for exploring Venus surface mineralogy at shorter (75 mm) and long (9 m) distances from the samples both during daytime and nighttime. The remote Raman system could also be used for measuring profiles of molecular species in the dense Venus atmosphere during descent as well as on the surface.

  20. Perspective View of Venus (Center Latitude 45 Degrees N., Center Longitude 11 Degrees E.)

    Science.gov (United States)

    1992-01-01

    This perspective view of Venus, generated by computer from Magellan data and color-coded with emissivity, shows part of the lowland plains in Sedna Planitia. Circular depressions with associated fracture patterns called 'coronae' are apparently unique to the lowlands of Venus, and tend to occur in linear clusters along the planet's major tectonic belts. Coronae differ greatly in size and detailed morphology: the central depression may or may not lie below the surrounding plains, and may or may not be surrounded by a raised rim or a moat outside the rim. The corona shown here is relatively small (100 km in diameter and 1 km deep) and is of the subtype known as an 'arachnoid' because of the spider-like configuration of concentric (body) and radial (legs) fractures. Coronae are thought to be caused by localized 'hot spot' magmatic activity in Venus' subsurface. Intrusion of magma into the crust first pushes up the surface, after which cooling and contraction create the central depression and generate a pattern of concentric fractures. In some cases, lava may be extruded onto the surface. The fractured ridge at the left is classified as a 'nova' or 'stellate fracture center' and is believed to represent an early phase of corona formation, in which subsidence due to cooling has not yet created the central depression, and the fracture pattern is still entirely radial. Magellan MIDR quadrangle* containing this image: C1-45N011. Image resolution (m): 225. Size of region shown (E-W x N-S, in km): 439 x 474. Range of emissivities from violet to red: 0.82 -- 0.88. Vertical exaggeration: 100. Azimuth of viewpoint (deg clockwise from East): 150. Elevation of viewpoint (km): 600. *Quadrangle name indicates approximate center latitude (N=north, S=south) and center longitude (East).