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Sample records for venus express science

  1. The clouds of Venus - an overview of Venus Express results

    Science.gov (United States)

    Wilson, C. F.; Marcq, E.; Markiewicz, W. J.; Montmessin, F.; Fedorova, A.; Wilquet, V.; Petrova, E. V.; Ignatiev, N. I.; Shalygina, O. S.; Maattanen, A. E.; McGouldrick, K. M.; Hashimoto, G. L.; Imamura, T.; Rossi, L.; Luginin, M.; Oschlisniok, J.; Haus, R.; Parkinson, C. D.; Titov, D. V.; Zasova, L. V.; Limaye, S. S.

    2015-10-01

    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

  2. Venus express: Highlights of the nominal mission

    OpenAIRE

    Titov, DV; Svedhem, H.; Taylor, FW; Barabash, S.; Bertaux, J-L; Drossart, P.; Formisano, V.; Haeusler, B; O. Korablev; Markiewicz, WJ; Nevejans, D; Paetzold, M.; Piccioni, G.; Sauvaud, J-A; Zhang, TL

    2009-01-01

    Venus Express is the first European (ESA) mission to the planet Venus. Its main science goal is to carry out a global survey of the atmosphere, the plasma environment, and the surface of Venus from orbit. The payload consists of seven experiments. It includes a powerful suite of remote sensing imagers and spectrometers, instruments for in-situ investigation of the circumplanetary plasma and magnetic field, and a radio science experiment. The spacecraft, based on the Mars Express bus modified ...

  3. The Challenges and Opportunities for International Cooperative Radio Science; Experience with Mars Express and Venus Express Missions

    Science.gov (United States)

    Holmes, Dwight P.; Thompson, Tommy; Simpson, Richard; Tyler, G. Leonard; Dehant, Veronique; Rosenblatt, Pascal; Hausler, Bernd; Patzold, Martin; Goltz, Gene; Kahan, Daniel; Valencia, Jose

    2008-01-01

    Radio Science is an opportunistic discipline in the sense that the communication link between a spacecraft and its supporting ground station can be used to probe the intervening media remotely. Radio science has recently expanded to greater, cooperative use of international assets. Mars Express and Venus Express are two such cooperative missions managed by the European Space Agency with broad international science participation supported by NASA's Deep Space Network (DSN) and ESA's tracking network for deep space missions (ESTRAK). This paper provides an overview of the constraints, opportunities, and lessons learned from international cross support of radio science, and it explores techniques for potentially optimizing the resultant data sets.

  4. 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; O. Korablev; 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...

  5. The inversion layer at the tropopause of the Venus atmosphere: new insights from the Radio Science Experiment (VeRa) onboard Venus Express

    Science.gov (United States)

    Herrmann, M.; Oschlisniok, J.; Remus, S.; Tellmann, S.; Häusler, B.; Pätzold, M.

    2015-10-01

    The inversion layer at the tropopause of the Venus atmosphere is a very common and prominent feature in the vertical temperature profile at higher latitudes. The inversion layer is of particular interest because it separates the stratified troposphere from the highly variable mesosphere. The altitude range of the inversion layer is therefore a likely location for the formation of gravity waves [1]. The Radio Science Experiment (VeRa) onboard Venus Express [2,3] is capable to sound the Venus atmosphere from 100 km downward to 40 km [4,5] and delivered more than 800 vertical profiles of temperature, pressure and neutral number density at almost all local times and latitudes. The tropopause is typically located at 60 km altitude. Spatial changes of the refractive index over a short altitude range lead to multi-path effects which cannot be fully retrieved with common closed-loop recording methods. The development of a new data processing tool based on VeRa open loop data sets provided the necessary frequency resolution to fully resolve multipath effects occurring along a short range of 2 km at the tropopause location. The inversion layer presents itself up to 15K colder than commonly thought. The new results shall help to find a consistent picture of the Venus' thermal atmosphere structure and therefore help to improve atmospheric models.

  6. The legacy of Venus Express: highlights from the first European planetary mission to Venus

    Science.gov (United States)

    Drossart, Pierre; Montmessin, Franck

    2015-11-01

    The ESA/Venus Express mission spent more than 8 years in orbit around Venus to extensively study its atmosphere, ionosphere and plasma environment and unveil new aspects of its surface. Extensive reviews of the work of Venus Express are underway, to cover in-depth studies of the new face of Venus revealed by Venus Express and ground-based concurrent observations. This paper intends to give a summarized and wide overview of some of the outstanding results in all the science areas studied by the mission. This paper will first review the main aspects of the mission and its instrumental payload. Then, a selection of results will be reviewed from the outermost layers interacting with the Solar wind, down to the surface of Venus. As Venus Express is already considered by space agencies as a pathfinder for the future of Venus exploration, perspectives for future missions will be given, which will have to study Venus not only from orbital view, but also down to the surface to solve the many remaining mysteries of the sister planet of the Earth.

  7. Experimental Aerobraking with Venus Express

    Science.gov (United States)

    Svedhem, Hakan

    2013-10-01

    Venus Express has successfully orbited Venus in its polar 24 hour, 250km by 66000 km, orbit since April 2006 and has provided a wealth of new data from our sister planet. Approaching the end of the mission we are now planning an experimental campaign dedicated to aerobraking at altitudes down to as low as about 130km. These low pericentre passes will provide direct measurements of density, temperature, magnetic field and energetic particles in a region not accessible by other methods. Experience of operations and studies of spacecraft responses will be valuable knowledge for possible future missions that might need this techniques as a part of its nominal operations. Aerobraking was considered in the early design phase of the mission but it was fairly soon realised that the nominal mission would not need this. However, a few important design features were maintained in order to allow for this in case it should be needed at a later stage. The inherently stable geometry of the spacecraft configuration and the inclusion of a software mode for aerobraking are the two most important elements from this early design phase. An recent study by industry has determined the constraints for the spacecraft and identified several potential scenarios. The present highly elliptical orbit has as one of its inherent features a downward drift of the pericentre altitude of between 1 and 4 km/day. However, at certain times, when the Sun is in the orbital plane, this drift disappears for a period of up to two weeks. This is a very well suited time to carry out these initial experiments as it is makes operations safer and it reduces the heat input on the spacecraft as the solar panels will be edge-on towards the sun during the aerobraking. Already a number of low altitude operations have been carried out during the so called atmospheric drag campaigns. The spacecraft has then dipped down to altitudes as low as 165 km and a good characterisation of this region has been performed. This collected information will be helpful for the planning of the aerobraking itself.

  8. Venus Express: Scientific goals, instrumentation, and scenario of the mission

    OpenAIRE

    Titov, DV; Svedhem, H.; MCCOY, D; Lebreton, J-P; Barabash, S.; Bertaux, J-L; Drossart, P.; Formisano, V.; Haeusler, B; Korablev, OI; Markiewicz, W; Neveance, D; Petzold, M; Piccioni, G.; Zhang, TL

    2006-01-01

    The first European mission to Venus (Venus Express) is described. It is based on a repeated use of the Mars Express design with minor modifications dictated in the main by more severe thermal environment at Venus. The main scientific task of the mission is global exploration of the Venusian atmosphere, circumplanetary plasma, and the planet surface from an orbiting spacecraft. The Venus Express payload includes seven instruments, five of which are inherited from the missions Mars Express and ...

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

    OpenAIRE

    L. Guicking; K.-H. Glassmeier; H.-U. Auster; Delva, M.; U. Motschmann; Narita, Y.; Zhang, T. L.

    2010-01-01

    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...

  10. Venus Monitoring Camera Observations and Results from Venus Express

    Science.gov (United States)

    Limaye, Sanjay; Krauss, R. J.; Markiewicz, W. J.; Titov, D. V.; Khatuntsev, I.; Patsaeva, M.

    2010-10-01

    The Venus Monitoring Camera (VMC) on ESA's Venus Express mission has been systematically imaging the planet in four filters since June 2006. These images from the 24-hour eccentric, polar orbit show the dynamic behavior of the Venus cloud cover with rapid changes in relative brightness on global, regional and small scales and presence of planetary scale and small scale gravity waves (high Northern latitudes). They have enabled estimates of the large scale circulation of the cloud level flow from multiple, independent efforts for the southern hemisphere which is imaged routinely. The results are generally consistent and appear to show presence of planetary waves and solar thermal tides. The precise vertical level of the measured cloud motions is not known but has been estimated to be between 70 km at low latitudes and 65 km in polar regions with a rise near the mid-latitudes to about 73 km. Temporal or local solar time changes in the cloud top level appear possible but have not been investigated. Thus some of the apparent temporal variability can be due to cloud level changes. The short term average zonal flow is observed to fluctuate between 80 m/s - 100 m/s at low latitudes while its meridional dependence shows either a weak increase with latitude or near constant magnitude to mid-latitudes and decreasing towards the pole, generally consistent with the profile expected for a vortex circulation. The mean meridional flow is poleward at most latitudes, peaking in mid-latitudes. Higher resolution images with shorter time interval tend to show slightly faster motions of clouds and thus the VMC large scale tracking results should be interpreted with caution. Space time composites of the southern hemisphere images consistently show the presence of hemispheric vortex centered at the south pole.

  11. Retrieval of Venus' clouds parameters with polarization using SPICAV-IR onboard Venus Express

    Science.gov (United States)

    Rossi, Loïc; Marcq, Emmanuel; Montmessin, Franck; Fedorova, Anna; Stam, Daphne; Bertaux, Jean-Loup; Korablev, Oleg

    2015-04-01

    Understanding the structure and dynamics of Venus' clouds is essential as they have a strong impact on the radiative balance and atmospheric chemistry of the planet. Polarimetry has greatly contributed to our knwoledge about the properties of the cloud layers located between 48 and ~ 70 km. Hansen and Hovenier (1974), using ground-based observations, found the cloud particles to be ~ 1?m spherical droplets, with a refractive index corresponding to a concentrated sulfuric acid-water solution. Later, Kawabata et al. (1980), using polarimetric data from OCPP onboard Pioneer Venus retrieved the properties of the haze: effective radius of ~ 0.25?m, refractive indices consistent with a sulfuric acid-water solution, variance of the particle size distribution. We introduce here new measurements obtained with the SPICAV-IR spectrometer onboard ESA's Venus Express. Observing Venus in the visible and IR from 650 nm to 1625 nm with a good spatial and temporal converage, SPICAV's sensitivity to the degree of linear polarization gives us an opportunity to put better constraints on haze and cloud particles at Venus cloud top, as well as their spatial and temporal variability. These observations reveal a particular feature called glory, observed by SPICAV-IR and VMC (Markiewicz et al. 2014). Using a radiative transfer code taking into account polarization (de Haan et al. 1987, de Rooij et al. 1984, Stam et al. 1999), we model the cloud layers and the glory allowing us to retrieve the real part of the refractive index, the effective radius and variance of the particle size distribution from the main cloud layer. Our results confirm that the particles are spherical, with a narrow size distribution and with refractive indices that are compatible with H2SO4-H2O solutions (Rossi et al. 2014). Using the large latitudinal coverage of the data, we can also retrieve the variation of the overlying haze layer optical thickness. We find that ?h is increasing with increasing latitude, in agreement with previous measurements from Braak et al. (2002) and Knibbe et al. (1997). References Hansen, J. E. and Hovenier, J. W., 1974, Interpretation of the polarization of Venus., Journal of Atmospheric Sciences, 31. Kawabata et al., 1980, Cloud and haze properties from Pioneer Venus Polarimetry, J. Geophys. Res., 85. Markiewicz, W.J. et al., 2014, Glory on venus cloud tops and the unknown UV absorber, Icarus, 234. de Haan, J. F. et al, 1987, The adding method for multiple scattering calculations of polarized light, Astron. Astrophys., 183. de Rooij, W. A. and van der Stap, C. C. A. H., 1984, Expansion of Mie scattering matrices in generalized spherical functions, Astron. Astrophys., 131 Stam, D. M. et al., 1999, Degree of linear polarization of light emerging from the cloudless atmosphere in the oxygen A band, J. Geophys. Res., 104. Rossi, L. et al., 2014, Preliminary study of Venus cloud layers with polarimetric data from SPICAV/VEx, Planet. Space Sci., In Press. Braak, C. J. et al., 2002, Spatial and temporal variations of Venus haze properties obtained from Pioneer Venus Orbiter polarimetry, J. Geophys. Res. (Planets), 107. Knibbe, W. J. J. et al., 1997,A biwavelength analysis of Pioneer Venus polarization observations, J. Geophys. Res., 102.

  12. Thermal structure of Venus nightside upper atmosphere measured by stellar occultations with SPICAV/Venus Express

    Science.gov (United States)

    Piccialli, A.; Montmessin, F.; Belyaev, D.; Mahieux, A.; Fedorova, A.; Marcq, E.; Bertaux, J.-L.; Tellmann, S.; Vandaele, A. C.; Korablev, O.

    2015-08-01

    The thermal structure of Venus upper atmosphere (90-140 km) was investigated using stellar occultation measurements acquired by the SPICAV experiment on board Venus Express. The SPICAV ultraviolet channel provides CO2 local density and temperature vertical profiles with a vertical resolution of Venus atmosphere at these altitudes: temperatures show an increase of ~ 20 K on the morning side compared to the evening side. The homopause altitude was also determined; it varies between 119 and 138 km of altitude, increasing from the evening side to the morning side. SPICAV temperature profiles were compared to several literature results from ground-based observations, previous spacecraft missions and the Venus Express mission.

  13. Models of the global cloud structure on Venus derived from Venus Express observations

    OpenAIRE

    Barstow, JK; Tsang, CCC; Wilson, CF; Irwin, PGJ; Taylor, FW; McGouldrick, K; Drossart, P.; Piccioni, G.; Tellmann, S

    2012-01-01

    Spatially-resolved near-infrared spectra from the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) on Venus Express have been used to derive improved models of the vertical structure and global distribution of cloud properties in the southern hemisphere of Venus. VIRTIS achieved the first systematic, global mapping of Venus at wavelengths within transparency windows in the 1.6-2.6. ?m range, which are sensitive on the nightside to absorption by the lower and middle cloud layers of t...

  14. Venus Aerobot Surface Science Imaging System (VASSIS)

    Science.gov (United States)

    Greeley, Ronald

    1999-01-01

    The VASSIS task was to design and develop an imaging system and container for operation above the surface of Venus in preparation for a Discovery-class mission involving a Venus aerobot balloon. The technical goals of the effort were to: a) evaluate the possible nadir-viewed surface image quality as a function of wavelength and altitude in the Venus lower atmosphere, b) design a pressure vessel to contain the imager and supporting electronics that will meet the environmental requirements of the VASSIS mission, c) design and build a prototype imaging system including an Active-Pixel Sensor camera head and VASSIS-like optics that will meet the science requirements. The VASSIS science team developed a set of science requirements for the imaging system upon which the development work of this task was based.

  15. Venus Atmospheric Maneuverable Platform Science Mission

    Science.gov (United States)

    Polidan, Ronald S.; Lee, Gregory; Ross, Floyd; Sokol, Daniel; Bolisay, Linden

    2015-11-01

    Over the past several years, we have explored a possible new approach to Venus upper atmosphere exploration by applying recent Northrop (non-NASA) development programs and have come up with a new class of exploration vehicle: an atmospheric rover. We will discuss a possible suite of instruments and measurements to study the current climate through detailed characterization of cloud level atmosphere and to understand the processes that control climate on Earth-like planets.Our Venus atmospheric rover concept, the Venus Atmospheric Maneuverable Platform (VAMP), is a hypersonic entry vehicle with an ultra-low ballistic coefficient that transitions to a semi-buoyant air vehicle (AV) after entering the Venus atmosphere. Prior to entry, the AV fully deploys to enable lifting entry and eliminates the need for an aeroshell. The mass savings realized by eliminating the aeroshell allows VAMP to accommodate significantly more instruments compared to previous Venus in situ exploration missions. VAMP targets the global Venus atmosphere between 50–65 km altitudes and would be an ideal, stable platform for atmospheric and surface interaction measurements. We will present a straw man concept of VAMP, including its science instrument accommodation capability and platform’s physical characteristics (mass, power, wingspan, etc). We will discuss the various instrument options.VAMP’s subsonic flight regime starts at ~94 km and after Venus at mid-latitude. The stability of the AV and its extended residence time provide the very long integration times required for isotopic mass analysis. VAMP communicates with the orbiter, which provides data relay and possibly additional science measurements complementing the in situ measurements from the AV. We will specifically focus upon key factors impacting the design and performance of VAMP science.

  16. MESSENGER and Venus Express Observations of the Solar Wind Interaction with Venus: A Dual Spacecraft Study

    Science.gov (United States)

    Slavin, James A.; Acuna, M. H.; Anderson, B. J.; Barabash, S.; Benna, M.; Boardsen, S. A.; Fraenz, M.; Gloeckler, G.; Gold, R. E.; Ho, G. C.; Korth, H.; Krimigis, S. M.; McNutt, R. L., Jr.; Raines, J. M.; Sarantos, M.; Solomon, S. C.; Zhang, T.; Zurbuchen, T. H.

    2007-01-01

    At 23:08 UT on 5 June 2007 the MESSENGER spacecraft reached its closest approach altitude (338 krn) during its second flyby of Venus en route to its 201 1 orbit insertion at Mercury. Whereas no measurements were collected during MESSENGER'S first Venus flyby in October 2006, the Magnetometer (MAG) and the Energetic Particle and Plasma Spectrometer (EPPS) operated successfully throughout this second encounter. Venus provides the solar system's best example to date of a solar wind - ionosphere planetary interaction. Pioneer Venus Orbiter measurements have shown that this interaction affects the upper atmosphere and ionosphere down to altitudes of - 150 km. Here we present an initial overview of the MESSENGER observations during the - 4 hrs that the spacecraft spent within 10 planet radii of Venus and, together with Venus Express measurements, examine the influence of solar wind plasma and interplanetary magnetic field conditions on the solar wind interaction at solar minimum.

  17. 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

  18. MESSENGER and Venus Express Observations of the Solar Wind Interaction with Venus

    Science.gov (United States)

    Slavin, James A.; Acuna, Mario H.; Anderson, Brian J.; Barabash, Stas; Benna, Mehdi; Boardsen, Scott A.; Fraenz, Markus; Gloeckler, George; Gold, Robert E.; Ho,George C.; Korth, Haje; Krimigis, Stamatios M.; McNutt, Ralph L., Jr.; Raines, Jim M.; Sarantos, Menelaos; Solomon, Sean C.; Zhang, Tielong; Zurbuchen, Thomas H.

    2009-01-01

    At 23:08 UTC on 5 June 2007 the MESSENGER spacecraft reached its closest approach altitude of 338 kin during its final flyby of Venus en route to its 2011 orbit insertion at Mercury. The availability of the simultaneous Venus Express solar wind and interplanetary magnetic field measurements provides a rare opportunity to examine the influence of upstream conditions on this planet's solar wind interaction. We present MESSENGER observations of new features of the Venus - solar wind interaction including hot flow anomalies upstream of the bow shock, a flux rope in the near-tail and a two-point determination of the timescale for magnetic flux transport through this induced magnetosphere. Citation: Stavin, J. A., et al. (2009), MESSENGER and Venus Express observations of the solar wind interaction with Venus,

  19. VIRTIS for the ESA Venus Express Mission

    Science.gov (United States)

    Piccioni, G.; Drossart, P.; Coradini, A.; Arnold, G.

    The VIRTIS experiment for the ESA Rosetta mission was considered perfectly suitable, after some minor modifications, to be one of the instrument core payload for an ESA mission called Venus Express. At the time when this abstract is written, the mission will undergo the final step for possible official approval. VIRTIS consists of two channels: VIRTIS-M, a mapping spectrometer with moderate spectral resolution and VIRTIS-H, an high spectral resolution spectrometer having its field of view within thefield of view of UM. The spectral range of VIRTIS-M is between 0.25um and 5um in two channels with a boundary at 1um and a resolution of 3nm and 30 nm respectively. The spectral range of VIRTIS-H is from 2 to 5um with a resolution of about 3nm. The main scientific objectives of VIRTIS for Venus are: study of the lower atmosphere composition below the clouds and its variations (CO, OCS, SO2, H2O); study of the cloud structure, composition, and scattering properties; cloud tracking in the UV (~70 km, day side) and IR (~50 km, night side); measurements of the temperature field with subsequent determination of the zonal wind in the altitude range 60-100km (night side); lightning search (night side); mesospheric sounding; search for variations related to surface/atmosphere interaction, dynamics, meteorology, and volcanism; temperature mapping of the surface, search for hot spots related to volcanic activity; search for seismic waves from propagation of acoustic waves amplified in the mesosphere. This mission would give us a great opportunity for an extensive observation of Venus after the first attempts of imaging spectrometry performed by NIMS/Galileo and VIMS/Cassini whose flybys gave us the idea of the powerful of this type of investigation.

  20. Venus Express observations of ULF and ELF waves in the Venus ionosphere: Wave properties and sources

    Science.gov (United States)

    Russell, C. T.; Leinweber, H.; Hart, R. A.; Wei, H. Y.; Strangeway, R. J.; Zhang, T. L.

    2013-11-01

    Electrical activity in a planetary atmosphere enables chemical reactions that are not possible under conditions of local thermodynamic equilibrium. In both the Venus and terrestrial atmospheres, lightning forms nitric oxide. Despite the existence of an inventory of NO at Venus like the Earth’s, and despite observations of the signals expected from lightning at optical, VLF, and ELF frequencies, the existence of Venus lightning still is met with some skepticism. The Venus Express mission was equipped with a fluxgate magnetometer gradiometer system sampling at rates as high as 128 Hz, and making measurements as low as 200 km altitude above the north polar regions of Venus. However, significant noise levels are present on the Venus Express spacecraft. Cleaning techniques have been developed to remove spacecraft interference at DC, ULF, and ELF frequencies, revealing two types of electromagnetic waves, a transverse right-handed guided mode, and a linearly polarized compressional mode. The propagation of both types of signals is sensitive to the magnetic field in ways consistent with propagation from a distant source to the spacecraft. The linearly polarized compressional waves generally are at lower frequencies than the right-handed transverse waves. They appear to be crossing the usually horizontal magnetic field. At higher frequencies above the lower hybrid frequency, waves cannot enter the ionosphere from below when the field is horizontal. The arrival of signals at the spacecraft is controlled by the orientation of the magnetic field. When the field dips into the atmosphere, the higher frequency guided mode above the lower hybrid frequency can enter the ionosphere by propagating along the magnetic field in the whistler mode. These properties are illustrated with examples from five orbits during Venus Express’ first year in orbit. These properties observed are consistent with the linearly polarized compressional waves being produced at the solar wind interface and the transverse guided waves being produced in the atmosphere.

  1. Collapse of Venus' polar thermosphere density as detected by Venus Express.

    Science.gov (United States)

    Rosenblatt, P.; Bruinsma, S.; Müller-Wodarg, I. C. F.; Svedhem, H.; Häusler, B.

    2011-10-01

    The Venus Express (VEX) spacecraft offers the opportunity to probe in-situ the density of the polar atmosphere of Venus at altitude range between 165- 185 km. Two methods have been used to derive the density at dedicated campaigns of the Venus Express Atmospheric Drag Experiment (VExADE). The first method uses the tracking data of the spacecraft to precisely compute the drag acceleration of its motion when passing through the thermosphere at the periapsis pass of its orbit [1]. The second method uses the inertial wheels on board the spacecraft to measure the torque generated by the atmospheric drag during the periapsis pass [2]. Both methods provide reliable and similar estimates of the density at the periapsis pass. The estimated density from the first three campaigns is about 2-3 times lower than the one predicted from available empirical models. It suggests either polar collapse of the thermospheric structure or colder thermospheric temperatures than predicted by the models.

  2. Addressing High-Priority Venus Science Objectives with Orbital and Surface-Based Nuclear Spectroscopy

    Science.gov (United States)

    Lawrence, D. J.; Peplowski, P. N.

    2015-04-01

    We explore the use of gamma-ray and neutron measurements at Venus to address important Venus science questions. Low-resource instrumentation provides high heritage solutions for addressing questions related to Venus' atmosphere and surface.

  3. Dynamics of Venus’ southern polar vortex from over two years of VIRTIS/Venus Express observations

    OpenAIRE

    Luz, David; Berry, David; Peralta, Javier; Piccioni, Giuseppe

    2011-01-01

    Recently, the results of an initial study of the southern 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. 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, detec...

  4. Variability of CO concentrations in the Venus troposphere from Venus Express/VIRTIS using a band ratio technique

    OpenAIRE

    Tsang, CCC; Taylor, FW; Wilson, CF; Liddell, SJ; Irwin, PGJ; Piccioni, G.; Drossart, P.; Calcutt, SB

    2009-01-01

    A fast method is presented for deriving the tropospheric CO concentrations in the Venus atmosphere from near-infrared spectra using the night side 2.3 ?m window. This is validated using the spectral fitting techniques of Tsang et al. [Tsang, C.C.C., Irwin, P.G.J., Taylor, F.W., Wilson, C.F., Drossart, P., Piccioni, G., de Kok, R., Lee, C., Calcutt, S.B., and the Venus Express/VIRTIS Team, 2008a. Tropospheric carbon monoxide concentrations and variability on Venus with Venus Express/VIRTIS-M o...

  5. Coordinated Hubble Space Telescope and Venus Express Observations of Venus' upper cloud deck

    Science.gov (United States)

    Jessup, Kandis Lea; Marcq, Emmanuel; Mills, Franklin; Mahieux, Arnaud; Limaye, Sanjay; Wilson, Colin; Allen, Mark; Bertaux, Jean-Loup; Markiewicz, Wojciech; Roman, Tony; Vandaele, Ann-Carine; Wilquet, Valerie; Yung, Yuk

    2015-09-01

    Hubble Space Telescope Imaging Spectrograph (HST/STIS) UV observations of Venus' upper cloud tops were obtained between 20N and 40S latitude on December 28, 2010; January 22, 2011 and January 27, 2011 in coordination with the Venus Express (VEx) mission. The high spectral (0.27 nm) and spatial (40-60 km/pixel) resolution HST/STIS data provide the first direct and simultaneous record of the latitude and local time distribution of Venus' 70-80 km SO and SO2 (SOx) gas density on Venus' morning quadrant. These data were obtained simultaneously with (a) VEx/SOIR occultation and/or ground-based James Clerk Maxwell Telescope sub-mm observations that record respectively, Venus' near-terminator SO2 and dayside SOx vertical profiles between ?75 and 100 km; and (b) 0.36 ?m VEx/VMC images of Venus' cloud-tops. Updating the (Marcq, E. et al. [2011]. Icarus 211, 58-69) radiative transfer model SO2 gas column densities of ?2-10 ?m-atm and ?0.4-1.8 ?m-atm are retrieved from the December 2010 and January 2011 HST observations, respectively on Venus' dayside (i.e., at solar zenith angles (SZA) < 60°); SO gas column densities of 0.1-0.11 ?m-atm, 0.03-0.31 ?m-atm and 0.01-0.13 ?m-atm are also retrieved from the respective December 28, 2010, January 22, 2011 and January 27, 2011 HST observations. A decline in the observed low-latitude 0.24 and 0.36 ?m cloud top brightness paralleled the declining SOx gas densities. On December 28, 2010 SO2 VMR values ?280-290 ppb are retrieved between 74 and 81 km from the HST and SOIR data obtained near Venus' morning terminator (at SZAs equal to 70° and 90°, respectively); these values are 10× higher than the HST-retrieved January 2011 near terminator values. Thus, the cloud top SO2 gas abundance declined at all local times between the three HST observing dates. On all dates the average dayside SO2/SO ratio inferred from HST between 70 and 80 km is higher than that inferred from the sub-mm the JCMT data above 84 km confirming that SOx photolysis is more efficient at higher altitudes. The direct correlation of the SOx gases provides the first clear evidence that SOx photolysis is not the only source for Venus' 70-80 km sulfur reservoir. The cloud top SO2 gas density is dependent in part on the vertical transport of the gas from the lower atmosphere; and the 0.24 ?m cloud top brightness levels are linked to the density of the sub-micron haze. Thus, the new results may suggest a correlation between Venus' cloud-top sub-micron haze density and the vertical transport rate. These new results must be considered in models designed to simulate and explore the relationship between Venus' sulfur chemistry cycle, H2SO4 cloud formation rate and climate evolution. Additionally, we present the first photochemical model that uniquely tracks the transition of the SO2 atmosphere from steady to non-steady state with increasing SZA, as function of altitude within Venus' mesosphere, showing the photochemical and dynamical basis for the factor of ?2 enhancements in the SOx gas densities observed by HST near the terminator above that observed at smaller SZA. These results must also be considered when modeling the long-term evolution of Venus' atmospheric chemistry and dynamics.

  6. Hydrogen halides measurements in the Venus mesosphere retrieved from SOIR on board Venus express

    Science.gov (United States)

    Mahieux, A.; Wilquet, V.; Vandaele, A. C.; Robert, S.; Drummond, R.; Chamberlain, S.; Grau Ribes, A.; Bertaux, J. L.

    2015-08-01

    The SOIR instrument on board Venus Express regularly sounds the Venus mesosphere using the solar occultation technique. Densities and volume mixing ratios of HCl and HF are measured in the 70-115 km and 75-110 km altitude region respectively, at the Venus terminator. All latitudes from pole to pole are covered. In this work, we study the latitude and long-term variations of the volume mixing ratio (VMR) of HCl, and the long-term time trend of HF, from June 2006 to February 2013. This period of time corresponds to approximately eleven Venusian years. Large variations in the VMR profiles are observed, mostly on the short-term. Both hydrogen halides present unforeseen positive exponential gradients of their VMR with pressure, which shows time and latitude variations. Long-term trends on the whole period of the HCl VMR are also observed at certain pressure levels in the equatorial and polar regions. HF also presents a time dependence of its VMR at certain pressure levels. Results are compared to previous HCl and HF VMR observations. The ability of SOIR to target both H35Cl and H37Cl isotopologues has also been investigated. Numerous concomitant density profiles lead to the determination of the 37Cl/35Cl isotopic ratio on Venus, found to be equal to 0.34±0.13, which is compatible with the value found on Earth.

  7. Venus

    Science.gov (United States)

    Martin, Paula; Stofan, Ellen

    2004-01-01

    On 8 June 2004 Venus will pass in front of the Sun as seen from the Earth. Many people will watch the small dark dot cross the solar disk, but will they stop to think about Venus as a real place? In this article we discuss what we know about Venus, what it looks like from orbit, what you might see if you were on the surface and future plans for…

  8. 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.

  9. Spectral inventory of the SOIR spectra onboard Venus Express

    Science.gov (United States)

    Robert, Séverine; Mahieux, Arnaud; Wilquet, Valérie; Drummond, Rachel; Carine Vandaele, Ann

    2013-04-01

    The set of spectra recorded by the SOIR instrument on board Venus Express have been carefully studied from a spectroscopic point of view. The SOIR instrument combines an echelle spectrometer and an Acousto-Optical Tunable Filter for order selection. It performs solar occultation measurements in the IR region (2.2 - 4.4 ?m) at a resolution of 0.10 - 0.24 cm-1 [1]. The wavelength range probed by SOIR allows a detailed chemical inventory of the Venus atmosphere above the cloud layer (65 to 180 km) with emphasis on the vertical distribution of gases (CO2, CO, H2O, HCl, HF, ...). The sensitivity of the SOIR instrument and the high concentration of CO2 on Venus, coupled with the long absorption paths sounded during solar occultations, enable us to detect weak absorption bands of rare CO2 isotopologues [2, 3]. The spectra are analysed using ASIMAT, an in-house Matlab algorithm [4]. It is based on the Optimal Estimation Method [5] with the aim to deduce physical characteristics (densities, temperature) of the Venus atmosphere from the spectra recorded using SOIR. The spectra were fitted using HITRAN 2008 [6]. A tool of automatic assignment was developed and applied to each spectrum leading to the creation of the wavenumber list of each line visible in the SOIR spectra. The tools used to calibrate the spectra, to characterize the residuals and to produce the line list will be described extensively for a selected number of orbits. References 1. Nevejans, D., et al., Compact high-resolution space-borne echelle grating spectrometer with AOTF based on order sorting for the infrared domain from 2.2 to 4.3 micrometer. Applied Optics, 2006. 45(21): p. 5191-5206. 2. Wilquet, V., et al., Line parameters for the 01111-00001 band of 12C16O18O from SOIR measurements of the Venus atmosphere. J. Quant. Spectrosc. Radiat. Transfer, 2008. 109: p. 895-905. 3. Robert, S., et al., Assignment and rotational analysis of new absorption bands of carbon dioxide isotopologues in Venus spectra. J. Quant. Spectrosc. Radiat. Transfer, 2013. 114: p. 29-41. 4. Mahieux, A., et al., Densities and temperatures in the Venus mesosphere and lower thermosphere retrieved from SOIR onboard Venus Express: Retrieval technique. J. Geophys. Res., 2010. 115(E12014): p. 10.1029/2010JE003589. 5. Rodgers, C., Inverse methods for atmospheric sounding: Theory and practice. World Scientific, ed. N.J. Hackensack. 2000: University of Oxford. 6. Rothman, L.S., et al., The HITRAN 2008 molecular spectroscopic database. J. Quant. Spectrosc. Radiat. Transfer, 2009. 110(9-10): p. 533-572.

  10. Rotational temperatures of Venus upper atmosphere as measured by SOIR on board Venus Express

    Science.gov (United States)

    Mahieux, A.; Vandaele, A. C.; Robert, S.; Wilquet, V.; Drummond, R.; López Valverde, M. A.; López Puertas, M.; Funke, B.; Bertaux, J. L.

    2015-08-01

    SOIR is a powerful infrared spectrometer flying on board the Venus Express spacecraft since mid-2006. It sounds the Venus atmosphere above the cloud layer using the solar occultation technique. In the recorded spectra, absorption structures from many species are observed, among them carbon dioxide, the main constituent of the Venus atmosphere. Previously, temperature vertical profiles were derived from the carbon dioxide density retrieved from the SOIR spectra by assuming hydrostatic equilibrium. These profiles show a permanent cold layer at 125 km with temperatures of ~100 K, surrounded by two warmer layers at 90 and 140 km, reaching temperatures of ~200 K and 250-300 K, respectively. In this work, temperature profiles are derived from the SOIR spectra using another technique based on the ro-vibrational structure of carbon dioxide observed in the spectra. The error budget is extensively investigated. Temperature profiles obtained by both techniques are comparable within their respective uncertainties and they confirm the vertical structure previously determined from SOIR spectra.

  11. Venus mesospheric sulfur dioxide measurement retrieved from SOIR on board Venus Express

    Science.gov (United States)

    Mahieux, A.; Vandaele, A. C.; Robert, S.; Wilquet, V.; Drummond, R.; Chamberlain, S.; Belyaev, D.; Bertaux, J. L.

    2015-08-01

    SOIR on board Venus Express sounds the Venus upper atmosphere using the solar occultation technique. It detects the signature from many Venus atmosphere species, including those of SO2 and CO2. SO2 has a weak absorption structure at 4 ?m, from which number density profiles are regularly inferred. SO2 volume mixing ratios (VMR) are calculated from the total number density that are also derived from the SOIR measurements. This work is an update of the previous work by Belyaev et al. (2012), considering the SO2 profiles on a broader altitude range, from 65 to 85 km. Positive detection VMR profiles are presented. In 68% of the occultation spectral datasets, SO2 is detected. The SO2 VMR profiles show a large variability up to two orders of magnitude, on a short term time scales. We present mean VMR profiles for various bins of latitudes, and study the latitudinal variations; the mean latitude variations are much smaller than the short term temporal variations. A permanent minimum showing a weak latitudinal structure is observed. Long term temporal trends are also considered and discussed. The trend observed by Marcq et al. (2013) is not observed in this dataset. Our results are compared to literature data and generally show a good agreement.

  12. On the magnetic configuration near Venus: EOF modeling and statistical analyses based on Venus Express measurements

    Science.gov (United States)

    He, M.; Vogt, J.; Zhang, T.; Rong, Z.

    2015-10-01

    More than 2000 orbits of Venus Express magnetic field measurementsare used for Orthogonal Function (EOF) analysis to study and model the magnetic environment over the Venus northern polar cap. The modeling results extract the dominant coherent variations, separate the known physical phenomenaon different EOFs and identify the most important driving factors. EOF1 represents the magnetic draping configuration of IMF Bz component whereas EOF2 is controlled by IMF By component and presents the draping and piling-up of IMF By. Besides, our analysis illustrates an asymmetric response of magnetic By component to IMF between the ±E hemispheres,constricted over the terminator (about 90-93° Solar Zeniths Angle) below 300km altitude. The magnetic By component increases as the increase of the parallel IMF component in the +E hemisphere but antiparallel IMF component the -E. To detail the asymmetry, we define a new coordinate system referring to the Sun-Venus-VEX plane which is more robust in comparison with the SVE or VSO coordinate system, and develop a new data averaging method which balances the significance and resolution of data representation.Our result suggests the asymmetry is neither resulting from a large plane of current nor a line of current.

  13. 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 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.

  14. 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.

  15. Investigation of air temperature on the nightside of Venus derived from VIRTIS-H on board Venus-Express

    OpenAIRE

    Migliorini, A.; D. Grassi; Montabone, L.; Lebonnois, S.; Drossart, P.; Piccioni, G.

    2012-01-01

    We present the spatial distribution of air temperature on Venus' night side, as observed by the high spectral resolution channel of VIRTIS (Visible and Infrared Thermal Imaging Spectrometer), or VIRTIS-H, on board the ESA mission Venus Express. The present work extends the investigation of the average thermal fields in the northern hemisphere of Venus, by including the VIRTIS-H data. We show results in the pressure range of 100-4. mbar, which corresponds to the altitude range of 65-80. km. Wi...

  16. First Results from Venus Express Aerobraking Campaign

    Science.gov (United States)

    Svedhem, Håkan

    After a very successful mission orbiting Venus for more than 8 years, slowly the fuel is running out and the spacecraft will inevitably end up in the hot and acid atmosphere of the planet. Before this will happen we are taking the opportunity to dip down to around 130 km in a controlled manner in order to make detailed in situ investigations of this for remote sensing instruments difficult to access region. The spacecraft will use an aerobraking technique which maximizes the atmospheric drag by placing the solar panels perpendicular to the flight direction and will benefit from the inherent dynamically stable configuration this will provide. The on board accelerometers will give a direct measurement of the deceleration which in turn is directly proportional to the local atmospheric density. This will provide an excellent way to study both the total density profile and small scale density variations in the region of the pericentre. At the time of this campaign the pericentre will be located near the terminator at about 75 degrees Northern latitude. Aerobraking is a very efficient method of reducing the pericentre velocity and thereby reducing the apocentre altitude and the orbital period. Using this technique missions otherwise not feasible due to mass and fuel constraints can be enabled. This will be the first time an ESA spacecraft will be used for aerobraking and therefore it is run on an experimental basis as only limited resources are available. The so called “walk-in” phase will start at 190 km altitude on 17 May and the campaign ends on 11 July. Depending on the atmospheric densities encountered the orbital period may be reduced with up to 30 minutes. This presentation will report on the initial findings from this aerobraking campaign.

  17. Venus cloud morphology: monitoring by the VMC/ Venus Express camera continued

    Science.gov (United States)

    Titov, Dmitrij V.; Markiewicz, Wojciech J.; Ignatiev, Nikolay I.

    2013-04-01

    Venus Monitoring Camera (VMC) onboard the ESA Venus Express spacecraft continues investigations of the cloud morphology in ultraviolet, visible, and near-IR spectral bands with spatial resolution from 50 km at apocentre to a few hundred of meters at pericentre. The imaging shows strong spatial and latitudinal variations of the cloud pattern and significant temporal changes on all scales. The camera discovered new cloud features like bright "lace clouds" and cloud columns at the low latitudes, dark polar oval and narrow circular and spiral "grooves" in the polar regions, different types of waves at the high latitudes. The VMC observations revealed detailed structure of the sub-solar region and the afternoon convective wake, the bow-shape features and convective cells, the mid-latitude transition region and the "polar cap". Besides the cloud morphology the VMC observations have important implications for the problems of the unknown UV absorber, microphysical processes, dynamics and radiative energy balance at the cloud tops. We will present an overview of the recent VMC observations and compare them to the earlier results.

  18. Aerobraking at Venus: A science and technology enabler

    Science.gov (United States)

    Hibbard, Kenneth; Glaze, Lori; Prince, Jill

    2012-04-01

    Venus remains one of the great unexplored planets in our solar system, with key questions remaining on the evolution of its atmosphere and climate, its volatile cycles, and the thermal and magmatic evolution of its surface. One potential approach toward answering these questions is to fly a reconnaissance mission that uses a multi-mode radar in a near-circular, low-altitude orbit of ?400 km and 60-70° inclination. This type of mission profile results in a total mission delta-V of ?4.4 km/s. Aerobraking could provide a significant portion, potentially up to half, of this energy transfer, thereby permitting more mass to be allocated to the spacecraft and science payload or facilitating the use of smaller, cheaper launch vehicles.Aerobraking at Venus also provides additional science benefits through the measurement of upper atmospheric density (recovered from accelerometer data) and temperature values, especially near the terminator where temperature changes are abrupt and constant pressure levels drop dramatically in altitude from day to night.Scientifically rich, Venus is also an ideal location for implementing aerobraking techniques. Its thick lower atmosphere and slow planet rotation result in relatively more predictable atmospheric densities than Mars. The upper atmosphere (aerobraking altitudes) of Venus has a density variation of 8% compared to Mars' 30% variability. In general, most aerobraking missions try to minimize the duration of the aerobraking phase to keep costs down. These short phases have limited margin to account for contingencies. It is the stable and predictive nature of Venus' atmosphere that provides safer aerobraking opportunities.The nature of aerobraking at Venus provides ideal opportunities to demonstrate aerobraking enhancements and techniques yet to be used at Mars, such as flying a temperature corridor (versus a heat-rate corridor) and using a thermal-response surface algorithm and autonomous aerobraking, shifting many daily ground activities to onboard the spacecraft. A defined aerobraking temperature corridor, based on spacecraft component maximum temperatures, can be employed on a spacecraft specifically designed for aerobraking, and will predict subsequent aerobraking orbits and prescribe apoapsis propulsive maneuvers to maintain the spacecraft within its specified temperature limits. A spacecraft specifically designed for aerobraking in the Venus environment can provide a cost-effective platform for achieving these expanded science and technology goals.This paper discusses the scientific merits of a low-altitude, near-circular orbit at Venus, highlights the differences in aerobraking at Venus versus Mars, and presents design data using a flight system specifically designed for an aerobraking mission at Venus. Using aerobraking to achieve a low altitude orbit at Venus may pave the way for various technology demonstrations, such as autonomous aerobraking techniques and/or new science measurements like a multi-mode, synthetic aperture radar capable of altimetry and radiometry with performance that is significantly more capable than Magellan.

  19. Water vapor near Venus cloud tops from VIRTIS-H/Venus express observations 2006-2011

    Science.gov (United States)

    Cottini, V.; Ignatiev, N. I.; Piccioni, G.; Drossart, P.

    2015-08-01

    This work aims to give a summary of the water vapor at the cloud top of Venus atmosphere using the complete set of observations made using high spectral resolution channel (-H) of Visible and Infrared Thermal Imaging Spectrometer (VIRTIS), on board the ESA Venus Express orbiter, to measure the cloud top altitude and the water vapor abundance near this level. An initial analysis of these measurements by Cottini et al. (2012) was limited to data in 140 orbits in the period 2007-2008. These observations were limited to the Northern hemisphere due to observational geometry in this early part of the mission. In the present paper, the analysis is extended to a larger dataset covering the years 2006-2011, significantly improving the latitudinal coverage. Altitude of the cloud tops, corresponding to unit optical depth at a wavelength of 2.5 ?m, is equal to 69±1 km at low latitudes, and decreases toward the pole to 62-64 km. The water vapor abundance is equal to 3±1 ppm in low latitudes and it increases reaching a maximum of 5±2 ppm at 70-80° of latitude in both hemispheres, with a sharp drop in the polar regions. This can be explained by the specific dynamics of the atmosphere of Venus affecting the distribution of water vapor such as the transfer of water vapor in the Hadley cell and the dynamic in the polar vortex. The average height of the cloud tops and the H2O near this level are symmetric with respect to the equator. As a function of local solar time, the water vapor shows no particular dependence, and the cloud tops exhibit just a weak maximum around noon. Over 5 years of observations the average values of the cloud top altitude and the water vapor were quite stable in low and middle latitudes, while in high latitudes both quantities in 2009-2011 years are systematically higher than in 2006-2008. Short period variations increasing with latitude are observed, from approximately less than ±1 km for cloud tops and ±1 ppm for water vapor in low latitudes to, respectively, ±2 km and ±2 ppm in high latitudes. As a rule there is no correlation between variations of the cloud top altitude, the water vapor content, and the UV brightness. However, numerous examples can be found when UV dark features, with a characteristic size of a few degrees of latitude (several hundred kilometers), coincide with regions of higher cloud tops.

  20. Study and Implementation of the End-to-End Data Pipeline for the Virtis Imaging Spectrometer Onbaord Venus Express: "From Science Operations Planning to Data Archiving and Higher Lever Processing"

    Science.gov (United States)

    Cardesín Moinelo, Alejandro

    2010-04-01

    This PhD Thesis describes the activities performed during the Research Program undertaken for two years at the Istituto Nazionale di AstroFisica in Rome, Italy, as active member of the VIRTIS Technical and Scientific Team, and one additional year at the European Space Astronomy Center in Madrid, Spain, as member of the Mars Express Science Ground Segment. This document will show a study of all sections of the Science Ground Segment of the Venus Express mission, from the planning of the scientific operations, to the generation, calibration and archiving of the science data, including the production of valuable high level products. We will present and discuss here the end-to-end diagram of the ground segment from the technical and scientific point of view, in order to describe the overall flow of information: from the original scientific requests of the principal investigator and interdisciplinary teams, up to the spacecraft, and down again for the analysis of the measurements and interpretation of the scientific results. These scientific results drive to new and more elaborated scientific requests, which are used as feedback to the planning cycle, closing the circle. Special attention is given here to describe the implementation and development of the data pipeline for the VIRTIS instrument onboard Venus Express. During the research program, both the raw data generation pipeline and the data calibration pipeline were developed and automated in order to produce the final raw and calibrated data products from the input telemetry of the instrument. The final raw and calibrated products presented in this work are currently being used by the VIRTIS Science team for data analysis and are distributed to the whole scientific community via the Planetary Science Archive. More than 20,000 raw data files and 10,000 calibrated products have already been generated after almost 4 years of mission. In the final part of the Thesis, we will also present some high level data processing methods developed for the Mapping channel of the VIRTIS instrument. These methods have been implemented for the generation of high level global maps of measured radiance over the whole planet, which can then be used for the understanding of the global dynamics and morphology of the Venusian atmosphere. This method is currently being used to compare different emissions probing at different altitudes from the low cloud layers up to the upper mesosphere, by using the averaged projected values of radiance observed by the instrument, such as the near infrared windows at 1.7 ?m and 2.3?m, the thermal region at 3.8?m and 5?m plus the analysis of particular emissions in the night and day side of the planet. This research has been undertaken under guidance and supervision of Giuseppe Piccioni, VIRTIS co-Principal Investigator, with support of the entire VIRTIS technical and scientific team, in particular of the Archiving team in Paris (LESIA-Meudon). The work has also been done in close collaboration with the Science and Mission Operations Centres in Madrid and Darmstadt (European Space Agency), the EGSE software developer (Techno Systems), the manufacturer of the VIRTIS instrument (Galileo Avionica) and the developer of the VIRTIS onboard software (DLR Berlin). The outcome of the technical and scientific work presented in this thesis is currently being used by the VIRTIS team to continue the investigations on the Venusian atmosphere and plan new scientific observations to improve the overall knowledge of the solar system. At the end of this document we show some of the many technical and scientific contributions, which have already been published in several international journals and conferences, and some articles of the European Space Agency used for public outreach.

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

    OpenAIRE

    Peralta, Javier; Luz, David; Berry, David; Piccioni, Giuseppe; Drossart, Pierre; Hueso, Ricardo; Sánchez-Lavega, Agustin

    2011-01-01

    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 ...

  2. Ionospheric Modulation of Venus Express Lightning Detection Rates

    Science.gov (United States)

    Hart, Richard A.; Russell, Christopher T.; Zhang, Tielong

    2015-11-01

    Venus Express completed its nearly 9 year campaign at Earth’s sister planet in late 2014. During this period the onboard fluxgate magnetometer collected data up to 64 Hz in frequency while near periapsis. This is the expected frequency range for lightning-generated whistler-mode waves at Venus, between the local electron and ion gyrofrequencies. These waves are right-hand circularly polarized and are guided by the local magnetic field. When the Venusian ionopause is low enough in altitude to reside in the collisional region, the interplanetary magnetic field can get carried down with the ions and magnetize the lower ionosphere. As the field travels towards the terminator it gains a radial component, enabling whistlers to reach higher altitudes and be detected by the spacecraft. The mission covered almost an entire solar cycle and frequently observed a magnetized ionosphere during the solar minimum phase when the ionosphere was weak due to reduced incident EUV. Detection was most common at 250 km altitude where the waves travel more slowly due to reduced ionospheric density. In response they increase in amplitude in order to conserve magnetic energy flux. Here, we examine the changes in the ionospheric properties associated with the evolution of the solar cycle and the rate of detection of these lightning-generated signals.

  3. The Venus ground-based image Active Archive: a database of amateur observations of Venus in ultraviolet and infrared light

    OpenAIRE

    Barentsen, Geert; Koschny, Detlef

    2013-01-01

    The Venus ground-based image Active Archive is an online database designed to collect ground-based images of Venus in such a way that they are optimally useful for science. The Archive was built to support ESA's Venus Amateur Observing Project, which utilises the capabilities of advanced amateur astronomers to collect filtered images of Venus in ultraviolet, visible and near-infrared light. These images complement the observations of the Venus Express spacecraft, which canno...

  4. Europe Scores New Planetary Success: Venus Express Enters Orbit around the Hothouse Planet

    Science.gov (United States)

    2006-04-01

    During the next four weeks, the Venus Express probe will perform a series of manoeuvres to reach the scheduled operational orbit for its scientific mission. It will move from its current highly elongated 9-day orbit to a 24-hour polar orbit, culminating at 66,000 km. From this vantage point, the orbiter will conduct an in-depth observation of the structure, chemistry and dynamics of the atmosphere of Venus for at least two Venusian days (486 Earth days). Enigmatic atmosphere From previous missions to Venus as well as observations directly from Earth, we already know that our neighbouring planet is shrouded in a thick atmosphere where extremes of temperature and pressure conditions are common. This atmosphere creates a greenhouse effect of tremendous proportions as it spins around the planet in four days in an unexplained “super-rotation” phenomenon. The mission of Venus Express will be to carry out a detailed characterisation of this atmosphere, using state-of-the-art sensors in order to answer the questions and solve the mysteries left behind by the first wave of explorers. It will also be the first Venus orbiter to conduct optical observations of the surface through “visibility windows” discovered in the infrared spectrum.V The commissioning of the onboard scientific instruments will begin shortly and the first raw data are expected within days. The overall science payload is planned to be fully operational within two months. Europe explores the Solar System With this latest success, ESA is adding another celestial body to its range of solar system studies. ESA also operates Mars Express around Mars, SMART-1 around the Moon and is NASA’s partner on the Cassini orbiter around Saturn. In addition, ESA is also operating the Rosetta probe en route to comet 67P/Churyumov-Gerasimenko. It should reach its target and become the first spacecraft ever to enter orbit around a comet nucleus by 2014. Meanwhile, ESA also plans to complete the survey of our celestial neighbours with the launch of the BepiColombo mission to Mercury in 2013. “With the arrival of Venus Express, ESA is the only space agency to have science operations under way around four planets: Venus, the Moon, Mars and Saturn” underlines Professor David Southwood, the Director of ESA’s science programmes. “We are really proud to deliver such a capability to the international science community.” “To better understand our own planet, we need to explore other worlds in particular those with an atmosphere,” said Jean-Jacques Dordain, ESA Director General. “We’ve been on Titan and we already are around Mars. By observing Venus and its complex atmospheric system, we will be able to better understand the mechanisms that steers the evolution of a large planetary atmosphere and the change of climates. In the end, it will help us to get better models of what is actually going on in our own atmosphere, for the benefit of all Earth citizens.” State-of-the-art science package Venus Express was developed for ESA by a European industrial team led by EADS Astrium incorporating 25 main contractors from 14 European countries. Its design is derived from that of its highly successful predecessor, Mars Express, and its payload accommodates seven instruments including upgraded versions of three instruments developed for Mars Express and two for Rosetta. The PFS spectrometer will determine the temperature and composition profile of the atmosphere at very high resolution. It will also monitor the surface temperature and search for hot spots from possible volcanic activity. The UV/infrared SpicaV/SOIR spectrometer and the VeRa radioscience experiment will probe the atmosphere by observing the occultation of distant starts or the fading of radio signals on the planetary limb. SpicaV/SOIR will be particularly looking for traces of water molecules, molecular oxygen and sulphur compounds, which are suspected to exist in the atmosphere of Venus. The Virtis spectrometer will map the different layers of the atmosphere and provide imagery of the cloud systems at multipl

  5. 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.

  6. Interplanetary Coronal Mass Ejections observed by MESSENGER and Venus Express

    CERN Document Server

    Good, S W

    2015-01-01

    Interplanetary coronal mass ejections (ICMEs) observed by the MESSENGER (MES) and Venus Express (VEX) spacecraft have been catalogued and analysed. The ICMEs were identified by a relatively smooth rotation of the magnetic field direction consistent with a flux rope structure, coinciding with a relatively enhanced magnetic field strength. A total of 35 ICMEs were found in the surveyed MES data (primarily from March 2007 to April 2012), and 84 ICMEs in the surveyed VEX data (from May 2006 to December 2013). The ICME flux rope configurations have been determined. Ropes with northward leading edges were about four times more common than ropes with southward leading edges, in agreement with a previously established solar cycle dependence. Ropes with low inclinations to the solar equatorial plane were about four times more common than ropes with high inclinations, possibly an observational effect. Left and right-handed ropes were observed in almost equal numbers. In addition, data from MES, VEX, STEREO-A, STEREO-B ...

  7. Dayside temperatures in the Venus upper atmosphere from Venus Express/VIRTIS nadir measurements at 4.3 ?m

    Science.gov (United States)

    Peralta, J.; López-Valverde, M. A.; Gilli, G.; Piccialli, A.

    2016-01-01

    In this work, we analysed nadir observations of atmospheric infrared emissions carried out by VIRTIS, a high-resolution spectrometer on board the European spacecraft Venus Express. We focused on the ro-vibrational band of CO2 at 4.3 ?m on the dayside, whose fluorescence originates in the Venus upper mesosphere and above. This is the first time that a systematic sounding of these non-local thermodynamic equilibrium (NLTE) emissions has been carried out in Venus using this geometry. As many as 143,218 spectra have been analysed on the dayside during the period 14/05/2006 to 14/09/2009. We designed an inversion method to obtain the atmospheric temperature from these non-thermal observations, including a NLTE line-by-line forward model and a pre-computed set of spectra for a set of thermal structures and illumination conditions. Our measurements sound a broad region of the upper mesosphere and lower thermosphere of Venus ranging from 10-2-10-5 mb (which in the Venus International Reference Atmosphere, VIRA, is approximately 100-150 km during the daytime) and show a maximum around 195 ± 10 K in the subsolar region, decreasing with latitude and local time towards the terminator. This is in qualitative agreement with predictions by a Venus Thermospheric General Circulation Model (VTGCM) after a proper averaging of altitudes for meaningful comparisons, although our temperatures are colder than the model by about 25 K throughout. We estimate a thermal gradient of about 35 K between the subsolar and antisolar points when comparing our data with nightside temperatures measured at similar altitudes by SPICAV, another instrument on Venus Express (VEx). Our data show a stable temperature structure through five years of measurements, but we also found episodes of strong heating/cooling to occur in the subsolar region of less than two days. The table with numerical data and averaged temperatures displayed in Fig. 7A provided as a CSV data file is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/585/A53

  8. Update of the Venus density and temperature profiles at high altitude measured by SOIR on board Venus Express

    Science.gov (United States)

    Mahieux, A.; Vandaele, A. C.; Bougher, S. W.; Drummond, R.; Robert, S.; Wilquet, V.; Chamberlain, S.; Piccialli, A.; Montmessin, F.; Tellmann, S.; Pätzold, M.; Häusler, B.; Bertaux, J. L.

    2015-08-01

    The SOIR instrument on board Venus Express regularly sounds the Venus atmosphere using the solar occultation technique. The density and temperature profiles are inferred from SOIR spectra recorded in the infrared. The method has been described in a previous publication (Mahieux et al., 2012. J. Geophys. Res. 117. doi:10.1029/2012JE004058.). This paper is devoted to the update of the VAST (Venus Atmosphere from SOIR measurements at the Terminator) compilation that was initiated in the above cited work, which gives the mean CO2 number density and temperature profiles for different latitude bins. The method has been improved and has been applied to more data. The new compilation which is given on the same latitudinal grid now distinguishes between the two sides of the terminator. The compilation also confirms the main thermal layering characteristics that were identified in the earlier version: the succession of a warm layer (230±30 K, 1-? standard deviation) at a pressure level of 3.2×10-7 mbar (~140 km), a very cold layer (125±32 K) at 2.5×10-5 mbar (~123 km), a warm layer (204±17 K) at 0.01 mbar (~102 km) and finally a colder layer at 0.4 mbar (171±34 K, ~87 km). The layering of all the temperature profiles is explained by radiative rather than dynamical processes. The temporal temperature variation is larger than the mean latitudinal temperature variation. VAST is compared with temperature profiles obtained from other Venus Express instruments, VeRa and SPICAV-UV, and ground based measurements.

  9. Optical properties of the Venus upper clouds from the data obtained by Venus Monitoring Camera on-board the Venus Express

    Science.gov (United States)

    Shalygina, O. S.; Petrova, E. V.; Markiewicz, W. J.; Ignatiev, N. I.; Shalygin, E. V.

    2015-08-01

    During more than 6 years of the Venus Express (VEx) mission, the Venus Monitoring Camera (VMC) took around 300 000 images in four channels covering almost all the latitudes, including night and day sides. Here we give an overview of the VMC data and summarize results of retrievals of the optical properties of the Venus upper clouds. The in-flight characterization and calibration of VMC are also described. We model the phase dependence of brightness (phase range ? = 0 - 140 °) retrieved from the dayside images obtained in NIR1 VMC channel at various latitudes (30°N-60°S) and local solar times (6-18 h). The radiative transfer calculations were performed for the plane-parallel atmospheric layers, and the Mie theory was used for the calculations of the single scattering phase functions of the cloud aerosols. The size distribution of cloud particles and their refractive index were estimated for each of the regions observed. These retrievals show some temporal and spatial variations. In general, the particles at low latitudes are somewhat larger than in the regions closer to the southern pole (Reff = 1.2 - 1.4 ?mversus 0.9 - 1.05 ?m). At latitudes 40°S-60°S the refractive index is usually smaller than in the other regions (mr = 1.44 - 1.45versus 1.45-1.47 with sporadic spikes of up to 1.49). The retrievals robustly show presence of particles with a radius of about Reff = 0.9 ?m in the clouds and/or the haze above them in these mid-latitudes. Small submicron (Reff = 0.23 ?m) particles are detected mostly in the morning.

  10. The relationship between mesoscale circulation and cloud morphology at the upper cloud level of Venus from VMC/Venus Express

    Science.gov (United States)

    Patsaeva, M. V.; Khatuntsev, I. V.; Patsaev, D. V.; Titov, D. V.; Ignatiev, N. I.; Markiewicz, W. J.; Rodin, A. V.

    2015-08-01

    The Venus Monitoring Camera (VMC) acquired a set of ultraviolet (UV) images during the Venus Express mission unprecedented in its duration from May 2006 to September 2013. Here we present the results of digital tracking of the cloud features in the upper cloud layer at latitudes 25-75°S using images from 257 orbits with the best spatial coverage. The method relies on analysis of correlations between pairs of UV images separated in time. The bulk of data processed allows us to clarify the reasons why the mid-latitude jet is not always present in latitudinal wind profiles. Comparing VMC images with wind velocity fields we found a relationship between cloud morphology at middle latitudes and the circulation. The vector field in middle latitudes depends on the presence of a contrast global streak in the cloud morphology tilted with respect to latitude circles. The angle of the flow deflection (the angle between the wind velocity and latitudinal circles) and the difference of the zonal velocity on the opposite sides of the streak are in direct relationship to the angle between the streak and latitude circles. During such orbits the jet bulge does not appear in the latitudinal profile of the zonal wind component. Otherwise a zonal flow with small changes of the meridional velocity dominates in middle latitudes and manifests itself as a jet bulge. The relationship between the cloud cover morphology and circulation peculiarities can be attributed to the motion of global cloud features, like the Y-feature. We prepared plots of zonal and meridional velocities averaged with respect to the entire observation period. The average zonal velocity has a diurnal maximum at 15:00 local solar time and at 40°S. The meridional velocity reaches its maximum between 13:00 and 16:00 and at 50°S. The velocities obtained by the digital method are in good agreement with results of the visual method in the middle latitudes published earlier by Khatuntsev et al. (2013).

  11. Venus Phasing.

    Science.gov (United States)

    Riddle, Bob

    1997-01-01

    Presents a science activity designed to introduce students to the geocentric and heliocentric models of the universe. Helps students discover why phase changes on Venus knocked Earth out of the center of the universe. (DKM)

  12. Distribution of sulphuric acid aerosols in the clouds and upper haze of Venus using Venus Express VAST and VeRa temperature profiles

    Science.gov (United States)

    Parkinson, Christopher D.; Gao, Peter; Schulte, Rick; Bougher, Stephen W.; Yung, Yuk L.; Bardeen, Charles G.; Wilquet, Valérie; Vandaele, Ann Carine; Mahieux, Arnaud; Tellmann, Silvia; Pätzold, Martin

    2015-08-01

    Observations from Pioneer Venus and from SPICAV/SOIR aboard Venus Express (VEx) have shown the upper haze (UH) of Venus to be highly spatially and temporally variable, and populated by multiple particle size modes. Previous models of this system (e.g., Gao et al., 2014. Icarus 231, 83-98), using a typical temperature profile representative of the atmosphere (viz., equatorial VIRA profile), did not investigate the effect of temperature on the UH particle distributions. We show that the inclusion of latitude-dependent temperature profiles for both the morning and evening terminators of Venus helps to explain how the atmospheric aerosol distributions vary spatially. In this work we use temperature profiles obtained by two instruments onboard VEx, VeRa and SPICAV/SOIR, to represent the latitudinal temperature dependence. We find that there are no significant differences between results for the morning and evening terminators at any latitude and that the cloud base moves downwards as the latitude increases due to decreasing temperatures. The UH is not affected much by varying the temperature profiles; however, the haze does show some periodic differences, and is slightly thicker at the poles than at the equator. We also find that the sulphuric acid "rain" seen in previous models may be restricted to the equatorial regions of Venus, such that the particle size distribution is relatively stable at higher latitudes and at the poles.

  13. MESSENGER and Venus Express Observations of the Near-tail of Venus: Magnetic Flux Transport, Current Sheet Structure, and Flux Rope Formation

    Science.gov (United States)

    Slavin, James A.; Boardsen, S. A.; Sarantos, M.; Acuna, M. H.; Anderson, B. J.; Barabash, S.; Benna, M.; Fraenz, M.; Gloeckler, G.; Gold, R. E.; Ho, G. C.; Korth, H.; Krimigis, S. M.; McNutt, R. L., Jr.; Raines, J. M.; Solomon, S. C.; Zhang, T.-L.; Zurbuchen, T. H.

    2008-01-01

    At 23:08 UT on 5 June 2007 the MESSENGER spacecraft reached its closest approach altitude (338 km) during its second flyby of Venus en route to its 2011 orbit insertion at Mercury. Whereas no measurements were collected during MESSENGER'S first Venus flyby in October 2006, the Magnetometer (MAG) and the Energetic Particle and Plasma Spectrometer (EPPS) operated successfully throughout this second encounter. Venus provides the solar system's best example to date of a solar wind - ionosphere planetary interaction. We present MESSENGER observations of the near-tail of Venus with emphasis on determining the time scales for magnetic flux transport, the structure of the cross-tail current sheet at very low altitudes (approx. 300 to 1000 km), and the nature and origin of a magnetic flux rope observed in the current sheet. The availability of the simultaneous Venus Express upstream measurements provides a unique opportunity to examine the influence of solar wind plasma and interplanetary magnetic field conditions on this planet's solar wind interaction at solar minimum.

  14. 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, J.-L.; Khatunstsev, I. V.; Hauchecorne, A.; Markiewicz, W.; Marcq, E.; Lebonnois, S.; Patsaeva, M. V.; Turin, A. V.

    2015-10-01

    Based on the analysis of UV images (at 365 nm) of Venus cloud top collected with VMC camera on board Venus Express[4,5], it is found that the zonal wind speed south of the equator (from 5°S to 15°s) shows a conspicuous variation with geographic longitude of Venus, correlated with underlying relief of Aphrodite Terra. 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. The cloud albedo map at 365 nm varies also in longitude and latitude, perhaps the result of increased vertical mixing associated to wave breaking, and decreased abundance of the UV absorber which makes the contrast in images.

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

    Science.gov (United States)

    Zhang, Su-Jun; Jian, Nian-Chuan; Li, Jin-Ling; Ping, Jin-Song; Chen, Cong-Yan; Zhang, Ke-Fei

    2015-09-01

    Electron density profiles of Venus' ionosphere are inverted from the Venus Express (VEX) one-way open-loop radio occultation experiments carried out by the Shanghai 25 m antenna from November 2011 to January 2012 at solar maximum conditions and by the 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 the Shanghai station, shows a single peak near 147 km with a peak density of about 2 × 104 cm?3 at a solar zenith angle of 94°. As a comparison, the VEX radio science (VeRa) observations at the New Norcia station were also examined, including S- and 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 terms of the profile shape, compared with the X-band data. Generally, the S-band results slightly underestimate the magnitude of the peak density, while the X-band results overestimate it. The discrepancy in the X-band profile is probably due to the relatively larger unmodeled orbital errors. It is also expected that the ionopause height is sensitive to the solar wind dynamical pressure in high and intermediate solar activities, usually in the range of 200–1000 km on the dayside and much higher on the nightside. Structural variations (“bulges” and fluctuations) can be found in the electron density profiles during intermediate solar activity, which may be caused by the interaction of the solar wind with the ionosphere. Considerable ionizations can be observed in Venus' nightside ionosphere, which are unexpected for the Martian nightside ionosphere in most cases.

  16. Densities inferred from ESA's Venus Express aerobraking campaign at 130 km altitude

    Science.gov (United States)

    Bruinsma, Sean; Marty, Jean-Charles; Svedhem, Håkan; Williams, Adam; Mueller-Wodarg, Ingo

    2015-04-01

    In June-July 2014, ESA performed a planned aerobraking campaign with Venus Express to measure neutral densities above 130 km in Venus' atmosphere by means of the engineering accelerometers. To that purpose, the orbit perigee was lowered to approximately 130 km in order to enhance the atmospheric drag effect to the highest tolerable levels for the spacecraft; the accelerometer resolution and precision were not sufficient at higher altitudes. This campaign was requested as part of the Venus Express Atmospheric Drag Experiment (VExADE). A total of 18 orbits (i.e. days) were processed using the attitude quaternions to correctly orient the spacecraft bus and solar arrays in inertial space, which is necessary to accurately compute the exposed surface in the ram direction. The accelerometer data provide good measurements approximately from 130-140 km altitude; the length of the profiles is about 85 seconds, and they are on the early morning side (LST=4.5) at high northern latitude (70°N-82°N). The densities are a factor 2-3 larger than Hedin's VTS-3 thermosphere model, which is consistent with earlier results obtained via classical precise orbit determination at higher altitudes. Wavelike structures with amplitudes of 20% and more are detected, with wavelengths of about 100-500 km. We cannot entirely rule out that these waves are caused by the spacecraft or due to some unknown instrumental effect, but we estimate this probability to be very low.

  17. 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...

  18. Long-term variations of carbon monoxide and trace species in the Venus troposphere from Venus Express/VIRTIS between 2006-2009

    Science.gov (United States)

    Tsang, Constantine; McGouldrick, Kevin

    2015-11-01

    The understanding of spatial and temporal variations in tropospheric abundances of trace gases such as carbon monoxide is key to understanding the deep atmosphere of Venus. These gases are entrained in the global circulation, as well as being key ingredients to creating the sulfuric acid clouds. Long-term temporal variations of these species across Venus’s disc would be provide key insights into the large-scale circulation and cloud forming processes in the troposphere.The Venus Express spacecraft orbited Venus from April 2006 to December 2014. The VIRTIS instrument is a near-infrared imaging spectrometer that covers 0.3 to 5.0 µm. Nightside thermal emissions at 2.32 µm is sensitive to CO at 35 km. We present long term abundances of CO and other trace abundances as observed by VIRTIS from April 2006 through October 2008, when the MIR channel ceased operations. We compare the methods of Tsang et al. (2009) and Barstow et al. (2012) of deriving CO from band ratios. We will also provide long-term variations of cloud particle sizes. This work is done in conjunction with a study of long-term variations of 1.73 µm thermal emission brightnesses, a proxy of cloud optical depth in the lower atmosphere, with the same data (McGouldrick and Tsang 2015). This work is supported by NASA’s Planetary Mission Data Analysis Program, grant number NNX14AP94G.

  19. Future Exploration of Venus: Opportunities and Challenges

    Science.gov (United States)

    Limaye, Sanjay; Svedhem, Håkan; Nakamura, Masato; Zasova, Ludila; Kiran Kumar, A. S.; Bullock, Mark; Wilson, Colin

    2012-07-01

    The successful fly-by of Venus by Mariner 2 began a half century of planetary exploration. During the last three decades Venus has been explored by orbiters, probes and balloons and even opportunistic fly-bys of VeGA, Galileo, Cassini and MESSENGER spacecraft, and currently ESA's Venus Express orbiter is returning data from its 24-hour highly eccentric polar orbit and JAXA's Akatsuki spacecraft awaits orbit insertion around Venus in 2015 or 2016. Recently the Planetary Science Decadal Survey (2013-2022) conducted by the US National Academies recommended a flagship mission to Venus. The current and future budget scenarios for NASA indicate that such a mission can be realized through international partnerships and collaborations. It is useful therefore to examine the scientific observations of Venus that have not yet been obtained and explore the current technological capabilities that have been developed and can be useful for Venus missions. These include long lived balloons, more efficient electric power generation, Unmanned Aerial Vehicles (UAV), surface seismometry stations and others. NASA's Venus Exploration Analysis Group (VEXAG) provides a forum for the international Venus community to consider international collaborations and scientists are invited to participate in the discussions.

  20. Context images for Venus Express radio occultations: a search for a dynamical-convective origin of cloud-top UV contrasts

    Science.gov (United States)

    Wilson, C.; Roos-Serote, M.; Tellmann, S.; Häusler, B.

    2015-10-01

    In this paper, we present a comparative analysis between data from the Venus Express Radio Science experiment (VeRa) and the Venus Monitoring Camera (VMC) UV channel. We compare the temperature structure derived from VeRa measurements with VMC-UV brightness at that same location, in search for any correlation. In the data analysed to date - which were all obtained at high Southern latitudes - we find no strong correlations, implying that we can find no evidence for a dynamical-convective origin of the UV contrasts at these latitudes. We suggest that the contrasts are formed at lower latitudes, a hypothesis which will be examined by looking at lower-latitude observations.

  1. Venus Exploration opportunities within NASA's Solar System Exploration roadmap

    Science.gov (United States)

    Balint, Tibor; Thompson, Thomas; Cutts, James; Robinson, James

    2006-01-01

    Science goals to understand the origin, history and environment of Venus have been driving international space exploration missions for over 40 years. Past missions include the Magellan and Pioneer-Venus missions by the US; the Venera program by the USSR; and the Vega missions through international cooperation. Furthermore, the US National Research Council (NRC), in the 2003 Solar System Exploration (SSE) Decadal Survey, identified Venus as a high priority target, thus demonstrating a continuing interest in Earth's sister planet. In response to the NRC recommendation, the 2005 NASA SSE Roadmap included a number of potential Venus missions arching through all mission classes from small Discovery, to medium New Frontiers and to large Flagship class missions. While missions in all of these classes could be designed as orbiters with remote sensing capabilities, the desire for scientific advancements beyond our current knowledge - including what we expect to learn from the ongoing ESA Venus Express mission - point to in-situ exploration of Venus.

  2. Six years of Venus winds at the upper cloud level from UV, visible and near infrared observations from VIRTIS on Venus Express

    Science.gov (United States)

    Hueso, R.; Peralta, J.; Garate-Lopez, I.; Bandos, T. V.; Sánchez-Lavega, A.

    2015-08-01

    The Venus Express mission has provided a long-term monitoring of Venus atmosphere including the morphology and motions of its upper clouds. Several works have focused on the dynamics of the upper cloud visible on the day-side in ultraviolet images sensitive to the 65-70 km altitude and in the lower cloud level (50 km height) observable in the night-side of the planet in the 1.74 ?m spectral window. Here we use VIRTIS-M spectral images in nearby wavelengths to study the upper cloud layer in three channels: ultraviolet (360-400 nm), visible (570-680 nm) and near infrared (900-955 nm) extending in time the previous analysis of VIRTIS-M data. The ultraviolet images show relatively well contrasted cloud features at the cloud top. Cloud features in the visible and near infrared images lie a few kilometers below the upper cloud top, have very low contrast and are distinct to the features observed in the ultraviolet. Wind measurements were obtained on 118 orbits covering the Southern hemisphere over a six-year period and using a semi-automatic cloud correlation algorithm. Results for the upper cloud from VIRTIS-M ultraviolet data confirm previous analysis based on images obtained by the Venus Monitoring Camera (Khatuntsev et al. (2013)). At the cloud top the mean zonal and meridional winds vary with local time accelerating towards the local afternoon. The upper branch of the Hadley cell circulation reaches maximum velocities at 45° latitude and local times of 14-16 h. The mean zonal winds in the ultraviolet cloud layer accelerated in the course of the 2006-2012 period at least 15 m s-1. The near infrared and visible images show a more constant circulation without significant time variability or longitudinal variations. The meridional circulation is absent or slightly reversed in near infrared and visible images indicating that, either the Hadley-cell circulation in Venus atmosphere is shallow, or the returning branch of the meridional circulation extends to levels below the cloud level sensed in near infrared images. At subpolar to polar latitudes the three wavelength ranges show similar features and motions which is a signature of small vertical wind shear and may be affected by vertical convergence of both layers. At the clod top level observed in UV images there are signatures of a long-term acceleration of the zonal winds at afternoon hours when comparing zonal winds from the first years of Venus Express observations (2006-2008) to later dates (2009-2012) with a mean acceleration of zonal winds of 17±6 m s-1 between both time periods.

  3. The exploration of Venus

    International Nuclear Information System (INIS)

    This paper is an introduction to a special issue of Space Science Reviews dedicated to the exploration of Venus and the role played by the Pioneer Venus program. The Pioneer Venus program consists of a Multiprobe and Orbiter mission, both to be launched and to encounter Venus in 1978. The evolution of the program is traced from its conception in 1968 as the Goddard Space Flight Center Planetary Explorer Program through its transfer to Ames Research Center in 1971 as Pioneer Venus to the present. (Auth.)

  4. Morphology of the cloud tops as observed by the Venus Express Monitoring Camera

    Science.gov (United States)

    Titov, Dmitrij V.; Markiewicz, Wojciech J.; Ignatiev, Nikolay I.; Song, Li; Limaye, Sanjay S.; Sanchez-Lavega, Agustin; Hesemann, Jonas; Almeida, Miguel; Roatsch, Thomas; Matz, Klaus-Dieter; Scholten, Frank; Crisp, David; Esposito, Larry W.; Hviid, Stubbe F.; Jaumann, Ralf; Keller, Horst U.; Moissl, Richard

    2012-02-01

    Since the discovery of ultraviolet markings on Venus, their observations have been a powerful tool to study the morphology, motions and dynamical state at the cloud top level. Here we present the results of investigation of the cloud top morphology performed by the Venus Monitoring Camera (VMC) during more than 3 years of the Venus Express mission. The camera acquires images in four narrow-band filters centered at 365, 513, 965 and 1010 nm with spatial resolution from 50 km at apocentre to a few hundred of meters at pericentre. The VMC experiment provides a significant improvement in the Venus imaging as compared to the capabilities of the earlier missions. The camera discovered new cloud features like bright "lace clouds" and cloud columns at the low latitudes, dark polar oval and narrow circular and spiral "grooves" in the polar regions, different types of waves at the high latitudes. The VMC observations revealed detailed structure of the sub-solar region and the afternoon convective wake, the bow-shape features and convective cells, the mid-latitude transition region and the "polar cap". The polar orbit of the satellite enables for the first time nadir viewing of the Southern polar regions and an opportunity to zoom in on the planet. The experiment returned numerous images of the Venus limb and documented global and local brightening events. VMC provided almost continuous monitoring of the planet with high temporal resolution that allowed one to follow changes in the cloud morphology at various scales. We present the in-flight performance of the instrument and focus in particular on the data from the ultraviolet channel, centered at the characteristic wavelength of the unknown UV absorber that yields the highest contrasts on the cloud top. Low latitudes are dominated by relatively dark clouds that have mottled and fragmented appearance clearly indicating convective activity in the sub-solar region. At ˜50° latitude this pattern gives way to streaky clouds suggesting that horizontal, almost laminar, flow prevails here. Poleward from about 60°S the planet is covered by almost featureless bright polar hood sometimes crossed by dark narrow (˜300 km) spiral or circular structures. This global cloud pattern can change on time scales of a few days resulting in global and local "brightening events" when the bright haze can extend far into low latitudes and/or increase its brightness by 30%. Close-up snapshots reveal plenty of morphological details like convective cells, cloud streaks, cumulus-like columns, wave trains. Different kinds of small scale waves are frequently observed at the cloud top. The wave activity is mainly observed in the 65-80° latitude band and is in particular concentrated in the region of Ishtar Terra that suggests their possible orographic origin. The VMC observations have important implications for the problems of the unknown UV absorber, microphysical processes, dynamics and radiative energy balance at the cloud tops. They are only briefly discussed in the paper, but each of them will be the subject of a dedicated study.

  5. 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...

  6. 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, Japan, Taiwan and China.

  7. The Venus ground-based image Active Archive: a database of amateur observations of Venus in ultraviolet and infrared light

    CERN Document Server

    Barentsen, Geert

    2013-01-01

    The Venus ground-based image Active Archive is an online database designed to collect ground-based images of Venus in such a way that they are optimally useful for science. The Archive was built to support ESA's Venus Amateur Observing Project, which utilises the capabilities of advanced amateur astronomers to collect filtered images of Venus in ultraviolet, visible and near-infrared light. These images complement the observations of the Venus Express spacecraft, which cannot continuously monitor the northern hemisphere of the planet due to its elliptical orbit with apocentre above the south pole. We present the first set of observations available in the Archive and assess the usability of the dataset for scientific purposes.

  8. Visualization of RelB expression and activation at the single-cell level during dendritic cell maturation in Relb-Venus knock-in mice.

    Science.gov (United States)

    Seki, Takao; Yamamoto, Mami; Taguchi, Yuu; Miyauchi, Maki; Akiyama, Nobuko; Yamaguchi, Noritaka; Gohda, Jin; Akiyama, Taishin; Inoue, Jun-Ichiro

    2015-12-01

    RelB is activated by the non-canonical NF-?B pathway, which is crucial for immunity by establishing lymphoid organogenesis and B-cell and dendritic cell (DC) maturation. To elucidate the mechanism of the RelB-mediated immune cell maturation, a precise understanding of the relationship between cell maturation and RelB expression and activation at the single-cell level is required. Therefore, we generated knock-in mice expressing a fusion protein between RelB and fluorescent protein (RelB-Venus) from the Relb locus. The Relb(Venus) (/) (Venus) mice developed without any abnormalities observed in the Relb(-/-) mice, allowing us to monitor RelB-Venus expression and nuclear localization as RelB expression and activation. Relb(Venus) (/) (Venus) DC analyses revealed that DCs consist of RelB(-), RelB(low) and RelB(high) populations. The RelB(high) population, which included mature DCs with projections, displayed RelB nuclear localization, whereas RelB in the RelB(low) population was in the cytoplasm. Although both the RelB(low) and RelB(-) populations barely showed projections, MHC II and co-stimulatory molecule expression were higher in the RelB(low) than in the RelB(-) splenic conventional DCs. Taken together, our results identify the RelB(low) population as a possible novel intermediate maturation stage of cDCs and the Relb(Venus) (/) (Venus) mice as a useful tool to analyse the dynamic regulation of the non-canonical NF-?B pathway. PMID:26115685

  9. Radial Evolution of a Magnetic Cloud: MESSENGER, STEREO, and Venus Express Observations

    Science.gov (United States)

    Good, S. W.; Forsyth, R. J.; Raines, J. M.; Gershman, D. J.; Slavin, J. A.; Zurbuchen, T. H.

    2015-07-01

    The Solar Orbiter and Solar Probe Plus missions will provide observations of magnetic clouds closer to the Sun than ever before, and it will be good preparation for these missions to make full use of the most recent in situ data sets from the inner heliosphere—namely, those provided by MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) and Venus Express—for magnetic cloud studies. We present observations of the same magnetic cloud made by MESSENGER at Mercury and later by Solar TErrestrial RElations Observatory-B (STEREO-B), while the spacecraft were radially aligned in 2011 November. Few such radial observations of magnetic clouds have been previously reported. Estimates of the solar wind speed at MESSENGER are also presented, calculated through the application of a previously established technique. The cloud's flux rope has been analyzed using force-free fitting; the rope diameter increased from 0.18 to 0.41 AU (corresponding to an {r}{{H}}0.94 dependence on heliocentric distance, rH), and the axial magnetic field strength dropped from 46.0 to 8.7 nT (an {r}{{H}}-1.84 dependence) between the spacecraft, clear indications of an expanding structure. The axial magnetic flux was ˜0.50 nT AU2 at both spacecraft, suggesting that the rope underwent no significant erosion through magnetic reconnection between MESSENGER and STEREO-B. Further, we estimate the change in the cloud's angular width by assuming helicity conservation. It has also been found that the rope axis rotated by 30° between the spacecraft to lie close to the solar equatorial plane at STEREO-B. Such a rotation, if it is a common feature of coronal mass ejection propagation, would have important implications for space weather forecasting.

  10. The CO2 continuum absorption in the 1.10- and 1.18-?m windows on Venus from Maxwell Montes transits by SPICAV IR onboard Venus express

    Science.gov (United States)

    Fedorova, Anna; Bézard, Bruno; Bertaux, Jean-Loup; Korablev, Oleg; Wilson, Colin

    2015-08-01

    One of the difficulties in modeling Venus' nightside atmospheric windows is the need to apply CO2 continuum opacity due to collision-induced CO2 bands and/or extreme far wings of strong allowed CO2 bands. Characterizing the CO2 continuum absorption at near-IR wavelengths as well as searching for a possible vertical gradient of minor species near the surface require observations over different surface elevations. The largest change in altitude occurs during a passage above Maxwell Montes at high northern latitudes. In 2011, 2012 and 2013 the SPICAV instrument aboard the Venus Express satellite performed three sets of observations over Maxwell Montes with variation of surface altitude from -2 to 9 km in the 1.10, 1.18 and 1.28-?m windows. The retrieved CO2 continuum absorption for the 1.10- and 1.18-?m windows varies from 0.29 to 0.66×10-9 cm-1 amagat-2 and from 0.30 to 0.78×10-9 cm-1 amagat-2, respectively, depending on the assumed input parameters. The retrieval is sensitive to possible variations of the surface emissivity. Our values fall between the results of Bézard et al., (2009, 2011) based on VIRTIS-M observations and laboratory measurements by Snels et al. (2014). We can also conclude that the continuum absorption at 1.28 ?m can be constrained below 2.0×10-9 cm-1 amagat-2. Based on the 1.18 ?m window the constant H2O mixing ratio varying from 25.7+1.4-1.2 ppm to 29.4+1.6-1.4 ppm has been retrieved assuming the surface emissivity of 0.95 and 0.6, respectively. No firm conclusion from SPICAV data about the vertical gradient of water vapor content at 10-20 km altitude could be drawn because of low signal-to-noise ratio and uncertainties in the surface emissivity.

  11. 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).

  12. Six-year operation of the Venus Monitoring Camera (Venus Express): spatial and temporal variations of the properties of particles in upper clouds of Venus from the phase dependence of the near-IR brightness

    Science.gov (United States)

    Shalygina, O. S.; Petrova, E. V.; Markiewicz, W. J.

    2015-10-01

    Since May, 2006, the Venus Monitoring Camera (VMC) [1] has been imaging Venus in four narrow spectral channels centered at the wavelengths of 0.365 ?m (UV), 0.513 ?m (VIS), 0.965 ?m (NIR1), and 1.010 ?m (NIR2). It took around 300 000 images in four channels covering almost all the latitudes, including night and day sides. We analyze the whole set of the VMC data processed to October, 2012, i.e. the data from orbits 60 - 2 352 obtained in the phase angle range

  13. Dependence of longitudinal distribution of zonal wind and UV albedo at cloud top level on Venus topography from VMC camera onboard Venus Express

    Science.gov (United States)

    Patsaeva, M.; Khatuntsev, I.; Bertaux, J.-L.; Turin, A.

    2015-10-01

    A set of UV images obtained by the Venus Monitoring Camera (VMC) [3] was processed by manual and digital methods [2]. Analysis of longitude-latitude distribution of the zonal wind for 49,700 (139 orbit) visual and 457,850 (722 orbit) digital individual wind measurements allowed us to find an influence of Venus topography on change of the average zonal wind in latitude range from 5°S to 15°S from -100.9 m/s in the longitude range 200-300° to -83.4 m/s in the range 60-100° [1]. Investigation of other latitude ranges by using a correlation method demonstrates that correlation shift depends on height of the obstacle streamlined by a flow. Dependence was found for both the average zonal stream and UV albedo averaged for the entire period of observations.

  14. 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.

  15. Lower atmosphere minor gas abundances as retrieved from Venus Express VIRTIS-M-IR data at 2.3 ?m

    Science.gov (United States)

    Haus, Rainer; Kappel, David; Arnold, Gabriele

    2015-01-01

    Minor gas abundances in the lower atmosphere of Venus' southern hemisphere are investigated using spectroscopic nightside measurements recorded by the Visible and InfraRed Thermal Imaging Spectrometer aboard ESA's Venus Express mission in the moderate spectral resolution infrared mapping channel (VIRTIS-M-IR, 1-5 ?m, FWHM=17 nm). The entire usable data archive is utilized including only radiation spectra sampled at long detector exposure times (?3.3 s) during eight Venus solar days between April 2006 and October 2008. Combined radiative transfer and retrieval techniques (Haus et al., 2013; Haus et al., 2014) are applied for a simultaneous determination of total cloud opacity and H2O, CO, and OCS abundances from the 2.3 ?m atmospheric transparency window that sounds the altitude range between about 30 and 45 km. A wavelength-dependent CO2 opacity correction is considered. Zonal averages of CO abundances at 35 km increase by about 35% from (22.9±0.8) ppmv at equatorial latitudes to (31.0±2.1) ppmv at 65 °S and then decrease to (29.4±2.4) ppmv at 80 °S The±figures refer to the statistical variability of retrieved abundances. In accordance with earlier results, the observed latitudinal variation of tropospheric CO is consistent with a Hadley cell-like circulation. Dawn side CO abundances at high latitudes are slightly smaller than dusk side values by about 7%. The latitudinal distribution of OCS at 35 km is anticorrelated with that of CO, ranging from about (1.15±0.2) ppmv at 65 °S to (1.60±0.2) ppmv at low latitudes (poleward decrease of 28%). Zonal averages of H2O abundances near 35 km slightly decrease toward the South Pole by about 10%, and the hemispheric average is (32.0±1.3) ppmv. A significant local time dependence of OCS and H2O is not observed. Detailed analyses of individual spectrum retrieval errors for different atmospheric models reveal that CO abundance results are reliable (error 4-7%), while H2O and OCS results have lower confidence (errors 30-47% and 41-86%, respectively). SO2 abundances cannot reliably be retrieved from VIRTIS-M-IR spectra.

  16. Exploring Venus.

    Science.gov (United States)

    The Universe in the Classroom, 1985

    1985-01-01

    Presents basic information on the planet Venus answering questions on location, size, temperature, clouds, water, and daylight. A weather forecast for a typical day and revelations from radar experiments are also included. (DH)

  17. Sampling the Cloudtop Region on Venus

    Science.gov (United States)

    Limaye, Sanjay; Ashish, Kumar; Alam, Mofeez; Landis, Geoffrey; Widemann, Thomas; Kremic, Tibor

    2014-05-01

    The details of the cloud structure on Venus continue to be elusive. One of the main questions is the nature and identity of the ultraviolet absorber(s). Remote sensing observations from Venus Express have provided much more information about the ubiquitous cloud cover on Venus from both reflected and emitted radiation from Venus Monitoring Camera (VMC) and Visible InfraRed Imaging Spectrometer (VIRTIS) observations. Previously, only the Pioneer Venus Large Probe has measured the size distribution of the cloud particles, and other probes have measured the bulk optical properties of the cloud cover. However, the direct sampling of the clouds has been possible only below about 62 km, whereas the recent Venus Express observations indicate that the cloud tops extend from about 75 km in equatorial region to about 67 km in polar regions. To sample the cloud top region of Venus, other platforms are required. An unmanned aerial vehicle (UAV) has been proposed previously (Landis et al., 2002). Another that is being looked into, is a semi-buoyant aerial vehicle that can be powered using solar cells and equipped with instruments to not only sample the cloud particles, but also to make key atmospheric measurements - e.g. atmospheric composition including isotopic abundances of noble and other gases, winds and turbulence, deposition of solar and infrared radiation, electrical activity. The conceptual design of such a vehicle can carry a much more massive payload than any other platform, and can be controlled to sample different altitudes and day and night hemispheres. Thus, detailed observations of the surface using a miniature Synthetic Aperture Radar are possible. Data relay to Earth will need an orbiter, preferably in a low inclination orbit, depending on the latitude region selected for emphasis. Since the vehicle has a large surface area, thermal loads on entry are low, enabling deployment without the use of an aeroshell. Flight characteristics of such a vehicle have been studied (Alam et al., 2014; Kumar et al., 2014) Acknowledgements Mr. Ashish Kumar and Mr. Mofeez Alam were supported by the Indo US Forum for Science and Technology (IUSSTF) as S.N. Bose Scholars at the University of Wisconsin, Madison as Summer interns. We are grateful for the guidance support provided by Dr. Kristen Griffin and Dr. Daniel Sokol, Northrop Grumman Aerospace Corporation. References Alam, M., K. Ashish, and S.S. Limaye. Aerodynamic Analysis of BlimPlane- a Conceptual Hybrid UAV for Venus Exploration. Accepted for publication, 2014 IEEE Aerospace Conference, Big Sky, Montana, 1-8 March 2014. Ashish, K., M. Alam, and S.S. Limaye, Flight Analysis of a Venus Atmospheric Mobile Platform. Accepted for publication, 2014 IEEE Aerospace Conference, Big Sky, Montana, 1-8 March 2014. Landis, G.A., A. Colozza, C.M. LaMarre, Atmospheric flight on Venus. NASA/TM—2002-211467, AIAA-2001-0819, June 2002

  18. The Venus oxygen nightglow and density distributions

    OpenAIRE

    Soret, Lauriane; Gérard, Jean-Claude; Montmessin, Franck; Piccioni, Giuseppe; Drossart, Pierre; Bertaux, Jean-Loup

    2010-01-01

    Observing Venus nightglow is a key tool to understand the composition and the dynamics of its atmosphere. Results deduced from observations can be implemented to produce a data model of Venus atmosphere. For instance, the Visible and Infra-Red Thermal Imaging Spectrometer (VIRTIS) instrument on board the Venus Express spacecraft is very useful to analyze the O2(a1?) nightglow at 1.27 µm in the Venus mesosphere. Nadir observations can be used to create a statistical map of the emission on Venu...

  19. Some questions about the Venus atmosphere from past measurements

    Science.gov (United States)

    Limaye, Sanjay

    2015-11-01

    The many missions undertaken in the past half a century to explore Venus with fly-by spacecraft, orbiters, descending probes, landers and floating balloons, have provided us with a wealth of data. These data have been supplemented by many ground based observations at reflected solar wavelengths, short and long wave infrared to radio waves. Inter-comparison of the results from such measurements provide a good general idea of the global atmosphere. However, re-visiting these observations also raises some questions about the atmosphere that have not received much attention lately but deserve to be explored and considered for future measurements.These questions are about the precise atmospheric composition in the deep atmosphere, the atmospheric state in the lower atmosphere, the static stability of the lower atmosphere, the clouds and hazes, the nature of the ultraviolet absorber and wind speed and direction near the surface from equator to the pole. The answers to these questions are important for a better understanding of Venus, its weather and climate. The measurements required to answer these questions require careful and sustained observations within the atmosphere and from surface based stations. Some of these measurements should and can be made by large missions such as Venera-D (Russia), Venus Climate Mission (Visions and Voyages – Planetary Science Decadal Survey 2013-2022 or the Venus Flagship Design Reference Mission (NASA) which have been studied in recent years, but some have not been addressed in such studies. For example, the fact that the two primary constituents of the Venus atmosphere – Carbon Dioxide and Nitrogen are supercritical has not been considered so far. It is only recently that properties of binary supercritical fluids are being studied theoretically and laboratory validation is needed.With the end of monitoring of Venus by Venus Express orbiter in November 2014 after nearly a decade of observations and the imminent insertion of JAXA’s Akatsuki spacecraft into orbit around Venus, it is a good moment to consider the unanswered or unexplored questions about Venus.

  20. Search for ongoing volcanic activity on Venus

    Science.gov (United States)

    Shalygin, E. V.; Markiewicz, W. J.; Basilevsky, A. T.; Titov, D. V.; Ignatiev, N. I.; Head, J. W.

    2015-10-01

    We report results of systematical analysis of the whole data-set obtained by the Venus Monitoring Camera(VMC)on-board the Venus Express (VEx) spacecraft at the night side of the planet. In this data set we searched for transient bright events which exhibit behaviour of a hot spot on the surface.

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

    OpenAIRE

    Muñoz, A. García; Hueso, R.; 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...

  2. Venus Atmosphere and Surface Explorer

    Science.gov (United States)

    Esposito, Larry W.; Hall, Jeff; Schofield, Tim

    2014-11-01

    ContextVenus is Earth’s twin planet, but it is an evil twin! To understand how Venus went wrong, to understand the terrestrial planets in our Solar System, those around other stars, and the future of the Earth… we must understand Venus history, evolution and current processes. This requires entering the Venus atmosphere and examining its surface. Future missions will land on Venus, but they need better characterization of its atmosphere and of possible landing sites. VASE can build on discoveries from previous missions, on technical advances in the last decades and on improved balloon technology. The hybrid mission links together a single vertical profile with two weeks of temporal and longitudinal data on a global scale. We can investigate the linked surface and atmosphere processes. We will measure the noble gases which retain indicators of Venus formation; clouds, winds, and chemistry that drive the current Venus processes; and take descent images that extend the Magellan RADAR results to sub-1m resolution, providing ground truth for Magellan’s global mapping and to characterize possible future landing sites.Science Objectives VASE will measure the complete inventory of atmospheric noble gas and light stable isotopes to constrain theories of planetary formation and evolution. It will take nested surface images on descent. It will provide the first complete atmospheric structure profile from clouds to surface of temperature, pressure and wind. VASE will measure with critical accuracy the trace and reactive gas composition profile from clouds to surface. VASE will map the surface emissivity along the surface below two balloon circumnavigations of Venus.Mission VASE is a hybrid Venus mission consisting of a large balloon and a small probe. It reaches Venus after a 4 month trip from Earth. The probe deploys from the entry vehicle and falls to surface in 1.5 hours. The balloon mission lasts 2 weeks, flying in the clouds at 55 km and circumnavigating Venus twice. The balloon communicates directly to Earth and serves as the telecom relay for the probe.

  3. Hot Flow Anomalies at Venus

    Science.gov (United States)

    Collinson, G. A.; Sibeck, David Gary; Boardsen, Scott A.; Moore, Tom; Barabash, S.; Masters, A.; Shane, N.; Slavin, J.A.; Coates, A.J.; Zhang, T. L.; Sarantos, M.

    2012-01-01

    We present a multi-instrument study of a hot flow anomaly (HFA) observed by the Venus Express spacecraft in the Venusian foreshock, on 22 March 2008, incorporating both Venus Express Magnetometer and Analyzer of Space Plasmas and Energetic Atoms (ASPERA) plasma observations. Centered on an interplanetary magnetic field discontinuity with inward convective motional electric fields on both sides, with a decreased core field strength, ion observations consistent with a flow deflection, and bounded by compressive heated edges, the properties of this event are consistent with those of HFAs observed at other planets within the solar system.

  4. The Pioneer Venus program

    International Nuclear Information System (INIS)

    The Pioneer Venus program encompasses two spacecraft missions, Orbiter and Multiprobe, to be launched and to encounter Venus during the 1978 Venus mission opportunity. The missions are described in detail including mission and spacecraft descriptions, scientific objectives and payloads. The ways in which the payloads address the major scientific questions concerning Venus are treated in subsequent papers. (Auth.)

  5. Geology of Venus planet

    International Nuclear Information System (INIS)

    Nowadays data of geological-morphological analysis of the Venus surface obtained as a result of the analysis of ''Venus-15 and -16'' space probes images are presented. The specific features of the Venus relief - plains, mountains, craters are considered and geological-morphological map of the Venus survey zone by ''Venus-15 and -16'' space probes is presented. Data on potassium, uranium, torium and main rockforming elements in the Venus surface rocks by the data of ''Venus-8;-9;-10;-13 and -14'' and ''Vega-1 and -2'' space probes are given

  6. Robotic Technology for Exploration of Venus

    Science.gov (United States)

    Landis, Geoffrey A.

    2003-01-01

    Venus, the "greenhouse planet", is a scientifically fascinating place. A huge number of important scientific questions remain to be answered. Venus is sometimes called Earth's "sister planet" due to the fact that it is closest to the Earth in distance and similar to Earth in size. Despite its similarity to Earth, however, the climate of Venus is vastly different from Earth's. Understanding the atmosphere, climate, geology, and history of Venus could shed considerable light on our understanding of our own home planet. The surface of Venus is a hostile environment, with an atmosperic pressure of over 90 bar of carbon dioxide, temperature of 450 C, and shrouded in sulphuric-acid clouds. Venus has been explored by a number of missions from Earth, including the Russian Venera missions which landed probes on the surface, the American Pioneer missions which flew both orbiters and atmospheric probes to Venus, the Russian "Vega" mission, which floated balloons in the atmosphere of Venus, and most recently the American Magellan mission which mapped the surface by radar imaging. While these missions have answered basic questions about Venus, telling us the surface temperature and pressure, the elevations and topography of the continents, and the composition of the atmosphere and clouds, scientific mysteries still abound. Venus is of considerable interest to terrestrial atmospheric science, since of all the planets in the solar system, it is the closest analogue to the Earth in terms of atmosphere. Yet Venus' atmosphere is an example of "runaway greenhouse effect." Understanding the history and the dynamics of Venus' atmosphere could tell us considerable insight about the workings of the atmosphere of the Earth. It also has some interest to astrobiology-- could life have existed on Venus in an earlier, pre-greenhouse-effect phase? Could life still be possible in the temperate middle-atmosphere of Venus? The geology of Venus also has interest in the study of Earth. surface robot will require new technologies; specifically, it will require electronics, scientific instruments, power supplies, and mechanical linkages designed to operate at a temperature above 450 C-hot enough to melt the solder on a standard electronic circuit board. This will require devices made from advanced semiconductor materials, such as silicon carbide, or even new approaches, such as micro-vacuum tube electronics. Such materials are now being developed in the laboratory.

  7. Venus cartography

    Science.gov (United States)

    Batson, R. M.; Kirk, R. L.; Edwards, Kathleen; Morgan, H. F.

    1994-01-01

    The entire surface of the planet Venus is being mapped at global and regional scales (1:50 million through 1:1.5 million) with synthetic aperture radar (SAR), radar altimeter, and radiometer measurements of physical properties from the Magellan spacecraft. The mapping includes SAR image mosaics, shaded relief maps, and topographic contour overlays made from altimetry data and by radargrammetric methods. Methods used include new techniques of radar image processing that became operational as a result of the Magellan mission. Special cartographic support products prepared by the USGS include: synthetic stereograms, color thematic maps of physical properties, digital shaded relief maps from opposite-look SAR, and topographic maps by radargrammetry. The area being mapped (at a resolution of 75 m/pixel) is roughly equivalent to that of Earth, including seafloors. The mapping is designed to support geologic and geophysical investigations.

  8. 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.

  9. Mirror mode structures near Venus and Comet P/Halley

    OpenAIRE

    Schmid, D; Volwerk, M.; Plaschke, F; Vörös, Z.; Zhang, T. L.; Baumjohann, W.; Narita, Y.

    2014-01-01

    In this paper, we study where mirror mode structures are generated near unmagnetized solar system bodies (Venus and comet P/Halley measured in situ by Venus Express and Giotto). To estimate the location of the mirror mode source region at Venus, we apply a turbulent diffusion model of mirror mode structures, which has already been successfully tested in planetary magnetosheaths (Earth, Jupiter, Saturn). It enables us to estimate the distance between the measured location of ...

  10. About the various contributions in Venus rotation rate and LOD

    OpenAIRE

    Cottereau, L.; Rambaux, N.; Lebonnois, S.; Souchay, J.

    2011-01-01

    % context heading (optional) {Thanks to the Venus Express Mission, new data on the properties of Venus could be obtained in particular concerning its rotation.} % aims heading (mandatory) {In view of these upcoming results, the purpose of this paper is to determine and compare the major physical processes influencing the rotation of Venus, and more particularly the angular rotation rate.} % methods heading (mandatory) {Applying models already used for the Earth, the effect o...

  11. The Atmosphere and Climate of Venus

    Science.gov (United States)

    Bullock, M. A.; Grinspoon, D. H.

    Venus lies just sunward of the inner edge of the Sun's habitable zone. Liquid water is not stable. Like Earth and Mars, Venus probably accreted at least an ocean's worth of water, although there are alternative scenarios. The loss of this water led to the massive, dry CO2 atmosphere, extensive H2SO4 clouds (at least some of the time), and an intense CO2 greenhouse effect. This chapter describes the current understanding of Venus' atmosphere, established from the data of dozens of spacecraft and atmospheric probe missions since 1962, and by telescopic observations since the nineteenth century. Theoretical work to model the temperature, chemistry, and circulation of Venus' atmosphere is largely based on analogous models developed in the Earth sciences. We discuss the data and modeling used to understand the temperature structure of the atmosphere, as well as its composition, cloud structure, and general circulation. We address what is known and theorized about the origin and early evolution of Venus' atmosphere. It is widely understood that Venus' dense CO2 atmosphere is the ultimate result of the loss of an ocean to space, but the timing of major transitions in Venus' climate is very poorly constrained by the available data. At present, the bright clouds allow only 20% of the sunlight to drive the energy balance and therefore determine conditions at Venus' surface. Like Earth and Mars, differential heating between the equator and poles drives the atmospheric circulation. Condensable species in the atmosphere create clouds and hazes that drive feedbacks that alter radiative forcing. Also in common with Earth and Mars, the loss of light, volatile elements to space produces long-term changes in composition and chemistry. As on Earth, geologic processes are most likely modifying the atmosphere and clouds by injecting gases from volcanos as well as directly through chemical reactions with the surface. The sensitivity of Venus' atmospheric energy balance is quantified in this chapter in terms of the initial forcing due to a perturbation, radiative response, and indirect responses, which are feedbacks — either positive or negative. When applied to one Venus climate model, we found that the albedo-radiative feedback is more important than greenhouse forcing for small changes in atmospheric H2O and SO2. An increase in these gases cools the planet by making the clouds brighter. On geologic timescales the reaction of some atmospheric species (SO2, CO, OCS, S, H2O, H2S, HCl, HF) with surface minerals could cause significant changes in atmospheric composition. Laboratory data and thermochemical modeling have been important for showing that atmospheric SO2 would be depleted in ~10 m.y. if carbonates are available at the surface. Without replenishment, the clouds would disappear. Alternatively, the oxidation of pyrite could add SO2 to the atmosphere while producing stable Fe oxides at the surface. The correlation of near-infrared high emissivity (dark) surface features with three young, large volcanos on Venus is strong evidence for recent volcanic activity at these sites, certainly over the timescale necessary to support the clouds. We address the nature of heterogeneous reactions with the surface and the implications for climate change on Venus. Chemical and mineralogical signatures of past climates must exist at the surface and below, so in situ experiments on the composition of surface layers are vital for reconstructing Venus' past climate. Many of the most Earth-like planets found around other stars will probably resemble Venus or a younger version of Venus. We finish the chapter with discussing what Venus can tell us about life in the universe, since it is an example of a planetary climate rendered uninhabitable. It also resembles our world's likely future. As with the climate history of Venus, however, the timing of predictable climate transitions on the Earth is poorly constrained by the data.

  12. Infrared spectra of Venus

    International Nuclear Information System (INIS)

    A historical account of observations of Venus and their interpretation is given. The major constituent of the atmosphere on Venus (CO2) was detected spectroscopically forty years ago, and minor constituents (CO,HF,HCl) have been found more recently. The infrared spectra also provide a means of studying the motions of her cloudy atmosphere. The composition of the clouds has been sought in the reflection spectrum of Venus, and some of the evidence for their nature is discussed. (Auth.)

  13. Venus: discoveries and problems

    International Nuclear Information System (INIS)

    Modern state of studies on the question of the Venus origin is discussed. It is indicated that calculations of the planet thermal evolution model pointed up the Venus and Earth resemblance not only from the viewpoint of external parameters but also on the subject of their interior. The Venus probably has an iron core (about 7000 km in diameter), a layer with decreased viscosity which approximately begins from the depth of 200 km and a several dozens kilometers thick crust. The unique peculiarity of the Venus atmosphere is the existence of extended rarefied clouds which occupy a vast region of the atmosphere on a height of 48-65 km. The steam content in the Venus atmosphere is by three orders of magnitude less than in the Earth atmosphere; but there is no water on the Venus surface due to very high temperature. But much water may be in a gaseous state deep in the planet at temperatures higher than the critical one (374 deg C). In the originally rarefied Venus atmosphere water had to boil away promoting the development of a heavy ''hotbed'' effect and further growth of surface temperature. The above model of the Venus thermal evolution is one of probable hypotheses

  14. 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.

  15. Venus’s Southern Polar Vortex Reveals Precessing Circulation

    OpenAIRE

    Luz, D; Berry, DL; Piccioni, G.; Drossart, P.; Politi, R.; Wilson, CF; Erard, S; Nuccilli, F

    2011-01-01

    Initial images of Venus’s south pole by the Venus Express mission have shown the presence of a bright, highly variable vortex, similar to that at the planet’s north pole. Using high-resolution infrared measurements of polar winds from the Venus Express Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) instrument, we show the vortex to have a constantly varying internal structure, with a center of rotation displaced from the geographic south pole by ~3 degrees of latitude and that dri...

  16. Improved Knowlegde of Venus Atmospheric Structure

    Science.gov (United States)

    Limaye, S. S.; Bougher, S.; Chamberlain, S.; Clancy, R. T.; Gilli, G.; Grassi, D.; Haus, R.; Herrmann, M.; Imamura, T.; Kohler, E.; Krause, P.; Lebonnois, S.; Mahieux, A.; Sandor, A.; Sornig, M.; Svedhem, H.; Tellmann, S.; Vandaele, A. C.; Widemann, T.; Wilson, C.; Mueller-Wodarg, I.; Zasova, L.

    2015-10-01

    Experiments onboard the European Space Agency's Venus Express orbiter has extended our knowledge about the vertical temperature and density structure above the clouds. The observations have been obtained by different techniques at different local times and latitudes and with different vertical and horizontal resolutions and coverage.

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

    OpenAIRE

    Yamauchi, M; Y. Futaana; A. Fedorov; R. A. Frahm; Winningham, J. D.; Dubinin, E.; Lundin, R.; Barabash, S.; Holmström, M; Mazelle, C.; J.-A. Sauvaud; Zhang, T. L.; Baumjohann, W.; Coates, A J; Fraenz, M.

    2011-01-01

    Foreshock ions are compared between Venus and Mars at energies of 0.6 similar to 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 similar to 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 ...

  18. Does Venus wobble

    International Nuclear Information System (INIS)

    The free wobble damping time for Venus due to solar tides and rotational flexing is found to be tauapprox. =0.7 x 106 Q/sub ?/ years, where Q/sub ?/ is the dissipation function associated with the wobble period of approx.105 years. As a result, a simple scaling of the Earth's Chandler wobble excitation rate to that of Venus suggests that an appreciable wobble could exist. Detection (or lack thereof) of a free wobble may thus place constraints on the dynamic activity (e.g., mantle convection, Venusquakes, etc.) of the Venus interior

  19. Venus questions answered

    International Nuclear Information System (INIS)

    Data obtained from the five probes which penetrated the atmosphere of Venus and the Orbiter spacecraft circling the planet, which are part of the NASA Pioneer Venus mission, are examined. As a result of these data a picture of the planet's atmospheres is now available. The thickness, temperature, opacity, density and chemical composition of each layer are given. The discovery that below the clouds there is 0.1 to 0.4% water vapour and 60 ppm of free oxygen strengthens the speculation that Venus initially had abundant water. Mechanisms to account for the planet's ability to retain sufficient heat to maintain high surface temperatures are discussed. (UK)

  20. Oxygen ion escape from Venus in a global hybrid simulation: role of the ionospheric O+ ions

    OpenAIRE

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

    2009-01-01

    We study the solar wind induced oxygen ion escape from Venus' upper atmosphere and the Venus Express observations of the Venus-solar wind interaction by the HYB-Venus hybrid simulation code. We compare the simulation to the magnetic field and ion observations during an orbit of nominal upstream conditions. Further, we study the response of the induced magnetosphere to the emission of planetary ions. The hybrid simulation is found to be able to reproduce the main observed regions of the Venusi...

  1. Seasons on Venus - cloud cover signatures

    Science.gov (United States)

    Limaye, Sanjay; Markiewicz, Wojciech; Krauss, Robert

    2015-04-01

    With the smallest obliquity and orbital eccentricity of any planet around the Sun, Venus is not generally expected to show any seasonal variations in its atmosphere. Careful analysis of the global images obtained by the Venus Monitoring Camera (VMC) on board European Space Agency's Venus Express orbiter from 12 June 2006 orbit 24) till 15 September 2014 (orbit 3043) reveal short term variations and a detectable periodic variation in the normalized intensity (reflectance) as well as in unit optical depth at a fixed local time at low latitudes as well as at high latitudes. VMC ultraviolet images were brightness normalized using Minnaert Law and the brightness at the sub-solar meridian at different latitudes in the southern hemisphere. The unit optical dept was inferred by precision location of the limb location in images acquired during the apoapsis portion of the orbit at range greater than ~ 30,000 km from Venus center. The temporal changes of the unit optical depth was monitored at fixed solar zenith angles and latitude. The seasonal signature is more pronounced at high latitudes compared to low latitudes. The data suggest that the variations in insolation due to heliocentric range and the small obliquity are responsible for the periodic changes in the Venus cloud cover. Concurrent changes in the cloud changes are also observed at other three wavelengths (550, 950 and 1050 nm) at which VMC obtained images, but the number of images at these wavelengths is much smaller. A secular decrease in the image brightness is observed over the life of the Venus Express mission, most likely due to the degradation of the some of the optical/sensor elements.

  2. Venus Landsailing Rover Project

    Data.gov (United States)

    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...

  3. Plate tectonics on Venus

    Science.gov (United States)

    Anderson, D. L.

    1981-01-01

    The high surface temperature of Venus implies a permanently buoyant lithosphere and a thick basaltic crust. Terrestrial-style tectonics with deep subduction and crustal recycling is not possible. Overthickened basaltic crust partially melts instead of converting to eclogite. Because mantle magmas do not have convenient access to the surface the Ar-40 abundance in the atmosphere should be low. Venus may provide an analog to Archean tectonics on the earth.

  4. Sox10-Venus mice: a new tool for real-time labeling of neural crest lineage cells and oligodendrocytes

    Directory of Open Access Journals (Sweden)

    Shibata Shinsuke

    2010-10-01

    Full Text Available Abstract Background While several mouse strains have recently been developed for tracing neural crest or oligodendrocyte lineages, each strain has inherent limitations. The connection between human SOX10 mutations and neural crest cell pathogenesis led us to focus on the Sox10 gene, which is critical for neural crest development. We generated Sox10-Venus BAC transgenic mice to monitor Sox10 expression in both normal development and in pathological processes. Results Tissue fluorescence distinguished neural crest progeny cells and oligodendrocytes in the Sox10-Venus mouse embryo. Immunohistochemical analysis confirmed that Venus expression was restricted to cells expressing endogenous Sox10. Time-lapse imaging of various tissues in Sox10-Venus mice demonstrated that Venus expression could be visualized at the single-cell level in vivo due to the intense, focused Venus fluorescence. In the adult Sox10-Venus mouse, several types of mature and immature oligodendrocytes along with Schwann cells were clearly labeled with Venus, both before and after spinal cord injury. Conclusions In the newly-developed Sox10-Venus transgenic mouse, Venus fluorescence faithfully mirrors endogenous Sox10 expression and allows for in vivo imaging of live cells at the single-cell level. This Sox10-Venus mouse will thus be a useful tool for studying neural crest cells or oligodendrocytes, both in development and in pathological processes.

  5. 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...

  6. Venus Altitude Cycling Balloon Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The ISTAR Group ( IG) and team mate Thin Red Line Aerospace (TRLA) propose a Venus altitude cycling balloon (Venus ACB), an innovative superpressure balloon...

  7. Ionospheric photoelectrons at Venus. A statistical review covering the first year of the VEX mission

    International Nuclear Information System (INIS)

    Complete text of publication follows. At unmagnetised bodies, such as Venus, the solar wind interacts directly with the planet's atmosphere, causing an induced magnetosphere to form. Ionospheric photoelectrons are created when the solar HeII 30.4nm line ionises the upper part of the atmosphere, producing ionospheric photoelectrons and positive ions. Theory predicts these photoelectrons will be seen as two distinct peaks, at 21-24eV and 27eV, in the electron energy spectrum. These events have recently been seen at Venus as well as in other parts of the solar system, such as Earth, Mars, Titan and Saturn's rings. Several case studies at Venus have previously been published by the authors using electron, and corresponding ion, data from the Venus Express instrument ASPERA-4. We will now present a statistical review of ionospheric photoelectrons at Venus in the main ionosphere, and in the tail region, covering the first year of the Venus Express mission.

  8. A conceptual venus rover mission using advanced radioisotope power system

    Science.gov (United States)

    Evans, Michael; Shirley, James H.; Abelson, Robert Dean

    2006-01-01

    The primary goal of this study is to examine the feasibility of using the novel Advanced RPS-driven Stirling thermoacoustic system to enable extended science operations in the extremely hostile surface environment of Venus. The mission concept entails landing a rover onto the Venus surface, conducting science measurements in different areas on the surface, and returning the science data to Earth. The study focused on developing a rover design to satisfy the science goals with the capability to operate for 60 days. This mission life influences several design parameters, including Earth elevation angle and the maximum communications range to Earth.

  9. Wireless Seismometer for Venus

    Science.gov (United States)

    Ponchak, George E.; Scardelletti, Maximilian C.; Taylor, Brandt; Beard, Steve; Clougherty, Brian; Meredith, Roger D.; Beheim, Glenn M.; Kiefer, Walter S.; Hunter, Gary W.

    2014-01-01

    Measuring the seismic activity of Venus is critical to understanding its composition and interior dynamics. Because Venus has an average surface temperature of 462 C and the challenge of providing cooling to multiple seismometers, a high temperature, wireless sensor using a wide bandgap semiconductor is an attractive option. This paper presents progress towards a seismometer sensor with wireless capabilities for Venus applications. A variation in inductance of a coil caused by a 1 cm movement of a ferrite probe held in the coil and attached to a balanced leaf-spring seismometer causes a variation of 80 MHz in the transmitted signal from the oscillator sensor system at 420 C, which correlates to a 10 kHz mm sensitivity when the ferrite probe is located at the optimum location in the coil.

  10. Characterizing Volcanic Eruptions on Venus: Some Realistic (?) Scenarios

    Science.gov (United States)

    Stofan, E. R.; Glaze, L. S.; Grinspoon, D. H.

    2011-01-01

    When Pioneer Venus arrived at Venus in 1978, it detected anomalously high concentrations of SO2 at the top of the troposphere, which subsequently declined over the next five years. This decline in SO2 was linked to some sort of dynamic process, possibly a volcanic eruption. Observations of SO2 variability have persisted since Pioneer Venus. More recently, scientists from the Venus Express mission announced that the SPICAV (Spectroscopy for Investigation of Characteristics of the Atmosphere of Venus) instrument had measured varying amounts of SO2 in the upper atmosphere; VIRTIS (Visible and Infrared Thermal Imaging Spectrometer) measured no similar variations in the lower atmosphere (ESA, 4 April, 2008). In addition, Fegley and Prinn stated that venusian volcanoes must replenish SO2 to the atmosphere, or it would react with calcite and disappear within 1.9 my. Fegley and Tremain suggested an eruption rate on the order of approx 1 cubic km/year to maintain atmospheric SO2; Bullock and Grinspoon posit that volcanism must have occurred within the last 20-50 my to maintain the sulfuric acid/water clouds on Venus. The abundance of volcanic deposits on Venus and the likely thermal history of the planet suggest that it is still geologically active, although at rates lower than Earth. Current estimates of resurfacing rates range from approx 0.01 cubic km/yr to approx 2 cubic km/yr. Demonstrating definitively that Venus is still volcanically active, and at what rate, would help to constrain models of evolution of the surface and interior, and help to focus future exploration of Venus.

  11. A Unique Approach for Studying Venus’s Atmosphere: Technology Development for the Venus Atmospheric Maneuverable Platform (VAMP)

    Science.gov (United States)

    Samuele, Rocco; Lee, Greg; Sokol, Daniel; Polidan, Ron; Griffin, Kristen; Bolisay, Linden; Michi, Yuki; Barnes, Nathan

    2014-11-01

    We are investigating a novel, reduced-risk approach to long-duration upper atmosphere exploration of Venus. The Venus Atmospheric Maneuverable Platform (VAMP) concept is a semi-buoyant plane with a science payload that can perform in situ measurements of Venus’s atmosphere. VAMP is also capable of revisiting scientifically interesting locations. Designed with a low ballistic coefficient, VAMP deploys in space and enters Venus’s atmosphere without an aeroshell. Once in the atmosphere, it can engage in a variety of science campaigns while varying its altitude between 50 and 68 km as it circumnavigates Venus. During daytime, VAMP will be able to make continuous science measurements at a range of latitudes, longitudes, and altitudes, while at night the vehicle will descend to a fully-buoyant, lower-power state, capable of performing modest science measurements at the float altitude. Near the end of VAMP’s mission life, the vehicle may attempt an end-of-life trajectory into higher latitudes or descend to lower altitudes. This presentation focuses on the technology roadmap that will allow the vehicle to accomplish these science measurements. The roadmap is driven by high priority science measurements and the technology needed to implement VAMP’s main mission phases: deployment, entry into Venus’s atmosphere, and the transition to flight and science flight performance. The roadmap includes materials tests, planform aerodynamic characterization, various subscale and full-scale packaging and deployment tests, and a full-scale suborbital flight and is being produced with extensive science community interaction to define the science measurements that would be uniquely possible with this new science platform.

  12. The clouds of Venus

    International Nuclear Information System (INIS)

    The current state of knowledge of the Venusian clouds is reviewed. The visible clouds of Venus are shown to be quite similar to low level terrestrial hazes of strong anthropogenic influence. Possible nucleation and particle growth mechanisms are presented. The Pioneer Venus experiments that emphasize cloud measurements are described and their expected findings are discussed in detail. The results of these experiments should define the cloud particle composition, microphysics, thermal and radiative heat budget, rough dynamical features and horizontal and vertical variations in these and other parameters. This information should be sufficient to initialize cloud models which can be used to explain the cloud formation, decay, and particle life cycle. (Auth.)

  13. Systems Analysis for a Venus Aerocapture Mission

    Science.gov (United States)

    Lockwood, Mary Kae; Starr, Brett R.; Paulson, John W., Jr.; Kontinos, Dean A.; Chen, Y. K.; Laub, Bernard; Olejniczak, Joseph; Wright, Michael J.; Takashima, Naruhisa; Justus, Carl G.

    2006-01-01

    Previous high level analysis has indicated that significant mass savings may be possible for planetary science missions if aerocapture is employed to place a spacecraft in orbit. In 2001 the In-Space Propulsion program identified aerocapture as one of the top three propulsion technologies for planetary exploration but that higher fidelity analysis was required to verify the favorable results and to determine if any supporting technology gaps exist that would enable or enhance aerocapture missions. A series of three studies has been conducted to assess, from an overall system point of view, the merit of using aerocapture at Titan, Neptune and Venus. These were chosen as representative of a moon with an atmosphere, an outer giant gas planet and an inner planet. The Venus mission, based on desirable science from plans for Solar System Exploration and Principal Investigator proposals, to place a spacecraft in a 300km polar orbit was examined and the details of the study are presented in this paper.

  14. The Pioneer Venus Missions.

    Science.gov (United States)

    National Aeronautics and Space Administration, Mountain View, CA. Ames Research Center.

    This document provides detailed information on the atmosphere and weather of Venus. This pamphlet describes the technological hardware including the probes that enter the Venusian atmosphere, the orbiter and the launch vehicle. Information is provided in lay terms on the mission profile, including details of events from launch to mission end. The…

  15. Planetary Radio Interferometry and Doppler Experiment (PRIDE) for studying the thermosphere of Venus

    Science.gov (United States)

    Bocanegra Bahamón, T. M.; Cimò, G.; Duev, D. A.; Gurvits, L. I.; Marty, J. C.; Molera Calvés, G.; Pogrebenko, S. V.; Rosenblatt, P.

    2013-09-01

    Planetary Radio Interferometry and Doppler Experiment (PRIDE) is a generic experimental setup of on-board and Earth-based radio devices and facilities, which serves as an enhancement of the science return of planetary missions. The main goal of this technique is to provide precise estimates of the spacecraft state vectors, by performing precise Doppler tracking of the spacecraft carrier signal, at one or more Earth-based radio telescopes, and VLBI-style correlation of these signals in phase referencing mode [1]. By allowing an accurate examination of the changes in phase and amplitude of the radio signal propagating from the spacecraft to the multiple stations on Earth, the PRIDE technique can be used for several fields of research, among them: atmospheric and ionospheric structure of planets and their satellites, planetary gravity fields, planets' shapes, masses and ephemerides, solar plasma and different aspects of the theory of general relativity. The PRIDE-team is participating in the so-called Venus Express Atmospheric Drag Experiment (VEx-ADE) campaigns by tracking ESA's Venus Express with multiple radio telescopes on Earth. During each campaign, VEX's orbit pericenter is lowered into an altitude range of approximately 165 to 175 km in order to probe Venus upper atmosphere above its north pole. The first VExADE campaigns were carried out between 2009-2010 using Doppler tracking data acquired by the VEX radio science experiment (VeRa), which provided the first in situ measurements of the density of Venus' polar thermosphere at solar minimum conditions [2]. The last campaign was conducted in December 2012, in which the PRIDE-team participated by tracking VEX with several radio telescopes from the European VLBI Network (EVN) during pericenter passage. A Doppler frequency drop of ?40 mHz was detected as VEX reached the lowest altitudes at around 170 km. The tracking data for each pericenter pass is fitted for precise orbit determination, from which drag acceleration estimates and the corresponding atmospheric mass density estimates are derived. The results of this campaign will give the opportunity to trace the density of the polar thermosphere along the increasing phase of the solar cycle, and to provide a wider data set of density estimates which will eventually contribute to the construction of a new empirical model of Venus' polar thermosphere.

  16. 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. 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

  17. Implications of 36A excess on Venus

    International Nuclear Information System (INIS)

    The finding of 36A excess on Venus by the mass-spectroscopic measurement of the Venus Pioneer appears to endorse the more rapid accretion theory of Venus than the Earth and the secondary origin of the terrestrial atmosphere. (Auth.)

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

    Energy Technology Data Exchange (ETDEWEB)

    Kane, Stephen R. [Department of Physics and Astronomy, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132 (United States); Kopparapu, Ravi Kumar [Department of Geosciences, Penn State University, 443 Deike Building, University Park, PA 16802 (United States); Domagal-Goldman, Shawn D., E-mail: skane@sfsu.edu [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2014-10-10

    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 (?{sub ?}) of 0.32{sub ?0.07}{sup +0.05} and 0.45{sub ?0.09}{sup +0.06} for M dwarfs and GK dwarfs, respectively.

  19. 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

  20. Tectonics and composition of Venus

    International Nuclear Information System (INIS)

    The uncompressed density of Venus is a few percent less than the Earth. The high upper mantle temperature of Venus deepens the eclogite stability field and inserts a partial melt field. A thick basaltic crust is therefore likely. The anomalous density of Venus relative to the progression from Mercury to Mars may therefore have a tectonic rather than a cosmochemical explanation. There may be no need to invoke differences in composition or oxidization state

  1. Venus, Earth, Xenon

    Science.gov (United States)

    Zahnle, K. J.

    2013-12-01

    Xenon has been regarded as an important goal of many proposed missions to Venus. This talk is intended to explain why. Despite its being the heaviest gas found in natural planetary atmospheres, there is more evidence that Xe escaped from Earth than for any element apart from helium: (i) Atmospheric Xe is very strongly mass fractionated (at about 4% per amu) from any known solar system source. This suggests fractionating escape that preferentially left the heavy Xe isotopes behind. (ii) Xe is underabundant compared to Kr, a lighter noble gas that is not strongly mass fractionated in air. (iii) Radiogenic Xe is strongly depleted by factors of several to ~100 compared to the quantities expected from radioactive decay of primordial solar system materials. In these respects Xe on Mars is similar to Xe on Earth, but with one key difference: Xe on Mars is readily explained by a simple process like hydrodynamic escape that acts on an initially solar or meteoritic Xe. This is not so for Earth. Earth's Xe cannot be derived by an uncontrived mass fractionating process acting on any known type of Solar System Xe. Earth is a stranger, made from different stuff than any known meteorite or Mars or even the Sun. Who else is in Earth's family? Comets? We know nothing. Father Zeus? Data from Jupiter are good enough to show that jovian Xe is not strongly mass-fractionated but not good enough to determine whether Jupiter resembles the Earth or the Sun. Sister Venus? Noble gas data from Venus are incomplete, with Kr uncertain and Xe unmeasured. Krypton was measured by several instruments on several spacecraft. The reported Kr abundances are discrepant and were once highly controversial. These discrepancies appear to have been not so much resolved as forgotten. Xenon was not detected on Venus. Upper limits were reported for the two most abundant xenon isotopes 129Xe and 132Xe. From the limited data it is not possible to tell whether Venus's affinities lie with the solar wind, or with the chondrites, with Earth, or with none of the above. Modern spacecraft mass spectrometers are at least 100-fold more sensitive to noble gases. Sending such an instrument to Venus may be the last best hope for decrypting what Earth's noble gases have been trying to tell us.

  2. Magellan unveils Venus

    Energy Technology Data Exchange (ETDEWEB)

    Lerner, E.J.

    1991-07-01

    Images obtained after an eight month Venusian year, during which the radar mapper Magellan surveyed nearly all of Venus, are described. It is observed that, instead of rigid plates moving as on earth, Venus appears covered with plumes of hot upwellings that dome out over hundreds or thousands of kilometers, feeding a continuous volcanic resurfacing of the planet. Although the Venusian surface is changing relatively rapidly by vulcanism and tectonic processes, the Magellan images make it clear that erosion is very slow. It is seen that some of the lava flows are highly fluid, etching narrow channels for hundreds of kilometers through the crust. Magellan also revealed some peculiarly Venusian formations, the tesserated areas where ridges and faults crosshatch the region into large blocks.

  3. Coordination of Mars Express and Beagle 2 Science Operations - Update

    Science.gov (United States)

    Trautner, R.; Chicarro, A. C.; Martin, P. D.

    2003-04-01

    The Mars Express orbiter and the Beagle 2 lander will arrive at Mars in late December 2003. Both spacecraft carry a comprehensive set of instruments for the investigation of the Martian environment. While the Beagle2 lander will acquire in-situ data on the landing site in Isidis Planitia (11.60°N 90.75°E in IAU 2000 coordinates), the Mars Express orbiter will provide global coverage with its set of remote sensing instruments. A coordination of orbiter and lander observations will provide ground truth to the orbiter instruments, and allow the comparison of orbiter and lander data on the landing site. Lessons learned from this comparison can be used to improve the global datasets provided by the orbiter instruments. The planning of coordinated operations needs to be part of the standard operations planning procedures of both spacecraft. The science operations of the Mars Express orbiter instruments are based on a long-term plan called the Master Science Plan (MSP). On the lander side, the planning of science activities will be dominated by a short-term operations plan worked out in the time between radio contacts. This will involve a Coordinated Operations Timeline (COT), which contains the lander instrument activities requested during coordination opportunities. The scientific goals of the orbiter and lander instruments are recapitulated. The PI team interests in coordinated operations are presented. The operations planning concepts for both spacecraft are discussed, and strategies for the coordination of orbiter and lander science operations are explained.

  4. 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)

  5. Encounters of the dust trails of comet 45P/Honda-Mrkos-Pajdusakova with Venus in 2006

    OpenAIRE

    Vaubaillon, Jeremie; Christou, Apostolos A.

    2006-01-01

    Aims. We aim to investigate the dynamical fate of meteoroids ejected during past perihelion passages of comet 45P/Honda-Mrkos-Pajdusakova that intersect the orbit of Venus. Of particular interest is the possibility, borne of previous work, that a significant flux of these particles will reach the planet during early June and late August 2006, when the Venus Express spacecraft will be operating in orbit around Venus. Methods. We have simulated the generation of meteoroid trails ejected by the ...

  6. Sensor Amplifier for the Venus Ground Ambient

    Science.gov (United States)

    DelCastillo, Linda Y.; Johnson, Travis W.; Hatake, Toshiro; Mojarradi, Mohammad M.; Kolawa, Elizabeth A.

    2006-01-01

    Previous Venus Landers employed high temperature pressure vessels, with thermally protected electronics, to achieve successful missions, with a maximum surface lifetime of 127 minutes. Extending the operating range of electronic systems to the temperatures (480 C) and pressures (90 bar) of the Venus ground ambient would significantly increase the science return of future missions. Toward that end, the current work describes the innovative design of a sensor preamplifier, capable of working in the Venus ground ambient and designed using commercial components (thermionic vacuum tubes, wide band gap transistors, thick film resistors, advanced high temperature capacitors, and monometallic interfaces) To identify commercial components and electronic packaging materials that are capable of operation within the specified environment, a series of active devices, passive components, and packaging materials were screened for operability at 500C, assuming a 10x increase in the mission lifetime. In addition. component degradation as a function of time at 500(deg)C was evaluated. Based on the results of these preliminary evaluations, two amplifiers were developed.

  7. Venus atmosphere and extreme surface topography

    Science.gov (United States)

    Zasova, L.; Khatuntsev, I.; Patsaeva, M.; Ignatiev, N.; Rodin, A.; Turin, A.; Markiewicz, W.; Piccioni, G.

    2015-10-01

    The temperature fields at several levels in the Venus mesosphere(60-95 km)as well as the altitude of the upper boundary of clouds retrieved from Venera-15 (FS-V15) [1], and the zonal wind fields and albedo of the upper clouds, measured by VMC Venus Express [2], and altitude of the upper boundary of clouds VIRTIS-M VEX [3] data are compared with the topographic map, obtained by Magellan [4] . The results show that the isotherms and the altitude isolines of the upper clouds boundary reproduce the extended surface features Ishtar and Atalanta Planitia. In turn, the shapes of wind isovelocities and albedo at the upper boundary of clouds (VMC) closely follow the details of relief of Terra Aphrodite as well the isolines of altitude of the cloud tops (VIRTIS). In all cases the isolines are shifted with respect to topography by about 30° in the direction of superrotation. Non-hydrostatic general circulation model of the Venus atmosphere[5] demonstrates that the major topographic features such as Maxwell Montes and Terra Aphrodite provide a prominent impact on the atmospheric dynamics at levels as high as 90-95 km.

  8. VENUS-2 Experimental Benchmark Analysis

    International Nuclear Information System (INIS)

    The VENUS critical facility is a zero power reactor located at SCK-CEN, Mol, Belgium, which for the VENUS-2 experiment utilized a mixed-oxide core with near-weapons-grade plutonium. In addition to the VENUS-2 Core, additional computational variants based on each type of fuel cycle VENUS-2 core (3.3 wt.% UO2, 4.0 wt.% UO2, and 2.0/2.7 wt.% MOX) were also calculated. The VENUS-2 critical configuration and cell variants have been calculated with MCU-REA, which is a continuous energy Monte Carlo code system developed at Russian Research Center ''Kurchatov Institute'' and is used extensively in the Fissile Materials Disposition Program. The calculations resulted in a keff of 0.99652 ± 0.00025 and relative pin powers within 2% for UO2 pins and 3% for MOX pins of the experimental values

  9. Stagnation Point Radiative Heating Relations for Venus Entry

    Science.gov (United States)

    Tauber, Michael E.; Palmer, Grant E.; Prabhu, Dinesh K.

    2012-01-01

    Improved analytic expressions for calculating the stagnation point radiative heating during entry into the atmosphere of Venus have been developed. These analytic expressions can be incorporated into entry trajectory simulation codes. Together with analytical expressions for convective heating at the stagnation point, the time-integrated total heat load at the stagnation point is used in determining the thickness of protective material required, and hence the mass of the fore body heatshield of uniform thickness.

  10. 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.

  11. The transit of Venus enterprise in Victorian Britain

    CERN Document Server

    Ratcliff, Jessica

    2015-01-01

    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.

  12. 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

  13. Little or no solar wind enters Venus' atmosphere at solar minimum.

    Science.gov (United States)

    Zhang, T L; Delva, M; Baumjohann, W; Auster, H-U; Carr, C; Russell, C T; Barabash, S; Balikhin, M; Kudela, K; Berghofer, G; Biernat, H K; Lammer, H; Lichtenegger, H; Magnes, W; Nakamura, R; Schwingenschuh, K; Volwerk, M; Vörös, Z; Zambelli, W; Fornacon, K-H; Glassmeier, K-H; Richter, I; Balogh, A; Schwarzl, H; Pope, S A; Shi, J K; Wang, C; Motschmann, U; Lebreton, J-P

    2007-11-29

    Venus has no significant internal magnetic field, which allows the solar wind to interact directly with its atmosphere. A field is induced in this interaction, which partially shields the atmosphere, but we have no knowledge of how effective that shield is at solar minimum. (Our current knowledge of the solar wind interaction with Venus is derived from measurements at solar maximum.) The bow shock is close to the planet, meaning that it is possible that some solar wind could be absorbed by the atmosphere and contribute to the evolution of the atmosphere. Here we report magnetic field measurements from the Venus Express spacecraft in the plasma environment surrounding Venus. The bow shock under low solar activity conditions seems to be in the position that would be expected from a complete deflection by a magnetized ionosphere. Therefore little solar wind enters the Venus ionosphere even at solar minimum. PMID:18046399

  14. Thermal structure and minor species distribution of Venus mesosphere by ALMA submm observations

    Science.gov (United States)

    Piccialli, Arianna; Moreno, Raphael; Encrenaz, Therese; Fouchet, Thierry; Lellouch, Emmanuel; Moullet, Arielle; Widemann, Thomas

    2015-11-01

    Venus upper atmosphere (70–150 km altitude) is a transition region characterized by a complex dynamics: strong retrograde zonal winds dominate the lower mesosphere while a solar-to-antisolar circulation is observed in the upper mesosphere/lower thermosphere. In addition, photochemical processes play an important role at these altitudes and affect the thermal structure and chemical stability of the entire atmosphere. Sulfur dioxide and water vapor are key species in the photochemical cycles taking place in the troposphere and mesosphere of Venus. They are carried by convective transport, together with the Hadley circulation, up to about 60 km where SO2 is photodissociated and oxydated, leading to the formation of H2SO4 which condenses in the clouds enshrouding the planet. Previous observations obtained by several instruments on board Venus Express and during ground-based campaigns have shown evidence of strong temporal variations, both on day-to-day as well as longer timescales, of density, temperature and SO2 abundance. Such strong variability is still not well understood.Submillimeter observations obtained with the Atacama Large Millimeter Array (ALMA) offer the possibility of probing Venus upper mesosphere and of monitoring minor species, winds and the thermal structure. A first set of observations was obtained on November 14, 15, 26 and 27, 2011 during the first ALMA Early Science observation cycle. These observations targeted SO2, SO, HDO and CO transitions around 345 GHz during four sequences of 30 minutes each. The Venus’ disk was about 11” with an illumination factor of 90%, so that mostly the dayside of the planet was mapped.Assuming nominal night-time and dayside CO abundance profiles from Clancy et al. 2013, we retrieved vertical temperature profiles over the entire disk as a function of latitude and local time for the four days of observation. Temperature profiles were later used to derive the abundances of minor species (HDO, SO, SO2) in each pixel of the disk in order to study their spatial and temporal variability.

  15. Short Large-Amplitude Magnetic Structures (SLAMS) at Venus

    Science.gov (United States)

    Collinson, G. A.; Wilson, L. B.; Sibeck, D. G.; Shane, N.; Zhang, T. L.; Moore, T. E.; Coates, A. J.; Barabash, S.

    2012-01-01

    We present the first observation of magnetic fluctuations consistent with Short Large-Amplitude Magnetic Structures (SLAMS) in the foreshock of the planet Venus. Three monolithic magnetic field spikes were observed by the Venus Express on the 11th of April 2009. The structures were approx.1.5->11s in duration, had magnetic compression ratios between approx.3->6, and exhibited elliptical polarization. These characteristics are consistent with the SLAMS observed at Earth, Jupiter, and Comet Giacobini-Zinner, and thus we hypothesize that it is possible SLAMS may be found at any celestial body with a foreshock.

  16. Venus as a more Earth-like planet.

    OpenAIRE

    Svedhem, H.; Titov, DV; Taylor, FW; Witasse, O.

    2007-01-01

    Venus is Earth's near twin in mass and radius, and our nearest planetary neighbour, yet conditions there are very different in many respects. Its atmosphere, mostly composed of carbon dioxide, has a surface temperature and pressure far higher than those of Earth. Only traces of water are found, although it is likely that there was much more present in the past, possibly forming Earth-like oceans. Here we discuss how the first year of observations by Venus Express brings into focus the evoluti...

  17. 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...

  18. Recent hotspot volcanism on Venus from VIRTIS emissivity data.

    Science.gov (United States)

    Smrekar, Suzanne E; Stofan, Ellen R; Mueller, Nils; Treiman, Allan; Elkins-Tanton, Linda; Helbert, Joern; Piccioni, Giuseppe; Drossart, Pierre

    2010-04-30

    The questions of whether Venus is geologically active and how the planet has resurfaced over the past billion years have major implications for interior dynamics and climate change. Nine "hotspots"--areas analogous to Hawaii, with volcanism, broad topographic rises, and large positive gravity anomalies suggesting mantle plumes at depth--have been identified as possibly active. This study used variations in the thermal emissivity of the surface observed by the Visible and Infrared Thermal Imaging Spectrometer on the European Space Agency's Venus Express spacecraft to identify compositional differences in lava flows at three hotspots. The anomalies are interpreted as a lack of surface weathering. We estimate the flows to be younger than 2.5 million years and probably much younger, about 250,000 years or less, indicating that Venus is actively resurfacing. PMID:20378775

  19. Statistical Survey of Whistler Mode Signals in the Venus Ionosphere: A Proxy Study of Venus Lightning

    Science.gov (United States)

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

    2015-10-01

    Venus Express has now completed its more than 8.5 year tenure in orbit around Venus. Throughout the mission it was in a 24 hour elliptical polar orbit with periapsis at ~80° latitude at orbital insertion in 2006. It then precessed near the pole in 2009 and ultimately finished its mission with periapsis at ~72° latitude (Figure 1). For the first few years the altitude of periapsis reached ~250 km above the surface, but later it commonly descended to ~165 km. In mid-2014 the spacecraft performed an aerobraking maneuver in which it descended further into the atmosphere down to ~130 km at its lowest point.Extremely low frequency(ELF) waves generated by lightning were most commonly detected when the spacecraft was near 250 km altitude. Here we present statistics of these lightning-induced ELF waves observed over the entire mission.

  20. Venus: A total mass estimate

    International Nuclear Information System (INIS)

    Reductions of four independent blocks of Pioneer Venus Orbiter Doppler radio tracking data have produced very consistent determinations of the GM of Venus (the product of the universal gravitational constant and total mass of Venus). These estimates have uncertainties that are significantly smaller than any values published to data. The value of GM is also consistent with previously published results in that it falls within their one-sigma uncertainties. The value of 324858.60 ± 0.05 km3/sec2 is the best estimate

  1. Storms on Venus: Lightning-induced chemistry and predicted products

    Science.gov (United States)

    Delitsky, M. L.; Baines, K. H.

    2015-08-01

    Observations by many spacecraft that have visited Venus over the last 40 years appear to confirm the presence of lightning storms in the Venus atmosphere. Recent observations by Venus Express indicate that lightning frequency and power is similar to that on Earth. While storms are occurring, energy deposition by lightning into Venus atmospheric constituents will immediately dissociate molecules into atoms, ions and plasma from the high temperatures in the lightning column (>30,000 K) and the associated shock waves and heating, after which these atom and ion fragments of C,O,S,N,H-containing molecules will recombine during cooldown to form new sets of molecules. Spark and discharge experiments in the literature suggest that lightning effects on the main atmospheric molecules CO2, N2, SO2, H2SO4 and H2O will yield carbon oxides and suboxides (COm, CnOm), sulfur oxides (SnO, SnOm), oxygen (O2), elemental sulfur (Sn), nitrogen oxides (NO, N2O, NO2), sulfuric acid clusters (HnSmOx-.aHnSmOx e.g. HSO4-.mH2SO4), polysulfur oxides, carbon soot and other exotic species. While the amounts generated in lightning storms would be much less than that derived from photochemistry, during storms these species can build up in a small area and so their local concentrations may increase significantly. For a storm of 100×100 km, the increase could be ~5 orders of magnitude if they remain in the storm region for a period before becoming well-mixed. Some of these molecular species may be detectable by instruments onboard Venus Express while they are concentrated in the storm regions. We explore the diversity of new products likely created in lightning storms on Venus.

  2. Evidence for lightning on Venus

    International Nuclear Information System (INIS)

    Measurements obtained by the Pioneer Orbiter of the electric field, magnetic field and the electron density of the Venus atmospheres are presented and the tentative conclusion that the events recorded are due to Venusian lightning is discussed. (UK)

  3. 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"

  4. Infrared thermal radiation of Venus

    International Nuclear Information System (INIS)

    Data on peculiarities of the infrared thermal radiation from Venus, obtained on the base of the ground and airborne measurements are given. The average value of the planet spherical albedo equals 0.766+-0.018 (228 K effective temperature). The equatorial and latitudinal distributions of escaping radiation are tabulated. The Venus thermal radiation is subject to an intensive effect of darkening at the edge, the nature of darkening being different for various longitudes and latitudes. Some specificities are characteristic of the polar region radiation. The solar-related (daily) component is clearly manifested, the night time planet radiation somewhat exceeding the daytime radiation. Numerous data testify to the variability of Venus thermal radiation global characteristics during the period of one year or several years. Such variability is supposed to be related to comparatively short flashes of aerosol particle formation in the atmosphere caused by a sharp increase of the Venus volcanic activity

  5. Mission Architecture and Technology Options for a Flagship Class Venus In Situ Mission

    Science.gov (United States)

    Balint, Tibor S.; Kwok, Johnny H.; Kolawa, Elizabeth A.; Cutts, James A.; Senske, David A.

    2008-01-01

    Venus, as part of the inner triad with Earth and Mars, represents an important exploration target if we want to learn more about solar system formation and evolution. Comparative planetology could also elucidate the differences between the past, present, and future of these three planets, and can help with the characterization of potential habitable zones in our solar system and, by extension, extrasolar systems. A long lived in situ Venus mission concept, called the Venus Mobile Explorer, was prominently featured in NASA's 2006 SSE Roadmap and supported in the community White Paper by the Venus Exploration Analysis Group (VEXAG). Long-lived in situ missions are expected to belong to the largest (Flagship) mission class, which would require both enabling and enhancing technologies beside mission architecture options. Furthermore, extreme environment mitigation technologies for Venus are considered long lead development items and are expected to require technology development through a dedicated program. To better understand programmatic and technology needs and the motivating science behind them, in this fiscal year (FY08) NASA is funding a Venus Flaghip class mission study, based on key science and technology drivers identified by a NASA appointed Venus Science and Technology Definition Team (STDT). These mission drivers are then assembled around a suitable mission architecture to further refine technology and cost elements. In this paper we will discuss the connection between the final mission architecture and the connected technology drivers from this NASA funded study, which - if funded - could enable a future Flagship class Venus mission and potentially drive a proposed Venus technology development program.

  6. Memristors in the Venus flytrap

    OpenAIRE

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

    2014-01-01

    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 cy...

  7. Rate of volcanism on Venus

    International Nuclear Information System (INIS)

    The maintenance of the global H2SO4 clouds on Venus requires volcanism to replenish the atmospheric SO2 which is continually being removed from the atmosphere by reaction with calcium minerals on the surface of Venus. The first laboratory measurements of the rate of one such reaction, between SO2 and calcite (CaCO3) to form anhydrite (CaSO4), are reported. If the rate of this reaction is representative of the SO2 reaction rate at the Venus surface, then we estimate that all SO2 in the Venus atmosphere (and thus the H2SO4 clouds) will be removed in 1.9 million years unless the lost SO2 is replenished by volcanism. The required rate of volcanism ranges from about 0.4 to about 11 cu km of magma erupted per year, depending on the assumed sulfur content of the erupted material. If this material has the same composition as the Venus surface at the Venera 13, 14 and Vega 2 landing sites, then the required rate of volcanism is about 1 cu km per year. This independent geochemically estimated rate can be used to determine if either (or neither) of the two discordant (2 cu km/year vs. 200 to 300 cu km/year) geophysically estimated rates is correct. The geochemically estimated rate also suggests that Venus is less volcanically active than the Earth

  8. Venus magnetic field and magnetosphere

    International Nuclear Information System (INIS)

    Magnetic field investigations have been conducted in the distance of 1500-3000 km and 1-6Rsub(?) from the Venus, where Rsub(?) - is the Venus radius. Magnetic field complex topology, observed at the Venus night side form ''Venera-9,10'' satellites is explained by the Venus having its own weak magnetic field and the action of outer source fields. There is a magnetic stub on the planet night side, in which 2 bunches of lines of force, devided by neutral layer, are directed from the planet (to the north of equator) and to the planet (to the south of equator). The magnetic stub narrows at approaching to the planet and is located inside the planet geometric shade near the planet. The planet magnetic field effects but slightly the character of the planet flow-around by the sun wind. The stub topology depends on the polarity mark and force of field in the planet transfer zone. The ''overuniting'' processes of magnetospheric field and fields of outer sources present permanent process in the Venus magnetosphere. Notwithstanding the weakness of the Venus field, it is similar to geomagnetic one in a model way, provided the planet rotation peculiarities are taken into account

  9. Crustal deformation: Earth vs Venus

    International Nuclear Information System (INIS)

    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

  10. Identification of Postclassic Maya Constellations from the Venus Pages of the Dresden Codex

    Scientific Electronic Library Online (English)

    Changbom, Park; Heajoo, Chung.

    Full Text Available La civilización maya, que floreció del 1200 a.C. a 1500 d.C., dejó numerosos textos jeroglíficos sobre el calendario y observaciones astronómicos. El Códice de Dresde, en particular, contiene el más detallado de dichos antiguos legados mayas. Las páginas 24 y 46 a 50 de dicho códice describen el cal [...] endario de Venus con los augurios correspondientes. Nosotros hemos notado que éste es un calendario Venus-Solar, y nuestro trabajo se enfoca sobre la posibilidad de que estuviera hecho para trabajar en conjunción con la aparición de determinadas constelaciones en el cielo. Es a través del análisis y descripción de las páginas de Venus que proponemos que las columnas en cada página describen el movimiento de Venus respecto de constelaciones mayores, en fechas que corresponden a eventos especiales, mientras que las fechas calendáricas se incrementan horizontalmente dentro del periodo sinódico de Venus. Aquí presentamos veinte constelaciones mayas identificadas desde las páginas de Venus asumiendo que la primera fecha, en la página 46, fue febrero 6 de 1228. También reportamos, como entendemos, las expresiones verbales sobre el movimiento de Venus y las constelaciones. Abstract in english Ancient Mayan civilization, flourished from 1200 B.C. to 1500 A.D., has left numerous hieroglyphic texts on astronomical observations and calendar. In particular, the Dresden Codex contains the most details of such ancient Mayan heritage. Page 24 and those from 46 to 50 of the Dresden Codex describe [...] the Mayan Venus calendar along with the augural descriptions. We note that the calendar in Dresden Codex is Venus-solar calendar. Our work focuses on the possibility that the calendar was made to work in conjunction with the periodic appearance of constellations on the sky. By analyzing the descriptions in the Venus pages, we propose that the columns in each page describe the motion of Venus with respect to major constellations at dates corresponding to special events while the calendar dates increase horizontally in the synodic period of Venus. We present twenty Mayan constellations identified from the Venus pages assuming that the first date of page 46 is February 6, 1228. We also report our understanding of verb expressions about the relative movement of constellations and Venus.

  11. Possible Signs of Fauna and Flora on Venus

    Science.gov (United States)

    Ksanfomality, Leonid V.; Selivanov, Arnold S.; Gektin, Yuryi M.

    2015-08-01

    Habitability of planets is a fundamental question of science. Some of exoplanets possess physical conditions close to those of Venus. The planet Venus, despite its dense and hot (735 K) oxygen-free atmosphere of CO2, having a high pressure of 9.2 MPa at the surface, can be a natural laboratory for this kind of studies. The only existing data on the planet’s surface are still the results obtained by the Soviet VENERA landers.The TV experiments of Venera-9 and 10 (October, 1975) and Venera-13 and 14 (March, 1982) delivered 41 panoramas of Venus surface (or their fragments). The experiments were of extreme technical complexity. There have not been any similar missions to Venus in the subsequent 40 and 33 years. In the absence of new landing missions to Venus, the VENERA panoramas have been re-processed by modern means. The results of these missions are studied anew. A dozen of relatively large objects, from a decimeter to half a meter in size, with an unusual morphology have been found which moved very slowly or changed slightly their shape. Certain unusual findings that have a structure similar to the Earth’ fauna and flora were found in different areas of the planet. There are more then 30 papers on the topic published in 2012-2014 (e.g., “Acta Astronautica”, 2014, V. 105, pp. 521-533). Due to the availability of up to eight duplicates of the images obtained and their low level of masking noise, the VENERA archive panoramas permit identifying and exploring some types of hypothetical life forms of Venus. Analysis of treated once again VENERA panoramic images revealed objects that might indicate the presence of about 12 hypothetical forms of Venusian flora and fauna. Among them is ‘amisada’ that stands out with its unusual lizard shape against the stone plates surrounding it.

  12. Critical components of Venus Lower and Upper atmospheres with FirefOx and Venus Neutron Spectrometer (VeNuS)

    Science.gov (United States)

    Izenberg, N. R.; Papadakis, S. J.; Monica, A. H.; Deglau, D. M.; Lawrence, D. J.; Peplowski, P. N.

    2015-10-01

    We present two instrument concepts for understanding critical aspects of Venus' upper and lower atmosphere. FirefOx is an oxygen fugacity sensor for the lower atmosphere, and The Venus Nuclear Spectrometer (VeNuS) studies composition and volcanic activity signals in the upper atmosphere.

  13. LIBS Testing in a Venus Environment Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Configure LIBS system to view samples in the Venus chamber Confirm STP results for LIBS in Venus Chamber configuration Conduct high temperature/high pressure...

  14. 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

  15. European Venus Explorer: An in-situ mission to Venus using a balloon platform

    Science.gov (United States)

    Chassefière, E.; Korablev, O.; Imamura, T.; Baines, K. H.; Wilson, C. F.; Titov, D. V.; Aplin, K. L.; Balint, T.; Blamont, J. E.; Cochrane, C. G.; Ferencz, Cs.; Ferri, F.; Gerasimov, M.; Leitner, J. J.; Lopez-Moreno, J.; Marty, B.; Martynov, M.; Pogrebenko, S. V.; Rodin, A.; Whiteway, J. A.; Zasova, L. V.; the EVE Team

    2009-07-01

    Planetary balloons have a long history already. A small super-pressure balloon was flown in the atmosphere of Venus in the eighties by the Russian-French VEGA mission. For this mission, CNES developed and fully tested a 9 m diameter super-pressure balloon, but finally replaced it by a smaller one due to mass constraints (when it was decided to send Vega to Halley's Comet). Furthermore, several kinds of balloons have been proposed for planetary exploration [Blamont, J., in: Maran, S.P. (Ed.), The Astronomy and Astrophysics Encyclopedia. Cambridge University Press, p. 494, 1991]. A Mars balloon has been studied for the Mars-94 Russian-French mission, which was finally cancelled. Mars and Venus balloons have also been studied and ground tested at JPL, and a low atmosphere Venus balloon is presently under development at JAXA (the Japanese Space Agency). Balloons have been identified as a key element in an ongoing Flagship class mission study at NASA, with an assumed launch date between 2020 and 2025. Recently, it was proposed by a group of scientists, under European leadership, to use a balloon to characterize - by in-situ measurements - the evolution, composition and dynamics of the Venus atmosphere. This balloon is part of a mission called EVE (European Venus Explorer), which has been proposed in response to the ESA AO for the first slice of the Cosmic Vision program by a wide international consortium including Europe, Russia, Japan and USA. The EVE architecture consists of one balloon platform floating at an altitude of 50-60 km, one short lived probe provided by Russia, and an orbiter with a polar orbit to relay data from the balloon and probe, and to perform remote sensing science observations. The balloon type preferred for scientific goals is one, which would oscillate in altitude through the cloud deck. To achieve this flight profile, the balloon envelope would contain a phase change fluid. While this proposal was not selected for the first slice of Cosmic Vision missions, it was ranked first among the remaining concepts within the field of solar system science.

  16. Venera-D -the future Russian mission to Venus

    Science.gov (United States)

    Zasova, Ludmila; Zelenyi, Lev; Korablev, Oleg; Sanko, N. F.; Khartov, Victor V.; Vorontsov, Victor A.; Basilevsky, A. T.; Pichkhadze, Konstantin M.; Elkin, Konstantin S.; Voron, Victor V.

    Venus was actively studied by Soviet and US mission in 60-80-th years of the last century. The investigations carried out both from the orbit and in situ were highly successful. After a 15-years break in space research of Venus, the ESA Venus Express mission, launched in 2005, successfully continues its work on orbit around Venus. In 2010 the launch of the Japanese Climate Orbiter (Planeta-C) mission is planned. However, many questions concerning the structure, and evolu-tions of planet Venus, which are the key questions of comparative planetology, very essential for understanding the evolution of the terrestrial climate, cannot be solved by observations from an orbit. Now in Russia the new investigation phase of Venus begins: the mission Venera-D is included in the Russian Federal Space Program to be launched in 2016. This mission includes the lander, balloons, and the orbiter. The long living balloons are planned to be deployed at different heights, in the clouds and under the clouds. Scientific goals of the mission include: -investigation of structure, chemical composition of the atmosphere, including noble gases abundance and isotopic ratio, structure and chemistry of the clouds; -study of dynamics of the atmosphere, nature of the superrotation, radiative balance, nature of an enormous greenhouse effect; -study of structure, mineralogy and geochemistry of the surface, search for seismic and volcanic activity, the lightening, interaction of the atmosphere and the surface; -investigation of the upper atmosphere, ionosphere, magnetosphere, and the escape rate; -study of the evolution of the atmosphere and the surface of Venus. The complex of experiments on the orbiter includes, among the others, several spectrometers in the spectral range from UV to MW, the mapping spectrometers and the plasma package. On the lander there are instruments to work during the descent, and on the surface: gas-chromatograph, PTW (meteo), nephelometer and the particle sizes spectrometer, optical package, active gamma-spectrometer, TV-complex, which includes panoramic, high resolution and descending cameras.. On the balloon which has to work near the lower boundary of clouds, the devices will be installed to study the lower atmosphere and to get the surface images with high resolution at 1 mkm. Successful realization of the project Venera-D will allow to solve the important scientific problems of comparative planetology. In particular it will help to understand why do Venus and the Earth (sister-planets), similar in many aspects, being formed at similar conditions in the protoplanet nebula, evolve by such a different way.

  17. Episodic plate tectonics on Venus

    Science.gov (United States)

    Turcotte, Donald

    1992-01-01

    Studies of impact craters on Venus from the Magellan images have placed important constraints on surface volcanism. Some 840 impact craters have been identified with diameters ranging from 2 to 280 km. Correlations of this impact flux with craters on the Moon, Earth, and Mars indicate a mean surface age of 0.5 +/- 0.3 Ga. Another important observation is that 52 percent of the craters are slightly fractured and only 4.5 percent are embayed by lava flows. These observations led researchers to hypothesize that a pervasive resurfacing event occurred about 500 m.y. ago and that relatively little surface volcanism has occurred since. Other researchers have pointed out that a global resurfacing event that ceased about 500 MYBP is consistent with the results given by a recent study. These authors carried out a series of numerical calculations of mantle convection in Venus yielding thermal evolution results. Their model considered crustal recycling and gave rapid planetary cooling. They, in fact, suggested that prior to 500 MYBP plate tectonics was active in Venus and since 500 MYBP the lithosphere has stabilized and only hot-spot volcanism has reached the surface. We propose an alternative hypothesis for the inferred cessation of surface volcanism on Venus. We hypothesize that plate tectonics on Venus is episodic. Periods of rapid plate tectonics result in high rates of subduction that cool the interior resulting in more sluggish mantle convection.

  18. Wave granulation in the Venus' atmosphere

    Science.gov (United States)

    Kochemasov, G.

    2007-08-01

    In unique venusian planetary system the solid body rotates very slowly and the detached massive atmosphere very rapidly. However both together orbit Sun and their characteristic orbital frequency -1/ 0.62 year - places them in the regular row of planets assigning them characteristic only for Venus wave produced granulation with a granule size ?R/6 [1& others]. Remind other bodies in the row with their granule sizes inversely proportional to their orbital frequencies: solar photosphere ?R/60, Mercury ?R/16, Venus ?R/6, Earth ?R/4, Mars ?R/2, asteroids ?R/1 (R-a body radius). Three planets have atmospheres with wave granulations having sizes equal to their lithospheric granules. But Venus, unlike Earth and Mars, has the detached atmosphere that can be considered as a separate body with its own orbital frequency around the center of the Venus' system. According to the correlation between an orbital frequency and a wave granule size the venusian wave granule will be ?R/338 (a scale can be Earth: orbital frequency 1/ 1year, granule size ?R/4 or Sun: frequency 1/1month, granule size ?R/60). So, ?R/338 = 57 km. This theoretical size is rather close to that observed by Galileo SC through a violet filter "the filamentary dark features. . . are here revealed to be composed of several dark nodules, like beads on a string, each about 60 miles across" (PIA00072). Actually all Venus' disc seen from a distance ?1.7mln.miles is peppered with these fine features seen on a limit of resolution. So, the Venus' atmosphere has two main frequencies in the solar system with corresponding wave granulations: around Sun 1/225 days (granule ?R/6) and around Venus 1/ 4 days (granule ?R/338). As was done for the Moon, Phobos, Titan and other icy satellites of Saturn [2, 3, 4 & others] one can apply the wave modulation technique also for the atmosphere of Venus. The lower frequency modulates the higher one by dividing and multiplying it thus getting two side frequencies and corresponding them wave granule sizes. (1/338 : 1/6)?R = ?R/56.3 = 342 km. (1/338 x 1/6)?R = ?R/2028 = 9.5 km. The larger granules as well arranged network were seen in the near IR Galileo image PIA00073 (several miles below the visible cloud tops). The smaller granules, hopefully, will be detected by the Venus Express cameras. So, the wave planetology applying wave methods to solid planetary bodies and to surrounding them gaseous envelopes shows their structural unity. This understanding may help to analyze and predict very complex behavior of atmospheric sells at Earth (anticyclones up to 5000 km across or ?R/4), other planets and Titan. Long time ago known the solar supergranules about 30000 km across were never fully understood. The comparative wave planetology placing them together with wave features of planets and satellites throws light on their origin and behavior and thus expands into an area of the solar physics. In this respect it is interesting to note that rather typical for Sun radio emission in 1 meter diapason also was never properly explained. But applying modulation of the solar photosphere frequency 1/ 1month by the Galaxy frequency 1/ 200 000 000 y. one can obtain such short waves [5]. Radio emissions of planets of the solar system also can be related to this modulation by Galaxy rotation [5]. References: [1] Kochemasov G.G. (1992) Comparison of blob tectonics (Venus) and pair tectonics (Earth) // LPS XXIII, Houston, LPI, pt. 2, 703-704; [2] Kochemasov G.G. (2000) Orbiting frequency modulation in Solar system and its imprint in shapes and structures of celestial bodies // Vernadsky-Brown microsymposium 32 on Comparative planetology, Oct. 9-11, 2000, Moscow, Russia, Abstracs, 88-89; [3] Kochemasov G.G. (2000) Titan: frequency modulation of warping waves // Geophys. Res. Abstr., v. 2, (CD-ROM); [4] Kochemasov G.G. (2005) Cassini' lessons: square craters, shoulderto- shoulder even-size aligned and in grids craters having wave interference nature must be taken out of an impact craters statistics to make it real // Vernadsky-Brown

  19. 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.

  20. Neurogenin2-d4Venus and Gadd45g-d4Venus transgenic mice: Visualizing mitotic and migratory behaviors of cells committed to the neuronal lineage in the developing mammalian brain

    OpenAIRE

    Kawaue, Takumi; Sagou, Ken; Kiyonari, Hiroshi; Ota, Kumiko; OKAMOTO, MAYUMI; Shinoda, Tomoyasu; Kawaguchi, Ayano; Miyata, Takaki

    2014-01-01

    To achieve highly sensitive and comprehensive assessment of the morphology and dynamics of cells committed to the neuronal lineage in mammalian brain primordia, we generated two transgenic mouse lines expressing a destabilized (d4) Venus controlled by regulatory elements of the Neurogenin2 (Neurog2) or Gadd45g gene. In mid-embryonic neocortical walls, expression of Neurog2-d4Venus mostly overlapped with that of Neurog2 protein, with a slightly (1 h) delayed onset. Although Neurog2-d4Venus and...

  1. 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…

  2. Unipolar induction effect in the Venus magnetotail

    International Nuclear Information System (INIS)

    The measurements of the magnetic field in the Venus tail at small distances from the planet obtained from the sputnics of ''Venus-9'', ''Venus-10'' and the ''Venus-4'' cosmic apparatus are considered. The connection between the field structure in the tail and the orientation of the transverse component of the interplanet magnetic field is found out. It is shown that the data of experiments in the Venus vicinity may be explained within the framework of the model of unipolar induction field which is formed in the day ionosphere and is stretched out at the night side while interacting with the solar wind

  3. 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

  4. 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...

  5. Introduction to the special issue on Venus exploration

    Science.gov (United States)

    Svedhem, H.; Wilson, C.; Piccioni, G.

    2015-08-01

    Venus Express ended its mission in December 2014 after an extraordinary successful eight and a half years at Venus. The first years of the mission concentrated on the original objectives of the mission, namely to study the dynamics, structure and chemistry of the atmosphere, to investigate the plasma environment and its interaction with the solar wind, and to study certain topics of the surface and the surface atmosphere interaction. The latter part of the mission was focussing on dedicated campaigns for the study of specific topics, often in coordination with ground based observations. The highly elliptical polar orbit permitted a study of all latitudes, particularly of the polar regions. The optimised payload and orbit of the mission, together with the systematic and long-term observations of the atmosphere has enabled a wealth of data to be analysed. It has already resulted in many exciting new findings and a significantly improved understanding of Venus, even if only a part of the data has been analysed so far. In the last year of the mission a two month long aerobraking campaign was performed, resulting in a valuable data set on the structure of the atmosphere down to below 130 km - a region difficult to sample with remote techniques, before the fuel ran out at the end of November 2014. This campaign also provided a lot of engineering and operational experience, useful for future missions that may use aerobraking techniques at Venus or other planets.

  6. Long-Lived Venus Lander Conceptual Design: How To Keep It Cool

    Science.gov (United States)

    Dyson, Ridger W.; Schmitz, Paul C.; Penswick, L. Barry; Bruder, Geoffrey A.

    2009-01-01

    Surprisingly little is known about Venus, our neighboring sister planet in the solar system, due to the challenges of operating in its extremely hot, corrosive, and dense environment. For example, after over two dozen missions to the planet, the longest-lived lander was the Soviet Venera 13, and it only survived two hours on the surface. Several conceptual Venus mission studies have been formulated in the past two decades proposing lander architectures that potentially extend lander lifetime. Most recently, the Venus Science and Technology Definition Team (STDT) was commissioned by NASA to study a Venus Flagship Mission potentially launching in the 2020- 2025 time-frame; the reference lander of this study is designed to survive for only a few hours more than Venera 13 launched back in 1981! Since Cytherean mission planners lack a viable approach to a long-lived surface architecture, specific scientific objectives outlined in the National Science Foundation Decadal Survey and Venus Exploration Advisory Group final report cannot be completed. These include: mapping the mineralogy and composition of the surface on a planetary scale determining the age of various rock samples on Venus, searching for evidence of changes in interior dynamics (seismometry) and its impact on climate and many other key observations that benefit with time scales of at least a full Venus day (Le. daylight/night cycle). This report reviews those studies and recommends a hybrid lander architecture that can survive for at least one Venus day (243 Earth days) by incorporating selective Stirling multi-stage active cooling and hybrid thermoacoustic power.

  7. Venus ionopause during solar minimum

    International Nuclear Information System (INIS)

    During solar minimum, the Venus ionosphere is weak and the solar wind depresses the ionopause to a limiting altitude (Knudsen et al., 1987). With the knowledge gained from the ion composition measurements on Pioneer Venus during solar maximum and during conditions of high solar wind pressure, the authors argue that the typical topside electron density profile at Venus during solar minimum has two distinct regimes; one from about 140 km (the altitude of peak electron density) to 180 km and the other above 180 km. While the former is dominated by O2+ ions which are in photochemical equilibrium, the latter is dominated by O+ ions which are strongly disturbed by the solar wind induced plasma transport. The disturbed ionosphere is formed in the photodynamical regime and has a scale height which is several times smaller than that expected under undisturbed conditions when the ionosphere is in diffusive equilibrium. The small scale height of the disturbed ionosphere is nearly equal to that of the ionizable constituent, atomic oxygen, and is only slightly larger than the chemical equilibrium scale height of the underlying chemical equilibrium region. While the photodynamical ionopause occurs rarely during solar maximum and only when the solar wind pressure is large, we believe that this kind of ionopause is observed much more frequently during solar minimum. The authors find evidence for this in the radio occultation data from Pioneer Venus, Mariner 10 and Venera 9 and 10

  8. Venus and Mercury as planets

    International Nuclear Information System (INIS)

    A general evolutionary history of the solar planetary system is given. The previously observed characteristics of Venus and Mercury (i.e. length of day, solar orbit, temperature) are discussed. The role of the Mariner 10 space probe in gathering scientific information on the two planets is briefly described

  9. Venus and Mercury as Planets

    Science.gov (United States)

    1974-01-01

    A general evolutionary history of the solar planetary system is given. The previously observed characteristics of Venus and Mercury (i.e. length of day, solar orbit, temperature) are discussed. The role of the Mariner 10 space probe in gathering scientific information on the two planets is briefly described.

  10. Non-Cooled Power System for Venus Lander

    Science.gov (United States)

    Salazar, Denise; Landis, Geoffrey A.; Colozza, Anthony J.

    2014-01-01

    The Planetary Science Decadal Survey of 2013-2022 stated that the exploration of Venus is of significant interest. Studying the seismic activity of the planet is of particular importance because the findings can be compared to the seismic activity of Earth. Further, the geological and atmospheric properties of Venus will shed light into the past and future of Earth. This paper presents a radioisotope power system (RPS) design for a small low-power Venus lander. The feasibility of the new power system is then compared to that of primary batteries. A requirement for the power source system is to avoid moving parts in order to not interfere with the primary objective of the mission - to collect data about the seismic activity of Venus using a seismometer. The target mission duration of the lander is 117 days, a significant leap from Venera 13, the longest-lived lander on the surface of Venus, which survived for 2 hours. One major assumption for this mission design is that the power source system will not provide cooling to the other components of the lander. This assumption is based on high-temperature electronics technology that will enable the electronics and components of the lander to operate at Venus surface temperature. For the proposed RPS, a customized General Purpose Heat Source Radioisotope Thermoelectric Generator (GPHSRTG) is designed and analyzed. The GPHS-RTG is chosen primarily because it has no moving parts and it is capable of operating for long duration missions on the order of years. This power system is modeled as a spherical structure for a fundamental thermal analysis. The total mass and electrical output of the system are calculated to be 24 kilograms and 26 Watts, respectively. An alternative design for a battery-based power system uses Sodium Sulfur batteries. To deliver a similar electrical output for 117 days, the battery mass is calculated to be 234 kilograms. Reducing mission duration or power required will reduce the required battery mass. Finally, the advantages and disadvantages of both power systems with regard to science return, risk, and cost are briefly compared. The design of the radioisotope power system is considerably riskier because it is novel and would require additional years of further refinement, manufacturing, safety analysis, and testing that the primary batteries do not need. However, the lifetime of the radioisotope power system makes its science return more promising.

  11. 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.

  12. Models of the internal structure of Venus

    International Nuclear Information System (INIS)

    A survey is made of the physics of the interiors of Venus. The introduction explains the main concepts used in the construction of models of Venus and the history of the question; observational data are gathered and analyzed. The method of constructing the models of the planet is explained and earth-like models of Venus and parametrically simple PVM models are discussed. Within the compass of a physical model of Venus, the thermodynamics of the mantle and core is constructed and questions are discussed concerning the heat conduction, temperature distribution in the lithosphere and the thermal flux from the interior of Venus, the electrical conduction and mechanical quality, and large-scale steady stresses in the mantle of Venus. A rheological model of the crust and mantle is constructed. In conclusion, the question as to the distribution of radioactivity and convection in the interior of the planet is discussed. (Auth.)

  13. The Transit of Venus: an Opportunity to Promote Astronomy

    Science.gov (United States)

    Ros, R. M.

    The transit of Venus was an excellent opportunity to promote Astronomy to everybody. In particular this occasion was used to encourage interest in Astronomy in schools. In our society, which has a good quality of life, interest in science has decreased. Every year the number of students interested in studying science degrees at university is smaller than in previous years. Our new generations do not seem to be motivated to study in the field of science. Probably this situation is a consequence of the lack of understanding of the true meaning of science. Of course, it is not possible that a student would decide to study a topic that they do not know about. In the media science appears less than sports, cinema, or business! In consequence, the general public is more concerned about items other than science. On June 8th we took advantage of an opportunity to introduce science and Astronomy into the lives of everybody, but especially in schools. This paper will show two projects related to the transit in schools: ”Pilla el Tránsito de Venus” and ”VT-2004” and a short appendix to another project for schools ”ALMA-ITP”

  14. Abstracts for the venus geoscience tutorial and venus geologic mapping workshop

    International Nuclear Information System (INIS)

    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

  15. A Venus Rover Capable of Long Life Surface Operations

    Science.gov (United States)

    Evans, M.; Shirley, J. H.; Abelson, R. D.

    2005-12-01

    Access to the surface of Venus would allow planetary scientists to address a number of currently open questions. Among these are the elemental and mineralogical composition of the surface; the interaction of the surface with the atmosphere; the atmospheric composition, especially isotope ratios of key species; the nature of the planetary volcanism (present activity, emissions to the atmosphere, and composition); planetary seismicity; the local surface meteorology (winds and pressure variability); and the surface geology and morphology at particular locations on the surface. A long lived Venus rover mission could be enabled by utilizing a novel Stirling engine system for both cooling and electric power. Previous missions to the Venus surface, including the Pioneer Venus and Venera missions, survived for only a few hours. The rover concept described in the present study is designed for a surface lifetime of 60 days, with the potential of operating well beyond that. A Thermo-Acoustic Stirling Heat Engine (TASHE) would convert the high-temperature (~1200 °C) heat from General Purpose Heat Source (GPHS) modules into acoustic power which then drives a linear alternator and a pulse tube cooler to provide electric power and remove the large environmental heat load. The "cold" side of the engine would be furnished by the ambient atmosphere at 460 °C. This short study focused on the feasibility of using the TASHE system in this hostile environment to power a ~650 kg rover that would provide a mobile platform for science measurements. The instrument suite would collect data on atmospheric and surface composition, surface stratigraphy, and subsurface structure. An Earth-Venus-Venus trajectory would be used to deliver the rover to a low entry angle allowing an inflated ballute to provide a low deceleration and low heat descent to the surface. All rover systems would be housed in a pressure vessel in vacuum with the internal temperature maintained by the TASHE below 50 °C. No externally deployed or articulated components would be used and penetrations through the pressure vessel are minimized. Science data would be returned direct to Earth using S-Band to minimize atmospheric attenuation.

  16. Next generation ECR ion sources: First results of the superconducting 28 GHz ECRIS - VENUS

    International Nuclear Information System (INIS)

    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. The goal of the VENUS ECR ion source project as the RIA R and D injector is the production of 200 e?A of U30+, a high current medium charge state beam. On the other hand, as an injector ion source for the 88-Inch Cyclotron the design objective is the production of 5 e?A of U48+, a low current, very high charge state beam. To achieve those ambitious goals, the VENUS ECR ion source has been designed for optimum operation at 28 GHz. The nominal design fields of the axial magnets are 4 T at injection and 3 T at extraction; the nominal radial design field strength at the plasma chamber wall is 2 T, making VENUS currently the world's most powerful ECR plasma confinement structure. Recently, the six year project has made significant progress. In June 2002, the first plasma was ignited at 18 GHz. During 2003, the VENUS ECR ion source was commissioned at 18 GHz, while preparations for 28 GHz operation were being conducted. In May 2004 28 GHz microwave power has been coupled into the VENUS ECR ion source for the first time. Preliminary performance-tests with oxygen, xenon and bismuth at 18 GHz and 28 GHz have shown promising results. Intensities close to or exceeding the RIA requirements have been produced for those few test beams. The paper will briefly describe the design of the VENUS source and its beam analyzing system. Results at 18 GHz and 28 GHz including first emittance measurements will be described

  17. VENUS - The Victoria Experimental Network Under the Sea: First Light

    Science.gov (United States)

    Dewey, R. K.; Tunnicliffe, V.; Round, A.

    2006-05-01

    The Victoria Experimental Network Under the Sea (VENUS) is a recently installed cabled ocean observatory representing the next generation of infrastructure technology. VENUS is scheduled to consist of two major segments, one in Saanich Inlet (installed in February 2006), and a second in the Strait of Georgia (planned for October 2006). The technologies associated with both the hardware and software that will deliver data from instruments to scientists is being developed in collaboration with both the NEPTUNE Canada and MARS observatories. The presentation will provide an overview of the science projects planned for stage one of the installed instruments, the engineering design of the infrastructure, the preliminary design of the Data Management and Archive System (DMAS), lessons learned so far, and preliminary results from the first few months of data from Saanich Inlet.

  18. Substorm activity in Venus's magnetotail

    Directory of Open Access Journals (Sweden)

    M. Volwerk

    2009-06-01

    Full Text Available The magnetotail of the induced magnetosphere of Venus is investigated through the magnetic field and plasma data of Venus Express. A comparison is made between two neutral sheet crossings. One crossing shows the magnetic field is rather quiet and the plasma instrument indicates a change from energetic (few 100 eV to low energy (few 10 eV ions. The other crossing shows more dynamics in the magnetic field, including signatures that are interpreted as characteristic of a reconnection site, and the plasma instrument indicates ions that are energized to 1500 to 2000 eV, in the same magnetospheric region where in the first crossing only low energy ions showed up.

  19. Venus as a more Earth-like planet.

    Science.gov (United States)

    Svedhem, Håkan; Titov, Dmitry V; Taylor, Fredric W; Witasse, Olivier

    2007-11-29

    Venus is Earth's near twin in mass and radius, and our nearest planetary neighbour, yet conditions there are very different in many respects. Its atmosphere, mostly composed of carbon dioxide, has a surface temperature and pressure far higher than those of Earth. Only traces of water are found, although it is likely that there was much more present in the past, possibly forming Earth-like oceans. Here we discuss how the first year of observations by Venus Express brings into focus the evolutionary paths by which the climates of two similar planets diverged from common beginnings to such extremes. These include a CO2-driven greenhouse effect, erosion of the atmosphere by solar particles and radiation, surface-atmosphere interactions, and atmospheric circulation regimes defined by differing planetary rotation rates. PMID:18046393

  20. The Venus ionosphere and solar wind interaction

    International Nuclear Information System (INIS)

    The current state of knowledge of the chemistry, dynamics and energetics of the upper atmosphere and ionosphere of Venus is reviewed together with the nature of the solar wind-Venus interaction. Because of the weak, though perhaps not negligible, intrinsic magnetic field of Venus, the mutual effects between these regions are probably strong and unique in the solar system. The ability of the Pioneer Venus Bus and Orbiter experiments to provide the required data to answer the questions outstanding is discussed in detail. (Auth.)

  1. Venus tectonics: another Earth or another Mars

    International Nuclear Information System (INIS)

    The presence of presumably primordial large craters has led to the suggestion that Venus may have a thick lithosphere like that of Mars despite its similarities to Earth in size and density. However, crust and upper mantle temperatures on Venus are very likely higher than on Earth so that a dry Venus could have a lithosphere with a thickness similar to that of Earth. If a trace of volatiles is present in the mantle, the lithosphere of Venus could be thinner. Due to the absence of liquid water, erosion and deposition will be much slower on Venus than on Earth, favoring retention of primordial cratered surfaces on portions of the crust that have not been destroyed or buried by tectonic and volcanic activity. Geochemical models of solar system origin and petrological considerations suggest that K is about as abundant in Venus as in Earth. The abundance of 40Ar in the atmosphere of Venus lies somewhere between the Earth value and one-tenth of the Earth value. Because erosional liberation of 40Ar on Venus will be relatively inefficient, this range for 40Ar abundance at least permits an active tectonic history, and if the 40Ar abundance is towards the high end of the range, it may well require an active tectonic history. Thus we are not constrained to a Mars-like model of Venus tectonics by craters and possible mantle dryness; an Earth-like model is equally probable

  2. How the Venus flytrap snaps

    Science.gov (United States)

    Forterre, Yoël; Skotheim, Jan M.; Dumais, Jacques; Mahadevan, L.

    2005-01-01

    The rapid closure of the Venus flytrap (Dionaea muscipula) leaf in about 100ms is one of the fastest movements in the plant kingdom. This led Darwin to describe the plant as ``one of the most wonderful in the world''. The trap closure is initiated by the mechanical stimulation of trigger hairs. Previous studies have focused on the biochemical response of the trigger hairs to stimuli and quantified the propagation of action potentials in the leaves. Here we complement these studies by considering the post-stimulation mechanical aspects of Venus flytrap closure. Using high-speed video imaging, non-invasive microscopy techniques and a simple theoretical model, we show that the fast closure of the trap results from a snap-buckling instability, the onset of which is controlled actively by the plant. Our study identifies an ingenious solution to scaling up movements in non-muscular engines and provides a general framework for understanding nastic motion in plants.

  3. Magellan at Venus - First results

    International Nuclear Information System (INIS)

    First results of mapping the Venusian surface on the basis of data from the Magellan spacecraft are presented, together with the description of the Magellan measurement instruments. These consist of a SAR, which bounces short pulses of radio energy off the planet's surface for 37 min of each orbit, when it is closest to Venus, and a radar altimeter, which repeatedly determines the height of the landscape directly below it. The paper describes key features of several impact craters mapped by Magellan, including the Crater Golubkina, the crater farm and the Gumby feature near the Lavinia Planitia region, a 9 x 12-km kidney-shaped crater, and a radar-bright feature considered to be an evidence of explosive volcanism on Venus

  4. 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

  5. How the Venus Flytrap Snaps

    OpenAIRE

    Forterre, Yoel; Skotheim, Jan M.; Dumais, Jacques; Mahadevan, Lakshminarayanan

    2005-01-01

    The rapid closure of the Venus flytrap (Dionaea muscipula) leaf in about 100 ms is one of the fastest movements in the plant kingdom. This led Darwin to describe the plant as "one of the most wonderful in the world". The trap closure is initiated by the mechanical stimulation of trigger hairs. Previous studies have focused on the biochemical response of the trigger hairs to stimuli and quantified the propagation of action potentials in the leaves. Here we complement these studies by consideri...

  6. 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

  7. Electromagnetic waves observed on a flight over a Venus electrical storm

    Science.gov (United States)

    Russell, C. T.; Leinweber, H.; Zhang, T. L.; Daniels, J. T. M.; Strangeway, R. J.; Wei, H.

    2013-01-01

    The occurrence of electrical discharges in planetary atmospheres produces high temperatures and pressures enabling chemical reactions that are not possible under local thermodynamic equilibrium conditions. On Earth, electrical discharges in clouds produce nitric oxide. Similar abundances of nitric oxide exist in the Venus atmosphere, but the existence of extensive electrical activity in its substantive cloud system is not as firmly established. To determine the strength and occurrence rate of lightning, the Venus Express mission included dual magnetometers sampling at 128 Hz to detect the electromagnetic signals produced by lightning. We report herein evidence of the apparent overflight of electrical storms by the Venus Express spacecraft. These observations reveal two types of signals reaching the spacecraft: one in the ELF band that exhibits dispersion and travels along the magnetic field, and one in the ULF band that appears to travel vertically across the magnetic field from below.

  8. Tidal constraints on the interior of Venus

    Science.gov (United States)

    Dumoulin, C.; Tobie, G.; Verhoeven, O.; Rosenblatt, P.; Rambaux, N.

    2015-10-01

    As a prospective study for a future exploration of Venus, we propose to systematically investigate the signature of the internal structure in the gravity field and the rotation state of Venus, through the determination of the moment of inertia and the tidal Love number.

  9. Surface and the crust of Venus planet

    International Nuclear Information System (INIS)

    Modern information on surface of the Venus planet obtained by radiolocation investigations from the Earth and orbiters ''Pioneer-Venera'', ''Venera'' and ''Vega'' is presented in a popular form. The surface panoramas of the planet, obtained with automatic interplanetary stations ''Venera-9, 10, 13, 14'' are presented. Physico-chemical properties of Venus rocks are considered

  10. Venus Atmospheric Circulation from Digital Tracking of VMC Images

    Science.gov (United States)

    Limaye, S.; Moissl, R.; Markiewicz, W.; Titov, D.

    2008-09-01

    The Venus Monitoring Camera on Venus Express has been returning images of Venus in four filters since April 2006 on almost every orbit. These images portray the southern hemisphere of Venus at spatial resolutions ranging from ~ 50 km per pixel to better than ~ 10 km per pixel depending on when the planet was imaged from orbit. Images covering a substantial portion of the planet and separated by ~ 45 min to one hour have been mapped into rectilinear projection to enable use of digital tracking technique for the measurement of cloud motions on an orbit by orbit basis. The aggregate results are in good agreement with visual tracking results as well as from the previous missions [1] and show evidence of temporal variations, large scale waves and solar thermal tides in low and mid latitudes. The digital tracking results for the meridional component confirm the poleward flow increasing from low latitudes to mid-latitudes and then showing a tendency to weaken. However, the confidence in high latitude measurements is lower due to the peculiar nature of the cloud morphology that is generally streaky and quite different from the low latitudes. The meridional profile of the average zonal wind at higher latitudes is of considerable interest. At high and polar latitudes, a vortex organization is evident in the data consistently, with the core region centered over the pole. The images show variability in structure of the ultraviolet signature of the "S" shaped feature seen in the VIRTIS data on the capture orbit [2]. However, the cloud morphologies seen poleward of ~ 50 degrees latitude also makes digital tracking less reliable due to absence of discrete features at the spatial resolution of the VMC images acquired in the apoapsis portion of the Venus Express orbit. It is expected that images obtained closer to the planet will enable a determination of the zonal wind profile with better confidence which will be useful in elucidating the nature of the transient features seen in the core region of the Venus vortex. References [1] Limaye, S. S. Venus atmospheric circulation: Known and unknown, J. Geophys. Res., 112, E04S09, doi:10.1029/2006JE002814 (2007). [2] Piccioni, G, Drossart, P., Sanchez-Lavega, A., Hueso, R., Taylor, F., Wilson, C., Grassi, D., Zasova, L., Moriconi, M., Adriani, A., Lebonnois, S., Coradini, A., Bézard, B., Angrilli, F., Arnold, G., Baines, K. H., Bellucci, G., Benkhoff, J., Bibring, J. P., Blanco, A., Blecka, M. I., Carlson, R. W., Di Lellis, A., Encrenaz, T., Erard, S., Fonti1, S., Formisano, V., Fouchet, T., Garcia1, R., Haus, R., J. Helbert, J., Ignatiev, N. I., Irwin, P., Langevin,Y.,Lopez-Valverde, M. A., Luz, D., Marinangeli, L., Orofino, V., Rodin, A. V., Roos-Serote, M. C., Saggin, B., ,Stam, D. M., Titov, D., Visconti, G., and Zambelli M. South-polar features on Venus similar to those near the north, Nature, 450, 637-640, doi:10.1038/nature06209 (2007).

  11. 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

  12. Exploring the veiled planet. [Venus observations

    Science.gov (United States)

    1980-01-01

    An overview of data obtained from various experiments which characterize geological features and atmospheric properties of Venus is presented. Data from the two Pioneer sounder probes (one located at Venus's equator and the other near the north pole) exhibit a reversal in the equator-to-pole temperature patterns at 60 km altitude which suggests that two circulation cells exist within the atmospheric region. However, the atmospheric temperature and pressure beneath the clouds are found to be nearly identical everywhere on Venus and both temperature and pressure conditions at the surface are lower than first expected. The identification of sulphur dioxide clouds which appear to coincide with Venus's characteristic global patterns of C- and Y-shaped dark markings support the hypothesis of a regular pattern of planet spanning breaks in the upper cloud layer. Explanations of a Venus sulphur cycle and of observed magnetic field structures are suggested

  13. Comments on the tectonism of Venus

    International Nuclear Information System (INIS)

    Preliminary tectonic mapping of Venus from Venera 15/16 images shows unquestionable evidence of at least limited horizontal tectonism. The majority of tectonic features on Venus have no relation to topography. In fact, many axes of disruption interconnect, and cross sharp topographic boundaries at large angles, thereby discounting gravity as the driving force. Compressional zones (CZ's), unlike Extensional zones (EZ's), tend to be discontinuous, and, whereas EZ's cross tectonic and topographic boundaries at various angles, many CZ's on Venus are subparallel to these boundaries. Strike-like faulting is curiously lacking from the mapping, possible due to the steep incidence angle of the radar, which is far from optimal for detecting faults of small throw. A chronology of horizontal crustal movements, and hence the analysis of Venus' thermal development, is large dependent on understanding the crater form features. Regardless of their uncertain origin, the craters still could hold the answer to whether, and to what extent, crustal shuffling is occurring on Venus

  14. Observations of Night OH in the Mesosphere of Venus

    Science.gov (United States)

    Martin-Torres, F. J.; Parkinson, C. D.; Allen, M.; Bougher, S. W.; Brecht, A.; Mills, F. P.; Mlynczak, M. G.; Yung, Y. L.

    2009-12-01

    Satellite measurements of the terrestrial night-side mesosphere from the MLS/Aura MLS and SABER instruments show a layer of OH in the mesopause. This layer confirms earlier measurements by ground-based UVFTS. These observations allow the study of the lowest vibrational state (MLS and UVFTS) and the chemically related emission from the high OH states (SABER) that originate the OH Meinel bands in the near infrared. The Caltech 1-D KINETICS model has been extended to include vibrational dependence of OH reactions and shows good agreement with MLS OH data and with observations of the Meinel bands (Pickett et al, 2006). The model shows a chemical lifetime of HOx that increases from less than a day at 80 km to over a month at 87 km. Above this altitude transport processes become an important part of HOx chemistry. The model predicts that ground state OH represents 99% of the total OH up to 84 km. Similarly, Venus airglow emissions detected at wavelengths of 1.40-1.49- and 2.6-3.14 micron in limb observations by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) on the Venus Express spacecraft are attributed to the OH (2-0) and (1-0) Meinel band transitions as well (Piccioni et al., 2008). The integrated emission rates for the OH (2-0) and (1-0) bands were measured to be 100±40 and 880±90 kR respectively, both peaking at an altitude of 96±2 km near midnight local time for the considered orbit. We use the same Caltech 1-D KINETICS model to model these observations for Venus as was used for the Earth (Pickett et al., 2006) and discuss the conclusions, highlighting the similarities and differences between Venus and Earth.

  15. Geologic Map of the Niobe Planitia Quadrangle (V-23), Venus

    Science.gov (United States)

    Hansen, Vicki L.

    2009-01-01

    The Niobe Planitia quadrangle (V-23) encompasses approximately 8,000,000 km2 of the Venusian equatorial region extending from lat 0 deg to 25 deg N. and from long 90 deg to 120 deg E. (approximately 9,500 15-minute quadrangles on Earth). The map area lies along the north margin of the equatorial highland, Aphrodite Terra (V-35), and extends into the lowland region to the north, preserving a transition from southern highlands to northern lowlands (figs. 1, 2, map sheet). The northern parts of the crustal plateau, Ovda Regio and Haasttse-baad Tessera, mark the south margin of the map area; Niobe and Sogolon Planitiae make up the lowland region. The division between Niobe and Sogolon Planitiae is generally topographic, and Sogolon Planitia forms a relatively small elongate basin. Mesolands, the intermediate topographic level of Venus, are essentially absent or represented only by Gegute Tessera, which forms a slightly elevated region that separates Niobe Planitia from Llorona Planitia to the east (V-24). Lowlands within the map area host five features currently classified as coronae: Maya Corona (lat 23 deg N., long 97 deg E.) resides to the northwest and Dhisana, Allatu, Omeciuatl, and Bhumiya Coronae cluster loosely in the east-central area. Lowlands extend north, east, and west of the map area. Mapping the Niobe Planitia quadrangle (V-23) provides an excellent opportunity to examine a large tract of lowlands and the adjacent highlands with the express goal of clarifying the processes responsible for resurfacing this part of Venus and the resulting implications for Venus evolution. Although Venus lowlands are widely considered to have a volcanic origin, lowlands in the map area lack adjacent coronae or other obvious volcanic sources.

  16. Venus as a laboratory for studying planetary surface, interior, and atmospheric evolution

    Science.gov (United States)

    Smrekar, S. E.; Hensley, S.; Helbert, J.

    2013-12-01

    As Earth's twin, Venus offers a laboratory for understanding what makes our home planet unique in our solar system. The Decadal Survey points to the role of Venus in answering questions such as the supply of water and its role in atmospheric evolution, its availability to support life, and the role of geology and dynamics in controlling volatiles and climate. On Earth, the mechanism of plate tectonics drives the deformation and volcanism that allows volatiles to escape from the interior to the atmosphere and be recycled into the interior. Magellan revealed that Venus lacks plate tectonics. The number and distribution of impact craters lead to the idea Venus resurfaced very rapidly, and inspired numerous models of lithospheric foundering and episodic plate tectonics. However we have no evidence that Venus ever experienced a plate tectonic regime. How is surface deformation affected if no volatiles are recycled into the interior? Although Venus is considered a ';stagnant' lid planet (lacking plate motion) today, we have evidence for recent volcanism. The VIRTIS instrument on Venus Express mapped the southern hemisphere at 1.02 microns, revealing areas likely to be unweathered, recent volcanic flows. Additionally, numerous studies have shown that the crater population is consistent with ongoing, regional resurfacing. How does deformation and volcanism occur in the absence of plates? At what rate is the planet resurfacing and thus outgassing? Does lithospheric recycling occur with plate tectonics? In the 25 years since Magellan, the design of Synthetic Aperture Radar has advanced tremendously, allowing order of magnitude improvements in altimetry and imaging. With these advanced tools, we can explore Venus' past and current tectonic states. Tesserae are highly deformed plateaus, thought to be possible remnants of Venus' earlier tectonic state. How did they form? Are they low in silica, like Earth's continents, indicating the presence of abundant water? Does the plains volcanism cover an earlier tectonic surface, or perhaps cover ancient impact basins? Was there an abrupt transition in tectonic style, perhaps due to degassing of the crust or a more gradual shift? What is the nature of Venus' modern tectonics? Is the lithosphere still deforming? Is there recent or active volcanism? Is volcanism confined to hotspots, areas above mantle plumes? Has plains volcanism ceased? What are the implications for volatile history? These questions can be addressed via a combination of high resolution altimetry, imaging, and surface emissivity mapping.

  17. Estimation of lithosphere thickness of Venus from its gravity field

    International Nuclear Information System (INIS)

    The density heterogeneities do not perturb Venus' flattening but completely define the horizontal axes of the three-axial geodetic ellipsoid. Venus' measured flattening is ancient and it is supported by a very thick lithosphere, about 900 km. Venus' lithosphere may be thicker and more rigid than that of the Earth, provided Venus' mantle is very dry, as compared to the Earth's one. Perhaps Venus atmosphere is too dense due to mantle degassing

  18. First Results of the Superconducting ECR Ion Source Venus with 28 GHz

    International Nuclear Information System (INIS)

    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. The magnetic confinement configuration consists of three superconducting axial coils and six superconducting radial coils in a sextupole configuration. The nominal design fields of the axial magnets are 4T at injection and 3T at extraction; the nominal radial design field strength at the plasma chamber wall is 2T, making VENUS the world most powerful ECR plasma confinement structure. From the beginning, VENUS has been designed for optimum operation at 28 GHz with high power (10 kW).In 2003 the VENUS ECR ion source was commissioned at 18 GHz, while preparations for 28 GHz operation were being conducted. During this commissioning phase with 18 GHz, tests with various gases and metals have been performed with up to 2000 W RF power. At the initial commissioning tests at 18 GHz, 1100 e?A of O6+, 160 e?A of Xe20+, 160 e?A of Bi25+ and 100 e?A of Bi30+ and 11 e?A of Bi41+ were produced.In May 2004 the 28 GHz microwave power has been coupled into the VENUS ECR ion source. At initial operation more than 320 e?A of Xe20+ (twice the amount extracted at 18 GHz), 240 e?A of Bi24+ and Bi25+, and 245 e?A of Bi29+ were extracted. The paper briefly describes the design of the VENUS source, the 28 GHz microwave system and its beam analyzing system. First results at 28 GHz including emittance measurements are presented

  19. Polygonal Impact Craters on Venus

    Science.gov (United States)

    Aittola, M.; Ohman, T.

    The polygonal impact craters, i.e. craters that are more or less angular instead of circular or ellipsoidal, are present - and usually rather common - on the Moon, Earth, Venus, Mercury, Mars and several asteroids and icy moons (e.g. Europa). Thus, they exist on all kinds of celestial bodies that have cratered and fractured rigid crusts. Recent studies of the polygonal craters in the Hellas area on Mars have shown that these craters can be used in determining the systematics in the directions and distributions of fractures or other zones of weakness in the crust. This method should be applicable also on Venus, which has rigid cratered crust and thus the craters could be used as a tool to reveal some properties of the target material and to determine the regional stresses. It is known that the polygonal impact craters are at least present on the Venusian surface, but there are no detailed studies of them. Therefore, the first goal of this study is to determine the abundance of this type of craters on planet's surface. The preliminary survey has shown that the population of polygonal impact craters is surprisingly large. Additionally, in few studied cases, the orientations of the straight crater walls seem to be parallel with the dominant local tectonics. Therefore, it is very likely that these craters can be used as a tool to reveal the secrets of the Venusian crust, which is still rather unknown. The aim of our ongoing work is hereby to study the distribution of polygonal craters and also to check how they reflect the structural and tectonic features of the crust on Venus.

  20. Mars and Venus: unequal planets.

    Science.gov (United States)

    Zimmerman, T S; Haddock, S A; McGeorge, C R

    2001-01-01

    Self-help books, a pervasive and influential aspect of society, can have a beneficial or detrimental effect on the therapeutic process. This article describes a thematic analysis and feminist critique of the best-selling self-help book, Men are from Mars, Women are from Venus. This analysis revealed that the author's materials are inconsistent with significant family therapy research findings and key principles of feminist theories. His descriptions of each gender and his recommendations for improving relationships serve to endorse and encourage power differentials between women and men. PMID:11215990

  1. 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 kinetic temperature of the O+ component is estimated as 105--106 K in order of magnitude

  2. 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

    Measurement of noble gas abundances on Venus remain a high priority for planetary science. These studies are only possible through in situ measurement, and can be accomplished by a modern neutral mass spectrometer (NMS) such as that developed at NASA Goddard, based on flight-proven technology. Here we show how the measurement of noble gases can be secured using demonstrated enrichment techniques.

  3. Construction of global maps of atmospheric and surface features of Venus based on new retrieval methods

    Science.gov (United States)

    Arnold, G.; Haus, R.; Kappel, D.

    2012-04-01

    The exploration of Venus in the context of comparative planetology and solar system research is an important key to understand crucial aspects of planetary evolution, geology, and climate. Sufficient information can only be gained by applying a long-term remote sensing observation strategy. Early missions to Venus established some basic information about atmospheric and surface features, but only since ESA's Venus Express (VEX) mission is orbiting the planet, the first global database for systematic atmospheric and surface studies became available. It brings Venus back into the focus of exploration of the terrestrial planets after a period of more than 20 years. The Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) on Venus Express, after six years in a polar Venus orbit, provided an enormous amount of new data and a four-dimensional picture of the planet (2D imaging + spectral dimension + temporal variations). The spectral dimension permits a sounding at different levels of the atmosphere from the ground up to the thermosphere. The planned work focuses on the investigation of temperature fields, cloud composition and altitude distribution, and trace gas concentrations in the atmosphere of Venus. Studies will be mainly performed on the nightside of the planet where the narrow atmospheric window emissions are not obscured by the more intense solar radiation reflected by the clouds. The resulting multi-dimensional maps of atmospheric state parameters will be used to calculate atmospheric net fluxes, heating and cooling rates, and the radiative energy balance of the middle and lower atmosphere of Venus, and to produce required input data for global circulation models. The quantification and elimination of atmospheric impact factors on surface emissivity retrievals are additional important components of this work. The construction of emissivity maps and specification of local emissivity variations will allow of acquire clues on different soil compositions that enable statements about the geologic development of the planet. Recently by the authors newly developed and verified radiative transfer models and special algorithms, which simultaneously use information from different atmospheric windows for each individual spectrum (multi-window application), can be improved to a large extent by adaptation of new multi-spectrum retrieval techniques (multi-spectrum application) and by the utilization of all available a priori information on surface and atmospheric parameters. In combination with new developments for sophisticated data calibration and pre-processing of VIRTIS-M-IR data this will seriously enhance the accuracy of retrieved atmospheric and surface parameters. The paper will discuss the capability of the new multi-spectrum retrieval technique as well as the main scientific objectives of the planned work on global atmospheric and surface features of Venus.

  4. Contribution from SOIR/VEX to the updated Venus International Reference Atmosphere (VIRA)

    Science.gov (United States)

    Vandaele, A. C.; Chamberlain, S.; Mahieux, A.; Ristic, B.; Robert, S.; Thomas, I.; Trompet, L.; Wilquet, V.; Belyaev, D.; Fedorova, A.; Korablev, O.; Bertaux, J. L.

    2016-01-01

    The SOIR instrument on-board Venus Express is an infrared spectrometer covering the 2.2-4.3 ?m spectral region. This instrument allows the detection of several key species of the Venus atmosphere, including CO2, CO, H2O/HDO, HCl, HF and SO2. From the CO2 density measurements, temperature is inferred giving information on the thermal structure of the atmosphere. Here we described the kind of data (profiles, latitudinal average, etc.) that will be provided to the updated VIRA compilation.

  5. The distributions of the OH (?v=1) and (?v=2) emissions on the Venus nightside

    OpenAIRE

    Soret, Lauriane; Gérard, Jean-Claude; Piccioni, Giuseppe; Drossart, Pierre

    2010-01-01

    The presence of OH was detected in the spectrum of the Venus mesosphere observed at the limb with the VIRTIS instrument on board the Venus Express spacecraft [3]. The (1-0) and (2-1) transitions at 2.80 and 2.94 mm, respectively and the (2-0) band at 1.43 mm were clearly identified. The results of this study show that a correlation is observed between the emissions associated to the ?v=1 and the ?v=2 sequences.

  6. Characterization of Atmospheric Waves at the Upper Clouds in the Polar Region of Venus

    OpenAIRE

    Peralta, Javier; Luz, David; Berry, David; Tsang, Constantine; Migliorini, Alessandra; Piccioni, Giuseppe; Drossart, Pierre

    2012-01-01

    Non solar-fixed waves at the cloud tops of the southern polar region of Venus are studied in the winds measured with 3.9 and 5.0 ?m images taken by the instrument VIRTIS-M onboard Venus Express. Wavenumbers 1, 2 and 3 are detected, with wave amplitudes ranging from 3.6 to 8.0 m/s. The evolution of the phase has been studied in 16 orbits, finding in a subset of orbits wavenumbers 1 and 2 propagating in different directions (zonal wind), and a westward progression with a phase velocity of appro...

  7. Solar Migrating Atmospheric Tides in the Winds of the Polar Region of Venus

    OpenAIRE

    Peralta, Javier; Luz, David; Berry, David; Tsang, Constantine; Sánchez-Lavega, Agustín; Huelso, Ricardo; Piccioni, Giuseppe; Drossart, Pierre

    2012-01-01

    We study the effects of migrating solar tides on the winds at the cloud tops of the polar region of Venus. The winds were measured using cloud tracking on images obtained at wavelengths of 3.9 and 5.0 ?m by the instrument VIRTIS-M onboard Venus Express. These wavelengths probe about the same altitude close to the cloud tops, allowing for the first time to retrieve winds simultaneously in the day and nightside of the planet. We use a dataset with observations from 16 orbits, covering a time sp...

  8. 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.

  9. Quantitative tests for plate tectonics on Venus

    Science.gov (United States)

    Kaula, W. M.; Phillips, R. J.

    1981-01-01

    Quantitative comparisons are made between the characteristics of plate tectonics on the earth and those which are possible on Venus. Considerations of the factors influencing rise height and relating the decrease in rise height to plate velocity indicate that the rate of topographic dropoff from spreading centers should be about half that on earth due to greater rock-fluid density contrast and lower temperature differential between the surface and interior. Statistical analyses of Pioneer Venus radar altimetry data and global earth elevation data is used to identify 21,000 km of ridge on Venus and 33,000 km on earth, and reveal Venus ridges to have a less well-defined mode in crest heights and a greater concavity than earth ridges. Comparison of the Venus results with the spreading rates and associated heat flow on earth reveals plate creation rates on Venus to be 0.7 sq km/year or less and indicates that not more than 15% of Venus's energy is delivered to the surface by plate tectonics, in contrast to values of 2.9 sq km a year and 70% for earth.

  10. Evidence For And Against 8-day Planetary Waves In Ground-based Cloud-tracking Observations Of Venus' Nightside

    Science.gov (United States)

    Young, Eliot F.; Bullock, M. A.; Limaye, S.; Bailey, J.; Tsang, C. C. C.

    2010-10-01

    Several groups have estimated wind fields on Venus by tracking clouds that appear as silhouettes on Venus’ nightside in CO2 windows at 1.74 or 2.3 microns. In 2008, we presented 10 days of cloud-tracking results from July 2004 that suggested the presence of an 8-day wave manifested by velocity variations in clouds presumed to be at altitudes of 48 - 55 km. A variety of waves are key predictions of recent Venus GCMs (e.g., Yamamoto and Takahashi 2006, Lebonnois et al. 2010) and important areas of comparison between observations and modeling efforts. Although we have measured equatorial zonal wind velocity variations of 15 m/s for observations separated by 24 hours, Hueso, Peralta and Sanchez-Lavega (2010) presented cloud-tracking results from VIRTIS-M image sequences in which velocities are mostly confined to 55 to 65 m/s in the 30°S - 10°S latitude range. We now present cloud-tracking results from ground-based observations obtained during July and September 2007. On some dates we are able to combine observations between the AAT and IRTF to increase the time baseline between images to roughly 4 hours and reduce the errors by about a factor of two. Akatsuki image sequences should resolve the question of zonal velocity variations in the near future. --- References Hueso, Peralta and Sanchez-Lavega, 2010, "Temporal and spatial variability of Venus winds at cloud level from VIRTIS during the Venus Express mission.” Presented at the Venus Express Workshop in Aussois, June 2010. Lebonnois et al., 2010, "Superrotation of Venus’ atmosphere analyzed with a full general circulation model.” JGR 115, E06006. Yamamoto and Takahashi, 2006, "Superrotation maintained by meridional circulation and waves in a Venus-like AGCM.” J. Amtos Sci., 63, 3296.

  11. 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.

  12. A correlated-k model of radiative transfer in the near-infrared windows of Venus

    International Nuclear Information System (INIS)

    We present a correlated-k-based model for generating synthetic spectra in the near-infrared window regions, from 1.0 to 2.5 ?m, emitted from the deep atmosphere of Venus on the nightside. This approach is applicable for use with any near-infrared instrument, ground-based and space-borne, for analysis of the thermal emissions in this spectral range. We also approach this work with the view of using the model, in conjunction with a retrieval algorithm, to retrieve minor species from the Venus Express/VIRTIS instrument. An existing radiative-transfer model was adapted for Venusian conditions to deal with the prevailing high pressures and temperatures and other conditions. A comprehensive four-modal cloud structure model based on Pollack et al. [Near-infrared light from venus' nightside: a spectroscopic analysis. Icarus 1993;103:1-42], using refractive indices for a 75% H2SO425% H2O mixture from Palmer and Williams [Optical constants of sulfuric acid; application to the clouds of Venus? Appl Opt 1975;14(1):208-19], was also implemented. We then utilized a Mie scattering algorithm to account for the multiple scattering effect between cloud and haze layers that occur in the Venusian atmosphere. The correlated-k model is shown to produce good agreement with ground-based spectra of Venus in the near infrared, and to match the output from a line-by-line radiative-transfer model to better than 10%

  13. Mitigating Extreme Environments for In-Situ Jupiter and Venus Missions

    Science.gov (United States)

    Balint, Tibor S.; Kolawa, Elizabeth A.; Cutts, James A.

    2006-01-01

    In response to the recommendations by the National Research Council (NRC), NASA's Solar System Exploration (SSE) Roadmap identified the in situ exploration of Venus and Jupiter as high priority science objectives. For Jupiter, deep entry probes are recommended, which would descend to approx.250 km - measured from the 1 bar pressure depth. At this level the pressure would correspond to approx.100 bar and the temperature would reach approx.500(deg)C. Similarly, at the surface of Venus the temperature and pressure conditions are approx.460(deg)C and approx.90 bar. Lifetime of the Jupiter probes during descent can be measured in hours, while in{situ operations at and near the surface of Venus are envisioned over weeks or months. In this paper we discuss technologies, which share commonalities in mitigating these extreme conditions over proposed mission lifetimes, specially focusing on pressure and temperature environments.

  14. Energetics of the Oxygen Ion Escape From Venus in a Hybrid Simulation

    Science.gov (United States)

    Jarvinen, R.; Kallio, E. J.; Janhunen, P.; Zhang, T.; Barabash, S.; Pohjola, V.; Sillanpaa, I.

    2009-12-01

    We study the Venus Express observations of the Venus-solar wind interaction and the related atmospheric ion erosion by a hybrid simulation (HYB-Venus). Oxygen is the dominant ion species in the Venusian atmosphere and its total escape rate from the planet is about 1025 s-1. According to our recent study this value is close a limit at which the planetary ions start to affect the global structure of the magnetosphere in a hybrid simulation. Here we consider possible causes for this limit and study the energetics of the oxygen ion acceleration. Further, we also consider the global energy flow as the Poynting flux and the plasma kinetic energy in the system including the bulk and thermal components.

  15. 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.

  16. VizieR Online Data Catalog: Horizontal temperature at Venus upper atmosphere (Peralta+, 2016)

    Science.gov (United States)

    Peralta J., Lopez-Valverde M.A., Gilli G., Piccialli A.

    2015-11-01

    The dayside atmospheric temperatures in the UMLT of Venus (displayed in Figure 7A of this article) are listed as a CSV data file. These values consist of averages in bins of 5° in latitude and 0.25-hours in local time from dayside temperatures covering five years of data (from 2006/05/14 to 2011/06/05). These temperatures were inferred from the CO2 NLTE nadir spectra measured by the instrument VIRTIS-H onboard Venus Express (see article for full description of the procedure), and are representative of the atmospheric region between 10-2 to 10-5mb. Along with the temperatures, we also provide the corresponding error and the number of temperatures averaged in each bin. The format of the CSV file reasonably agrees with the expected format of the data files to be provided in the future version of the Venus International Reference Atmosphere (VIRA). (1 data file).

  17. 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

  18. Ultraviolet absorbers in the Venus clouds

    International Nuclear Information System (INIS)

    Some absorption features in the ultraviolet spectrum of Venus observed by the OAO-2 cannot be interpreted in terms of H2SO4. Carbon suboxide polymer has a yellow colour and absorption at 2000 A. Fine graphite grains have an absorption band at about 2175 A as is well known in the case of the interstellar extinction curves. A mixture of these substances which is inevitably formed in the Venus atmosphere by photochemical reactions is the best candidate for explaining the Venus absorption features in the ultraviolet. (Auth.)

  19. The ionosphere and upper atmosphere of Venus

    International Nuclear Information System (INIS)

    The Mariner 10 flyby of Venus has provided a second close look at the upper atmosphere of a planet which has intrigued aeronomers for a long time. Far UV spectra (1200-1900A) of Venus with moderate spectral resolution (approximately 20A) have been obtained from a number of rocket experiments. These spectra have lead to the identification of several minor constituents in the upper atmosphere. This paper summarizes the current understanding of the upper atmosphere and ionosphere of Venus and its interaction with solar wind. (Auth.)

  20. Signs of hypothetical fauna of Venus

    OpenAIRE

    Ksanfomality Leonid V.

    2014-01-01

    On March 1 and 5, 1982, experiments in television photography instrumented by the landers VENERA-13 and -14, yielded 37 panoramas (or their fragments) of the Venus surface at the landing site. Over the past 31 years, no similar missions have been sent to Venus. Using a modern technique the VENERA panoramas were re-examined. A new analysis of Venusian surface panoramas’ details has been made. A few relatively large objects of hypothetical fauna of Venus were found with size ranging from a deci...

  1. Extreme Environment Simulation - Current and New Capabilities to Simulate Venus and Other Planetary Bodies

    Science.gov (United States)

    Kremic, Tibor; Vento, Dan; Lalli, Nick; Palinski, Timothy

    2014-01-01

    Science, technology, and planetary mission communities have a growing interest in components and systems that are capable of working in extreme (high) temperature and pressure conditions. Terrestrial applications range from scientific research, aerospace, defense, automotive systems, energy storage and power distribution, deep mining and others. As the target environments get increasingly extreme, capabilities to develop and test the sensors and systems designed to operate in such environments will be required. An application of particular importance to the planetary science community is the ability for a robotic lander to survive on the Venus surface where pressures are nearly 100 times that of Earth and temperatures approach 500C. The scientific importance and relevance of Venus missions are stated in the current Planetary Decadal Survey. Further, several missions to Venus were proposed in the most recent Discovery call. Despite this interest, the ability to accurately simulate Venus conditions at a scale that can test and validate instruments and spacecraft systems and accurately simulate the Venus atmosphere has been lacking. This paper discusses and compares the capabilities that are known to exist within and outside the United States to simulate the extreme environmental conditions found in terrestrial or planetary surfaces including the Venus atmosphere and surface. The paper then focuses on discussing the recent additional capability found in the NASA Glenn Extreme Environment Rig (GEER). The GEER, located at the NASA Glenn Research Center in Cleveland, Ohio, is designed to simulate not only the temperature and pressure extremes described, but can also accurately reproduce the atmospheric compositions of bodies in the solar system including those with acidic and hazardous elements. GEER capabilities and characteristics are described along with operational considerations relevant to potential users. The paper presents initial operating results and concludes with a sampling of investigations or tests that have been requested or expected.

  2. 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 (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

  3. The Venus-solar wind interaction: Is it purely ionospheric?

    Science.gov (United States)

    Luhmann, J. G.; Ma, Y. J.; Villarreal, M. N.; Wei, H. Y.; Zhang, T. L.

    2015-12-01

    The Venus solar wind interaction is often regarded as the prototypical example of an induced magnetosphere. Pioneer Venus Orbiter (PVO) observations during a period of moderate to strong solar EUV fluxes led to a fairly detailed picture in which the currents in the conducting ionosphere produce a nearly impenetrable obstacle to the incident magnetized plasma flow, resulting in a classical draped field magnetosheath region and a comet-like magnetotail. Inspired by the availability of Venus Express (VEX) observations from the north polar region, and their sometimes unexpected behavior, we reanalyzed the observed Venus wake magnetic fields in the altitude range ~150 to ~450 km to determine whether some signature of a weak planetary field could have been missed. Our results suggest the presence of a small (few nT) but persistent radial field direction bias in the deep nightside, low to mid-latitude range sampled on PVO. The bias has a hemispheric dependence, with the more positive (outward) fields in the south and the more negative (inward) fields in the north. However the VEX counterpart of these data, obtained just nightward of the north polar terminator, shows no significant bias. This observation raises several questions about our understanding of the fields at the surface of Venus. We investigate whether the PVO radial field bias could be the subtle signature of a weak global dipole with , higher by ~10× than the previously established upper limits. A weak dipole solar wind interaction model produces results in the center of the low altitude wake that compare favorably with the observed field bias seen by PVO; however, the lack of agreement with the higher latitude and VEX observations suggests other explanations need to be considered. For example, effects related to previously observed convection electric field-controlled hemispheric asymmetries provide a possible alternative, as are external fields that diffuse into and through the interior. This work points out the need for better understanding the features introduced by species-dependent plasma processes, and the role of the planet itself, in deciphering weakly magnetized planet interactions.

  4. Magnetic fields in the Venus ionosphere

    International Nuclear Information System (INIS)

    Qualitative analysis of non-stationary plasma and magnetic field convection in the daytime Venus atmosphere and comparison of various hypothesis of large-scale field and magnetic force line cords in ionosphere on the base of plasma convection picture are conducted. It is shown that the observed large-scale field or the magnetic belt in the Venus daytime inosphere appears to be a result of evolution of solar wind magnetic field pressed through ionosphere; the magnetic field upper boundary runs in the vicinity of the phtochemical equilibrium area upper boundary. With regard to plasma convection and results of investigation into the venus ionopause stability, the destruction of interplanetary magnetic field pressed through ionosphere under high dynamic solar wind pressure appears to be the most probable source of magnetic cords in the lower ionosphere of Venus

  5. Mantle convection and crustal evolution on Venus

    International Nuclear Information System (INIS)

    Venus is probably similar to the Earth in that recycling of basaltic crust has been induced by the development of cratons: combinations of siliceous crust with high Mg:Fe mantle. Venus has less remaining energy sources at depth, but still enough to support the great plateaus, and to deliver appreciable heat close to the surface by convection. The main differences of Venus from the Earth arise from its lack of water, rather than higher temperatures. Lack of water (plus lower stress levels due to lesser energy) makes the upper mantle more viscous, and hence Venus tectonics more driven by bulk mantle, rather than boundary layer, characteristics. Making tectonics difficult to infer from Magellan imagery will be shallower and more widespread layers of weakness in crustal rocks obscuring the mantle-driven patterns

  6. The development of studies of Venus

    Science.gov (United States)

    Cruikshank, D. P.

    1983-01-01

    An historical account is given of the major figures, observational techniques and theories involved in Venus studies prior to space probe-based researches. Those who followed Galileo Galilei (1610) with the simple telescopes of the 17th and early 18th centuries confirmed the phases of the illuminated face of Venus. Lomonosov (1761) noted a gray halo surrounding the planet as it was partially silhouetted against the sun, and correctly inferred that Venus has an atmosphere. The brightness and nearly featureless appearance of the planet, together with the halo effect, led to the early conclusion that the atmosphere is cloudy. While visual and photographic spectroscopy had been applied to Venus many times, the first indication of spectral features different from the solar spectrum was found in 1932 with the high dispersion spectrograph on the Mt. Wilson 2.5-m telescope.

  7. High Temperature, Wireless Seismometer Sensor for Venus

    Science.gov (United States)

    Ponchak, George E.; Scardelletti, Maximilian C.; Taylor, Brandt; Beard, Steve; Meredith, Roger D.; Beheim, Glenn M.; Hunter Gary W.; Kiefer, Walter S.

    2012-01-01

    Space agency mission plans state the need to measure the seismic activity on Venus. Because of the high temperature on Venus (462? C average surface temperature) and the difficulty in placing and wiring multiple sensors using robots, a high temperature, wireless sensor using a wide bandgap semiconductor is an attractive option. This paper presents the description and proof of concept measurements of a high temperature, wireless seismometer sensor for Venus. A variation in inductance of a coil caused by the movement of an aluminum probe held in the coil and attached to a balanced leaf-spring seismometer causes a variation of 700 Hz in the transmitted signal from the oscillator/sensor system at 426? C. This result indicates that the concept may be used on Venus.

  8. Sapphire Viewports for a Venus Probe Project

    Data.gov (United States)

    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...

  9. Balloons on planet Venus - Final results

    Science.gov (United States)

    Blamont, J.; Boloh, L.; Kerzhanovich, V.; Kogan, L.; Kurganskii, M.; Linkin, V.; Matveenko, L.; Roy, M.; Patsaev, D.; Pichkhadze, K.

    1993-01-01

    On June 11 and 15, 1985 two packages with balloons have been inserted in the atmosphere of Venus from the Soviet VEGA landing modules. This paper summarizes the pressure, temperature, wind illumination and backscattering data from the balloons.

  10. Venus and the Archean Earth: Thermal considerations

    International Nuclear Information System (INIS)

    The Archean Era of the Earth is not a direct analog of the present tectonics of Venus. In this regard, it is useful to review the state of the Archean Earth. Most significantly, the temperature of the adiabatic interior of the Earth was 200 to 300 C hotter than the current temperature. Preservation biases limit what can be learned from the Archean record. Archean oceanic crust, most of the planetary surface at any one time, has been nearly all subducted. More speculatively, the core of the Earth has probably cooled more slowly than the mantle. Thus the temperature contrast above the core-mantle boundary and the vigor of mantle plumes has increased with time on the Earth. The most obvious difference between Venus and the present Earth is the high surface temperature and hence a low effective viscosity of the lithosphere. In addition, the temperature contrast between the adiabatic interior and the surface, which drives convection, is less on Venus than on the Earth. It appears that the hot lithosphere enhanced tectonics on the early Venus significantly enough that its interior cooled faster than the Earth's. The best evidence for a cool interior of Venus comes from long wavelength gravity anomalies. The low interior temperatures retard seafloor spreading on Venus. The high surface temperatures on Venus enhance crustal deformation. That is, the lower crust may become ductile enough to permit significant flow between the upper crust and the mantle. There is thus some analogy to modern and ancient areas of high heat flow on the Earth. Archean crustal blocks typically remained stable for long intervals and thus overall are not good analogies to the deformation style on Venus

  11. ADS transmutation research based on Venus 1#

    International Nuclear Information System (INIS)

    The transmutation reaction rate of the 9 kinds of MA and LLFP nuclides were calculated based on ADS subcritical facility Venus 1#. The transmutation reaction rate of 137CS in the fast-thermal coupled zone was measured, and the transmutation speed of 137Cs was 10 times to natural decay. The results that Venus 1# has a certain transmutation ability, and the calculated result of the transmutation reaction rate for 137Cs agrees with the measuring result. (authors)

  12. Venus Then and Now: Simulating Sulfuric Acid Clouds Using Latitudinally Dependent VIRA and VeRA Temperature Profiles

    Science.gov (United States)

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

    2014-12-01

    Observations from the Pioneer Venus Orbiter (PVO) and from SPICAV/SOIR aboard Venus Express (VEx) have shown the upper haze (UH) of Venus to be highly spatially and temporally variable. Previous models of this system, using typical temperature profiles representative of the Venus atmosphere as a whole, did not investigate the effects of temperature variations on the UH particle distributions. Parkinson et al. (2014, submitted) showed that the inclusion of latitudinally dependent temperature profiles retrieved from SPICAV/SOIR observations in the Venus cloud model of Gao et al. (2014) resulted in markedly different cloud distributions between the different latitude cases, such as a lowered cloud base near the equator and a slightly thicker UH at the poles. Thus, temperature variations across Venus could help explain spatial variations in the atmospheric aerosol distribution. In this work, we expand on the aforementioned study by including VIRA temperature profiles derived from Venera and PVO observations (Kliore et al. 1985) at similar latitudes as the SPICAV/SOIR profiles to assess how the aerosol distribution varies spatially and temporally. By comparing the simulated cloud and haze distributions arising from the two sets of temperature profiles, we can evaluate whether secular changes have occurred in the ~30 years between the PVO and VEx epochs.

  13. Infrared radiation of the Venus louds

    International Nuclear Information System (INIS)

    IR radiation of the Venus clouds is investigated by radiometers set up on the Venus-9 and Venus-10 space probes. The characteristics of radiometers are: angular resolution 1 deg, 2; threshold sensitivity about 70 K; operating range of wavelengths 8-13 and 18-28 ?m. The heat radiation of the Venus is generated in the upper layer of the planet cloudy coating. The brightness temperature of the radiating layer is determined by the measured brightness and then with the help of the Venus atmosphere model the altitude of the cloudy layer upper part is found to be equal to 64-67 km. Physical properties of the radiating medium have been given. The results of measurements show asymmetry of the Venus heat radiation. Stable excess of night temperatures (224 K) over the daytime ones (233-234 K) is observed. The results obtained are compared with the Mariner-10 data, the reasons of the differences are analyzed. The probable reason of the daytime temperature decreasing is supposed to be power convective fluxes in the daytime zone

  14. 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.

  15. Results of the first statistical study of pioneer Venus orbiter plasma observations in the distant Venus tail: Evidence for a hemispheric asymmetry in the pickup of ionospheric ions

    International Nuclear Information System (INIS)

    Pioneer Venus Orbiter plasma and magnetometer observations from the first nine tail seasons of crossings of the Venus wake are used to study ion pickup in the far wake of an unmagnetized object embedded in the solar wind. This first statistical study treats all of the plasma spectra containing pickup ions in the vicinity of the Venus tail. The author finds a hemispheric asymmetry in the pickup of ionospheric ions, with approximately four times more O+ events observed in the northern magnetic hemisphere (where Z double-prime > O), i.e., the induced electric field points outward, (away from the ionopause boundary) than in the southern (Z double-prime + events, 125, or 75%, occurred in the northern hemisphere when position is calculated in terms of Venus radii and 129 or 77% occurred in the northern hemisphere when position is expressed in gyroradii. This hemisphere asymmetry in ion pickup is consistent with the prediction of the Cloutier et al. (1974) mass loading model for Venusian ions above the ionopause boundary

  16. Validity of space weather prediction to Venus and Mars

    Science.gov (United States)

    Opitz, A.; Vech, D.; Sanchez-Diaz, E.; Szego, K.; Witasse, O.; Andre, N.

    2015-10-01

    Both Venus and Mars have ionospheres, but no strong intrinsic magnetospheres, only Mars has some inhomogeneously distributed crustal field. The solar wind interaction with the ionosphere of these unmagnetized planets is highly important in defining the planets' plasma environment. The properties of their induced magnetospheres depend strongly on the solar input arriving at the planet. In order to study this interaction of the solar wind and the planetary plasma environment, ideally we would need measurements both in the solar wind and in this induced magnetosphere the same time. When there is only one spacecraft around the planet, it cannot perform such simultaneous observations, thus the prediction of solar wind properties and solar events to the different planetary objects becomes important. These predictions can be validated by in situ measurements onboard the planetary spacecraft such as Mars Express and Venus Express while these are located in the solar wind. The solar predictions are based on solar spacecraft observations such as SOHO, ACE, WIND, STEREO A and B, which are at different distances from the investigated planets. We show how the prediction accuracy depends on the spatial separation of the solar and the planetary spacecraft.

  17. Geologic map of the Artemis Chasma quadrangle (V-48), Venus

    Science.gov (United States)

    Bannister, Roger A.; Hansen, Vicki L.

    2010-01-01

    Artemis, named for the Greek goddess of the hunt, represents an approximately 2,600 km diameter circular feature on Venus, and it may represent the largest circular structure in our solar system. Artemis, which lies between the rugged highlands of Aphrodite Terra to the north and relatively smooth lowlands to the south, includes an interior topographic high surrounded by the 2,100-km-diameter, 25- to 200-km-wide, 1- to 2-km-deep circular trough, called Artemis Chasma, and an outer rise that grades outward into the surrounding lowland. Although several other chasmata exist in the area and globally, other chasmata have generally linear trends that lack the distinctive circular pattern of Artemis Chasma. The enigmatic nature of Artemis has perplexed researchers since Artemis Chasma was first identified in Pioneer Venus data. Although Venus' surface abounds with circular to quasi-circular features at a variety of scales, including from smallest to largest diameter features: small shield edifices (>1 km), large volcanic edifices (100-1,000 km), impact craters (1-270 km), coronae (60-1,010 km), volcanic rises and crustal plateaus (~1,500-2,500 km), Artemis defies classification into any of these groups. Artemis dwarfs Venus' largest impact crater, Mead (~280 km diameter); Artemis also lacks the basin topography, multiple ring structures, and central peak expected for large impact basins. Topographically, Artemis resembles some Venusian coronae; however Artemis is an order of magnitude larger than the average corona (200 km) and about twice the size of Heng-O Corona (which is 1,010 km in diameter), the largest of Venusian coronae. In map view Artemis' size and shape resemble volcanic rises and crustal plateaus; however, both of these classes of features differ topographically from Artemis. Volcanic rises and crustal plateaus form broad domical regions, and steep-sided regions with flat tops, respectively; furthermore, neither rises nor plateaus include circular troughs. So although it seems clear what Artemis is not, there is little consensus about what Artemis is, much less how Artemis formed. Debate during the past decade has resulted in the proposal of at least four hypotheses for Artemis' formation. The first (herein referred to as H1) is that Artemis Chasma represents a zone of northwest-directed convergence and subduction. The second hypothesis (herein referred to as H2) is that Artemis consists of a composite structure with a part of its interior region marking the exposure of deformed ductile deep-crustal rocks analogous to a terrestrial metamorphic core complex. The third (herein referred to as H3) is that Artemis reflects the surface expression of an ancient (>3.5 Ga) huge bolide impact event on cold strong lithosphere. The fourth hypothesis (herein referred to as H4) is that Artemis marks the surface expression of a deep mantle plume. Each of these hypotheses holds different implications for Venus geodynamics and evolution processes, and for terrestrial planet processes in general. Viability of H1 would provide support that terrestrial-like plate-tectonic processes once occurred on Earth's sister planet. The feasibility of H2 would require high values of crustal extension and therefore imply that significant horizontal displacements occurred on Venus-displacement that may or may not be related to terrestrial-like plate-tectonic processes. The possibility of H3 would suggest that Venus' surface is extremely old, and that Venus has experienced very little dynamic activity for the last 3.5 billion years or more; this would further imply that Venus is essentially tectonically dead, and has been for most of its history. This view contrasts strongly with studies that highlight a rich history of Venus including activity at least as young as 750 million years ago, and quite likely up to the present. If H4 has credibility, then Artemis could provide clues to cooling mechanisms of Earth's sister planet. Each of these hypotheses

  18. On the nature of solar wind interaction with the Venus

    International Nuclear Information System (INIS)

    Analyzed are the measurement results of ion fluxes near the Venus on the ''Venus-9'' and ''Venus-10'' automatic stations with the help of a nerrow-directed electrostatic analyser. It is found out that in the first approximation the Venus flow-up with the solar wind is satisfactorily described by the gas-dynamic model. The arguments of the Venus shock wave asymmetry conneced with the solar wind anisotropy were obtained. Description of magnetoplasma train of the Venus and boundary layer is given. Periodic plasma acceleration in the Venus train correlating with negative pulses of magnetic field was found out. These phenomena are interpreted as substorms in magnetosphere of the Venus. The positions of shock wave front unusually close to the planet were recorded

  19. High Temperature Venus Drill and Sample Delivery System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We proposed to design, build and test a high temperature Pneumatic Drill and Trencher system for Venus subsurface exploration. The Venus Drill and Trencher will be...

  20. 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 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)

  1. Closing of Venus Flytrap by Electrical Stimulation of Motor Cells

    OpenAIRE

    Volkov, Alexander G.; Adesina, Tejumade; Jovanov, Emil

    2007-01-01

    Electrical signaling and rapid closure of the carnivorous plant Dionaea muscipula Ellis (Venus flytrap) have been attracting the attention of researchers since XIX century, but the exact mechanism of Venus flytrap closure is still unknown. We found that the electrical stimulus between a midrib and a lobe closes the Venus flytrap leaf by activating motor cells without mechanical stimulation of trigger hairs. The closing time of Venus flytrap by electrical stimulation of motor cells is 0.3 s, t...

  2. Focal lengths of Venus Monitoring Camera from limb locations

    Science.gov (United States)

    Limaye, Sanjay S.; Markiewicz, W. J.; Krauss, R.; Ignatiev, N.; Roatsch, T.; Matz, K. D.

    2015-08-01

    The Venus Monitoring Camera (VMC) carried by European Space Agency's Venus Express orbiter (Svedhem et al., 2007) consists of four optical units, each with a separate filter casting an image on a single CCD (Markiewicz et al., 2007a, 2007b). The desire to capture as much of the planet in a single frame during the spacecraft's 24 h, 0.84 eccentricity orbit led to optics with 18° field of view. Analysis of Venus images obtained by the VMC indicated that the computed limb radius and altitude of haze layers were somewhat inconsistent with prior knowledge and expectations. Possible causes include errors in the knowledge of image geometry, misalignment of the optic axis from the pointing direction, and optical distortion. These were explored and eliminated, leaving only deviations from the ground and pre-solar damage estimate of the focal length lengths as the most likely reason. We use the location of planet's limb to estimate the focal length of each camera using images of the planet when the orbiter was more than 20,000 km from planet center. The method relies on the limb radius to be constant at least over a small range of solar zenith angles. We were able to achieve better estimates for the focal lengths for all four cameras and also estimate small offsets to the boresight alignment. An outcome of this analysis is the finding that the slant unit optical depth varies more rapidly with solar zenith angle in the afternoon as compared to morning, with lowest values at local noon. A variation of this level is also observed with latitude. Both are indicative of the presence of overlying haze above the clouds, and the morning afternoon asymmetry suggests different photochemical processes in destruction and production of the haze.

  3. Extreme Environments Technologies for Probes to Venus and Jupiter

    Science.gov (United States)

    Balint, Tibor S.; Kolawa, Elizabeth A.; Peterson, Craig E.; Cutts, James A.; Belz, Andrea P.

    2007-01-01

    This viewgraph presentation reviews the technologies that are used to mitigate extreme environments for probes at Venus and Jupiter. The contents include: 1) Extreme environments at Venus and Jupiter; 2) In-situ missions to Venus and Jupiter (past/present/future); and 3) Approaches to mitigate conditions of extreme environments for probes with systems architectures and technologies.

  4. Lithospheric and atmospheric interaction on the planet Venus

    Science.gov (United States)

    Volkov, Vladislav P.

    1991-01-01

    Lithospheric and atmospheric interaction in the planet Venus are discussed. The following subject areas are covered: (1) manifestation of exogenic processes using photogeological data; (2) the chemical composition and a chemical model of the troposphere of Venus; (3) the mineral composition of surface rock on Venus; and (4) the cycles of volatile components.

  5. Lithospheric and atmospheric interaction on the planet Venus

    International Nuclear Information System (INIS)

    Lithospheric and atmospheric interaction in the planet Venus are discussed. The following subject areas are covered: (1) manifestation of exogenic processes using photogeological data; (2) the chemical composition and a chemical model of the troposphere of Venus; (3) the mineral composition of surface rock on Venus; and (4) the cycles of volatile components

  6. Science from Mars Express after one year in orbit

    Science.gov (United States)

    2005-02-01

    With over a hundred presentations from scientists from Europe, the United States, Japan, Russia and other countries, the discussions will cover all aspects of this ground-breaking investigation, from an historical perspective to the latest surprising findings. The topics addressed include results from the interior and subsurface of Mars; its geology, mineralogical composition and surface chemistry; the polar regions and their ice caps; the climate and atmosphere of Mars and the interactions between surface and atmosphere; the space environment around Mars and its moons. A special session on exobiology and the search for life on Mars is being held on the afternoon of Thursday 24 February. Members of the media are invited to attend all sessions, but may be particularly interested in the conference summary on Friday 25 February, at 14:00 CET. During the briefing, lasting about an hour, the Principal Investigators of all active experiments on board Mars Express will summarise the major scientific achievements of the first year in orbit and outline the plans for future research. The briefing will include a summary of the discussions on exobiology and the search for life on Mars, and an overview of European plans for future exploration of Mars. A question-and-answer session will follow and ample time is set aside for one-on-one interviews. A detailed programme of the conference can be found at: http://www.congrex.nl/05C05 (click on PROGRAMME, upper left corner) Members of the media wishing to attend the briefing on February 25, or any other parts of the conference, should complete and return the attached form so that proper access badges can be prepared. Registration is free of charge for all media.

  7. Understanding Venus to understand the Earth

    Science.gov (United States)

    Widemann, T.; Tanga, P.

    2012-12-01

    Despite having almost the same size and bulk composition as the Earth, Venus possesses an extreme climate with a surface pressure of 90 bars and temperatures of 740 K. At visible wavelengths the Venus disk appears covered by thick clouds.The core atmospheric processes of Venus and the Earth are similar, despite the different, extraordinary paths they took since their simultaneous formation in the solar system's habitable zone. There are several indications that the composition of the Venus atmosphere has undergone large changes, such as an early runaway climate, and it is likely that the planet has lost a large amount of water through dissociation in the upper atmosphere due to ultraviolet radiation and the subsequent escape of hydrogen. SO2 is thought to originate from volcanism. H2O and SO2 react to form H2SO4 which condenses to form clouds. In past centuries, astronomers and explorers including Captain James Cook observed transits to measure the scale of the solar system. On 5-6 June 2012 we observed the last transit of Venus in this century. Close to the ingress and egress phases, the fraction of Venus disk outside the solar photosphere appears outlined by a thin arc of light, called the aureole. We have shown that the deviation due to refraction and the luminosity of the aureole are related to the local density scale height and the altitude of the refraction layer. As different portions of the arc can yield different values of these parameters, the rare transit event thus provides a unique insight of the Venus mesosphere. The polar region, significantly brighter in initial phases due to larger scale height of the polar mesosphere, appears consistently offset toward morning terminator by about 15deg. latitude, peaking at 75N at 6:00 local time. This result reflects local latitudinal structure in the polar mesosphere, either in temperature or aerosol altitude distribution. Detailed comparative climatology of Venus, an Earth-size planet and understanding why it evolved so differently in its history is crucial to assert the long term evolution of our own planet. Exploring Venus' atmosphere also helps characterize the variety of Earth-size planets near their habitable zone to be discovered around other stars.he atmospheric arc, or aureole, seen from the DST/Interferometric BIdimensional Spectrometer (IBIS) at ~8.5 minutes prior to first contact (NSO/Arcetri)

  8. The vertical density profile of the mesosphere of Venus by independent measurements from SPICAV/SOIR and aureole photometry

    Science.gov (United States)

    Père, C.; Tanga, P.; Widemann, T.; Mahieux, A.; Wilquet, V.; Vandaele, A. C.

    2015-10-01

    The mesosphere of Venus,above the optically thick cloud deck,remains poorly known and shows an important variability as a function of position and time as revealed by Venus Express (VEx) data (SPICAV/SOIR experiment). For the first time, we validate the SOIR vertical density profile by reproducing the accurate photometry of the aureole of Venus obtained by the HMI instrument onboard SDO, during the solar transit of Venus on June 5-6, 2012.The aureole is produced by sunlight refraction in theme sosp, and is highly sensitive to the of the vertical density variations. For this task, we use the data that SOIR has captured from the enus Express orbiter at the time Venus transited the Sun. The photometry of the aureole at the same latitude is then fitted by a multi - layer model adopting the vertical profile of SOIR. We find that our fit is sensitive to the variations of the CO2 mixing ratio, the altitude of the opaque layer at visible wavelengths, and the scale height of the aerosols above them .In particular, we determine the last two parameters. As the inversion method has been validated, we will invert the photometric light curve at all other latitudes observed on the evening .limb

  9. 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

  10. Submillimeter mapping of mesospheric minor species on Venus with ALMA

    Science.gov (United States)

    Encrenaz, T.; Moreno, R.; Moullet, A.; Lellouch, E.; Fouchet, T.

    2015-08-01

    Millimeter and submillimeter heterodyne spectroscopy offers the possibility of probing the mesosphere of Venus and monitoring minor species and winds. ALMA presents a unique opportunity to map mesospheric species of Venus. During Cycle 0, we have observed Venus on November 14 and 15, 2011, using the compact configuration of ALMA. The diameter of Venus was 11? and the illumination factor was about 90%. Maps of CO, SO, SO2 and HDO have been built from transitions recorded in the 335-347 GHz frequency range. A mean mesospheric thermal profile has been inferred from the analysis of the CO transition at the disk center, to be used in support of minor species retrieval. Maps of SO and SO2 abundance show significant local variations over the disk and contrast variations by as much as a factor 4. In the case of SO2, the spatial distribution appears more "patchy", i.e. shows short-scale structures apparently disconnected from day-side and latitudinal variations. For both molecules, significant changes occur over a timescale of one day. From the disk averaged spectrum of SO recorded on November 14 at 346.528 GHz, we find that the best fit is obtained with a cutoff in the SO vertical distribution at 88±2 km and a uniform mixing ratio of 8.0±2.0 ppb above this level. The SO2 map of November 14, derived from the weaker transition at 346.652 GHz, shows a clear maximum in the morning side at low latitudes, which is less visible in the map of November 15. We find that the best fit for SO2 is obtained for a cutoff in the vertical distribution at 88±3 km and a uniform mixing ratio of 12.0±3.5 ppb above this level. The HDO maps retrieved from the 335.395 GHz show some enhancement in the northern hemisphere, but less contrasted variations than for the sulfur species maps, with little change between November 14 and 15. Assuming a typical D/H ratio of 200 times the terrestrial value in the mesosphere of Venus, we find that the disk averaged HDO spectrum is best fitted with a uniform H2O mixing ratio of 2.5±0.6 ppm (corresponding to a HDO mixing ratio of 0.165±0.040 ppm). We note that our spectrum is also compatible with a H2O mixing ratio of 1.5 ppm in the 80-90 km altitude range, and a mixing ratio of 3 ppm outside this range, as suggested by the photochemical model of Zhang et al. (2012, Icarus, vol. 217, pp. 714-739). Our results are in good general agreement with previous single dish submillimeter observations of Sandor and Clancy (2005, Icarus, vol. 177, pp. 129-143), Gurwell et al. (2007, Icarus, vol. 188, p. 288), and Sandor et al. (2010, Icarus, vol. 208, pp. 49-60; 2012, Icarus, vol. 217, pp. 839-844) and with SPICAV/Venus Express results of Fedorova et al. (2008, J. Geophys. Res., vol. 113, p. E00B25) and Belyaev et al. (2012).

  11. 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 the sc...

  12. 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.

  13. 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.

  14. Plasma diffusion into the wake of Venus

    International Nuclear Information System (INIS)

    A model of the diffusion of ionosheath plasma into the wake region of Venus is presented. It is shown that particle diffusion, which is assumed to be a consequence of the fluctuating magnetic field observed in the wake of Venus by Pioneer Venus and Veneras 9 and 10, can explain the plasma observations made in the wake by Veneras 9 and 10. The pressure due to these diffusing particles when balanced against the ionospheric pressure yield ionopause heights less than 1000 km for zenith angles less than about 1350. The model also predicts significant fluxes of low energy electrons and ions for zenith angles less than 1300, which are capable of producing the observed nightside ionosphere

  15. Sulfur Dioxide variability in the Venus Atmosphere

    Science.gov (United States)

    Vandaele, A. C.; Korablev, O.; Mahieux, A.; Wilquet, V.; Chamberlain, S.; Belayev, D.; Encrenaz, Th.; Esposito, L.; Jessup, K. L.; Lefèvre, F.; Limaye, S.; Marcq, E.; Mils, F.; Parkinson, C.; Sandor, B.; Stolzenbach, A.; Wilson, C.

    2015-10-01

    Recent observations of sulfur oxides (SO2, SO, OCS, and H2 SO4) in Venus' mesosphere have generated controversy and great interest in the scientific community. These observations revealed u nexpected spatial patterns and spatial/temporal variability that have not been satisfactorily explained by models. Particularly intriguing are the layer of enhanced gas-phase SO2 and SO in the upper mesosphere, and variability in the maximum observed SO2 a bundance and the equator -to-pole SO2 abundance gradient, seemingly on multi-year cycles, that is not uniquely linked to local time variations. Sulfur oxide chemistry on Venus is closely linked to the global-scale cloud and haze layers, which are composed primarily of concentrated sulfuric acid. Consequently, sulfur oxide observations provide important insight into the ongoing chemical evolution of Venus' atmosphere, atmospheric dynamics, and possible volcanism.

  16. An Orbit Plan toward AKATSUKI Venus Reencounter and Orbit Injection

    Science.gov (United States)

    Kawakatsu, Yasuhiro; Campagnola, Stefano; Hirose, Chikako; Ishii, Nobuaki

    2012-01-01

    On December 7, 2010, AKATSUKI, the Japanese Venus explorer reached its destination and tried to inject itself into Venus orbit. However, due to a malfunction of the propulsion system, the maneuver was interrupted and AKATSUKI again escaped out from the Venus into an interplanetary orbit. Telemetry data from AKATSUKI suggests the possibility to perform orbit maneuvers to reencounter the Venus and retry Venus orbit injection. Reported in this paper is an orbit plan investigated under this situation. The latest results reflecting the maneuvers conducted in the autumn 2011 is introduced as well.

  17. 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.

  18. Carbon monoxide short term variability observed on Venus with SOIR/VEX

    Science.gov (United States)

    Vandaele, A. C.; Mahieux, A.; Robert, S.; Drummond, R.; Wilquet, V.; Bertaux, J. L.

    2015-08-01

    The SOIR instrument on board the ESA Venus Express mission has been operational since the insertion of the satellite around Venus in 2006. Since then, it has delivered high quality spectra of the atmosphere of Venus. Spectra are recorded in the IR spectral region (2.2-4.3 ?m) using the solar occultation geometry and give access to a vast number of ro-vibrational lines and bands of several key species of the atmosphere of Venus. Here we present the retrieval strategy applied to obtain high quality vertical profiles of carbon monoxide (CO) densities and volume mixing ratios (vmr), spanning the 65-150 km altitude range. We discuss the methodology used to derive the profiles and the validation process implemented to ensure the quality and reproducibility of the results. Influence of ancillary data, such as temperature, is discussed. High variability of CO densities and vmr is observed in relatively short term periods. Correlation between CO and CO2 densities, as well as between CO and temperature above 110 km, corroborates that the major process at those altitudes is the photodissociation of CO2 into CO.

  19. Ionospheric photoelectrons at Venus: Case studies and first observation in the tail

    Science.gov (United States)

    Tsang, S. M. E.; Coates, A. J.; Jones, G. H.; Frahm, R. A.; Winningham, J. D.; Barabash, S.; Lundin, R.; Fedorov, A.

    2015-08-01

    The presence of photoelectrons in ionospheres, including that of unmagnetised Venus, can be inferred from their characteristic spectral peaks in the electron energy spectrum. The electrons within the peaks are created by the photoionisation of neutrals in the upper atmosphere by the solar HeII 30.4 nm line. Here, we present some case studies of photoelectron spectra observed by the ASPERA-4 instrument aboard Venus Express with corresponding ion data. In the first case study, we observe photoelectron peaks in the sunlit ionosphere, indicating relatively local production. In the second case study, we observe broadened peaks in the sunlit ionosphere near the terminator, which indicate scattering processes between a more remote production region and the observation point. In the third case study, we present the first observation of ionospheric photoelectrons in the induced magnetotail of Venus, which we suggest is due to the spacecraft being located at that time on a magnetic field line connected to the dayside ionosphere at lower altitudes. Simultaneously, low energy ions are observed moving away from Venus. In common with observations at Mars and at Titan, these imply a possible role for the relatively energetic electrons in producing an ambipolar electric field which enhances ion escape.

  20. Mesospheric vertical thermal structure and winds on Venus from HHSMT CO spectral-line observations

    CERN Document Server

    Rengel, M; Jarchow, C

    2008-01-01

    We report vertical thermal structure and wind velocities in the Venusian mesosphere retrieved from carbon monoxide (12CO J=2-1 and 13CO J=2-1) spectral line observations obtained with the Heinrich Hertz Submillimeter Telescope (HHSMT). We observed the mesosphere of Venus from two days after the second Messenger flyby of Venus (on June 5 2007 at 23:10 UTC) during five days. Day-to-day and day-to-night temperature variations and short-term fluctuations of the mesospheric zonal flow were evident in our data. The extensive layer of warm air detected recently by SPICAV at 90 - to 100 km altitude is also detected in the temperature profiles reported here. These data were part of a coordinated ground-based Venus observational campaign in support of the ESA Venus Express mission. Furthermore, this study attempts to cross-calibrate space- and ground-based observations, to constrain radiative transfer and retrieval algorithms for planetary atmospheres, and to contribute to a more thorough understanding of the global pa...

  1. Oxygen ion escape from Venus in a global hybrid simulation: role of the ionospheric O+ ions

    Directory of Open Access Journals (Sweden)

    T. L. Zhang

    2009-11-01

    Full Text Available We study the solar wind induced oxygen ion escape from Venus' upper atmosphere and the Venus Express observations of the Venus-solar wind interaction by the HYB-Venus hybrid simulation code. We compare the simulation to the magnetic field and ion observations during an orbit of nominal upstream conditions. Further, we study the response of the induced magnetosphere to the emission of planetary ions. The hybrid simulation is found to be able to reproduce the main observed regions of the Venusian plasma environment: the bow shock (both perpendicular and parallel regions, the magnetic barrier, the central tail current sheet, the magnetic tail lobes, the magnetosheath and the planetary wake. The simulation is found to best fit the observations when the planetary oxy~escape rate is in the range from 3×1024 s?1 to 1.5×1025 s?1. This range was also found to be a limit for a test particle-like behaviour of the planetary ions: the higher escape rates manifest themselves in a different global configuration of the Venusian induced magnetosphere.

  2. Venus: Mantle convection, hotspots, and tectonics

    International Nuclear Information System (INIS)

    The putative paradigm that planets of the same size and mass have the same tectonic style led to the adaptation of the mechanisms of terrestrial plate tectonics as the a priori model of the way Venus should behave. Data acquired over the last decade by Pioneer Venus, Venera, and ground-based radar have modified this view sharply and have illuminated the lack of detailed understanding of the plate tectonic mechanism. For reference, terrestrial mechanisms are briefly reviewed. Venusian lithospheric divergence, hotspot model, and horizontal deformation theories are proposed and examined

  3. Aeolian features on Venus - Preliminary Magellan results

    Science.gov (United States)

    Greeley, Ronald; Arvidson, Raymond E.; Elachi, Charles; Geringer, Maureen A.; Plaut, Jeffrey J.; Saunders, R. S.; Schubert, Gerald; Stofan, Ellen R.; Thouvenot, Eric J. P.; Wall, Stephen D.

    1992-01-01

    About 44 percent of the surface of Venus has been searched in a reconnaissance mode for wind-related features using primarily cycle 1 Magellan radar data. The aeolian features, including possible dune fields, yardangs, and various types of wind streaks, are described, and the geological settings and properties of the surfaces in which they occur are assessed. Attention is also given to possible modes of formation of the most common aeolian features (wind streaks), with reference made to terrestrial examples. The relationships between aeolian features and atmospheric circulation patterns on Venus are considered.

  4. A Survey for Satellites of Venus

    OpenAIRE

    Sheppard, Scott S.; Trujillo, Chadwick A.

    2009-01-01

    We present a systematic survey for satellites of Venus using the Baade-Magellan 6.5 meter telescope and IMACS wide-field CCD imager at Las Campanas observatory in Chile. In the outer portions of the Hill sphere the search was sensitive to a limiting red magnitude of about 20.4, which corresponds to satellites with radii of a few hundred meters when assuming an albedo of 0.1. In the very inner portions of the Hill sphere scattered light from Venus limited the detection to sat...

  5. Emplacement Scenarios for Volcanic Domes on Venus

    Science.gov (United States)

    Glaze, Lori S.; Baloga, Steve M.; Stofan, Ellen R.

    2012-01-01

    One key to understanding the history of resurfacing on Venus is better constraints on the emplacement timescales for the range of volcanic features visible on the surface. A figure shows a Magellan radar image and topography for a putative lava dome on Venus. 175 such domes have been identified with diameters ranging from 19 - 94 km, and estimated thicknesses as great as 4 km. These domes are thought to be volcanic in origin and to have formed by the flow of viscous fluid (i.e., lava) on the surface.

  6. Galileo infrared imaging spectroscopy measurements at venus

    Science.gov (United States)

    Carlson, R.W.; Baines, K.H.; Encrenaz, Th.; Taylor, F.W.; Drossart, P.; Kamp, L.W.; Pollack, James B.; Lellouch, E.; Collard, A.D.; Calcutt, S.B.; Grinspoon, D.; Weissman, P.R.; Smythe, W.D.; Ocampo, A.C.; Danielson, G.E.; Fanale, F.P.; Johnson, T.V.; Kieffer, H.H.; Matson, D.L.; McCord, T.B.; Soderblom, L.A.

    1991-01-01

    During the 1990 Galileo Venus flyby, the Near Infrared Mapping Spectrometer investigated the night-side atmosphere of Venus in the spectral range 0.7 to 5.2 micrometers. Multispectral images at high spatial resolution indicate substantial cloud opacity variations in the lower cloud levels, centered at 50 kilometers altitude. Zonal and meridional winds were derived for this level and are consistent with motion of the upper branch of a Hadley cell. Northern and southern hemisphere clouds appear to be markedly different. Spectral profiles were used to derive lower atmosphere abundances of water vapor and other species.

  7. Investigating the Geophysics of Venus: Result of the post-Alpbach Summer School 2014

    Science.gov (United States)

    Koopmans, Robert-Jan; ?osiak, Anna; Bia?ek, Agata; Donohoe, Anthony; Fernández Jiménez, María; Frasl, Barbara; Gurciullo, Antonio; Kleinschneider, Andreas; Mannel, Thurid; Muñoz Elorza, Iñigo; Nilsson, Daniel; Oliveira, Marta; Sørensen-Clark, Paul; Timoney, Ryan; van Zelst, Iris

    2015-04-01

    Venus has been investigated by only five dedicated mission programs since the beginning of space flight. This relatively low level of interest is remarkable when considering that mass and radius of Venus are very similar to Earth's, while at the same time characteristics such as spin rate, atmospheric composition, pressure and temperature, make Venus a very different, inhabitable world. The underlying causes of these differences are not well understood. Apprehending Venus' tectonics and internal structure would not only shed light on the question why those two planets evolved so differently, but also help refining current models of planetary systems formation. In order to answer the question about reasons for differences in evolution of those two planets a group of 15 young scientists and engineers designed a mission to Venus during a follow-up of the Alpbach Summer School 2014. The primary objective of this mission is to learn whether Venus is tectonically active and on what time scale. In order to accomplish this goal the mission will determine the crustal structure of Venus, the current activity and distribution of active volcanoes and the movement of continental plates. The secondary objective is to further constrain the models of Venus' internal structure and composition. To achieve this, the mission will investigate the size, state and composition of the core as well as the state and composition of the mantle. The proposed mission consists of an orbiter in a near-polar circular orbit around Venus and a balloon for in-situ measurements operating during the initial phase of the mission. The balloon carries a nephelometer, a magnetometer, a mass spectrometer and stereo microphones and meteorological package. The orbiter carries a gradiometer for determining the gravity field, a synthetic aperture radar for investigating small changes in surface topography and mapping microwave signals from the surface and an IR and UV spectrometer and IR camera for monitoring heat signatures from volcanoes. By using the previous landers as reference points it will also be possible to accurately determine the spin rate with the radar. The nominal mission duration is planned to be five years starting from the release of the balloon. The balloon will operate for 25 days during which it oscillates vertically in the atmosphere between an altitude of 40 and 60 kilometres in a period of about six hours. At the same time, due to prevailing wind directions on Venus, it will gradually spiral from the equator towards higher latitudes. During the balloon science phase the orbiter will be in an elliptical orbit to maximise the time of visibility of the balloon with the orbiter. After this phase, the orbiter will be brought into a circular orbit at an altitude of 250 kilometres. To save fuel, apoapsis lowering will be achieved by aerobreaking in Venus' atmosphere. In the presentation further details about the mission timeline will be given. Particular engineering problems such as thermal control and data communication and the proposed solutions will be presented.

  8. Pioneer Venus observations of the Venus dayglow spectrum 1250--1430 A

    International Nuclear Information System (INIS)

    The spectrum of the dayglow of Venus between 1250 and 1430 A has been measured by the Pioneer Venus Orbiter Ultraviolet Spectrometer. Four bands of the (14,v'') progression in the fourth positive system of carbon monoxide are identified and their excitation mechanism is shown to be fluorescent scattering of the solar Lyamn alpha line. The (14,3) and (14,4) bands at 1317 and 1354 A are blended with the atomic oxygen 1304 and 1356 A lines. The (14,5) band at 1392 A is a prominent unblended spectral feature in the Venus dayglow. This identification provides an additional remote sensing technique to determine the density distribution of carbon monoxide in the upper atmosphere of Venus

  9. A modified density model of the Venus atmosphere at 130-200 km altitude

    Science.gov (United States)

    Svedhem, Håkan; Mueller-Wodarg, Ingo; Rosenblatt, Pascal; Grotheer, Emmanuel

    2014-05-01

    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 configuration 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 2013 several campaigns, with altitudes going as low as 165 km, were held. The highest density measured was 1.3 10-11kg/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.

  10. Variability of the Venus condensational clouds from analysis of VIRTIS-M-IR observations of the near-infrared spectral windows

    Science.gov (United States)

    McGouldrick, Kevin; Tsang, Constantine C. C.

    2015-11-01

    The Medium Resolution, Infrared wavelength channel of the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS-M-IR) on the Venus Express spacecraft observed the atmosphere and surface of Venus for 921 orbits following orbit insertion in April 2006 until the failure of the cooling unit in October 2008. The clouds of Venus were long thought to be a uniform sort of perpetual stratocumulus, but near infrared observations by fly-by spacecraft such as Galileo (Near Infrared Mapping Spectrometer) and Cassini (Visible and Infrared Mapping Spectrometer), as well as ground-based observations, indicated a great deal of temporal and spatial inhomogeneity. The nearly three-year lifetime of the VIRTIS-M-IR instrument on Venus Express presents an unprecedented opportunity to quantify these spatial and temporal variations of the Venus clouds. Here, we present the results of an initial quantification of the overall tendencies of the Venus clouds, as measured by variations in the near infrared spectral windows located between wavelengths of 1.0 µm and 2.6 µm. In a companion submission, we also investigate the variations of carbon monoxide and other trace species quantifiable in these data (Tsang and McGouldrick 2015). This work is supported by the Planetary Mission Data Analysis Program, Grant Number NNX14AP94G.

  11. Water vapor abundance in Venus' middle atmosphere from Pioneer Venus OIR and Venera 15 FTS measurements

    OpenAIRE

    Koukouli, ME; Irwin, PGJ; Taylor, FW

    2005-01-01

    The Pioneer Venus Orbiter Infrared Radiometer and Venera 15 Fourier Transform Spectrometer observations of thermal emission from Venus' middle atmosphere between 10degreesS and 50degreesN have been independently re-analyzed using a common method to determine global maps of temperature, cloud optical depth, and water vapor abundance. The spectral regions observed include the strong 15 mum carbon dioxide band and the 45 mum fundamental rotational water band. The different spatial and spectral r...

  12. Genesis of Flux Ropes Observed by Pioneer-Venus Orbiter in the Photoequilibrium Region At Venus

    OpenAIRE

    Krymskii, A. M.; Bojkov, D. I.

    1998-01-01

    Genesis of flux ropes observed by Pioneer-Venus Orbiter in the photoequilibrium region at Venus is analysed. Stability analysis of the large-scale magnetic field pushed deep inside during period of high dynamic pressure of solar wind had shown that the top-side boundary of the magnetic belt located within the region of photoequilibrium is unstable. The finite conductivity of plasma tends to stabilise the instability so that the bottom-side part of the magnetic belt is regula...

  13. 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.

  14. 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.

  15. First ever in-situ density measurements in Venus' polar upper atmosphere by combined drag and torque measurements

    Science.gov (United States)

    Svedhem, Håkan; Mueller, Michael; Mueller-Wodarg, Ingo

    Information on the atmospheric density in the altitude range 150-200 km in the atmosphere of Venus is difficult to gather remotely. The Pioneer Venus Orbiter Neutral Mass Spectrometer measured gas densities in the equatorial upper atmosphere in-situ, but no such measurements have ever been made in the polar regions of Venus. The Venus Express spacecraft on its orbit approaches the planet in the northern polar region, but is not equipped with a mass spectrometer instrument for in-situ gas density measurements. By reducing the pericentre altitude the total mass density can however 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 year 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 asymmetry is large, and offers a further 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. First torque measurements carried out during last years' low pericentre passes have confirmed the density measurements by the VExADE drag measurements to an amazingly good accuracy and added to the confidence in the results from these measurements. New combined measurements, where the asymmetry is increased by rotating the solar panels, are planned for February and April 2010. The new results will be discussed at the meeting.

  16. 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.

    2015-10-01

    Measurement of noble gas abundances on Venus remain a high priority for planetary science [1,2]. These studies are only possible through in situ measurement, and can be accomplished by a modern neutral mass spectrometer (NMS) such as that developed at NASA Goddard, based on flight-proven technology. Here we show how the measurement of noble gases can be secured using demonstrated enrichment techniques.

  17. 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.

  18. Electrical discharges in the atmosphere of Venus

    Science.gov (United States)

    Ksanfomaliti, L. V.; Vasilchikov, N. M.; Ganpantserova, O. F.; Petrova, Y. V.; Suvorov, A. P.; Filippov, G. F.; Yablonskaya, O. V.; Yabrova, L. V.

    1979-01-01

    Data received from Venera 11 and 12 experiments involving the electrical activity of the atmosphere of Venus show that the electrical discharges occur in the cloud layer. Their energy is roughly the same as in terrestrial lightning, but with a pulse repetition frequency of the discharges which is much greater.

  19. The surface and interior of Venus

    International Nuclear Information System (INIS)

    Present ideas about the surface and interior of Venus are based on data obtained from (1) Earth-based radio and radar: temperature, rotation, shape, and topography; (2) fly-by and orbiting spacecraft: gravity and magnetic fields; and (3) landers: winds, local structure, gamma radiation. Surface features, including large basins, crater-like depressions, and a linear valley, have been recognized from recent ground-based radar images. Pictures of the surface acquired by the USSR's Venera 9 and 10 show abundant boulders and apparent wind erosion. On the Pioneer Venus 1978 Orbiter mission, the radar mapper experiment will determine surface heights, dielectric constant values and small-scale slope values along the sub-orbital track between 500S and 750N. This experiment will also estimate the global shape and provide coarse radar images (40-80 km identification resolution) of part of the surface. Gravity data will be obtained by radio tracking. Maps combining radar altimetry with spacecraft and ground-based images will be made. A fluxgate magnetometer will measure the magnetic fields around Venus. The radar and gravity data will provide clues to the level of crustal differentiation and tectonic activity. The magnetometer will determine the field variations accurately. Data from the combined experiments may constrain the dynamo mechanism; if so, a deeper understanding of both Venus and Earth will be gained. (Auth.)

  20. The guinevere project at the venus facility

    International Nuclear Information System (INIS)

    The GUINEVERE project is a European project in the framework of FP6 IP-EUROTRANS. The IP-EUROTRANS project aims at addressing the main issues for ADS development in the framework of partitioning and transmutation for nuclear waste volume and radiotoxicity reduction. The GUINEVERE project is carried out in the context of Domain 2 of IP-EUROTRANS, ECATS, devoted to specific experiments for the coupling of an accelerator, a target and a subcritical core. These experiments should provide an answer to the questions of on-line reactivity monitoring, subcriticality determination and operational procedures (loading, start-up, shutdown, etc.) in an ADS by 2009-2010. The GUINEVERE project will make use of the VENUS reactor, serving as a lead fast critical facility, coupled to a continuous beam accelerator. In order to achieve this goal, the VENUS facility has to be adapted and a modified GENEPI-C accelerator has to be designed and constructed. During the years 2007 and 2008, the VENUS facility will he modified in order to allow the experimental programme to start in 2009. The paper describes the main achievements with regard to the modifications for the VENUS facility. (authors)

  1. Venus: A contrast in evolution to Earth

    International Nuclear Information System (INIS)

    Of the planets, Venus and Earth are by far the most similar in primary properties, yet they differ markedly in secondary properties. A great impact into Earth is believed to have created its moon and removed its atmosphere; the lack of such an impact into Venus apparently led to a greatly differing atmospheric evolution. The lack of an ocean on Venus prevents the recycling of volatiles and inhibits subduction, so that its crust is probable more voluminous than Earth's, although distorted and quite variable in thickness. Venus's upper mantle appears to be depleted in both volatiles and energy sources because, in addition to the lack of volatile recycling, melts of mantel rocks are more dense than their solid matrix at pressures above 8 gigapascals and hence sink if they occur at depths below 250 kilometers. Appreciable energy sources persist at great depths to sustain the few great mountain complexes. The greatest current problem is reconciling the likelihood of a voluminous crust with indications of considerable strength at shallow depths of 20 to 100 kilometers

  2. A correlated-k model of radiative transfer in the near-infrared windows of Venus

    Energy Technology Data Exchange (ETDEWEB)

    Tsang, C.C.C. [Atmospheric, Oceanic and Planetary Physics, Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford, Oxon OX1 3BH (United Kingdom)], E-mail: con@atm.ox.ac.uk; Irwin, P.G.J.; Taylor, F.W.; Wilson, C.F. [Atmospheric, Oceanic and Planetary Physics, Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford, Oxon OX1 3BH (United Kingdom)

    2008-04-15

    We present a correlated-k-based model for generating synthetic spectra in the near-infrared window regions, from 1.0 to 2.5 {mu}m, emitted from the deep atmosphere of Venus on the nightside. This approach is applicable for use with any near-infrared instrument, ground-based and space-borne, for analysis of the thermal emissions in this spectral range. We also approach this work with the view of using the model, in conjunction with a retrieval algorithm, to retrieve minor species from the Venus Express/VIRTIS instrument. An existing radiative-transfer model was adapted for Venusian conditions to deal with the prevailing high pressures and temperatures and other conditions. A comprehensive four-modal cloud structure model based on Pollack et al. [Near-infrared light from venus' nightside: a spectroscopic analysis. Icarus 1993;103:1-42], using refractive indices for a 75% H{sub 2}SO{sub 4}25% H{sub 2}O mixture from Palmer and Williams [Optical constants of sulfuric acid; application to the clouds of Venus? Appl Opt 1975;14(1):208-19], was also implemented. We then utilized a Mie scattering algorithm to account for the multiple scattering effect between cloud and haze layers that occur in the Venusian atmosphere. The correlated-k model is shown to produce good agreement with ground-based spectra of Venus in the near infrared, and to match the output from a line-by-line radiative-transfer model to better than 10%.

  3. 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.

  4. Protecting Venus from Asteroids, Comets, and Meteors

    Science.gov (United States)

    McKinnon, William B.; Zahnle, K. J.; Cuzzi, Jeffrey (Technical Monitor)

    1996-01-01

    It is well accepted that the dense, thick atmosphere of Venus prevents most small cosmic bodies from reaching the surface and forming craters. We have examined this atmospheric intervention in detail, incorporating the lessons learned from the extensive modeling of impactor deceleration and flattening motivated by the SL-9 impacts with Jupiter. We employ a "pancake" model, which best matches detailed code simulations of atmospheric energy deposition, and Schmidt-Holsapple crater scaling modified for complex (flattened) craters. We adopt the distributions of Venus-crossing asteroids and comets determined by E.M. Shoemaker and co-workers, as well as generalizations of these distributions. Our nominal simulation of the venusian crater record is shown below, calibrated to the total number of venusian craters (940). As nearly all craters on Venus are well-preserved and relatively uniformly distributed, such simulations constrain the age of the surface. The fit is reasonable, with a nominal crater retention age of approx. 700 Ma. The fit at the large-crater end is improved if the number of large asteroids is increased, which Shoemaker argues is in fact more representative of the long-term (over several 100 Ma) average, and if Halley-family comets are included. The ages we obtain under a variety of modeling choices that produce good fits (including using Shoemaker's preferred crater scaling) are approx. 700-900 Ma, substantially greater than the most widely cited age estimate in the literature (-300 Ma). The key difference is that we find very large depletions in the production of 20-30-km craters (see figure) compared with previous estimates, the size range at which atmospheric effects are often calibrated or assumed nearly negligible. As venusian global resurfacing recedes deeper into history, the likelihood that Venus is resting between bouts of activity diminishes. Venus, like Mars, may instead be dying or dead.

  5. Aeolian Processes and Features on Venus

    Science.gov (United States)

    Greeley, Ronald; Bender, Kelly C.; Saunders, Stephen; Schubert, Gerald; Weitz, Catherine M.

    1997-01-01

    Aeolian features on Venus include dune fields, eroded hills (yardangs), wind streaks, (miniature dunes of 10 to 30 cm wavelength). Although and possibly microdunes (in repetitive imaging by Magellan did show changes in the appearance of the surface, these changes are attributed to radar artifacts as a consequence of look direction rather than to physical changes of the surface. Nonetheless, measurements of wind speeds near the surface of Venus and wind tunnel simulations suggest that aeolian processes could be currently active on Venus. Study of radar images of terrestrial analogs shows that radar wavelength, polarization, and viewing geometry, including look direction and incidence angle, all influence the detection of dunes, yardangs, and wind streaks. For best detection, dune crests and yardangs should be oriented perpendicular to look direction. Longer wavelength systems can penetrate sand sheets a meter or more thick, rendering them invisible, especially in arid regions. For wind streaks to be visible, there must be a contrast in surface properties between the streak and the background on which it occurs. Nonetheless, more than 6000 aeolian features have been found on Magellan images of Venus, the most common of which are various wind streaks. Mapping wind streak orientations enables near-surface wind patterns to be inferred for the time of their formation. Type P streaks are associated with parabolic ejecta crater deposits and are considered to have formed in association with the impact event. Most Type P streaks are oriented westward, indicative of the upper altitude superrotation winds of Venus. Non Type P streaks have occurrences and orientations consistent with Hadley circulation. Some streaks in the southern hemisphere are oriented to the northeast, suggesting a Coriolis effect.

  6. 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.

  7. 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.

  8. 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.

  9. Experimental comparison studies with the VENUS-II disassembly code

    International Nuclear Information System (INIS)

    The Kiwi-TNT, SNAPTRAN-2 and SNAPTRAN-3 reactor disassembly experiments have been analyzed using the VENUS-II disassembly code. Modifications to the basic VENUS-II model required for the analysis of these tests are discussed. Key results from the analyses are compared to the experimental data and conclusions are drawn concerning the experimental validation of VENUS-II afforded by these comparisons

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

    OpenAIRE

    Hedelt, P.; Alonso, R.; 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...

  11. The escape of natural satellites from Mercury and Venus

    International Nuclear Information System (INIS)

    It is suggested that the slow rotations of Mercury and Venus may be connected with the absence of natural satellites around them. If Mercury or Venus possessed a satellite at the time of formation, the tidal evolution would have caused the satellite to recede. At a sufficiently large distance from the planet, the Sun's gravitational influence makes the satellite orbit unstable. The natural satellites of Mercury and Venus might have escaped as a consequence of this instability. (Auth.)

  12. 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.

  13. USGS Magellan stereomapping of Venus

    Science.gov (United States)

    Howington-Kraus, E.; Kirk, R. L.; Galuszka, D.; Redding, B.

    Introduction: The Magellan spacecraft went into Venus orbit in 1990 and by 1992 had made three complete cycles of polar orbits, each cycle covering the full range of longitudes. During this time the spacecraft obtained synthetic aperture radar (SAR) images of >96% of the planet at a resolution of 75 m/pixel [1]. Images taken with a decreased look angle from vertical, primarily during Cycle 3, provide stereo coverage of 17% of the planet when combined with images with same-side illumination from earlier in the mission. The stereo geometry of these images is extremely favorable, allowing elevation measurements with an estimated vertical precision (EP) of ˜10 m [2]. Magellan also obtained radar altimetry data at a horizontal resolution of 10x25 km, but photogrammetric analysis of the stereoimagery can yield topographic maps with a horizontal resolution more than an order of magnitude superior to that of the altimeter. We therefore developed software needed to utilize Magellan stereomagery on our photogrammetric workstation running commercial (SOCET SET R BAE) software [3,4]. The special hardware and SOCET SET software of this system provide many useful capabilities for stereomapping which can be extended by programming with the SOCET SET Developer's Toolkit (DEVKIT). The unique properties of the Magellan SAR data made it necessary to develop both translation software (of image data and supporting geometric information) and a sensor model [5]. Sensor Model: A sensor model is a function that specifies the transformation between image space (lines, samples) and object or ground coordinates (latitude, longitude, elevation). Our Magellan SAR sensor model includes all the physics of the Magellan imaging process, and accounts for the fact that during the Magellan imaging process, the images have been partially orthorectified as part of the correlation process: distortions attributable to topography were removed (but only those accounted for in the very low resolution pre-Magellan topo model) and must be put back in for the images to be matched correctly. The sensor model is designed to work with any combination of unmosaicked (F-BIDR), Mission-mosaicked (F- and C-MIDR), and USGS- mosaicked (FMAP) images. Information about the spacecraft position and velocity can be taken either from the F-BIDR headers or from separate NAIF SPICE kernels, letting us take advantage of post-mission improvements to the spacecraft ephemerides. In addition, the SOCET SET bundle-adjustment software can be used to estimate corrections to the ephemeris of each orbit. The form of the corrections, offsets in three orthogonal directions (along-track, across-track, and radial) suffices to correct the orbits over short arcs and reconcile SAR and altimetry observations. 1 Validation: We rigorously tested and accounted for potential error sources in our mapping process. We first addressed the well-known "cliffs," artifacts in the stereo data caused by discrepancies between the mission ephemeris solutions for successive blocks of orbits. Alex Konopliv of JPL reprocessed the entire set of orbital tracking and navigation data based on the detailed gravity observations from the end of the mission and claimed that errors in the new orbit solutions were decreased 1.5 orders of magnitude (to 50-200 m) in all 3 axes [6]. To produce seamless elevation data, we found it necessary to collect image-to-image tie point measurements and use these to estimate local position/velocity corrections to the orbits. We concluded that both the improved orbit/tracking solution and corrections based on the images themselves are necessary for successful stereomapping. Secondly, because we constrain elevations of control points based on the Magellan altimetry, the question arose of how sensitive our bundle adjustment process is to artifacts in the Magellan altimetry. (Elevations of individual altimeter footprints can be in error by several kilometers at high-contrast boundaries in the surface scattering function.) We demonstrated that the adjustable parameters allow each imag

  14. 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...

  15. Assignment and rotational analysis of new absorption bands of carbon dioxide isotopologues in Venus spectra

    International Nuclear Information System (INIS)

    We present absorption bands of carbon dioxide isotopologues, detected by the Solar Occultation for the Infrared Range (SOIR) instrument on board the Venus Express Satellite. The SOIR instrument combines an echelle spectrometer and an Acousto-Optical Tunable Filter (AOTF) for order selection. It performs solar occultation measurements in the Venus atmosphere in the IR region (2.2–4.3 ?m), at a resolution of 0.12–0.18 cm?1. The wavelength range probed by SOIR allows a detailed chemical inventory of the Venus atmosphere above the cloud layer (65–150 km) to be made with emphasis on the vertical distributions of gases. Thanks to the SOIR spectral resolution, a new CO2 absorption band was identified: the 21101–01101 band of 16O12C18O with R branch up to J=31. Two other previously reported bands were observed dispelling any doubts about their identifications: the 20001–00001 band of 16O13C18O [Villanueva G, et al. J Quant Spectrosc Radiat Transfer 2008;109:883–894] and the 01111–00001 band of 16O12C18O [Villanueva G, et al. J Quant Spectrosc Radiat Transfer 2008;109:883–894 and Wilquet V, et al. J Quant Spectrosc Radiat Transfer 2008;109:895–905]. These bands were analyzed, and spectroscopic constants characterizing them were obtained. The rotational assignment of the 20001–00001 band was corrected. The present measurements are compared with data available in the HITRAN database. -- Highlights: ? The spectra recorded by the SOIR instrument onboard Venus Express are analyzed. ? One new band of 16O12C18O was identified for the first time. ? Two other bands 16O13C18O and 16O12C18O were reanalyzed. ? Spectroscopic constants have been obtained for the three bands.

  16. 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.

  17. The cartography of Venus with Magellan data

    Science.gov (United States)

    Kirk, R. L.; Morgan, H. F.; Russell, J. F.

    1993-01-01

    Maps of Venus based on Magellan data are being compiled at 1:50,000,000, 1:5,000,000 and 1:1,500,000 scales. Topographic contour lines based on radar altimetry data are overprinted on the image maps, along with feature nomenclature. Map controls are based on existing knowledge of the spacecraft orbit; photogrammetric triangulation, a traditional basis for geodetic control for bodies where framing cameras were used, is not feasible with the radar images of Venus. Preliminary synthetic aperture radar (SAR) image maps have some data gaps and cosmetic inconsistencies, which will be corrected on final compilations. Eventual revision of geodetic controls and of the adopted Venusian spin-axis location will result in geometric adjustments, particularly on large-scale maps.

  18. Plasma channels in the Venus upper ionosphere

    Directory of Open Access Journals (Sweden)

    H. Pérez de Tejada

    2001-05-01

    Full Text Available The structure of the Venus nightside ionosphere is modeled in terms of a flow configuration derived from the position of the intermediate transition along the flanks of the ionosheath downstream from the magnetic polar regions. It is suggested that the shocked solar wind erodes more strongly the polar ionosphere producing plasma channels that extend downstream from the magnetic polar regions. Such features represent the main source of mass loss along the plasma tail and imply a small overall solar wind-induced depletion of the planetary ionosphere. The plasma channels can account for the observation of ionospheric holes in PVO passes through the Venus wake. The expected flow distribution within the wake is consistent with the entry of plasma fluxes from the magnetic polar regions that was suggested earlier to account for geometry of the nightside ionopause (Pérez de Tejada, 1980.

  19. Venus y el fin del mundo

    Directory of Open Access Journals (Sweden)

    Gonzalo Munévar

    2006-01-01

    Full Text Available Este artículo busca demostrar que los argumentos generales acerca de la exploración científica valen también para las ciencias espaciales. El trabajo se basa en el ejemplo de la exploración de Venus y lo que esta nos dice acerca de nuestro propio planeta. Argumenta que el concepto de la probabilidad de Leslie es incorrecto, como también lo son las dudas sobre la evidencia Venusiana. Así mismo, concluye que no se puede rechazar la importancia que tienen los descubrimientos inesperados que han resultado de la exploración de Venus para ayudarnos a comprender nuestro propio planeta. Y que si van a ser rechazados estos descubrimientos debe ser por razones científicas, no por intuiciones acerca de la probabilidad.

  20. Deuterium content of the Venus atmosphere

    International Nuclear Information System (INIS)

    The abundance of deuterium in the atmosphere of Venus is an important clue to the planet's history, because ordinary and deuterated water escape at different rates. Using the high-resolution mode of the International Ultraviolet Explorer (IUE), we measured hydrogen Lyman-?-emission but found only an upper limit on deuterium Lyman-?-emission, from which we inferred a D/H ratio of less than 2-5 x 10-3. This is smaller by a factor of 3-8 than the D/H ratio derived from measurements by the Pioneer Venus Large Probe, and may indicate either a stratification of D/H ratio with altitude or a smaller overall ratio than previously thought. (author)

  1. The change of resurfacing regimes on Venus

    Science.gov (United States)

    Ivanov, M. A.

    2015-01-01

    The change of volcanic resurfacing regimes on Venus is discussed. The frequency-size distribution of the regional and lobate plains fields suggest that regional plains had likely been formed due to lava flooding. The geological ratios of impact craters with plains units of different ages are analyzed. Only 3% of the craters located on the older regional plains are found to be embayed by plains material. About 50% of the craters located on the younger lobate plains are found to be embayed by plains lavas. Both the frequency-size distribution of the regional plains fields and the number of embayed craters indicate their catastrophic formation. For lobate plains, these parameters indicate a gradual and time-stretched accumulation of their material. Thus, the volcanic resurfacing regimes must have been changing radically throughout the observable portion of the geological history of Venus.

  2. An Atmospheric Variability Model for Venus Aerobraking Missions

    Science.gov (United States)

    Tolson, Robert T.; Prince, Jill L. H.; Konopliv, Alexander A.

    2013-01-01

    Aerobraking has proven to be an enabling technology for planetary missions to Mars and has been proposed to enable low cost missions to Venus. Aerobraking saves a significant amount of propulsion fuel mass by exploiting atmospheric drag to reduce the eccentricity of the initial orbit. The solar arrays have been used as the primary drag surface and only minor modifications have been made in the vehicle design to accommodate the relatively modest aerothermal loads. However, if atmospheric density is highly variable from orbit to orbit, the mission must either accept higher aerothermal risk, a slower pace for aerobraking, or a tighter corridor likely with increased propulsive cost. Hence, knowledge of atmospheric variability is of great interest for the design of aerobraking missions. The first planetary aerobraking was at Venus during the Magellan mission. After the primary Magellan science mission was completed, aerobraking was used to provide a more circular orbit to enhance gravity field recovery. Magellan aerobraking took place between local solar times of 1100 and 1800 hrs, and it was found that the Venusian atmospheric density during the aerobraking phase had less than 10% 1 sigma orbit to orbit variability. On the other hand, at some latitudes and seasons, Martian variability can be as high as 40% 1 sigmaFrom both the MGN and PVO mission it was known that the atmosphere, above aerobraking altitudes, showed greater variability at night, but this variability was never quantified in a systematic manner. This paper proposes a model for atmospheric variability that can be used for aerobraking mission design until more complete data sets become available.

  3. Gasdynamic modeling of the Venus magnetotail

    International Nuclear Information System (INIS)

    A gasdynamic, convected magnetic field model of the solar wind interaction with Venus is used for the first time to model the steady state Venus magnetotail. Model results are directly compared with observations. The obstacle shape is an input parameter to this model. An initial obstacle shape, accurate on the dayside, is defined by balancing a hydrostatic equilibirum approximation for the internal plasma pressure with an external flow pressure approximation. These pressure approximations produce a cylindrical obstacle in the distant tail. A refined obstacle shape that attempts to balance this same internal pressure wuth the calculated external flow pressure tapers inward toward the tail axis downstream of the terminator. Cold fluid (photoionized planetary oxygen) is added to the flow about the tapered model obstacle. The resultant bulk plasma flow and magnetic field properties compare well with experimentally observed average proton velocity and magnetic field components in the magnetotail. The added oxygen plasma has significant number densities only within 1 Rv of the tail axis in the distant tail. The model predicts central magnetotail oxygen plasma number densities of about 0.2 cm-3 and temperatures on the order of 106 degree K, flowing tailward at speeds as low as 200 m/s. These properties are consistent with the flat, featureless Pioneer Venus Orbiter plasma analyzer spectra observed in the deep central tail. Pickup ions, in the test particle limit, match direct observations of tail pickup ions. These steady state model results suggest that the mass addition at Venus originating above the dayside ionopause is predominantly fluidlike and produces the slowed flows and severe field draping observed in the central distant tail

  4. Venus y el fin del mundo

    OpenAIRE

    Gonzalo Munévar

    2006-01-01

    Este artículo busca demostrar que los argumentos generales acerca de la exploración científica valen también para las ciencias espaciales. El trabajo se basa en el ejemplo de la exploración de Venus y lo que esta nos dice acerca de nuestro propio planeta. Argumenta que el concepto de la probabilidad de Leslie es incorrecto, como también lo son las dudas sobre la evidencia Venusiana. Así mismo, concluye que no se puede rechazar la importancia que tienen los descubrimientos inesperados que han ...

  5. VENUS meets SEMAT : How do they compare?

    OpenAIRE

    Geihs, Kurt; Evers, Christoph; Niemczyk, Stefan

    2014-01-01

    SEMAT (Software Engineering Methods And Theory) is an initiative to define a generic foundation for software engineering as a rigorous discipline. The so-called SEMAT kernel provides a thinking framework for software engineers that is not constrained to certain methods and processes but aims to encompass all kinds of proven principles and best practices. Our own interdisciplinary VENUS development method is designed to achieve similar generality and compatibility objectives, although the chos...

  6. 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...

  7. 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 ...

  8. Venus: the twin that went wrong

    International Nuclear Information System (INIS)

    Results obtained from recent Russian and American missions to the planet Venus are reviewed including observations made of noble gas abundances, the lack of water vapour in the planet's atmospheres, the extent and composition of the cloud layers, the structure of the planet's surface, its gravitational field and its climate. The impact of these observations on theories of the evolution of the Solar System, are considered. (U.K.)

  9. Atmospheric Chemistry of Venus-like Exoplanets

    OpenAIRE

    Schaefer, Laura; Fegley Jr, Bruce

    2010-01-01

    We use thermodynamic calculations to model atmospheric chemistry on terrestrial exoplanets that are hot enough for chemical equilibira between the atmosphere and lithosphere, as on Venus. The results of our calculations place constraints on abundances of spectroscopically observable gases, the surface temperature and pressure, and the mineralogy of the surface. These results will be useful in planning future observations of the atmospheres of terrestrial-sized exoplanets by ...

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

    Science.gov (United States)

    Paszota, Paulina; Escalante-Perez, Maria; Thomsen, Line R; Risør, Michael W; Dembski, Alicja; Sanglas, Laura; Nielsen, Tania A; Karring, Henrik; Thøgersen, Ida B; Hedrich, Rainer; Enghild, Jan J; Kreuzer, Ines; Sanggaard, Kristian W

    2014-02-01

    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. PMID:24275507

  11. Comparing Volcanic Terrains on Venus and Earth: How Prevalent are Pyroclastic Deposits on Venus?

    Science.gov (United States)

    Carter, Lynn M.; Campbell, B. A.; Glaze, L. S.

    2012-01-01

    In the last several years, astronomers have discovered several exoplanets with masses less than 10 times that of the Earth [1]. Despite the likely abundance of Earth-sized planets, little is known about the pathways through which these planets evolve to become habitable or uninhabitable. Venus and Earth have similar planetary radii and solar orbital distance, and therefore offer a chance to study in detail the divergent evolution of two objects that now have radically different climates. Understanding the extent, duration, and types of volcanism present on Venus is an important step towards understanding how volatiles released from the interior of Venus have influenced the development of the atmosphere. Placing constraints on the extent of explosive volcanism on Venus can provide boundary conditions for timing, volumes, and altitudes for atmospheric injection of volatiles. In addition, atmospheric properties such as near-surface temperature and density affect how interior heat and volatiles are released. Radar image data for Venus can be used to determine the physical properties of volcanic deposits, and in particular, they can be used to search for evidence of pyroclastic deposits that may result from explosive outgassing of volatiles. For explosive volcanism to occur with the current high atmospheric pressure, magma volatile contents must be higher than is typical on Earth (at least 2-4% by weight) [2,3]. In, addition, pyroclastic flows should be more prevalent on Venus than convective plumes and material may not travel as far from the vent source as it would on Earth [3]. Areas of high radar backscatter with wispy margins that occur near concentric fractures on Sapho Patera [4] and several coronae in Eastern Eistla Regio [5] have been attributed to collapse of eruption columns and runout of rough materials.

  12. Pioneer Venus orbiter magnetic field and plasma observations in the Venus magnetotail

    International Nuclear Information System (INIS)

    This study uses Pioneer Venus orbiter (PVO) magnetometer and plasma analyzer measurements to investigate the draped-field tail of Venus with an emphasis on determining the magnetic field and plasma conditions within the various tail regions and their dependence upon interplanetary magnetic field (IMF) orientation. For this purpose PVO orbits during which the spacecrafts high inclination trajectory took it through the central magnetotail were identified. Analysis of the observations taken during those orbits indicates that the distribution of plasma within the magnetotail is highly asymmetric and controlled by the orientation of the IMF. In the plasma sheet and adjacent lobe regions downstream of the Venus hemisphere over which the solar wind motional electric field, is directed away from the planet, PVO observed increasing fluxes of H+ and O+ as the spacecraft moves away from the tail axis toward the outer boundary of the tail. No O+ ions were observed outside of the magnetotail based upon the magnetic field data and the definitions adopted in this study. Downstream of the Venus hemisphere over which the solar wind motional electric field is directed in toward the planet, PVO does not usually observe significant fluxes of E/Q = 0-8 kV ions, except sometimes directly adjacent to the outer boundary of the tail. These results are interpreted as being due to the more efficient pick-up of newly ionized atmospheric neutrals over the Venus hemisphere where the initial gyromotion takes the newly created ions away from the dense, lower atmosphere where they might be lost due to scattering (Cloutier et al., 1974). The implications of these findings for the formation and maintenance of the Venus magnetotail are discussed

  13. Venus - Mosaic of Bahet and Onatah Coronae

    Science.gov (United States)

    1991-01-01

    This mosaic of Magellan data in the Fortuna region of Venus, centered at 49 degrees north latitude, 2 degrees longitude, shows two coronae. Coronae are large circular or oval structures first identified in Soviet radar images of Venus. The structure on the left, Bahet Corona, is about 230 kilometers (138 miles) long and 150 kilometers (90 miles) across. A portion of Onatah Corona, over 350 kilometers (210 miles) in diameter, can be seen on the right of the mosaic. Both features are surrounded by a ring of ridges and troughs, which in places cut more radially-oriented fractures. The centers of the features also contain radial fractures as well as volcanic domes and flows. Coronae are thought to form due to the upwelling of hot material from deep in the interior of Venus. The two coronae may have formed at the same time over a single upwelling, or may indicate movement of the upwelling or the upper layers of the planet to the west over time. A 'pancake' dome, similar to low-relief domes see in the southern hemisphere, is located just to the southwest of Bahet. Resolution of the Magellan data is about 120 meters (400 feet).

  14. 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 ...

  15. Signs of hypothetical fauna of Venus

    Directory of Open Access Journals (Sweden)

    Ksanfomality Leonid V.

    2014-04-01

    Full Text Available On March 1 and 5, 1982, experiments in television photography instrumented by the landers VENERA-13 and -14, yielded 37 panoramas (or their fragments of the Venus surface at the landing site. Over the past 31 years, no similar missions have been sent to Venus. Using a modern technique the VENERA panoramas were re-examined. A new analysis of Venusian surface panoramas’ details has been made. A few relatively large objects of hypothetical fauna of Venus were found with size ranging from a decimeter to half meter and with unusual morphology. Treated once again VENERA-14 panoramic images revealed ‘amisada’ object about 15 cm in size possessing apparent terramorphic features. The amisada’s body stands out with its lizard-like shape against the stone plates close by. The amisada can be included into the list of the most significant findings of the hypothetical Venusian fauna. The amisada’s body show slow movements, which is another evidence of the Venusian fauna’s very slow style of activity, which appears to be associated with its energy constraints or, and that is more likely, with the properties of its internal medium. The terramorphic features of the Venusian fauna, if they are confirmed, may point out at outstandingly important and yet undiscovered general laws of the animated nature on different planets.

  16. 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

  17. 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)

  18. Pioneer magnetometer observations of the Venus bow shock

    International Nuclear Information System (INIS)

    Magnetometer results are reported from the Pioneer Venus spacecraft which indicate that the Venus bow shock is not as strong as the terrestrial bow shock. Possible reasons for this difference are discussed and it is concluded that there is something basically different about the solar wind interactions with the two planets. (U.K.)

  19. 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

  20. 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.

  1. 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.

  2. 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.)

  3. Preliminary study of Venus cloud layers with polarimetric data from SPICAV/VEx

    Science.gov (United States)

    Rossi, Loïc; Marcq, Emmanuel; Montmessin, Franck; Fedorova, Anna; Stam, Daphne; Bertaux, Jean-Loup; Korablev, Oleg

    2015-08-01

    We present unique polarization data from the SPICAV-IR spectrometer onboard ESA's Venus Express (VEx) spacecraft and a first retrieval of cloud parameters. The polarization data have been collected from 2006 to 2010, and cover mostly the northern hemisphere, in the 0.65 to 1.7 ?m spectral range. They contain information about latitudinal and longitudinal variations in the properties of Venus clouds and hazes, and about temporal variations in these properties. The degree of polarization measured on a few test orbits is in agreement with previous observations from the ground and from Pioneer Venus. Using numerical modeling to interpret the nadir observations, we retrieve mean values of reff ~ 1 ?m and ?eff ~ 0.07 for, respectively, the effective radius and variance of the cloud particle size distribution and a refractive index nr = 1.42 ± 0.02 at ? = 1.101 ?m. We also derive an upper limit ?h = 0.17 at ? = 1.101 ?m for the haze optical thickness at high latitudes. All these values are in good agreement with previous determinations.

  4. Assignment and rotational analysis of new absorption bands of carbon dioxide isotopologues in Venus spectra

    Science.gov (United States)

    Robert, S.; Borkov, Yu. G.; Vander Auwera, J.; Drummond, R.; Mahieux, A.; Wilquet, V.; Vandaele, A. C.; Perevalov, V. I.; Tashkun, S. A.; Bertaux, J. L.

    2013-01-01

    We present absorption bands of carbon dioxide isotopologues, detected by the Solar Occultation for the Infrared Range (SOIR) instrument on board the Venus Express Satellite. The SOIR instrument combines an echelle spectrometer and an Acousto-Optical Tunable Filter (AOTF) for order selection. It performs solar occultation measurements in the Venus atmosphere in the IR region (2.2-4.3 ?m), at a resolution of 0.12-0.18 cm-1. The wavelength range probed by SOIR allows a detailed chemical inventory of the Venus atmosphere above the cloud layer (65-150 km) to be made with emphasis on the vertical distributions of gases. Thanks to the SOIR spectral resolution, a new CO2 absorption band was identified: the 21101-01101 band of 16O12C18O with R branch up to J=31. Two other previously reported bands were observed dispelling any doubts about their identifications: the 20001-00001 band of 16O13C18O [Villanueva G, et al. J Quant Spectrosc Radiat Transfer 2008;109:883-894] and the 01111-00001 band of 16O12C18O [Villanueva G, et al. J Quant Spectrosc Radiat Transfer 2008;109:883-894 and Wilquet V, et al. J Quant Spectrosc Radiat Transfer 2008;109:895-905]. These bands were analyzed, and spectroscopic constants characterizing them were obtained. The rotational assignment of the 20001-00001 band was corrected. The present measurements are compared with data available in the HITRAN database.

  5. 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.

  6. 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.

  7. Mineral reaction buffering of Venus' atmosphere: A thermochemical constraint and implications for Venus-like planets

    Science.gov (United States)

    Treiman, Allan H.; Bullock, Mark A.

    2012-02-01

    The equilibrium suggested as a buffer for CO 2 in the Venus atmosphere, CaCO 3 + SiO 2 = CaSiO 3 + CO 2, cannot act as a buffer at the Venus surface/troposphere - the pressure-temperature slope of the equilibrium and that of the atmosphere (dry adiabat with significant greenhouse heating) do not provide buffering capacity (if indeed CaCO 3 were present). Instead, perturbations to T or P(CO 2) can produce catastrophic expansion or collapse of the atmosphere. This instability can be generalized to all devolatilization reactions that produce a radiatively active gas in a planetary atmosphere dominated by such gases, and gives a simple thermochemical criterion for whether a reaction could buffer such an atmosphere. Simple decarbonation reactions fail this criterion, suggesting that the abundance of CO 2 in a CO 2-dominated atmosphere cannot be buffered by chemical reactions with the surface; a similar conclusion holds for the abundance of H 2O in an H 2O-dominated (steam) atmosphere. Buffering of minor gases is more likely; a mineral buffer equilibrium for SO 2 proposed for Venus, FeS 2 + CO 2 = Fe 3O 4 + SO 2 + CO, passes the thermochemical criterion, as does a reaction involving Ca sulfate. These inferences can be generalized to atmospheres in 'moist' adiabatic equilibria, and to extrasolar Venus-like planets, and will help in interpreting the compositions of their atmospheres.

  8. Coordinated Sounding Rocket, HST, and SPICAV Observations of Venus in Nov. 2013

    Science.gov (United States)

    Clarke, J. T.; Bertaux, J.; Carveth, C. J.; Chaufray, J.; Gladstone, R.; Darling, N.

    2013-12-01

    A coordinated set of observations of Venus in Nov. 2013 will address the escape of water from the upper atmosphere as related to measurements of the ratio of deuterium to hydrogen at various altitude levels. The observations will be performed by the Venus Spectral Rocket (VeSpR) sounding rocket experiment, the HST Space Telescope Imaging Spectrograph (STIS), and the SPICAV/SOIR instruments on Venus Express. The VeSpR experiment is a high spectral resolution system designed specifically to resolve the D and H Ly alpha emissions from planetary atmospheres. The present version of this payload will measure the D/H ratio at the level above CO2 photo-absorption, or above roughly 110 km altitude. Similar observations are now permitted using the HST/STIS in echelle mode, where previously HST observations of Venus were not allowed. The SOIR instrument has previously measured the ratio of HDO/H2O in the middle atmosphere between 70-110 km, and found a variation with altitude in the D/H ratio. New observations will be made for comparison with the other instruments. The goal is to understand the path that both D and H atoms take as water is photodissociated, and the atoms move to the top of the atmosphere where they can escape into space. The detailed physical processes must be understood to know how to relate the measured tow order of magnitude enhancement in the Venusian D/H ratio to the historic escape of a volume of water from the early atmosphere. We expect to present the initial scientific results from these combined observations.

  9. A statistical study of the low-altitude ionospheric magnetic fields over the north pole of Venus

    Science.gov (United States)

    Zhang, T. L.; Baumjohann, W.; Russell, C. T.; Villarreal, M. N.; Luhmann, J. G.; Teh, W. L.

    2015-08-01

    Examination of Venus Express (VEX) low-altitude ionospheric magnetic field measurements during solar minimum has revealed the presence of strong magnetic fields at low altitudes over the north pole of Venus. A total of 77 events with strong magnetic fields as VEX crossed the northern polar region were identified between July 2008 and October 2009. These events all have strong horizontal fields, slowly varying with position. Using the superposed epoch method, we find that the averaged peak field is about 45 nT, which is well above the average ambient ionospheric field of 20 nT, with a full width at half maximum duration of 32 s, equivalent to a width of about 300 km. Considering the field orientation preference and spacecraft trajectory geometry, we conclude that these strong fields are found over the northern hemisphere with an occurrence frequency of more than 33% during solar minimum. They do not show a preference for any particular interplanetary magnetic field (IMF) orientation. However, they are found over the geographic pole more often when the interplanetary field is in the Venus orbital plane than when it is perpendicular to the orbital plane of Venus. The structures were found most frequently in the -E hemisphere, determined from the IMF orientation. The enhanced magnetic field is mainly quasi perpendicular to solar wind flow direction, and it is suggested that these structures form in the low-altitude collisional ionosphere where the diffusion and convection times are long.

  10. 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.

  11. Space weather effects on the bow shock, the magnetic barrier, and the ion composition boundary at Venus

    Science.gov (United States)

    Vech, D.; Szego, K.; Opitz, A.; Kajdic, P.; Fraenz, M.; Kallio, E.; Alho, M.

    2015-06-01

    We present a statistical study on the interaction between interplanetary coronal mass ejections (ICMEs) and the induced magnetosphere of Venus when the peak magnetic field of the magnetic barrier was anomalously large (>65 nT). Based on the entire available Venus Express data set from April 2006 to October 2014, we selected 42 events and analyzed the solar wind parameters, the position of the bow shock, the size and plasma properties of the magnetic barrier, and the position of the ion composition boundary (ICB). It was found that the investigated ICMEs can be characterized with interplanetary shocks and unusually large tangential magnetic fields with respect to the Venus-Sun line. In most of the cases the position of the bow shock was not affected by the ICME. In a few cases the interaction between magnetic clouds and the induced magnetosphere of Venus was observed. During these events the small magnetosonic Mach numbers inside magnetic clouds caused the bow shock to appear at anomalously large distances from the planet. The positions of the upper and lower boundaries of the magnetic barrier were not affected by the ICMEs. The position of the ICB on the nightside was found closer to the planet during ICME passages which is attributed to the increased solar wind dynamic pressure.

  12. Study of aerosol properties in the upper haze of Venus from SPICAV IR data

    Science.gov (United States)

    Luginin, Mikhail; Fedorova, Anna; Belyaev, Denis; Montmessin, Franck; Wilquet, Valérie; Korablev, Oleg; Bertaux, Jean-Loup; Vandaele, Ann-Carine

    2015-04-01

    Upper haze of Venus lies above cloud layer and extends from 70 to 90 km. According to previous missions results the upper haze consists of submicron particles that are considered to be droplets of concentrated sulfuric acid (75%) [Kawabata et al., 1980; Lane and Opstbaum, 1983; Sato et al., 1996]. Recently, from the observations of Venus Express spacecraft a bimodal particle distribution was discovered as well as presence of detached haze layers at 80-90 km. This may be due to abundance of different kinds of particles [Montmessin et al., 2008; Wilquet et al., 2009]. Moreover, study of aerosol particles at altitudes above 90 km could be the key to solution of the sulfur oxides problem recently discovered in this altitude range [Belyaev et al., 2012]. SPICAV IR spectrometer is a part of SPICAV/SOIR experiment on board the Venus Express orbiter [Korablev et al., 2012]. It measures a vertical structure of Venus atmosphere using solar occultation method at altitudes 70-100 km in spectral range of 0.65 1.7 µm. The spectrometer is sensitive to abundance of submicron (mode 1) and micron (mode 2) particles in the Venus' upper haze. Using sulfuric acid refractive indices, Mie scattering theory, and spectral dependence of aerosol extinction, one can derive vertical distribution of particles size and number density assuming bimodal as well as unimodal cases. In this paper we present vertical profiles of extinction, number density and size distribution from more than 200 occultations obtained between May 2006 and September 2014. Aerosol scale height is found to be equal to ~4 km in the upper haze. At the equator, upper haze top lies at higher altitudes than near the North Pole. A detached haze layers were observed in ~50% of all observations in latitude range from 60°N to 90°N where the best spatial resolution is achieved. According to our statistics bimodal distribution is typical for altitudes from 75 to 85 km, while unimodal distribution dominates at altitudes 70-75 km and above 85 km. For bimodal size distribution effective radii of particles and ratio of density are fitted and effective variances are held fixed, effective radii vary between 0.05-0.4 µm (mode 1) and 0.4-1.1 µm (mode 2). For unimodal size distribution effective radius is fitted and effective variance is held fixed, effective radius varies between 0.2-0.8 µm. Diurnal variations have been analysed. This work is supported by the grant 11.G34.31.0074 from Russian government to MIPT and the Program 22 of the RAS Presidium.

  13. Spectroscopy of the Venus night glow by the Venera 9 and Venera 10 interplanetary automatic stations

    International Nuclear Information System (INIS)

    The Venus night airglow is investigated. The spectrum has been studied by diffraction monochromators with the operating range of 3000-8000 A on the Venus-9 and Venus-10 space probes. The monochromator is described in detail. The spectrum of the Venus night airglow, the altitude profile and day variations of the glow have been obtained. The authors believe the night glow of the Venus atmosphere to be caused by the O+O+CO2?O2+CO2* process

  14. Hydrogen Coronae around Mars and Venus

    Science.gov (United States)

    Gröller, H.; Lichtenegger, H.; Lammer, H.; Shematovich, V. I.

    2015-10-01

    We present Monte-Carlo simulatios of the hydrogen corona around Mars and Venus for various possible photochemical sources of hot (energetic) hydrogen atoms. The aim of this study is to investigate those possible sources which may significantly contribute to the hydrogen corona and to compare the obtained densities with observations. The model includes the initial energy distribution of hot atoms, elastic, inelastic, and quenching collisions between the suprathermal atoms and the ambient cooler neutral atmosphere, and uses energy dependent total and differential cross sections for the determination of the collision probability and the scattering angles.

  15. 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)

  16. Chemical composition of Earth, Venus, and Mercury

    OpenAIRE

    MORGAN, JOHN W; Anders, Edward

    1980-01-01

    Model compositions of Earth, Venus, and Mercury are calculated from the premise that planets and chondrites underwent four identical fractionation processes in the solar nebula. Because elements of similar properties stay together in these processes, five constraints suffice to define the composition of a planet: mass of the core, abundance of U, and the ratios K/U, Tl/U, and FeO/(FeO + MgO). Complete abundance tables, and normative mineralogies, are given for all three planets. Review of ava...

  17. Venus orogenic belt environments: Architecture and origin

    International Nuclear Information System (INIS)

    Orogenic belt environments (Danu, Akna, Freyja, and Maxwell Montes) in Western Ishtar Terra, Venus, display a range of architectural elements, including (from the center of Western Ishtar outward) an inboard plateau (Lakshmi Planum), the linear orogenic belts themselves, outboard plateaus, steep scarps bounding Ishtar, adjacent linear foredeeps and outboard rises, and outboard low-lying volcanic plains. The main elements of the architecture are interpreted to be due to the convergence, underthrusting, and possible subduction of lowland plains at the margins of a preexisting tessera plateau of thicker crust

  18. Recent results from VENUS at TRISTAN

    International Nuclear Information System (INIS)

    TRISTAN, the highest energy e+e- collider, has been in operation since Nov. 1986 and has gradually had its energy and luminosity increased. The VENUS detector was operational for TRISTAN's first beams and has since collected an integrated luminosity of 16 pb-1. Using this data sample, we report on measurements of fundamental processes such as e+e- ? ??, e+e-, ?+?-, hadrons and searches for excited electrons and charged sequential heavy leptons. Tests of QED and the electroweak standard model are presented together with the results from TOPAZ and AMY. (orig.)

  19. Transit of Venus Culture: A Celestial Phenomenon Intrigues the Public

    Science.gov (United States)

    Bueter, Chuck

    2012-01-01

    When Jeremiah Horrocks first observed it in 1639, the transit of Venus was a desirable telescopic target because of its scientific value. By the next transit of Venus in 1761, though, the enlightened public also embraced it as a popular celestial phenomenon. Its stature elevated over the centuries, the transit of Venus has been featured in music, poetry, stamps, plays, books, and art. The June 2004 transit emerged as a surprising global sensation, as suggested by the search queries it generated. Google's Zeitgeist deemed Venus Transit to be the #1 Most Popular Event in the world for that month. New priorities, technologies, and media have brought new audiences to the rare alignment. As the 2012 transit of Venus approaches, the trend continues with publicly accessible capabilities that did not exist only eight years prior. For example, sites from which historic observations have been made are plotted and readily available on Google Earth. A transit of Venus phone app in development will, if fully funded, facilitate a global effort to recreate historic expeditions by allowing smartphone users to submit their observed transit timings to a database for quantifying the Astronomical Unit. While maintaining relevance in modern scientific applications, the transit of Venus has emerged as a cultural attraction that briefly intrigues the mainstream public and inspires their active participation in the spectacle.

  20. Distant ionospheric photoelectron energy peak observations at Venus

    Science.gov (United States)

    Coates, A. J.; Wellbrock, A.; Frahm, R. A.; Winningham, J. D.; Fedorov, A.; Barabash, S.; Lundin, R.

    2015-08-01

    The dayside of the Venus ionosphere at the top of the planet's thick atmosphere is sustained by photoionization. The consequent photoelectrons may be identified by specific peaks in the energy spectrum at 20-30 eV which are mainly due to atomic oxygen photoionization. The ASPERA-4 electron spectrometer has an energy resolution designed to identify the photoelectron production features. Photoelectrons are seen not only in their production region, the sunlit ionosphere, but also at more distant locations on the nightside of the Venus environment. Here, we present a summary of the work to date on observations of photoelectrons at Venus, and their comparison with similar processes at Titan and Mars. We expand further by presenting new examples of the distant photoelectrons measured at Venus in the dark tail and further away from Venus than seen before. The photoelectron and simultaneous ion data are then used to determine the ion escape rate from Venus for one of these intervals. We compare the observed escape rates with other rates measured at Venus, and at other planets, moons and comets. We find that the escape rates are grouped by object type when plotted against body radius.

  1. Cloud tracked winds at the lower cloud level using Venus' night side observations at 2.28 ?m with TNG/NICS

    Science.gov (United States)

    Machado, P.; Luz, D.; Oliveira, J.; Peralta, J.

    2015-10-01

    We present results based on observations carried out with the Near Infrared Camera and Spectrograph(NICS) of the Telescopio Nazionale Galileo (TNG), in La Palma, on July 2012. We observed for periods of 2.5 hours starting just before dawn, for three consecutive nights. We acquired a set of images of the night side of Venus with the continuum K filter at 2.28 microns, which allows to monitor motions at the lower cloud level of the atmosphere of Venus, close to 48 km altitude. Our objective has been to measure the horizontal wind field in order to characterize the latitudinal zonal wind profile, to study variability, to help constrain the effect of large scale planetary waves in the maintenance of superrotation, and to map the cloud distribution. These observations were part of the network of ground-based observations of Venus coordinated with ESA's Venus Express orbiter for the 2012 Venus transit campaign. Ground-based observa- tions are complementary to orbiter measurements, allowing simultaneous determination of the winds. We will present first results of cloud tracked winds from ground-based TNG observations and winds retrieved from coordinated space-based VEx/VIRTIS observations.

  2. Line parameters for the 01111-00001 band of {sup 12}C{sup 16}O{sup 18}O from SOIR measurements of the Venus atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Wilquet, V. [Belgian Institute for Space Aeronomy, 3 av. Circulaire, B-1180 Brussels (Belgium)], E-mail: valerie.wilquet@aeronomie.be; Mahieux, A.; Vandaele, A.C. [Belgian Institute for Space Aeronomy, 3 av. Circulaire, B-1180 Brussels (Belgium); Perevalov, V.I.; Tashkun, S.A. [Institute of Atmospheric Optics, Akademitcheskii av., 1, 634055 Tomsk (Russian Federation); Fedorova, A.; Korablev, O. [Space Research Institute (IKI), 84/32 Profsoyuznaya, 117810 Moscow (Russian Federation); Montmessin, F.; Dahoo, R.; Bertaux, J.-L. [Service d' Aeronomie du CNRS, BP3, 91371, Verrieres-le-Buisson (France); Universite Pierre et Marie Curie, Paris (France); Institut Pierre Simon Laplace, Universite de Versailles-Saint-Quentin, 78 Saint Quentin en Yvelines (France)

    2008-04-15

    CO{sub 2} is the major constituent of the atmosphere of Venus. Absorption lines due to its {sup 12}C{sup 16}O{sup 18}O isotopologue have been observed for the first time in Venus spectra in the 2930-3015 cm{sup -1} spectral region, where the HITRAN database does not contain any line from this isotopologue. The measurements were performed by the SOIR instrument, which is part of the SPICAV/SOIR instrument on board the Venus Express mission of ESA. SOIR measured the atmospheric transmission of the upper atmosphere of Venus (z>70 km) by performing a solar occultation experiment using the atmosphere as a gigantic absorption cell. The identification of this newly observed band was first made recently from Mars atmosphere observations by US colleagues. We have made independent theoretical calculations of the positions of the lines of this new 01111-00001 absorption band, which coincide perfectly with the positions of the observed lines. Assuming an oxygen isotopic ratio similar to the one measured previously in the lower atmosphere of Venus, the line strengths of each observed line are deduced and listed.

  3. Evaluation of Long Duration Flight on Venus

    Science.gov (United States)

    Landis, Geoffrey A.; Colozza, Anthony J.

    2006-01-01

    An analysis was performed to evaluate the potential of utilizing either an airship or aircraft as a flight platform for long duration flight within the atmosphere of Venus. In order to achieve long-duration flight, the power system for the vehicle had to be capable of operating for extended periods of time. To accomplish these, two types of power systems were considered, a solar energy-based power system utilizing a photovoltaic array as the main power source and a radioisotope heat source power system utilizing a Stirling engine as the heat conversion device. Both types of vehicles and power systems were analyzed to determine their flight altitude range. This analysis was performed for a station-keeping mission where the vehicle had to maintain a flight over a location on the ground. This requires the vehicle to be capable of flying faster than the wind speed at a particular altitude. An analysis was also performed to evaluate the altitude range and maximum duration for a vehicle that was not required to maintain station over a specified location. The results of the analysis show that each type of flight vehicle and power system was capable of flight within certain portions of Venus s atmosphere. The aircraft, both solar and radioisotope power proved to be the most versatile and provided the greatest range of coverage both for station-keeping and non-station-keeping missions.

  4. 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.

  5. Rapid lithification masks the Venus sedimentary cycle

    Science.gov (United States)

    Ghail, R.

    2015-10-01

    Venera lander data are usually assumed to indicate basaltic lavas but a significant fraction of the rock material must be volatiles, such as sulphur, implying at least strongly weathered basalts. The lander images most closely resemble sedimentary material, with layered strata (which may be pyroclastic in origin)that are sometimes broken into cobbles and fine grained sediment. The Magellan SAR was relatively insensitive to loose fine-grained material under Venus surface conditions but the reprocessed data reveal a range of weathering processes, particularly at higher elevations, and mass wasting of steep slopes. Mean wind speeds are strongly altitude dependent and are able to erode and transport material throughout the highland regions. In some areas, this material is deposited on adjacent plains where, under the extreme Venus surface conditions, lithification is an apparently rapid process. Thus the largely featureless plains may not be igneous at all but sedimentary in origin. The settling out and lithification of sedimentary material is consistent with observed crater degradation, in which low-lying crater floors are infilled first.

  6. Thermal evolution of Venus with argon degassing

    Science.gov (United States)

    O'Rourke, Joseph G.; Korenaga, Jun

    2015-11-01

    Decades-old measurements of atmospheric and elemental surface composition constrain the history of Venus. In this study, we search for a model featuring continuous evolution in the stagnant-lid regime that predicts the present-day atmospheric mass of radiogenic argon and satisfies the other available constraints. For comparison, we also consider the end-member scenario of a single catastrophic resurfacing event. Thermal evolution simulations are performed that track the mass transport of argon and potassium and include a simple model of upwelling mantle plumes. Sensitivity analyses and linear regression are used to quantify the range of initial conditions that will produce desired values for key model output parameters. Decompression melting of passively upwelling mantle causes considerable mantle processing and crustal growth during the early evolution of Venus. Mantle plumes have negligible effects on recent crustal production, but may be important to local surface features. For a wide range of initial conditions, continuous evolution in the stagnant-lid regime predicts the correct amount of argon degassing, along with the absence of a global magnetic field, crustal and lithosphere thicknesses matching modern estimates, and volcanism consistent with the cratering record. Argon degassing does not uniquely constrain mantle dynamics, but the success of simple stagnant-lid models diminishes the need to invoke dramatic changes like catastrophic resurfacing.

  7. The GUINEVERE project at the VENUS facility

    International Nuclear Information System (INIS)

    The GUINEVERE project is an international project in the framework of IP-EUROTRANS, the FP6 program which aims at addressing the main issues for ADS development in the framework of partitioning and transmutation for nuclear waste volume and radiotoxicity reduction. The GUINEVERE project is carried out in the context of domain 2 of IP-EUROTRANS, ECATS, devoted to specific experiments for the coupling of an accelerator, a target and a subcritical core. These experiments should provide an answer to the questions of online reactivity monitoring, sub-criticality determination and operational procedures (loading, start-up, shutdown,...) in an ADS by 2009-2010. The project has the objective to couple a fast lead core, within the VENUS building operated by the SCK.CEN, with a neutron generator able to work in three different modes: pulsed, continuous and continuous with beam interruptions at the millisecond scale. In order to achieve this goal, the VENUS facility has to be adapted and a modified GENEPI-3C accelerator has to be designed and constructed. The paper describes the main modifications to the reactor core and facility and to the accelerator, which will be executed during the years 2008 and 2009, and the experimental programme which will start in 2009. (authors)

  8. The GUINEVERE project at the VENUS facility

    Energy Technology Data Exchange (ETDEWEB)

    Baeten, P.; Ait Abderrahim, H.; Bergmans, G.; Heyse, J.; Maes, D.; Verboomen, B.; Vermeersch, F.; Vittiglio, G. [SCK.CEN, Boeretang 200, 2400 Mol (Belgium); Aoust, T.; Baylac, M.; Billebaud, A.; Bondoux, D.; Bouvier, J.; De Conto, J.M.; Grondin, D.; Marchand, D.; Micoud, R.; Planet, M. [LPSC-CNRS-IN2P3/UJF/INPG, 53 Avenue des Martyrs. 38026 Grenoble cedex (France); Ban, G.; Gautier, J.M.; Lecolley, F.R.; Lecouey, J.L.; Marie, N.; Merrer, Y.; Steckmeyer, J.C. [LPC Caen, ENSICAEN/Universite de Caen/ CNRS-IN2P3, Caen (France); Dessagne, P.; Gaudiot, G.; Heitz, G.; Kerveno, M.; Ruescas, C. [IPHC-DRS/ULP/CNRS-IN2P3, Strasbourg (France); Laune, B.; Reynet, D. [IPNO, CNRS-IN2P3/UPS, Orsay (France); Granget, G.; Mellier, F.; Rimpault, G. [CEA-Cadarache, 13108 Saint Paul lez Durance (France)

    2008-07-01

    The GUINEVERE project is an international project in the framework of IP-EUROTRANS, the FP6 program which aims at addressing the main issues for ADS development in the framework of partitioning and transmutation for nuclear waste volume and radiotoxicity reduction. The GUINEVERE project is carried out in the context of domain 2 of IP-EUROTRANS, ECATS, devoted to specific experiments for the coupling of an accelerator, a target and a subcritical core. These experiments should provide an answer to the questions of online reactivity monitoring, sub-criticality determination and operational procedures (loading, start-up, shutdown,...) in an ADS by 2009-2010. The project has the objective to couple a fast lead core, within the VENUS building operated by the SCK.CEN, with a neutron generator able to work in three different modes: pulsed, continuous and continuous with beam interruptions at the millisecond scale. In order to achieve this goal, the VENUS facility has to be adapted and a modified GENEPI-3C accelerator has to be designed and constructed. The paper describes the main modifications to the reactor core and facility and to the accelerator, which will be executed during the years 2008 and 2009, and the experimental programme which will start in 2009. (authors)

  9. Pioneer Venus and near-earth observations of interplanetary shocks

    International Nuclear Information System (INIS)

    Twenty-three transient interplanetary shocks observed near earth during 1978-1982, and mostly reported in the literature, have also been identified at the Pioneer Venus Orbiter spacecraft. There seems to be a fairly consistent trend for lower shock speeds, farther from the sun. Shock normals obtained using the Pioneer Venus data correspond well with published values from near earth. By referring to the portion of the Pioneer Venus plasma data used here from locations at longitudes within 37 degree of earth, it is found that shocks are weaker at earth, compared with closer to the sun

  10. Venus thermospheric response to short-term solar variations

    Science.gov (United States)

    Keating, G. M.; Bougher, S. W.

    1992-01-01

    The mechanism responsible for cooling the dayside thermosphere of Venus from about 700 K to 300 K (Noll and McElroy, 1972) is examined by analyzing in situ measurements made by the Pioneer Venus Orbiter of the weak response of the thermosphere to short-term solar variations related to 27-day solar rotation. It is shown that, in order to cool the Venus dayside thermosphere to observed levels and to simultaneously explain the weak 27-day variations in the atmosphere, it is necessary to invoke strong CO2 cooling which is controlled principally by collisions of CO2 with atomic oxygen.

  11. 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

  12. Venus - Concentrations of radar-reflective minerals by wind

    International Nuclear Information System (INIS)

    The effectiveness of wind in concentrating minerals with high radar reflectiveness on the surface of Venus is investigated experimentally in the Venus Wind Tunnel (Greeley et al., 1984) under CO2 densities typical of Venusian conditions. Density sorting of sand particles during the formation of microdunes is demonstrated, and calculations show that wind-blown deposits of dense conductive material such as ilmenite need to be only a few cm thick to account for the local enhancements of radar reflectivity observed by Pioneer Venus at wavelength 17 cm. 28 refs

  13. Radiative-transfer models of the night side of Venus

    International Nuclear Information System (INIS)

    The difference-equation algorithm for multiple scattering presently used, which is comparable to the matrix-operator method in accuracy and efficiency, is used to calculate the radiative transfer characteristics of a realistic model of the atmosphere and cloud layers of Venus. In order to obtain a fit between computation results and ground-based observations of the night side of Venus, special parameters accounting for the CO2 far-wing opacity and unidentified strong absorption bands must be introduced. For a region of average brightness, the fit thus obtained implies a depletion of water by a factor of 4 with respect to Pioneer Venus results. 41 refs

  14. Discovery of frequent lightning discharges in clouds on Venus

    International Nuclear Information System (INIS)

    Results are reported of the GROZA experiment, which was carried on board the Venera 11 and 12 spacecrafts in order to search for lightening in the Venus atmosphere. It was found that intensive and frequent discharges of lightning (up to 50s-1 in one active region) occur in the Venus cloud layer and that the origin of some gaseous components of the atmosphere can be associated with this lightning. The high lightning activity on Venus can explain the nightside glowing observed from the Earth. (UK)

  15. Asteroid 2012 XE133: a transient companion to Venus

    OpenAIRE

    Marcos, C. de la Fuente; Marcos, R. 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 (two): (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 analyse 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 ...

  16. 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)

  17. The atmospheres of Mars and Venus - a comparison

    International Nuclear Information System (INIS)

    In this short review the main areas of current interest for CO2 aeronomy are outlined i.e., the aeronomy of the atmospheres of Mars and Venus. The discussion is an attempt to distill the pertinent information from the many recent reviews containing information on CO2 atmospheres. In addition a summary of the most recent results (at the date of this meeting) is included which have been stimulated by the recent fly-by of Mariner 10 past Venus. On Venus the discussion is limited to the region above the cloud tops. (Auth.)

  18. Chemistry in the Venus clouds: Sulfuric acid reactions and freezing behavior of aqueous liquid droplets

    Science.gov (United States)

    Delitsky, M. L.; Baines, K. H.

    2015-11-01

    Venus has a thick cloud deck at 40-70 km altitude consisting of liquid droplets and solid particles surrounded by atmospheric gases. The liquid droplets are highly concentrated aqueous solutions of sulfuric acid ranging in concentration from 70-99 wt%. Weight percent drops off with altitude (Imamura and Hashimoto 2001). There will be uptake of atmospheric gases into the droplet solutions and the ratios of gas-phase to liquid-phase species will depend on the Henry’s Law constant for those solutions. Reactions of sulfuric acid with these gases will form products with differing solubilities. For example, uptake of HCl by H2SO4/H2O droplets yields chlorosulfonic acid, ClSO3H (Robinson et al 1998) in solution. This may eventually decompose to thionyl- or sulfuryl chlorides, which have UV absorbances. HF will also uptake, creating fluorosulfonic acid, FSO3H, which has a greater solubility than the chloro- acid. As uptake continues, there will be many dissolved species in the cloudwaters. Baines and Delitsky (2013) showed that uptake will have a maximum at ~62 km and this is very close to the reported altitude for the mystery UV absorber in the Venus atmosphere. In addition, at very strong concentrations in lower altitude clouds, sulfuric acid will form hydrates such as H2SO4.H2O and H2SO4.4H2O which will have very different freezing behavior than sulfuric acid, with much higher freezing temperatures (Carslaw et al, 1997). Using temperature data from Venus Express from Tellmann et al (2009), and changes in H2SO4 concentrations as a function of altitude (James et al 1997), we calculate that freezing out of sulfuric acid hydrates can be significant down to as low as 56 km altitude. As a result, balloons, aircraft or other probes in the Venus atmosphere may be limited to flying below certain altitudes. Any craft flying at altitudes above ~55 km may suffer icing on the wings, propellers, balloons and instruments which could cause possible detrimental effects (thermal changes, reduced buoyancy, effects on control surfaces, plugging of sample inlets, etc.). Therefore, de-icing equipment should be considered when designing aircraft expected to fly at high altitudes in the Venus clouds.

  19. Explosive volcanic activity on Venus: The roles of volatile contribution, degassing, and external environment

    Science.gov (United States)

    Airey, M. W.; Mather, T. A.; Pyle, D. M.; Glaze, L. S.; Ghail, R. C.; Wilson, C. F.

    2015-08-01

    We investigate the conditions that will promote explosive volcanic activity on Venus. Conduit processes were simulated using a steady-state, isothermal, homogeneous flow model in tandem with a degassing model. The response of exit pressure, exit velocity, and degree of volatile exsolution was explored over a range of volatile concentrations (H2O and CO2), magma temperatures, vent altitudes, and conduit geometries relevant to the Venusian environment. We find that the addition of CO2 to an H2O-driven eruption increases the final pressure, velocity, and volume fraction gas. Increasing vent elevation leads to a greater degree of magma fragmentation, due to the decrease in the final pressure at the vent, resulting in a greater likelihood of explosive activity. Increasing the magmatic temperature generates higher final pressures, greater velocities, and lower final volume fraction gas values with a correspondingly lower chance of explosive volcanism. Cross-sectionally smaller, and/or deeper, conduits were more conducive to explosive activity. Model runs show that for an explosive eruption to occur at Scathach Fluctus, at Venus' mean planetary radius (MPR), 4.5% H2O or 3% H2O with 3% CO2 (from a 25 m radius conduit) would be required to initiate fragmentation; at Ma'at Mons (~9 km above MPR) only ~2% H2O is required. A buoyant plume model was used to investigate plume behaviour. It was found that it was not possible to achieve a buoyant column from a 25 m radius conduit at Scathach Fluctus, but a buoyant column reaching up to ~20 km above the vent could be generated at Ma'at Mons with an H2O concentration of 4.7% (at 1300 K) or a mixed volatile concentration of 3% H2O with 3% CO2 (at 1200 K). We also estimate the flux of volcanic gases to the lower atmosphere of Venus, should explosive volcanism occur. Model results suggest explosive activity at Scathach Fluctus would result in an H2O flux of ~107 kg s-1. Were Scathach Fluctus emplaced in a single event, our model suggests that it may have been emplaced in a period of ~15 days, supplying 1-2×104 Mt H2O to the atmosphere locally. An eruption of this scale might increase local atmospheric H2O abundance by several ppm over an area large enough to be detectable by near-infrared nightside sounding using the 1.18 ?m spectral window such as that carried out by the Venus Express/VIRTIS spectrometer. Further interrogation of the VIRTIS dataset is recommended to search for ongoing volcanism on Venus.

  20. 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

  1. Prediction of neutron embrittlement in the reactor pressure vessel. Venus-1 and Venus-3 benchmarks

    International Nuclear Information System (INIS)

    The OECD/NEA Task Force on Computing Radiation Dose and Modelling of Radiation-Induced Degradation of Reactor Components (TFRDD) launched two international blind intercomparison exercises to examine the current computation techniques used in NEA Member countries for calculating neutron and gamma doses to reactor components. Various methodologies and different nuclear data were applied to predict dose rates in the Belgian VENUS-1 and three-dimensional VENUS-3 configurations for comparison with measured data. This report provides the detailed results from the two benchmarks.The exercise revealed that three-dimensional neutron fluence calculations provide results that are significantly more accurate than those obtained from two-dimensional calculations. Performing three-dimensional calculations is technically feasible given the power of today's computers. (author)

  2. 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

  3. 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.

  4. The 2004 Venus Transit: AN European Educational Project

    Science.gov (United States)

    Arlot, Jean-Eudes; Rocher, Patrick; Thuillot, William

    On June 8 2004 the planet Venus will pass in front of the disk of the Sun. This rare event (no one alive today has never seen such a transit) reminds us the story of the measurement of the Solar System and will be emphasized next year. We would like to take benefit of this event to organize a worldwide network of schools high schools and scientific centers to make the timing of the event of June 8. More we would like to help pupils students and general public to understand a scientific procedure needing an international collaboration and to be aware of the powerful tool that is a transit (detection of extra solar planets ...). Our plans are to organize a centralized computation of the Astronomical Unit through Internet thanks to individual timings of the event to provide notes and educational material to participantsto encourage the interest to science and to promote a safe observation of the Sun. Contacts: http://www.eso.org/outreach/eduoff/vt-2004/ http://www.imcce.fr/vt2004

  5. Nanoscale organization of {beta}{sub 2}-adrenergic receptor-Venus fusion protein domains on the surface of mammalian cells

    Energy Technology Data Exchange (ETDEWEB)

    Vobornik, Dusan; Rouleau, Yanouchka; Haley, Jennifer [Steacie Institute for Molecular Sciences, National Research Council Canada, Ottawa, ON, Canada K1A 0R6 (Canada); Bani-Yaghoub, Mahmud [Institute for Biological Sciences, National Research Council Canada, Ottawa, ON, Canada K1A 0R6 (Canada); Taylor, Rod [Steacie Institute for Molecular Sciences, National Research Council Canada, Ottawa, ON, Canada K1A 0R6 (Canada); Johnston, Linda J., E-mail: Linda.Johnston@nrc-cnrc.gc.ca [Steacie Institute for Molecular Sciences, National Research Council Canada, Ottawa, ON, Canada K1A 0R6 (Canada); Pezacki, John Paul, E-mail: John.Pezacki@nrc-cnrc.gc.ca [Steacie Institute for Molecular Sciences, National Research Council Canada, Ottawa, ON, Canada K1A 0R6 (Canada)

    2009-04-24

    Adrenergic receptors are a key component of nanoscale multiprotein complexes that are responsible for controlling the beat rate in a mammalian heart. We demonstrate the ability of near-field scanning optical microscopy (NSOM) to visualize {beta}{sub 2}-adrenergic receptors ({beta}{sub 2}AR) fused to the GFP analogue Venus at the nanoscale on HEK293 cells. The expression of the {beta}{sub 2}AR-Venus fusion protein was tightly controlled using a tetracycline-induced promoter. Both the size and density of the observed nanoscale domains are dependent on the level of induction and thus the level of protein expression. At concentrations between 100 and 700 ng/ml of inducer doxycycline, the size of domains containing the {beta}{sub 2}AR-Venus fusion protein appears to remain roughly constant, but the number of domains per cell increase. At 700 ng/ml doxycycline the functional receptors are organized into domains with an average diameter of 150 nm with a density similar to that observed for the native protein on primary murine cells. By contrast, larger micron-sized domains of {beta}{sub 2}AR are observed in the membrane of the HEK293 cells that stably overexpress {beta}{sub 2}AR-GFP and {beta}{sub 2}AR-eYFP. We conclude that precise chemical control of gene expression is highly advantageous for the use {beta}{sub 2}AR-Venus fusion proteins as models for {beta}{sub 2}AR function. These observations are critical for designing future cell models and assays based on {beta}{sub 2}AR, since the receptor biology is consistent with a relatively low density of nanoscale receptor domains.

  6. Nanoscale organization of ?2-adrenergic receptor-Venus fusion protein domains on the surface of mammalian cells

    International Nuclear Information System (INIS)

    Adrenergic receptors are a key component of nanoscale multiprotein complexes that are responsible for controlling the beat rate in a mammalian heart. We demonstrate the ability of near-field scanning optical microscopy (NSOM) to visualize ?2-adrenergic receptors (?2AR) fused to the GFP analogue Venus at the nanoscale on HEK293 cells. The expression of the ?2AR-Venus fusion protein was tightly controlled using a tetracycline-induced promoter. Both the size and density of the observed nanoscale domains are dependent on the level of induction and thus the level of protein expression. At concentrations between 100 and 700 ng/ml of inducer doxycycline, the size of domains containing the ?2AR-Venus fusion protein appears to remain roughly constant, but the number of domains per cell increase. At 700 ng/ml doxycycline the functional receptors are organized into domains with an average diameter of 150 nm with a density similar to that observed for the native protein on primary murine cells. By contrast, larger micron-sized domains of ?2AR are observed in the membrane of the HEK293 cells that stably overexpress ?2AR-GFP and ?2AR-eYFP. We conclude that precise chemical control of gene expression is highly advantageous for the use ?2AR-Venus fusion proteins as models for ?2AR function. These observations are critical for designing future cell models and assays based on ?2AR, since the receptor biology is consistent with a relatively low density of nanoscale receptor domains.

  7. Energetics of the ionosphere of Venus: A preliminary model based on Pioneer Venus observations

    International Nuclear Information System (INIS)

    A model of the energy balance of the dayside ionosphere of Venus is presented. The coupled energy equations for electrons and ions are solved numerically and the calculated temperatures are compared with temperatures measured by instrumentation on the Pioneer Venus Orbiter. Neutral and ion density profiles consistent with those measured by various Pioneer Venus experiments are used in the model. It was found that using standard EUV sources and thermal conductivities the calculations produce temperatures that are much lower than the measured ones. Consequently, further calculations were performed in which 1) the thermal conductivities were inhibited by means of an almost horizontal magnetic field and/or 2) heat inflow into both the electron and ion gas at the top of the ionosphere was assumed due to the solar wind interaction. It was found that the calculated and measured temperatures were in reasonably good agreement if the thermal conductivities were inhibited by a near horizontal field of about 10 gammas and if the electron and ion heat fluxes were taken to be 4 x 109 eV cm-2s-1 and 4 x 107 eV cm-2s-1, respectively

  8. 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.

  9. 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.

  10. VENUS-F: A fast lead critical core for benchmarking

    International Nuclear Information System (INIS)

    The zero-power thermal neutron water-moderated facility VENUS at SCK-CEN has been extensively used for benchmarking in the past. In accordance with GEN-IV design tasks (fast reactor systems and accelerator driven systems), the VENUS facility was modified in 2007-2010 into the fast neutron facility VENUS-F with solid core components. This paper introduces the projects GUINEVERE and FREYA, which are being conducted at the VENUS-F facility, and it presents the measurement results obtained at the first critical core. Throughout the projects other fast lead benchmarks also will be investigated. The measurement results of the different configurations can all be used as fast neutron benchmarks. (authors)

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

    Data.gov (United States)

    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...

  12. Geologic Map of the Meskhent Tessera Quadrangle (V-3), Venus

    Science.gov (United States)

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

    2008-01-01

    The Magellan spacecraft orbited Venus from August 10, 1990, until it plunged into the Venusian atmosphere on October 12, 1994. Magellan Mission objectives included (1) improving the knowledge of the geological processes, surface properties, and geologic history of Venus by analysis of surface radar characteristics, topography, and morphology and (2) improving the knowledge of the geophysics of Venus by analysis of Venusian gravity. The Meskhent Tessera quadrangle is in the northern hemisphere of Venus and extends from lat 50 degrees to 75 degrees N. and from long 60 degrees to 120 degrees E. In regional context, the Meskhent Tessera quadrangle is surrounded by extensive tessera regions to the west (Fortuna and Laima Tesserae) and to the south (Tellus Tessera) and by a large basinlike lowland (Atalanta Planitia) on the east. The northern third of the quadrangle covers the easternmost portion of the large topographic province of Ishtar Terra (northwestern map area) and the more localized upland of Tethus Regio (northeastern map area).

  13. A New Approach to Inferences for Pancake Domes on Venus

    Science.gov (United States)

    Glaze, Lori S.; Baloga, Steve M.; Stofan, Ellen R.

    2008-01-01

    Figure 1 shows a radar image and topography for flat-topped, steep-sided "pancake" domes on Venus. At least 145 such domes have been identified on Venus [I] and are thought to be volcanic in origin [2]. Based on analysis of the dome surfaces, [3] suggested that only the late stage surface fractures are preserved, indicating entrainment and annealing of fractures during emplacement, consistent with a basaltic composition. Figure 1 shows a radar image and topography for flat-topped, steep-sided "pancake" domes on Venus. At least 145 such domes have been identified on Venus [I] and are thought to be volcanic in origin [2]. Based on analysis of the dome surfaces, [3] suggested that only the late stage surface fractures are preserved, indicating entrainment and annealing of fractures during emplacement, consistent with a basaltic composition.

  14. 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)

  15. The planet Venus - A new periodic spectrum variable.

    Science.gov (United States)

    Young, L. G.; Young, A. T.; Young, J. W.; Bergstralh, J. T.

    1973-01-01

    The apparent strength of CO2 absorptions in the spectrum of Venus varies by 20% in a period of 4 days. The variations are synchronous over the disk, and thus represent a fundamental dynamical mode of the atmosphere.

  16. Earth-type planets (Mercury, Venus, and Mars)

    Science.gov (United States)

    Marov, M. Y.; Davydov, V. D.

    1975-01-01

    Spacecraft- and Earth-based studies on the physical nature of the planets Mercury, Venus, and Mars are reported. Charts and graphs are presented on planetary surface properties, rotational parameters, atmospheric compositions, and astronomical characteristics.

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

    Data.gov (United States)

    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....

  18. Water vapor and the cloud top variations in the Venus' mesosphere from the SPICAV observations

    Science.gov (United States)

    Fedorova, Anna; Marcq, Emmanuel; Montmessin, Franck; Korablev, Oleg; Luginin, Mikhail; Bertaux, Jean-Loup

    SPICAV VIS-IR is an AOTF (acousto-optical tunable filter) spectrometer working in the spectral range of 0.65-1.7 µm onboard the Venus Express mission. It provides measurements of the H2O abundance above Venus’ clouds based on the 1.38-µm band and the cloud top altitude based on the CO2 bands in the range of 1.4-1.6 ?m. The new calibrations of the instrument in 2010-2012 allowed updating of results reported earlier. The cloud top altitude has been routinely retrieved for all dataset from 2006 to 2014 taking into account multiple-scattering in the cloudy atmosphere. The ?=1 level at 1.48 ?m varies from 69 to 73 km at lower latitudes and from 64 to 68 km at high latitudes near the Poles. The long-term and year-to-year variations were studied. The H2O mixing ratio from the 1.38 ?m band varies from 4 to 12 ppm. The variations are higher than H2O mixing ratio variations at altitudes of 68-70 km observed by VIRTIS-H/Venus Express [Cottini et al., 2012] from 2.56 ?m. The 1.38 ?m H2O band is sensitivity to altitudes of 55-70 km and a vertical gradient of water within the upper clouds can be responsible for the water behavior. The spot pointing observations for wide variations of viewing angle in the near-IR spectral range are useful to determine the vertical gradient of water within the clouds. Long-term variations of water vapor in upper clouds were not found for period from 2007 to 2014 at all range of latitudes.

  19. Remote sensing of water vapour in Venus' middle atmospere

    OpenAIRE

    Koukouli, Mary Elizabeth.; Irwin, Patrick; Taylor, F.W.; Fred Taylor; Patrick Irwin

    2002-01-01

    ?The Pioneer Venus Orbiter Infrared Radiometer and Venera 15 Fourier Transform Spectrometer observations of thermal emission from Venus' middle atmosphere between 10°S and 50°N were used to determine global maps of temperature, cloud optical depth and water vapour abundance. The spectral regions observed include the strong 15 ?tm carbon dioxide band and the 45 ?m fundamental rotational water band. The main aim of this thesis is to reconcile the water vapour abundance results ...

  20. 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

  1. 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...

  2. 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...

  3. 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.

  4. 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...

  5. 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 ...

  6. Possible dynamical evolution of the rotation of Venus since formation

    International Nuclear Information System (INIS)

    The past evolution of the rotation of Venus has been studied by a numerical integration method using the hypothesis that only solar tidal torques and core-mantle couplings have been active since formation. It is found quite conceivable that Venus had originally a rotation similar to the other planets and has evolved in 4.5x109 years from a rapid and direct rotation (12-hour spin period and nearly zero obliquity) to the present slow retrograde one. (Auth.)

  7. 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)

  8. Its a Wind, Its a Wave, Its Two Phenomena in One: Jerry Schubert, Superrotation, and the UV Markings on Venus

    Science.gov (United States)

    DelGenio, Anthony

    1999-01-01

    In the early 1970's, ground-based astronomers had already discovered that Ultraviolet (UV) cloud markings on Venus reappeared every 4 days. When radar evidence later revealed a 243-day rotation period for the solid planet, planetary scientists were faced with a quandary: Could the Venus atmosphere really move 60 times as fast as the planet below, or were the apparent movements of the UV features just an illusion caused by propagating waves? The former explanation seemed unlikely - a planet that hardly rotates should generate only a very sluggish circulation. The historical impact of Jerry Schubert's moving flame theory was twofold: It was the forerunner of current thermal tide explanations of the cloud-level superrotation, but it was also the first plausible mechanism for explaining a seemingly inconsistent set of observations. In 1974, Mariner 10 acquired UV images of the Venus clouds at unprecedented levels of detail. Although few have noted it, this began the shift of planetary atmospheric research primarily from the domain of astronomy to that of meteorology. Jerry was among the first scientists to apply terrestrial meteorology to the analysis of planetary data. At that time a young UCLA graduate student with plans to do research on mantle convection, but having flunked the solid earth geophysics section of his departmental comprehensive exam, was gently invited by Jerry to switch to atmospheric science. Jerry suggested that the Venus UV features could be revealing both superrotating winds and planetary-scale waves at the same time, and that we could distinguish the two by looking at motions on different spatial scales. This was my first science research lesson - the complexity of real geophysical systems. Over the next couple of years I was inculcated with Jerry's philosophy of a comprehensive, rigorous approach to research, which manifested itself as a scouring of the literature and the UCLA meteorology faculty to learn about every possible type of planetary-scale wave. The resulting identification of large-scale UV features on Venus as the product of Kelvin and Rossby-type wave motions was validated by extensive Pioneer Venus observations a decade later and remains one of the best examples of the use of terrestrial knowledge to understand other planets.

  9. Geologic map of the Mead quadrangle (V-21), Venus

    Science.gov (United States)

    Campbell, Bruce A.; Clark, David A.

    2006-01-01

    The Magellan spacecraft orbited Venus from August 10, 1990, until it plunged into the Venusian atmosphere on October 12, 1994. Magellan Mission objectives included (1) improving the knowledge of the geological processes, surface properties, and geologic history of Venus by analysis of surface radar characteristics, topography, and morphology and (2) improving the knowledge of the geophysics of Venus by analysis of Venusian gravity. The Mead quadrangle (V-21) of Venus is bounded by lat 0 deg and 25 deg N., long 30 deg and 60 deg E. This quadrangle is one of 62 covering Venus at 1:5,000,000 scale. Named for the largest crater on Venus, the quadrangle is dominated by effusive volcanic deposits associated with five major coronae in eastern Eistla Regio (Didilia, Pavlova, Calakomana, Isong, and Ninmah), corona-like tectonic features, and Disani Corona. The southern extremity of Bell Regio, marked by lava flows from Nyx Mons, north of the map area, forms the north-central part of the quadrangle. The shield volcanoes Kali, Dzalarhons, and Ptesanwi Montes lie south and southwest of the large corona-related flow field. Lava flows from sources east of Mead crater flood low-lying areas along the east edge of the quadrangle.

  10. Dynamic model of Venus's gravity field

    Energy Technology Data Exchange (ETDEWEB)

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

    1984-08-01

    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.

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. Probing Venus's cloud structure with Galileo NIMS

    Science.gov (United States)

    Grinspoon, D. H.; Pollack, J. B.; Sitton, B. R.; Carlson, R. W.; Kamp, L. W.; Baines, K. H.; Encrenaz, TH.; Taylor, F. W.

    1993-01-01

    The spectral image cubes obtained by the Near-Infrared Mapping Spectrometer (NIMS) on Galileo as it flew by Venus have been analyzed to constrain the vertical structure of the clouds, the nature of the aerosol particles, and the location and particle properties of the opacity variations responsible for high-contrast features observed in the near-infrared windows at 1.7 and 2.3 micrometers. A radiative transfer program was used to simulate mid-latitude curves of limb darkening at 3.7 micrometers. Best-fit models to these curves demonstrate that the upper clouds are dominated by mode 2 particles (r-bar = 1.0 micrometers), with a contribution of approximately 15% of opacity from mode 1 particles (r-bar = 0.3 micrometers). The low-latitude upper cloud is well represented by a dual scale-height model, with a particle scale height of approximately 1 km from an altitude of 61-63 km, and a scale height of approximately 6 km above this, up to the level where tau = 1 at approximately 71 km. This model also successfully simulates limb-darkening curves at 11.5 micrometers from the Pioneer Venus Orbiter Infrared Radiometer. Successful simulations of correlation plots of 1.7 vs 2.3 micrometers intensities reveal that mode 3 particles (r-bar = 3.65 micrometers) represent the dominant source of opacity in the lower and middle clouds, and that variation in total cloud opacity reflects chiefly the addition and removal of mode 3 particles near the cloud base. We find that the full spectrum of brightnesses at 1.7 and 2.3 micrometers implies that the total cloud optical depth varies from approximately 25 to approximately 40.

  16. The radiative forcing variability caused by the changes of the upper cloud vertical structure in the Venus mesosphere

    Science.gov (United States)

    Lee, Y. J.; Titov, D. V.; Ignatiev, N. I.; Tellmann, S.; Pätzold, M.; Piccioni, G.

    2015-08-01

    The upper cloud layer of Venus is a key factor affecting radiative energy balance of the mesosphere. Observations of the temperature and the cloud top structure by Venus Express revealed their strong variability with latitude. We used the 1-D radiative transfer model to study the dependence of the radiative forcing on the cloud top structure. The cloud top altitude effectively controls outgoing thermal fluxes. Sharp cloud top boundary can produce a pronounced peak of both solar heating and thermal cooling that suggests a radiative origin of temperature inversions in the cold collar. Strong diurnal variation of net forcing at low latitudes can be responsible for the origin of convective cells observed in UV images. Latitudinal contrasts in the radiative forcing in the mesosphere can drive meridional Hadley-type circulation with meridional winds of few m/s and vertical motions with speed of few cm/s.

  17. Studying the Venus terminator thermal structure observed by SOIR/VEx with a 1D radiative transfer model

    Science.gov (United States)

    Mahieux, A.; Erwin, J. T.; Chamberlain, S.; Robert, S.; Thomas, I.; Vandaele, A. C.; Trompet, L.; Wilquet, V.; Yelle, R. V.

    2015-10-01

    The SOIR instrument on board Venus Express routinely measures the CO2 number density profiles in the mesosphere and thermosphere region at the Venus terminator using the solar occultation technique. Assuming the hydrostatic equilibrium, we derive temperature profiles, which show a permanent cold layer at 125 km, surrounded by two warmer layers at 100 km and 140 km. We developed a 1D conductive radiative transfer model to study the mean SOIR thermal profile, considering the main species, and carefully modelling the radiative terms. In order to correctly reproduce the thermal profile, aerosols cooling and heating terms are added. We describe how aerosols number density profiles can be calculated to have a good match of the thermal profiles.

  18. Cloning, purification, crystallization and preliminary X-ray analysis of a bacterial GABA receptor with a Venus flytrap fold

    International Nuclear Information System (INIS)

    A 1.35 Å resolution data set was collected from a crystal of the periplasmic GABA receptor Atu2422 from A. tumefaciens. Atu2422 adopts a closed Venus flytrap conformation. In response to infection by the pathogen Agrobacterium tumefaciens, plants synthesize several stress amino acids, including ?-aminobutyric acid (GABA), which modulates the expression of bacterial virulence factors. GABA penetrates into the bacterial cytoplasm via an ABC transporter that is associated with the periplasmic receptor Atu2422. Mature receptor Atu2422 (without its signal peptide) was overexpressed in Escherichia coli, purified and crystallized. A complete data set was collected to 1.35 Å resolution at 100 K. The crystals belonged to the monoclinic space group C2 and contained one molecule in the asymmetric unit. Molecular replacement was performed and the initial electron-density maps revealed a closed form of this Venus flytrap (VFT) receptor, suggesting the presence of an endogenous E. coli ligand

  19. Stylistique, science de l’expression, linguistique de la parole. Notes sur la nature du fait linguistique selon Charles Bally

    Directory of Open Access Journals (Sweden)

    Anamaria Curea

    2013-12-01

    Full Text Available La spécificité de la discipline scientifique conçue par Charles Bally sous le nom de stylistique réside en une pensée singulière de la complexité du fait linguistique. À l’origine de son projet se croisent l’adhésion à une science générale de l’expression et la volonté de faire avancer la linguistique saussurienne dans une nouvelle direction. À travers les concepts d’expression et de langue parlée, Charles Bally invite la perspective linguistique à s’ouvrir aux dimensions psychologique et sociologique du langage afin d’appréhender les rapports complexes entre la pensée et la langue dans l’activité de parler.

  20. 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.

  1. Mechanics without Muscles: Fast Motion of the Venus flytrap and Bio-inspired Robotics

    Science.gov (United States)

    Chen, Zi; Guo, Qiaohang; Zheng, Huang; Li, Wei; Ding, Yiting; Su, Guiping; Lin, Junjie; Liu, Yuxin; Chen, Wenzhe; Taber, Larry

    2013-03-01

    The rapid motion of plants has intrigued scientists for centuries. Plants have neither nerves nor muscles, yet the Venus flytrap can move in a fraction of a second to capture insects. Darwin did a first systematic study on the trap closure mechanism, and called this plant ``one of the most wonderful in the world''. Several physical mechanisms have since been proposed, such as the rapid loss of turgor pressure, an irreversible acid-induced wall loosening mechanism, and tsnap-through instability, but no unanimous agreement is reached. We propose a coupled mechanical bistable mechanism that explains the rapid closure of the Venus flytrap, consistent with experimental observations. Such bistable behaviors are theoretically modeled and validated with experiments. Biomimetic flytrap robots are also fabricated according to the learnt principles. It is thus promising to design smart bio-mimetic materials and devices with snapping mechanisms as sensors, actuators, artificial muscles and biomedical devices. Zi Chen and Qiaohang Guo contributed equally. We thank National Science Foundation of China (No. 11102040), American Academy of Mechanics Founder's Award and Society in Science-Branco Weiss fellowship.

  2. 76 FR 20802 - Culturally Significant Object Imported for Exhibition Determinations: “The Capitoline Venus

    Science.gov (United States)

    2011-04-13

    ...Imported for Exhibition Determinations: ``The Capitoline Venus'' SUMMARY: Notice is hereby given of the following determinations...the object to be included in the exhibition ``The Capitoline Venus,'' imported from abroad for temporary exhibition within...

  3. Relief and geology of the north polar region of the planet Venus

    Science.gov (United States)

    Kuzmin, R. O.; Burba, G. A.; Shashkina, V. P.; Bogomolov, A. F.; Zherikhin, N. V.; Skrypnik, G. I.; Kudrin, L. V.; Bergman, M. Y.; Rzhiga, O. N.; Sidorenko, A. I.

    1986-01-01

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

  4. Topography of Venus and earth - A test for the presence of plate tectonics

    Science.gov (United States)

    Head, J. W.; Yuter, S. E.; Solomon, S. C.

    1981-01-01

    Comparisons of earth and Venus topography by use of Pioneer/Venus radar altimetry are examined. Approximately 93% of the Venus surface has been mapped with a horizontal resolution of 200 km and a vertical resolution of 200 m. Tectonic troughs have been indicated in plains regions which cover 65% of Venus, and hypsometric comparisons between the two planets' elevation distributions revealed that while the earth has a bimodal height distribution, Venus displays a unimodal configuration, with 60% of the planet surface within 500 m of the modal planet radius. The effects of mapping the earth at the same resolution as the Venus observations were explored. Continents and oceans were apparent, and although folded mountains appeared as high spots, no indications of tectonic activity were discernible. A NASA Venus Orbiting Imaging radar is outlined, which is designed to detect volcanoes, folded mountain ranges, craters, and faults, and thereby allow definition of possible plate-tectonic activity on Venus.

  5. Status report of the 28 GHz superconducting electron cyclotron resonance ion source VENUS (invited)

    International Nuclear Information System (INIS)

    The superconducting versatile electron cyclotron resonance (ECR) ion source for nuclear science (VENUS) 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 rare isotope accelerator (RIA) front end, where the goal is to produce intense beams of medium-charge-state ions. Example beams for the RIA accelerator are 15 p ?A of Kr17+(260 e ?A), 12 p ?A of Xe20+ (240 e ?A of Xe20+), and 8 p ?A of U28+(230 e ?A). To achieve these high currents, VENUS has been optimized for operation at 28 GHz, reaching maximal confinement fields of 4 and 3 T axially and over 2.2 T on the plasma chamber wall radially. After a commissioning phase at 18 GHz, the source started the 28 GHz operation in the summer of 2004. During that ongoing 28 GHz commissioning process, record ion-beam intensities have been extracted. For instance, measured extracted currents for the low to medium charge states were 270 e ?A of Xe27+ and 245 e ?A of Bi29+, while for the higher charge states 15 e ?A of Xe34+, 15 e ?A of Bi41+, and 0.5 e ?A of Bi50+ could be produced. Results from the ongoing 28 GHz commissioning as well as results using double-frequency heating with 18 and 28 GHz for oxygen and xenon are presented. The effect of the minimum B field on the ion source performance has been systematically measured for 18 and 28 GHz. In both cases the performance peaked at a minimum B field of about 80% of the resonance field. In addition, a strong dependence of the x-ray flux and energy on the minimum B field value was found

  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. European Venus Explorer: An in-situ mission to Venus using a balloon platform

    OpenAIRE

    Chassefiere, E.; O. Korablev; Imamura, T.; Baines, KH; Wilson, CF; Titov, DV; Aplin, KL; Balint, T.; Blamont, JE; Cochrane, CG; Ferencz, C; Ferri, F (Fernando); Gerasimov, M; Leitner, JJ; Lopez-Moreno, J

    2009-01-01

    Planetary balloons have a long history already. A small super-pressure balloon was flown in the atmosphere of Venus in the eighties by the Russian-French VEGA mission. For this mission, CNES developed and fully tested a 9 m diameter super-pressure balloon, but finally replaced it by a smaller one due to mass constraints (when it was decided to send Vega to Halley's Comet). Furthermore, several kinds of balloons have been proposed for planetary exploration [Blamont, J., in: Maran, S.P. (Ed.), ...

  8. European Venus Explorer (EVE): an in-situ mission to Venus

    OpenAIRE

    Chassefiere, E.; O. Korablev; Imamura, T.; Baines, KH; Wilson, CF; Titov, DV; Aplin, KL; Balint, T.; Blamont, JE; Cochrane, CG; Ferencz, C; Ferri, F (Fernando); Gerasimov, M; Leitner, JJ; Lopez-Moreno, J

    2009-01-01

    The European Venus Explorer (EVE) mission was proposed to the European Space Agency in 2007, as an M-class mission under the Cosmic Vision Programme. Although it has not been chosen in the 2007 selection round for programmatic reasons, the EVE mission may serve as a useful reference point for future missions, so it is described here. It consists of one balloon platform floating at an altitude of 50-60 km, one descent probe provided by Russia, and an orbiter with a polar orbit which will relay...

  9. Calculation of neutron flux spectrum and average neutron energy for Venus No.1 assembly

    International Nuclear Information System (INIS)

    Venus No.1 assembly is a system consisting of both fast and thermal neutron zones for ADS research in China. The neutronics spectrum calculations in Venus No.1 assembly were performed with two-dimensional transport code TWODANT. The result shows that the neutron spectra in Venus No.1 assembly are hard enough for the ADS experiments. (authors)

  10. 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.

  11. Pinhole Effects on Venus Superpressure Balloon Lifetime

    Science.gov (United States)

    Hall, Jeffery L.; Yavrouian, Andre H.

    2013-01-01

    Experimental results are presented for a series of experiments that addressed the effect of small pinhole defects on the potential lifetime of a Venus superpressure balloon. The experiments were performed on samples of a candidate balloon envelope material through which a single small hole of 80 to 300 microns in diameter was deliberately made in each one by puncturing with a metal pin. The material was mounted horizontally in a test apparatus and then a 2-3 mm thick layer of sulfuric acid was placed on top to mimic balloon wetting at Venus. Acid penetration and damage manifested itself as a darkening of the aluminum metal and adhesive layers around the hole in the balloon material. There were no test conditions under which the acid simply fell through the pinhole due to gravity because the surface tension forces always compensated at this size. Very little acid-damaged material was observed for the smallest 80 micron pinholes while gas flowed through the hole due to balloon-like pressurization: the black spot size was approximately 0.2 mm in diameter after 6 days with 86% sulfuric acid. The damage area grew more quickly in the absence of gas flowing out of an 80 micron hole, namely at a rate of 2 mm/day. It was concluded that the flow of escaping gas out of the hole provides a substantial reduction of the rate of acid penetration and damage. Larger diameter pinholes of approximately 300 micron diameter showed larger growth rates of 0.7 mm/day with gas flow and 1.7 mm/day without. The pinhole size did not change over the duration of these experiments because the material has an outer layer of fluoropolymer film that remained intact during the process and thereby held the hole size constant. None of the damage rates measured in these experiments pose a threat to the lifetime of the balloon over the projected course of a 30 day mission because the affected area is too small to cause a structural failure either through direct damage or increased solar heating and attendant balloon pressurization leading to burst.

  12. Sulfur dioxide - Episodic injection shows evidence for active Venus volcanism

    Science.gov (United States)

    Esposito, L. W.

    1984-01-01

    Pioneer Venus ultraviolet spectra from the first 5 years of operation show a decline (by more than a factor of 10) in sulfur dioxide abundance at the cloud tops and in the amount of submicron haze above the clouds. At the time of the Pioneer Venus encounter, the values for both parameters greatly exceeded earlier upper limits. However, Venus had a similar appearance in the late 1950's, implying the episodic injection of sulfur dioxide possibly caused by episodic volcanism. The amount of haze in the Venus middle atmosphere is about ten times that found in earth's stratosphere after the most recent major volcanic eruptions, and the thermal energy required for this injection on Venus is greater by about an order of magnitude than the largest of these recent earth eruptions and about as large as the Krakatoa eruption of 1883. The episodic behavior of sulfur dioxide implies that steady-state models of the chemistry and dynamics of cloud-top regions may be of limited use.

  13. Benchmark calculations for VENUS-2 MOX -fueled reactor dosimetry

    International Nuclear Information System (INIS)

    As a part of a Nuclear Energy Agency (NEA) Project, it was pursued the benchmark for dosimetry calculation of the VENUS-2 MOX-fueled reactor. In this benchmark, the goal is to test the current state-of-the-art computational methods of calculating neutron flux to reactor components against the measured data of the VENUS-2 MOX-fuelled critical experiments. The measured data to be used for this benchmark are the equivalent fission fluxes which are the reaction rates divided by the U235 fission spectrum averaged cross-section of the corresponding dosimeter. The present benchmark is, therefore, defined to calculate reaction rates and corresponding equivalent fission fluxes measured on the core-mid plane at specific positions outside the core of the VENUS-2 MOX-fuelled reactor. This is a follow-up exercise to the previously completed UO2-fuelled VENUS-1 two-dimensional and VENUS-3 three-dimensional exercises. The use of MOX fuel in LWRs presents different neutron characteristics and this is the main interest of the current benchmark compared to the previous ones

  14. Venus: The First Habitable World of Our Solar System?

    Science.gov (United States)

    Way, Michael Joseph; Del Genio, Anthony; Kiang, Nancy; Sohl, Linda; Clune, Tom; Aleinov, Igor; Kelley, Maxwell

    2015-01-01

    A great deal of effort in the search for life off-Earth in the past 20+ years has focused on Mars via a plethora of space and ground based missions. While there is good evidence that surface liquid water existed on Mars in substantial quantities, it is not clear how long such water existed. Most studies point to this water existing billions of years ago. However,those familiar with the Faint Young Sun hypothesis for Earth will quickly realize that this problem is even more pronounced for Mars. In this context recent simulations have been completed with the GISS 3-D GCM (1) of paleo Venus (approx. 3 billion years ago) when the sun was approx. 25 less luminous than today. A combination of a less luminous Sun and a slow rotation rate reveal that Venus could have had conditions on its surface amenable to surface liquid water. Previous work has also provided bounds on how much water Venus could have had using measured DH ratios. It is possible that less assumptions have to be made to make Venus an early habitable world than have to be made for Mars, even thoughVenus is a much tougher world on which to confirm this hypothesis.

  15. Observations of Venus Atmosphere by Ultraviolet Imager (UVI) on Akatsuki

    Science.gov (United States)

    Watanabe, Shigeto; Yamazaki, Atsushi; Yamada, Manabu

    2012-07-01

    The ultraviolet imager (UVI) on Akatsuki measures the scattered ultraviolet (UV) lights of the solar radiation at the Venus cloud top with 283nm and 365nm wavelengths. There are absorption bands of SO2 and unknown absorber in these wavelength regions. The UV images result into measurements of the SO2 and the unknown absorber distributions, and the sequential images lead to understand the velocity vector of the wind at the cloud top altitude. The UVI is equipped with fast off-axial catadioptric optics, two bandpass filters and a diffuser installed in a filter wheel moving with a stepping motor, and a high-sensitive CCD devise with a UV coating. The UVI will nominally take a UV image of the Venus cloud top level every two hours from the altitude of ~300km at periapsis and 13RV at apoapsis, when the spatial resolution is ~60m and 16km on the cloud top level, respectively. The images have a signal-to-noise ratio of over 100 after a smear correction of onboard data processing. During flyby and cruising to Venus, the UVI has measured the scattered UV lights of the solar radiation at the Venus cloud top with 283nm and 365nm wavelengths. We found the superrotation of Venus clouds because of 4 day cycle change in the UV light intensity.

  16. 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.

  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. 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.

  19. Electron temperatures and densities in the venus ionosphere: Pioneer Venus orbiter electron temperature probe results

    International Nuclear Information System (INIS)

    Altitude profiles of electron temperature and density in the ionosphere of Venus have been obtained by the Pioneer Venus orbiter electron temperature probe. Elevated temperatures observed at times of low solar wind flux exhibit height profiles that are consistent with a model in which less than 5% of the solar wind energy is deposited at the ionopause and is conducted downward through an unmagnetized ionosphere to the region below 200 kilometers where electron cooling to the neutral atmosphere proceeds rapidly. When solar wind fluxes are higher, the electron temperatures and densities are highly structured and the ionopause moves to lower altitudes. The ionopause height in the late afternoon sector observed thus far varies so widely from day to day that any height variation with solar zenith angle is not apparent in the observations. In the neighborhood of the ionopause, measurements of plasma temperatures and densities and magnetic field strength indicate that an induced magnetic barrier plays an important role in the pressure transfer between the solar wind and the ionosphere. The bow shock is marked by a distinct increase in electron current collected by the instrument, a feature that provides a convenient identification of the bow shock location

  20. Receptor Response in Venus's Fly-Trap

    Science.gov (United States)

    Jacobson, Stuart L.

    1965-01-01

    The insect-trapping movement of the plant Dionaea muscipula (Venus's fly-trap) is mediated by the stimulation of mechanosensory hairs located on the surface of the trap. It is known that stimulation of the hairs is followed by action potentials which are propagated over the surface of the trap. It has been reported that action potentials always precede trap closure. The occurrence of non-propagated receptor potentials is reported here. Receptor potentials always precede the action potentials. The receptor potential appears to couple the mechanical stimulation step to the action potential step of the preying sequence. Receptor potentials elicited by mechanical stimulation of a sensory hair were measured by using the hair as an integral part of the current-measuring path. The tip of the hair was cut off exposing the medullary tissue; this provided a natural extension of the measuring electrode into the receptor region at the base of the hair. A measuring pipette electrode was slipped over the cut tip of the hair. Positive and negative receptor potentials were measured. Evidence is presented which supports the hypothesis that the positive and negative receptor potentials originate from independent sources. An analysis is made of (a) the relation of the parameters of mechanical stimuli to the magnitude of the receptor potential, and (b) the relation of the receptor potentials to the action potential. The hypothesis that the positive receptor potential is the generator of the action potential is consistent with these data. PMID:5862498

  1. 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.

  2. Venus volcanism: Initial analysis from Magellan data

    Science.gov (United States)

    Head, J.W.; Campbell, D.B.; Elachi, C.; Guest, J.E.; Mckenzie, D.P.; Saunders, R.S.; Schaber, G.G.; Schubert, G.

    1991-01-01

    Magellan images confirm that volcanism is widespread and has been fundamentally important in the formation and evolution of the crust of Venus. High-resolution imaging data reveal evidence for intrusion (dike formation and cryptodomes) and extrusion (a wide range of lava flows). Also observed are thousands of small shield volcanoes, larger edifices up to several hundred kilometers in diameter, massive outpourings of lavas, and local pyroclastic deposits. Although most features are consistent with basaltic compositions, a number of large pancake-like domes are morphologically similar to rhyolite-dacite domes on Earth. Flows and sinuous channels with lengths of many hundreds of kilometers suggest that extremely high effusion rates or very fluid magmas (perhaps komatiites) may be present. Volcanism is evident in various tectonic settings (coronae, linear extensional and compressional zones, mountain belts, upland rises, highland plateaus, and tesserae). Volcanic resurfacing rates appear to be low (less than 2 km3/yr) but the significance of dike formation and intrusions, and the mode of crustal formation and loss remain to be established.

  3. Characterization of the lower layer in the dayside Venus ionosphere and comparisons with Mars

    Science.gov (United States)

    Girazian, Zachary; Withers, Paul; Häusler, Bernd; Pätzold, Martin; Tellmann, Silvia; Peter, Kerstin

    2015-11-01

    The influence of solar zenith angle (SZA) and solar irradiance has been well characterized for the V2 layer in the Venus ionosphere, but not the V1 layer, where previous efforts were limited by data scarcity and incomplete SZA coverage. Here we use more than 200 radio occultation profiles from Venus Express with good SZA coverage to characterize how the V1 peak altitude, peak density, and morphology respond to changes in SZA and solar activity. The V1 and V2 peak altitudes vary little with SZA, and both peak electron densities vary with SZA in an approximately Chapman-like manner. These results imply that the thermal structures of the atmosphere and ionosphere between ?125 km and ?140 km vary little with SZA. As solar activity increases, the ratio of the V1 to V2 peak density increases, and the V1 morphology changes more than the V2 morphology. These results are due to the soft X-ray flux increasing relative to the EUV flux as solar activity increases. We compare the behavior of the V1 layer to the analogous M1 layer at Mars, and find that their peak altitudes respond differently to changes in SZA and solar activity. The V1 peak density also increases more with solar activity than the M1 peak density. These distinct behaviors arise from differences in their underlying neutral atmospheres.

  4. Probabilistic constraints from existing and future radar imaging on volcanic activity on Venus

    Science.gov (United States)

    Lorenz, Ralph D.

    2015-11-01

    We explore the quantitative limits that may be placed on Venus' present-day volcanic activity by radar imaging of surface landforms. The apparent nondetection of new lava flows in the areas observed twice by Magellan suggests that there is a ~60% chance that the eruption rate is ~1 km3/yr or less, using the eruption history and area/volume flow geometry of terrestrial volcanoes (Etna, Mauna Loa and Merapi) as a guide. However, if the detection probability of an individual flow is low (e.g. ~10%) due to poor resolution or quality and unmodeled viewing geometry effects, the constraint (Venus on a new mission (30 years after Magellan) would yield better than 99% chance of detecting a new lava flow, even if the volcanic activity is at the low end of predictions (~0.01 km3/yr) and is expressed through a single volcano with a stochastic eruption history. Closer re-examination of Magellan data may be worthwhile, both to search for new features, and to establish formal (location-dependent) limits on activity against which data from future missions can be tested. While Magellan-future and future-future comparisons should offer much lower detection thresholds for erupted volumes, a probabilistic approach will be required to properly understand the implications.

  5. Proton and alpha particle precipitation onto the upper atmosphere of Venus

    Science.gov (United States)

    Stenberg Wieser, G.; Ashfaque, M.; Nilsson, H.; Futaana, Y.; Barabash, S.; Diéval, C.; Fedorov, A.; Zhang, T. L.

    2015-08-01

    We study the precipitation of protons and alpha-particles onto the upper atmosphere of Venus, using particle data recorded by the Venus Express spacecraft inside the induced magnetosphere. Our investigations are limited to the dayside close to the terminator. We observe on average a net downward flux of protons, which originate partly from the planetary atmosphere and partly from the solar wind. We present median energy spectra of the precipitating protons divided into two energy ranges, 10-100 eV and 100 eV-30 keV. The total dayside precipitation of solar wind protons is estimated to be 3×1022 s-1, assuming only protons with energies above 500 eV will reach the exobase. Downgoing protons are frequently observed but only in 3% of the available data records we see He2+. These observations are made close to the induced magnetosphere boundary and we argue that at lower altitude the countrates for alpha-particles fall below detection limits. We estimate the precipitation of He2+ onto the dayside exobase to be 1×1021 s-1, which is not enough enough to replace the helium escaping from the planet.

  6. Factors controlling the location of the venus bow shock

    International Nuclear Information System (INIS)

    The location of the Venus bow shock determined from magnetic field measurements during the first and third years of Pioneer Venus orbiter operation is examined and compared with nearly simultaneously obtained interplanetary solar wind data to determine those factors that control the size of the Venus bow shock. The location of the intersection of the bow shock with the terminator that is best determined by the data does not vary significantly between years 1979 and 1981 and is only 16% more distant than the Venera 9 and 10 shock when account is taken of solar wind aberration. Alfvenic Mach number and magnetosonic Mach number affect the size of the bow shock significantly. Solar wind dynamic pressure has a lesser effect. No significant asymmmetries in the shock shape were found either as a result of the orientation of the clock angle of the IMF inn the terminator plane or the angle of the IMF relative to the shock normal

  7. 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

  8. Upper limits on argon isotope abundances in the Venus thermosphere

    Science.gov (United States)

    Mauersberger, K.; Von Zahn, U.; Krankowsky, D.

    1979-01-01

    On December 9, 1978 the neutral gas mass spectrometer aboard the NASA Pioneer Venus multiprobe bus has measured density, composition, and temperature of the Venus dayside thermosphere. There was no positive identification of argon down to the lowest measuring altitude of 130 km. For the altitude level of 135 km the following upper limits for the number densities of argon isotopes were derived: n(Ar-36) less than 1.3 times 10 to the 6th power per cu cm and n(Ar-40) less than 2.8 times 10 to the 6th power per cu cm. From our upper atmosphere observations we infer for the troposphere of Venus the following upper limits for the mixing ratios: n(Ar-36)/total number density less than 9 times 10 to the minus 6th power and n(Ar-40)/total number density less than 20 times 10 to the minus 6th power.

  9. Nature of the Venus clouds as derived from their polarization

    International Nuclear Information System (INIS)

    The linear polarization of sunlight reflected by Venus is analyzed by comparing observations with extensive multiple scattering computations. The analysis establishes that Venus is veiled by a cloud or haze layer of particles which have a narrow size distribution with a mean radius approximately 1 ?. The refractive index of the particles is 1.44 +- 0.015 at lambda = 0.55 ? with a small normal dispersion, the refractive index decreasing from the ultraviolet toward the infrared. The particles exist at a high level in the atmosphere, with the optical thickness unity occurring where the pressure is about 50 mb. The particle properties deduced from the polarization eliminate all but one of the cloud compositions which have been proposed for Venus. A concentrated solution of sulfuric acid (H2SO4-H2O) provides good agreement with the polarization data. (Auth.)

  10. 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.)

  11. Identification of CO molecule in the Venus nightglow emission spectrum

    International Nuclear Information System (INIS)

    In the spectrum of the Venus night airglow eight bright bands have been observed in the range of wavelengths from 3900 to 6500 A. An attempt has been made to interpret this spectrum. Carbon monoxide CO should be the most wide spread biatomic molecule in the Venus upper atmosphere. The band positions calculated of the CO fourth positive system for the difference of the oscillation numbers ?V=20-28 have been compared with the maxima of the bands observed. In all the cases the deviation does not exceed the spectrometer resolution. The bands of the Venus night airglow present sequents each corresponding to the constant difference of the oscillatory numbers of lower and upper electron states

  12. Model of the variability of the Venus ionpause altitude

    International Nuclear Information System (INIS)

    A model for the variability of the Venus ionopause as a function of solar wind dynamic pressure and EUV flux during quiescent solar wind conditions is presented. The radio occultation measurements of the Venus ionopause from Mariner 5, 10, and Venera 9, 10 spacecraft, as well as recent in situ Pioneer Venus measurements are interpreted in terms of this model. An ionospheric model consistent with observations in the 400--1000 km region is predominantly 0+ with densities approx.104 cm-3 and (T/sub e/+T/sub i/i) approx.4500--6500 0K. For ionopause measurements below 400 km the ionosphere appears severely compressed and density and temperature profiles cannot be simply described, although a strong correlation with solar wind dynamic pressure is observed. Possible effects of IMF direction switching on the dynamics and structure of the ionosphere are also considered and compared with available ionopause data

  13. 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.)

  14. Composition and structure of the atmosphere of Venus

    International Nuclear Information System (INIS)

    Although in recent years much has been learned about the atmospheric composition and structure of Venus, there are many key questions which remain unanswered. The Pioneer Venus set of experiments is designed to provide information both individually and collectively to help understand and explain first of all the present state of the atmosphere (the composition and distribution in both the lower and upper parts, the state property profiles, the cloud compositions, the role of phase in the thermal structure, the planet's surface and interior composition, the high surface temperature, the stability of CO2, the ionosphere - its chemistry and thermal structure, the existence of superrotation, the response of the upper atmosphere to changes in solar EUV and the solar wind) and secondly the origin and evolution of the atmosphere. This paper discusses these questions and the degree to which the Pioneer Venus instruments will respond to them. (Auth.)

  15. Evidence for mass-loading of the Venus magnetosheath

    International Nuclear Information System (INIS)

    The observed magnetic field configuration in the Venus magnetosheath contains information about the solar wind mass-loading processes occurring as a result of the extension of the neutral atmosphere into the magnetosheath. In this paper, magnetic field signatures of various mass-loading processes are discussed and experimental results from the Pioneer Venus Orbiter magnetometer experiment are examined for evidence of these signatures. The data suggest that the -V(bar)XB(bar) acceleration process, stochastic pickup of ionospheric ions, and J(bar)XB(bar) force scavenging at the ionopause all occur at various times. 16 references

  16. Atomic nitrogen in the upper atmosphere of Venus

    Science.gov (United States)

    Kasprzak, W. T.; Hedin, A. E.; Niemann, H. B.; Spencer, N. W.

    1980-01-01

    Atomic nitrogen has been detected in the upper atmosphere of Venus by the Pioneer-Venus Orbiter Neutral Mass Spectrometer (ONMS). Surface recombination of atomic nitrogen with atomic oxygen to form nitric oxide in the ion source allows it to be detected at mass 30. The scale height temperature of the mass 30 peak agrees with the scale height temperatures of the other species if it is assumed to be derived from atomic nitrogen. The diurnal variation of atomic nitrogen is approximately proportional to that of atomic oxygen with an estimated N/O ratio of 1.5% at 150 km.

  17. Heliospheric current sheet inclinations at Venus and Earth

    OpenAIRE

    Ma, G; K. Marubashi; Maruyama, T.

    1999-01-01

    We investigate the inclinations of heliospheric current sheet at two sites in interplanetary space, which are generated from the same solar source. From the data of solar wind magnetic fields observed at Venus (0.72 AU) and Earth (1 AU) during December 1978-May 1982 including the solar maximum of 1981, 54 pairs of candidate sector boundary crossings are picked out, of which 16 pairs are identified as sector boundaries. Of the remainder, 12 pairs are transient structures both at Venus and Eart...

  18. High Altitude Venus Operations Concept Trajectory Design, Modeling and Simulation

    Science.gov (United States)

    Lugo, Rafael A.; Ozoroski, Thomas A.; Van Norman, John W.; Arney, Dale C.; Dec, John A.; Jones, Christopher A.; Zumwalt, Carlie H.

    2015-01-01

    A trajectory design and analysis that describes aerocapture, entry, descent, and inflation of manned and unmanned High Altitude Venus Operation Concept (HAVOC) lighter-than-air missions is presented. Mission motivation, concept of operations, and notional entry vehicle designs are presented. The initial trajectory design space is analyzed and discussed before investigating specific trajectories that are deemed representative of a feasible Venus mission. Under the project assumptions, while the high-mass crewed mission will require further research into aerodynamic decelerator technology, it was determined that the unmanned robotic mission is feasible using current technology.

  19. Three-dimensional benchmark model establishment for VENUS-3 reactor

    International Nuclear Information System (INIS)

    The benchmark-models for VENUS-3 reactor are established as a part of International Reactor Physics Experiments Evaluation Project (IRPhEP) managed by OECD/NEA. The benchmark models for VENUS-3 experiment consist of critical configuration benchmark-model, reaction-rate distribution benchmark-model and power distribution benchmark-model. The criticality calculation is performed to obtain the keff and 3-dimensional power distributions, and the neutron transport calculation is performed to obtain the reaction rates distribution. The results obtained using these benchmark-models are compared with the experimental data

  20. Mars ionopause during solar minimum: A lesson from Venus

    International Nuclear Information System (INIS)

    The ion densities measured by the Viking landers (Hanson et al., 1977) do not show an abrupt falloff with height, giving the false impression that Mars has no ionopause. On the basis of knowledge gained from the solar wind interaction at Venus during solar minimum, they demonstrate that the observed O2+ profile above about 160 km on Mars is a distributed photodynamical ionosphere and can produce an ionopause at around 325 km, similar to that observed on Venus during solar minimum. They conclude that the solar wind interacts directly with the Mars ionosphere, suggesting that the planet does not have an intrinsic magnetic field of any consequence

  1. 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)

  2. High expression of Lifeact in Arabidopsis thaliana reduces dynamic reorganization of actin filaments but does not affect plant development.

    Science.gov (United States)

    van der Honing, Hannie S; van Bezouwen, Laura S; Emons, Anne Mie C; Ketelaar, Tijs

    2011-10-01

    Lifeact is a novel probe that labels actin filaments in a wide range of organisms. We compared the localization and reorganization of Lifeact:Venus-labeled actin filaments in Arabidopsis root hairs and root epidermal cells of lines that express different levels of Lifeact: Venus with that of actin filaments labeled with GFP:FABD2, a commonly used probe in plants. Unlike GFP:FABD2, Lifeact:Venus labeled the highly dynamic fine F-actin in the subapical region of tip-growing root hairs. Lifeact:Venus expression at varying levels was not observed to affect plant development. However, at expression levels comparable to those of GFP:FABD2 in a well-characterized marker line, Lifeact:Venus reduced reorganization rates of bundles of actin filaments in root epidermal cells. Reorganization rates of cytoplasmic strands, which reflect the reorganization of the actin cytoskeleton, were also reduced in these lines. Moreover, in the same line, Lifeact:Venus-decorated actin filaments were more resistant to depolymerization by latrunculin B than those in an equivalent GFP:FABD2-expressing line. In lines where Lifeact: Venus is expressed at lower levels, these effects are less prominent or even absent. We conclude that Lifeact: Venus reduces remodeling of the actin cytoskeleton in Arabidopsis in a concentration-dependent manner. Since this reduction occurs at expression levels that do not cause defects in plant development, selection of normally growing plants is not sufficient to determine optimal Lifeact expression levels. When correct expression levels of Lifeact have been determined, it is a valuable probe that labels dynamic populations of actin filaments such as fine F-actin, better than FABD2 does. PMID:21948789

  3. Venus trap in the mouse embryo reveals distinct molecular dynamics underlying specification of first embryonic lineages.

    Science.gov (United States)

    Dietrich, Jens-Erik; Panavaite, Laura; Gunther, Stefan; Wennekamp, Sebastian; Groner, Anna C; Pigge, Anton; Salvenmoser, Stefanie; Trono, Didier; Hufnagel, Lars; Hiiragi, Takashi

    2015-08-01

    Mammalian development begins with the segregation of embryonic and extra-embryonic lineages in the blastocyst. Recent studies revealed cell-to-cell gene expression heterogeneity and dynamic cell rearrangements during mouse blastocyst formation. Thus, mechanistic understanding of lineage specification requires quantitative description of gene expression dynamics at a single-cell resolution in living embryos. However, only a few fluorescent gene expression reporter mice are available and quantitative live image analysis is limited so far. Here, we carried out a fluorescence gene-trap screen and established reporter mice expressing Venus specifically in the first lineages. Lineage tracking, quantitative gene expression and cell position analyses allowed us to build a comprehensive lineage map of mouse pre-implantation development. Our systematic analysis revealed that, contrary to the available models, the timing and mechanism of lineage specification may be distinct between the trophectoderm and the inner cell mass. While expression of our trophectoderm-specific lineage marker is upregulated in outside cells upon asymmetric divisions at 8- and 16-cell stages, the inside-specific upregulation of the inner-cell-mass marker only becomes evident at the 64-cell stage. This study thus provides a framework toward systems-level understanding of embryogenesis marked by high dynamicity and stochastic variability. PMID:26142281

  4. Sox10-Venus mice: a new tool for real-time labeling of neural crest lineage cells and oligodendrocytes

    OpenAIRE

    Shibata Shinsuke; Yasuda Akimasa; Renault-Mihara Francois; Suyama Satoshi; Katoh Hiroyuki; Inoue Takayoshi; Inoue Yukiko U; Nagoshi Narihito; Sato Momoka; Nakamura Masaya; Akazawa Chihiro; Okano Hideyuki

    2010-01-01

    Abstract Background While several mouse strains have recently been developed for tracing neural crest or oligodendrocyte lineages, each strain has inherent limitations. The connection between human SOX10 mutations and neural crest cell pathogenesis led us to focus on the Sox10 gene, which is critical for neural crest development. We generated Sox10-Venus BAC transgenic mice to monitor Sox10 expression in both normal development and in pathological processes. Results Tissue fluorescence distin...

  5. Astronomers, Transits of Venus, and the Birth of Experimental Psychology

    Science.gov (United States)

    Sheehan, William; Thurber, S.

    2012-01-01

    The eighteenth century transits of Venus were regarded as the most important astronomical events of their era. Halley's expectation was that by observing the contact points between the limbs of Venus and the Sun, this distance could be determined to an accuracy of one part in 500. But in the event, it proved otherwise. But, as the British historian Agnes Clerke wrote in 1902: "A transit of Venus seems, at first sight, full of promise for solving the problem of the sun's distance. For nothing would appear easier than to determine exactly either the duration of the passage of a small, dark orb across a large brilliant disc, or the instant of its entry upon or exit from it". But in that word `exactly' what snares and pitfalls lie hid!” In the post-mortem analysis of the disappointing results, astronomers devoted a great deal of effort to understand the sources of errors. They rehearsed their observational techniques by observing, under strictly controlled conditions, transits of artificial planets across artificial Suns, and studied such parameters as attention and reflex reaction. In the process, the transits of Venus provided an important impetus to the early development of experimental psychology.

  6. Distribution of tessera terrain on Venus: Prediction for Magellan

    International Nuclear Information System (INIS)

    Tessera terrain is the dominant tectonic unit in the northern hemisphere of Venus and is characterized by complex sets of intersecting structural trends and distinctive radar properties due to a high degree of meter and sub-meter scale (5 cm to 10 m) roughness. Based on these distinctive radar properties, a prediction of the global distribution of tessera can be made using Pioneer Venus (PV) reflectivity and roughness data. Where available, Venera 15/16 and Arecibo images and PV diffuse scattering data were used to evaluate the prediction. From this assessment, the authors conclude that most of the regions with prediction values greater than 0.6 (out of 1) are likely to be tessera, and are almost certain to be tectonically deformed. Lada Terra and Phoebe Regio are very likely to contain tessera terrain, while much of Aphrodite Terra is most likely to be either tessera or a landform which has not yet been recognized on Venus. This prediction map will assist in targeting Magellan investigations of Venus tectonics

  7. The GUINEVERE project at the VENUS-F Facility

    International Nuclear Information System (INIS)

    Within the framework of the ECATS (Experimental activities on the Coupling of an Accelerator, a spallation Target and a Sub-critical blanket) research domain of the FP6 IP-EUROTRANS program, the GUINEVERE (Generation of Uninterrupted Intense Neutron pulses at the lead Venus Reactor) project was launched in 2006 in order to check in the experiments an open questions stay for the techniques used in the MUSE programme (CEA Cadarache, France, 2000-2004), related to the online reactivity monitoring, sub-criticality determination and operational procedure of an Accelerator Driven System. For this purpose, the VENUS light water critical reactor at the SCK-CEN site of Mol (Belgium) was modify into a subcritical fast core (VENUS-F) and the GENEPI accelerator, designed for the MUSE experiment was up-graded to the new GENEPI-3C accelerator. The VENUS-F coupled with the GENEPI-3C and a TiT target will provide a unique facility in Europe for fast sub-critical and critical reactor physics investigations. This paper describes the present status of the facility. (authors)

  8. Geologic Map of the Helen Planitia Quadrangle (V-52), Venus

    Science.gov (United States)

    Lopez, Ivan; Hansen, Vicki L.

    2008-01-01

    The Magellan spacecraft orbited Venus from August 10, 1990, until it plunged into the Venusian atmosphere on October 12, 1994. Magellan Mission objectives included (1) improving the knowledge of the geological processes, surface properties, and geologic history of Venus by analysis of surface radar characteristics, topography, and morphology and (2) improving the knowledge of the geophysics of Venus by analysis of Venusian gravity. The Helen Planitia quadrangle (V-52), located in the southern hemisphere of Venus between lat 25 deg S. and 50 deg S. and between long 240 deg E. and 270 deg E., covers approximately 8,000,000 km2. Regionally, the map area is located at the southern limit of an area of enhanced tectonomagmatic activity and extensional deformation, marked by a triangle that has highland apexes at Beta, Atla, and Themis Regiones (BAT anomaly) and is connected by the large extensional belts of Devana, Hecate, and Parga Chasmata. The BAT anomaly covers approximately 20 percent of the Venusian surface.

  9. Ion-aerosol interactions in the lower atmosphere of Venus

    OpenAIRE

    Aplin, K.L.

    2006-01-01

    All planetary atmospheres are electrified to some extent by cosmic ray ionisation, and Venus is no exception. There is increasing awareness that ion-aerosol interactions could modulate terrestial radiative processes, and this possibility will be investigated for the Venusian atmosphere. The likelihood of a Venusian global atmospheric electric circuit will also be discussed.

  10. Ultraviolet photometry of the Venus. Scattering layer above absorbing clouds

    International Nuclear Information System (INIS)

    The main problem of UV photometry of the Venus is the investigation of light scattering in the cloudy and overcloud layers of the planet atmosphere, the investigation of the cloudy layer upper part structure and of the nature of dark and light formations. Each space probe has three identical devices for measurements: photometer with the transmission maximum of the interference filter 3520 A (Venus-9) and 3450 A (Venus-10) and two multifilter photometers-polarimeters with 8 subranges from 3350 to 8000 A. The object under measurement is the upper level of the cloudy coating of the Venus at the altitude 64-67 km and also the atmosphere layers located somehow higher. The curves of the brightness variation have confirmed the presence of considerable contrasts (up to 10%) in 3500 A. In other wavelengths (4000-8000 A) the character of the brightness variation is very smooth. The UV profiles obtained are compared with calculations made by different scattering models. The absolute measurements of brightness in the UV range yield the value of 49 mW/cm2 x m x sr

  11. 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.

  12. Benchmark Calculation on the VENUS-7 MOX Fuel Experiments

    International Nuclear Information System (INIS)

    In the late 1960's and the early 1970's, SCK·CEN (Mol, Belgium) carried out a series of experiments entitled 'Plutonium Recycling Physics Project' using the VENUS (Vulcain Experimental Nuclear Study) facility. More than 100 different core configurations have been studied. Recognizing a further need for validation of computing methods and nuclear data for MOX-fuelled systems, SCK·CEN has released all sets of these experimental results to the OECD/NEA for the international community. After having examined, the OECD/NEA expert groups have selected three most interesting configurations for international benchmark exercises. A series of the benchmarks based on these configurations and their experimental results will be organized by the OECD/NEA. One of these experimental data is the configuration VENUS-7 for different types of MOX fuel with different Pu contents. As a part of this benchmark program, 3-dimensional benchmark models have been established based on the problem specification for the configuration VENUS-7 by the Mote Carlo code MCNP4C and the calculation results have been compared with some available VENUS-7 experimental data

  13. Electrotonic and action potentials in the Venus flytrap.

    Science.gov (United States)

    Volkov, Alexander G; Vilfranc, Chrystelle L; Murphy, Veronica A; Mitchell, Colee M; Volkova, Maia I; O'Neal, Lawrence; Markin, Vladislav S

    2013-06-15

    The electrical phenomena and morphing structures in the Venus flytrap have attracted researchers since the nineteenth century. We have observed that mechanical stimulation of trigger hairs on the lobes of the Venus flytrap induces electrotonic potentials in the lower leaf. Electrostimulation of electrical circuits in the Venus flytrap can induce electrotonic potentials propagating along the upper and lower leaves. The instantaneous increase or decrease in voltage of stimulating potential generates a nonlinear electrical response in plant tissues. Any electrostimulation that is not instantaneous, such as sinusoidal or triangular functions, results in linear responses in the form of small electrotonic potentials. The amplitude and sign of electrotonic potentials depend on the polarity and the amplitude of the applied voltage. Electrical stimulation of the lower leaf induces electrical signals, which resemble action potentials, in the trap between the lobes and the midrib. The trap closes if the stimulating voltage is above the threshold level of 4.4V. Electrical responses in the Venus flytrap were analyzed and reproduced in the discrete electrical circuit. The information gained from this study can be used to elucidate the coupling of intracellular and intercellular communications in the form of electrical signals within plants. PMID:23422156

  14. A heat pipe mechanism for volcanism and tectonics on Venus

    International Nuclear Information System (INIS)

    A heat pipe mechanism is proposed for the transport of heat through the lithosphere on Venus. This mechanism allows the crust and lithosphere on Venus to be greater than 150 km thick. A thick crust and thick lithosphere can explain the high observed topography and large associated gravity anomalies. For a 150-km-thick lithosphere the required volcanic flux on Venus is 200 km3/yr; this is compared with a flux of 17 km3/yr associated with the formation of the oceanic crust on Earth. A thick basaltic crust on Venus is expected to transform to eclogite at a depth of 60 to 80 km; the dense eclogite would contribute the lithospheric delamination that returns the crust to the interior of the planet completing the heat pipe cycle. Topography and the associated gravity anomalies can be explained by Airy compensation of the thick crust. The principal observation that is contrary to this hypothesis is the mean age of the surface that is inferred from crater statistics; the minimum mean age is about 130 Ma, and this implies an upper limit of 2 km3/yr for the surface volcanic flux. If the heat pipe mechanism was applicable on Earth in the Archean, it would provide the thick lithosphere implied by isotopic data from diamonds

  15. Venus bow shocks at unusually large distances from the planet

    Science.gov (United States)

    Steinolfson, R. S.; Cable, S.

    1993-01-01

    Recent analysis of data from the Pioneer Venus Orbiter (PVO) has shown that the bow shock often travels to unusually large distances from the planet when the solar wind magnetosonic Mach number is near unity. We suggest that distant bow shocks can be explained as an integral part of the response of the global solar wind/Venus interaction to the anomalous local solar wind conditions that existed during the time of these observations. The lower-than-normal plasma beta and magnetosonic Mach number are in a parameter regime for which the usual fast-mode bow shock close to the planet may not provide the necessary compression and deflection of the solar wind. Using MHD simulations we show that, for these conditions, the usual fast shock is replaced by a bow shock consisting of an intermediate shock near the Sun-Venus line and a fast shock at large distances from the Sun-Venus line. This composite bow shock propagates upstream away from the planet at a low speed and appears to be approaching a new equilibrium stand-off location at a large distance from the planet.

  16. On the theory of superrotation of the Venus atmosphere

    International Nuclear Information System (INIS)

    Partial solution of nonlinear system of dynamics equations for nonviscous gas mantle at slowly rotating planet is obtained. Solution represents circulation forming Hadley meridional cell with applied atmosphere superrotation that is with powerful zonal flow in the direction of planet eigenrotation. Features of qualitative similarity between this solution and observed circulation of the Venus atmosphere are discussed

  17. Surface age of Venus: applying the terrestrial cratering rate

    International Nuclear Information System (INIS)

    The population of Venusian craters having suspected impact crater morphology has been reported from 115 x 10 to the 6th power sq km of the northern hemisphere of the planet with the estimated average age of the surface to be approx. 1 b.y. (+ or - 0.5 b.y.) on the basis of lunar crater production curves corrected for Venus. Such an old average age is somewhat difficult to reconcile with the similarity in size and mass of Venus and Earth and with Earth's high heat flow and crustal resurfacing rate. Given the present uncertainties in the role of both active and inactive comet nuclei in the cratering history of Earth, it is concluded that the average age of the observed surface in the northern hemisphere of Venus could be as great as the 450 m.y. mean age of the Earth's crust. The surface of Venus might be even older, but no evidence from the crater observations support an age as great as 1 b.y

  18. 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.

  19. New Results with the superconducting ECR ion source VENUS

    Energy Technology Data Exchange (ETDEWEB)

    Lyneis, C.M.; Leitner, D.; Abbott, S.R.; Dwinell, R.D.; Leitner,M.; Silver, C.S.; Taylor, C.

    2004-05-13

    During the last year, the VENUS ECR ion source was commissioned at 18 GHz and preparations for 28 GHz operation, which is set to begin early in 2004, are now underway. The goal of the VENUS ECR ion source project as the RIA R&D injector is the production of 240emA of U30+, a high current medium charge state beam. On the other hand, as an injector ion source for the 88-Inch Cyclotron the design objective is the production of 5emA of U48+, a low current, very high charge state beam. During the commissioning phase with 18 GHz, tests with various gases and recently metals have been performed with up to 2000 W RF power and the performance is very promising. For example, 1100 e mu A of O6+,180 e mu A of Ar12+, 150 emA of Xe20+ and 100 emA of Bi24+ were produced in the early commissioning phase, ranking VENUS among the currently highest performance 18 GHz ECR ion sources. The emittance of the beams produced at 18 GHz was measured with a two axis emittance scanner. In FY04 a 10 kW, 28 GHz gyrotron system will be added, which will enable VENUS to reach full performance. The performance of the VENUS ion source, low energy beam transport (LEBT) and its closed loop cryogenic system are described in the paper. Recently, a new high temperature axial oven has been installed in the source and the first results on metal beams such as bismuth are given. The design of the 28 GHz, 10 kW gyrotron system is also be described. During the last year, the VENUS ECR ion source was commissioned at 18 GHz and preparations for 28 GHz operation, which is set to begin early in 2004, are now underway. The goal of the VENUS ECR+, a high current medium charge state beam. On the other hand, as an injector ion source for the 88-Inch Cyclotron the design objective is the production of 5 emA of U48+, a low current, very high charge state beam. During the commissioning phase with 18 GHz, tests with various gases and recently metals have been performed with up to 2000 W RF power and the performance is very promising. For example, 1100 e mu A of O6+, 180 e muA of Ar12+, 150 emA of Xe20+ and 100 emA of Bi24+ were produced in the early commissioning phase, ranking VENUS among the currently highest performance 18 GHz ECR ion sources. The emittance of the beams produced at 18 GHz was measured with a two axis emittance scanner. In FY04 a 10kW, 28 GHz gyrotron system will be added, which will enable VENUS to reach full performance. The performance of the VENUS ion source, low energy beam transport (LEBT) and its closed loop cryogenic system are described in the paper. Recently, a new high temperature axial oven has been installed in the source and the first results on metal beams such as bismuth are given. The design of the 28 GHz, 10 kW gyrotron system is also be described.

  20. New Results with the superconducting ECR ion source VENUS

    International Nuclear Information System (INIS)

    During the last year, the VENUS ECR ion source was commissioned at 18 GHz and preparations for 28 GHz operation, which is set to begin early in 2004, are now underway. The goal of the VENUS ECR ion source project as the RIA R and D injector is the production of 240emA of U30+, a high current medium charge state beam. On the other hand, as an injector ion source for the 88-Inch Cyclotron the design objective is the production of 5emA of U48+, a low current, very high charge state beam. During the commissioning phase with 18 GHz, tests with various gases and recently metals have been performed with up to 2000 W RF power and the performance is very promising. For example, 1100 e mu A of O6+,180 e mu A of Ar12+, 150 emA of Xe20+ and 100 emA of Bi24+ were produced in the early commissioning phase, ranking VENUS among the currently highest performance 18 GHz ECR ion sources. The emittance of the beams produced at 18 GHz was measured with a two axis emittance scanner. In FY04 a 10 kW, 28 GHz gyrotron system will be added, which will enable VENUS to reach full performance. The performance of the VENUS ion source, low energy beam transport (LEBT) and its closed loop cryogenic system are described in the paper. Recently, a new high temperature axial oven has been installed in the source and the first results on metal beams such as bismuth are given. The design of the 28 GHz, 10 kW gyrotron system is also be described. During the last year, the VENUS ECR ion source was commissioned at 18 GHz and preparations for 28 GHz operation, which is set to begin early in 2004, are now underway. The goal of the VENUS ECR+, a high current medium charge state beam. On the other hand, as an injector ion source for the 88-Inch Cyclotron the design objective is the production of 5 emA of U48+, a low current, very high charge state beam. During the commissioning phase with 18 GHz, tests with various gases and recently metals have been performed with up to 2000 W RF power and the performance is very promising. For example, 1100 e mu A of O6+, 180 e muA of Ar12+, 150 emA of Xe20+ and 100 emA of Bi24+ were produced in the early commissioning phase, ranking VENUS among the currently highest performance 18 GHz ECR ion sources. The emittance of the beams produced at 18 GHz was measured with a two axis emittance scanner. In FY04 a 10kW, 28 GHz gyrotron system will be added, which will enable VENUS to reach full performance. The performance of the VENUS ion source, low energy beam transport (LEBT) and its closed loop cryogenic system are described in the paper. Recently, a new high temperature axial oven has been installed in the source and the first results on metal beams such as bismuth are given. The design of the 28 GHz, 10 kW gyrotron system is also be described

  1. Ridge belts: Evidence for regional- and local-scale deformation on the surface of Venus

    International Nuclear Information System (INIS)

    The author evaluates models for the formation of the ridge belt fan assemblage on Venus through consideration of the orientation, spatial distribution, topographic expression and wavelengths of observed tectonic surface features. He favors a compressional mechanism for long wavelength deformation corresponding to the spacing of ridge belts (300???400 km). However, short wavelength ridges and grooves (10???20 km) that are contained within belts and trend parallel to them are likely to be compressional and extensional, and to reflect both regional and local stress fields. He hypothesizes that large-scale (much-gt ridge spacing) early-stage mantle downwelling is the source of regional compression responsible for the establishment of the long wavelength of deformation

  2. The evolution of Venus: Present state of knowledge and future exploration

    Science.gov (United States)

    Chassefière, Eric; Wieler, Rainer; Marty, Bernard; Leblanc, François

    2012-04-01

    A detailed characterization of the formation and evolution of Venus is a key link to the study of terrestrial planets, and to their divergent evolutions. While Earth and to a lesser extent Mars (thanks to the analysis of SNC meteorites) are extensively studied in a comparative planetology context, the history of the most Earth-like planet of the Solar System, Venus, is still poorly understood. For how long has Venus been in its current extreme climate state? When and how did it diverge from a (possible) early Earth-like state? Has Venus been a potentially habitable planet at some time of its early history? Did a "cool early Venus" stage occur between the end of accretion and the late heavy bombardment, like suspected for Earth? What are the implications of the Venus/Earth comparison for the nature and evolution of habitable terrestrial planets throughout the universe? A major observational missing link in our understanding of Venus' climate evolution is the elementary and isotopic pattern of noble gases and of stable isotopes in Venus' atmosphere, still poorly known. The concentrations of heavy noble gases (Kr, Xe) and their isotopes are mostly unknown, and our knowledge of light noble gases and stable isotopes is incomplete and inaccurate. In this paper, we summarize our present understanding of Venus' early evolution, including the crucial question of knowing if water ever condensed at the surface of the planet. Then, we assess the potential contribution of a precise measurement of noble gases, their isotopes and stable isotopes to improve of our understanding of Venus evolution, and list the main questions that noble gases and isotope measurements would help to answer. Finally, we show how future exploration of Venus could allow to gain a glimpse into the early evolution of Venus through a small in-situ mission based on a single balloon probe, called EVE (European Venus Explorer), proposed in the frame of the ESA Cosmic Vision program.

  3. Heliospheric current sheet inclinations at Venus and Earth

    Directory of Open Access Journals (Sweden)

    G. Ma

    Full Text Available We investigate the inclinations of heliospheric current sheet at two sites in interplanetary space, which are generated from the same solar source. From the data of solar wind magnetic fields observed at Venus (0.72 AU and Earth (1 AU during December 1978-May 1982 including the solar maximum of 1981, 54 pairs of candidate sector boundary crossings are picked out, of which 16 pairs are identified as sector boundaries. Of the remainder, 12 pairs are transient structures both at Venus and Earth, and 14 pairs are sector boundaries at one site and have transient structures at the other site. It implies that transient structures were often ejected from the coronal streamer belt around the solar maximum. For the 16 pairs of selected sector boundaries, we determine their normals by using minimum variance analysis. It is found that most of the normal azimuthal angles are distributed between the radial direction and the direction perpendicular to the spiral direction both at Venus and Earth. The normal elevations tend to be smaller than ~ 45° with respect to the solar equatorial plane, indicating high inclinations of the heliospheric current sheet, in particular at Earth. The larger scatter in the azimuth and elevation of normals at Venus than at Earth suggests stronger effects of the small-scale structures on the current sheet at 0.72 AU than at 1 AU. When the longitude difference between Venus and Earth is small (<40° longitudinally, similar or the same inclinations are generally observed, especially for the sector boundaries without small-scale structures. This implies that the heliospheric current sheet inclination tends to be maintained during propagation of the solar wind from 0.72 AU to 1 AU. Detailed case studies reveal that the dynamic nature of helmet streamers causes variations of the sector boundary structure.

    Key words. Interplanetary physics (interplanetary magnetic fields; sources of solar wind

  4. 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 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

  5. 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

  6. Dynamics of the Venus ionosphere. Final technical report, 1 January 1985-31 May 1988

    International Nuclear Information System (INIS)

    Data from the Pioneer-Venus orbiter has demonstrated the importance of understanding ion dynamics in the Venus ionosphere. The analysis of the data has shown that during solar maximum the topside Venus ionosphere in the dark hemisphere is generated almost entirely on the dayside of the planet during solar maximum, and flows with supersonic velocities across the terminator into the nightside. The flow field in the ionosphere is mainly axially-symmetric about the sun-Venus axis, as are most measured ionospheric quantities. The primary data base used consisted of the ion velocity measurements made by the RPA during three years that periapsis of the orbiter was maintained in the Venus ionosphere. Examples of ion velocities were published and modeled. This research examined the planetary flow patterns measured in the Venus ionosphere, and the physical implications of departures from the mean flow

  7. The VENUS/NWChem Software Package. Tight Coupling Between Chemical Dynamics Simulations and Electronic Structure Theory

    Energy Technology Data Exchange (ETDEWEB)

    Lourderaj, Upakarasamy; Sun, Rui; 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. 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 which 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.

  8. High expression of lifeact in Arabidopsis thaliana reduces dynamic reorganization of actin filaments but does not affect plant development

    OpenAIRE

    Honing, H.S., van der; Bezouwen, L., van; Emons, A.M.C.; Ketelaar, T.

    2011-01-01

    Lifeact is a novel probe that labels actin filaments in a wide range of organisms. We compared the localization and reorganization of Lifeact:Venus-labeled actin filaments in Arabidopsis root hairs and root epidermal cells of lines that express different levels of Lifeact: Venus with that of actin filaments labeled with GFP:FABD2, a commonly used probe in plants. Unlike GFP:FABD2, Lifeact:Venus labeled the highly dynamic fine F-actin in the subapical region of tip-growing root hairs. Lifeact:...

  9. 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 ...

  10. The EvolVe mission concept - unveiling the evolution of Venus

    Science.gov (United States)

    Koronczay, D.; Bailey, R.; Bertone, S.; Credendino, S.; Kleinschneider, A. M.; Lanzky, M.; ?osiak, A.; Marcenat, C.; Martin, P.; Muñoz Elorza, I.; Neidhart, T.; Rexer, M.; Wirnsberger, H.

    2015-10-01

    Venus and Earth are similar in size, bulk composition and distance from the Sun; both are located within the habitable zone. Nevertheless, their surface conditions reveal that they are two very different worlds; Venus, unlike Earth, cannot support life on its surface.The aim of this mission is to determine how and why Venus evolved so differently by exploring its past and present geologic activity. The concept was designed by young scientists and engineers during Alpbach Summer School 2014.

  11. Mission Sizing and Trade Studies for Low Ballistic Coefficient Entry Systems to Venus

    Science.gov (United States)

    Dutta, Soumyo; Smith, Brandon; Prabhu, Dinesh; Venkatapathy, Ethiraj

    2012-01-01

    The U.S and the U.S.S.R. have sent seventeen successful atmospheric entry missions to Venus. Past missions to Venus have utilized rigid aeroshell systems for entry. This rigid aeroshell paradigm sets performance limitations since the size of the entry vehicle is constrained by the fairing diameter of the launch vehicle. This has limited ballistic coefficients (beta) to well above 100 kg/m2 for the entry vehicles. In order to maximize the science payload and minimize the Thermal Protection System (TPS) mass, these missions have entered at very steep entry flight path angles (gamma). Due to Venus thick atmosphere and the steep-gamma, high- conditions, these entry vehicles have been exposed to very high heat flux, very high pressures and extreme decelerations (upwards of 100 g's). Deployable aeroshells avoid the launch vehicle fairing diameter constraint by expanding to a larger diameter after the launch. Due to the potentially larger wetted area, deployable aeroshells achieve lower ballistic coefficients (well below 100 kg/m2), and if they are flown at shallower flight path angles, the entry vehicle can access trajectories with far lower decelerations (50-60 g's), peak heat fluxes (400 W/cm2) and peak pressures. The structural and TPS mass of the shallow-gamma, low-beta deployables are lower than their steep-gamma, high-beta rigid aeroshell counterparts at larger diameters, contributing to lower areal densities and potentially higher payload mass fractions. For example, at large diameters, deployables may attain aeroshell areal densities of 10 kg/m2 as opposed to 50 kg/m2 for rigid aeroshells. However, the low-beta, shallow-gamma paradigm also raises issues, such as the possibility of skip-out during entry. The shallow-gamma could also increase the landing footprint of the vehicle. Furthermore, the deployable entry systems may be flexible, so there could be fluid-structure interaction, especially in the high altitude, low-density regimes. The need for precision in guidance, navigation and control during entry also has to be better understood. This paper investigates some of the challenges facing the design of a shallow-gamma, low-beta entry system.

  12. Comparisons of Selected Atmospheric Escape Mechanisms on Venus, Mars and Titan

    Science.gov (United States)

    Hartle, R. E.; Sittler, E. C.

    2008-01-01

    The similarities and differences of the escape mechanisms for H+ and D+ from Venus, H+ and D+ from Mars, and heavier ions (approximately 17 and approximately 28 amu) from Titan are described. The dominant escape process for hydrogen and deuterium on Venus is thought to originate in the night side ionosphere, located in the night side H and D bulge region, where the polarization electric field is the dominant force accelerating ionospheric H+ and D+ upward into the induced magnetic tail of Titan. The resulting loss rates approximately 8.6 x 10(exp26)/s and approximately 3.2 x 10(exp 23)/s for H+ and D+, respectively, are consistent with the large observed D/H ratio - 160 times that of terrestrial water and an ancient ocean more than 10 m of liquid uniformly distributed on the surface. In contrast, Jeans escape is the dominant loss mechanism for H and D on Mars, which has a D/H ratio approximately 5.3 times that of terrestrial water. The resulting loss rates for H and D of approximately 3.7 x 10(exp 26/s and approximately 10(exp 22)/s, respectively, can be related to possible ancient water reservoirs below the surface. When horizontal atmospheric winds are taken into account, the Jeans escape rates for H and D are enhanced considerably, as are the corresponding water reservoirs. On Titan, 28 amu ions were observed to escape along its induced magnetic tail by the Voyager 1 Plasma Science Instrument (PLS). In analogy with Venus, the escaping ions were thought to originate in the ionosphere. The Cassini mission permits a test of this principle due to the numerous flybys of Titan through both the ionosphere and the tail. A polarization electric field is obtained in the ionosphere of the TA flyby, yielding an upward acceleration of 17 and 28 amu ionospheric ions that is consistent with the flux of heavy ionospheric ions observed escaping along the magnetic tail by the Cassini Ion Mass Spectrometer (CAPS) during the T9 flyby.

  13. THE UPPER CLOUDS OF VENUS - DETERMINATION OF THE SCALE HEIGHT FROM NIMS-GALILEO INFRARED DATA

    OpenAIRE

    Roos, M; Drossart, P.; ENCRENAZ, T; Lellouch, E; BEZARD, B; Carlson, R; Baines, K; Kamp, L.; Taylor, F.; Collard, A; Calcutt, S; POLLACK, J; Grinspoon, D

    1993-01-01

    The 3-5 ?m thermal emission of the nightside of Venus, recorded by the NIMS instrument at the time of the Galileo flyby of Venus, is analysed to infer the properties of the upper cloud boundary. From the global maps of Venus at fixed wavelengths, the limb darkening of the flux is measured at several latitudes, within each infrared channel. By using the nominal Pioneer Venus thermal profile, these data give access to two parameters: the cloud deck temperature and the cloud scale height. It is ...

  14. The evaluation of preliminary extrapolation experimental results of the chinese ADS subcritical experimental assembly venus-1

    International Nuclear Information System (INIS)

    The design objectives and structure of' the Chinese accelerator-driven subcritical system (ADS) subcritical assembly VENUS-1 are presented. The experiment of source multiplication method is used to determine the final loading of the Chinese ADS VENUS-i subcritical assembly. The Keff of the assembly with the same loading as extrapolation experiment have been calculated. The results of calculation and experiment are evaluated. The final loading of the Chinese ADS VENUS-1 subcritical assembly has been determined by preliminary experiments on VENUS-1. (authors)

  15. The 1986 eastern (evening) apparition of the planet Venus - Visual and photographic observations

    International Nuclear Information System (INIS)

    This report summarizes visual and photographic observations of the planet Venus for the 1986 eastern (evening) apparition, based on an extensive analysis of data submitted by ALPO Venus Section observers in the U.S. and three other countries. Sources of data and the instruments used in acquiring information about Venus are emphasized, with a statistical analysis of the categories of features seen or suspected in the atmosphere of Venus at visual wavelengths, both in integrated light and with color filters. A similar treatment is given to the cusps, cusp-caps, and cusp-bands, together with a discussion of dark-hemisphere phenomena, including the ashen light. 5 refs

  16. Magellan - Early results from the Venus mapping mission

    International Nuclear Information System (INIS)

    Some results obtained with the Magellan Venus Radar Mapper are presented. Mapping was initiated on October 26, 1990 and has completed over 714 orbits of image data, covering 40 percent of the surface of Venus. Mapping began at 330 deg east longitude, mapping from the north pole to about 78 deg south latitude. Included are the regions of Ishtar Terra, Sedna, Guinevere and Lavinia Planitiae, and Lada Terra. Features discernable from the mapping include high and lowland plains, evidence of volcanic activity, and impact craters from 6 km to over 50 km across. Some Magellan scientific discoveries are listed, including evidence of a predominant role of ballistic volcanism, extensive and intensive tectonics, a moderate rate of volcanic and tectonic resurfacing, and a low rate of weathering and wind erosion. Other discoveries concerning techntonics, volcanism, impact cratering, and exogenous resurfacing are also listed. Magellan image coverage is discussed, and a chronology of the development of VOIR and Magellan is provided

  17. The depths of the largest impact craters on Venus

    Science.gov (United States)

    Ivanov, B. A.; Ford, P. G.

    1993-01-01

    The largest impact craters on Venus may be used as evidence of various geological processes within the Venusian crust. We are continuing to construct a data base for the further investigation of large craters on Venus (LCV). We hope to find evidence of crater relaxation that might constrain the thickness and thermal gradient of the crust, as was proposed in an earlier work. The current work concentrates on 27 impact craters with diameters (d) larger than 70 km, i.e., large enough that the footprint of the Magellan altimeter has a good chance of sampling the true crater bottom. All altimeter echoes from points located within (d/2)+70 km from the crater center have been inspected.

  18. VenLA: The LATMOS Venus cloud model

    Science.gov (United States)

    Määttänen, A.; Guilbon, S.; Stolzenbach, A.; Bekki, S.; Montmessin, F.

    2015-10-01

    The LATMOS Venus cloud model VenLA (Venus Liquid Aerosols) is based on a terrestrial Polar Stratospheric Cloud (PSC) model [7]. VenLA models the formation, growth and decay of sulfuric acid - water droplets. The model has undergone several updates. We will present results of reference runs and sensitivity tests based on input profiles from VIRA [5] for temperature and pressure and from occultation data concerning the vapors, as in [8]. We compare the results to the available observations on cloud particle number densities and sizes, and to other modeling studies. The VenLA model will define the baseline for a parallel project on development of a moment method scheme to be used in a global climate model (see abstract Guilbon et al., this conference [2]).

  19. Interpretation of gravitational anomalies on Mars, Venus and Earth

    Science.gov (United States)

    Tarakanov, Y. A.; Kambarov, N. S.; Prikhodko, V. A.; Bondarenko, D. R.

    1984-06-01

    Findings based on gravimetric observations that relate to gravitational anomalies on Mars, Venus, and Earth are presented. Results for the three planets were compared. Interpretation of the results was based on Stokes constants using figures for field characteristics in a finite number of isolated points. Details of interpretation of gravitational anomalies are given for each of three plants. The main conclusions are: there is substantial difference in the structure and nature of compression on the three planets, the Earth's lithosphere is sufficiently thin and flexible to retain the shape of a hydrostatic balanced body, the probable source of gravitational anomalies on Venus is variation in the depth of the second-phase mantle boundary, and 11 of the 13 major anomalies detected on Mars result from irregularities in the lithosphere-mantle disjunction.

  20. Mantle differentiation and thermal evolution of Mars, Mercury, and Venus

    International Nuclear Information System (INIS)

    In the present models for the thermal evolution of Mercury, Venus, and Mars encompass core and mantle chemical differentiation, lithospheric growth, and volcanic heat-transfer processes. Calculation results indicate that crust and lithosphere thicknesses are primarily dependent on planet size as well as the bulk concentration of planetary radiogenic elements and the lithosphere's thermal conductivity. The evidence for Martian volcanism for at least 3.5 Gyr, and in Mercury for up to 1 Gyr, in conjunction with the presence of a magnetic field on Mercury and its absence on Mars, suggest the dominance of a lithospheric conduction heat-transfer mechanism in these planets for most of their thermal history; by contrast, volcanic heat piping may have been an important heat-transfer mechanism on Venus. 50 refs

  1. Dynamics, winds, circulation and turbulence in the atmosphere of Venus

    International Nuclear Information System (INIS)

    With the possible exception of the lowest one or two scale heights, the dominant mode of circulation of Venus' atmosphere is a rapid, zonal, retrograde motion. Global albedo variations in the ultraviolet may reflect planetary scale waves propagating relative to the zonal winds. Other special phenomena such as cellular convection in the subsolar region and internal gravity waves generated in the interaction of the zonal circulation with the subsolar disturbance may also be revealed in ultraviolet imagery of the atmosphere. The contributions of experiments on the Orbiter and Entry Probes of Pioneer Venus toward unravelling the mystery of the planet's global circulation and the role played by waves, instabilities and convection therein are discussed. (Auth.)

  2. Venus: review of present understanding of solar wind interaction

    International Nuclear Information System (INIS)

    The results of Soviet and American spacecraft plasma and magnetic experiments show that a bow shock of Venus forms as a result of the direct interaction of the solar wind with the ionsphere. The shape and the position of the Venus bow shock, in general, correpond to a very weak dissipation of solar wind energy in the ionosphere. The measured magnetic field near the planet is strongly influenced by IMF; this fact is evidence of an induced magnetosphere. Some results of laboratory simulation and computer experiments are also in favor of such an induced magnetosphere. The interaction with the ionosphere manifests itself in the existence of a boundary region on the nightside where solar wind entry into the optical umbra of the planet is observed. (Auth.)

  3. Earthlike planets: Surfaces of Mercury, Venus, earth, moon, Mars

    Science.gov (United States)

    Murray, B.; Malin, M. C.; Greeley, R.

    1981-01-01

    The surfaces of the earth and the other terrestrial planets of the inner solar system are reviewed in light of the results of recent planetary explorations. Past and current views of the origin of the earth, moon, Mercury, Venus and Mars are discussed, and the surface features characteristic of the moon, Mercury, Mars and Venus are outlined. Mechanisms for the modification of planetary surfaces by external factors and from within the planet are examined, including surface cycles, meteoritic impact, gravity, wind, plate tectonics, volcanism and crustal deformation. The origin and evolution of the moon are discussed on the basis of the Apollo results, and current knowledge of Mercury and Mars is examined in detail. Finally, the middle periods in the history of the terrestrial planets are compared, and future prospects for the exploration of the inner planets as well as other rocky bodies in the solar system are discussed.

  4. Could plate tectonics on Venus be concealed by volcanic deposits

    Science.gov (United States)

    Kaula, W. M.; Muradian, L. M.

    1982-01-01

    The present investigation is supplementary to a study reported by Kaula and Phillips (1981). From an analysis of Pioneer Venus altimetry, Kaula and Phillips had inferred that any heat loss from the planet by plate tectonics must be small compared to that from the earth. However, it has been suggested by others that plate tectonic may exist on Venus, but that the expected 'square root of s' dependence of the topographic drop off is not observed because it is concealed by lava flows. The present investigation has the objective to conduct an examination whether this suggestion of concealment by lava flow is correct. On the basis of the performed analysis, it is concluded that the results obtained by Kaula and Phillips appear to be well justified.

  5. Kepler, Horrocks and the Transit of Venus in 1639

    Science.gov (United States)

    Posch, Thomas; Kerschbaum, Franz

    2004-08-01

    Kepler was the first astronomer to predict a transit of Venus in his 'Admonitio' from 1629. This prediction was based on his 'Rudolphine Tables', published three years before. Even though both works - making use of his ground-breaking new theory of the planetary motions - and the message of his 'Admonitio' are a great achievement, it turned out some years later that the latter contained some views that needed to be corrected. First of all, there was a small but -- for European observers -- fatal error concerning the exact time of the Venus transit of 1631, leading to its non-observation in Paris. Second, Kepler failed to predict the 1639 Venus transit. It was the English astronomer Horrocks who first recognized this and who did indeed observe the latter. Third, Kepler's ideas about the size of the solar system (and, hence, the apparent diameters of the planets) were substantially wrong. In our contribution, we analyze the historical background to these errors of a genius, based on his original texts, as well as Horrocks' and Hevelius' views and discoveries on the subject. It seems that Hevelius' annotated edition of Horrocks' account 'Venus in sole visa' has scarcely been studied in the way it would deserve -- which is maybe due to the fact that only a few libraries are still in possession of this book. There is little doubt that Kepler, had he lived until 1639, would have had to change his views on the proportions of our solar system dramatically. At the same time, it should be stressed that his predition and Horrocks' observations demonstrate that knowing the mechanism of the planetary motions is by far more important than knowing the actual size of the planetary orbits and planetary bodies.

  6. On reconstructing trajectories in the Venus lower atmosphere

    Science.gov (United States)

    Argentiero, P.; Wyatt, G.

    1972-01-01

    A Monte Carlo technique was utilized in order to demonstrate the feasibility of processing in situ measurements of temperature, pressure, and molecular weight. The technique assumes that the lower atmosphere of Venus obeys the ideal gas law and the hydrostatic equation. Time correlations are assumed to exist in the data. It is shown that the errors in trajectory reconstruction are due mostly to noise in the data rather than to inaccuracies in the numerical technique.

  7. Geologic Map of the Mylitta Fluctus Quadrangle (V-61), Venus

    Science.gov (United States)

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

    2006-01-01

    INTRODUCTION The Magellan Mission The Magellan spacecraft orbited Venus from August 10, 1990, until it plunged into the Venusian atmosphere on October 12, 1994. Magellan Mission objectives included: (1) improving knowledge of the geological processes, surface properties, and geologic history of Venus by analysis of surface radar characteristics, topography, and morphology, and (2) improving the knowledge of the geophysics of Venus by analysis of Venusian gravity. The Magellan spacecraft carried a 12.6-cm radar system to map the surface of Venus. The transmitter and receiver systems were used to collect three data sets: (1) synthetic aperture radar (SAR) images of the surface, (2) passive microwave thermal emission observations, and (3) measurements of the backscattered power at small angles of incidence, which were processed to yield altimetric data. Radar imaging, altimetric, and radiometric mapping of the Venusian surface was done in mission cycles 1, 2, and 3 from September 1990 until September 1992. Ninety-eight percent of the surface was mapped with radar resolution on the order of 120 meters. The SAR observations were projected to a 75-m nominal horizontal resolution, and these full-resolution data compose the image base used in geologic mapping. The primary polarization mode was horizontal-transmit, horizontal-receive (HH), but additional data for selected areas were collected for the vertical polarization sense. Incidence angles varied between about 20? and 45?. High resolution Doppler tracking of the spacecraft took place from September 1992 through October 1994 (mission cycles 4, 5, 6). Approximately 950 orbits of high-resolution gravity observations were obtained between September 1992 and May 1993 while Magellan was in an elliptical orbit with a periapsis near 175 km and an apoapsis near 8,000 km. An additional 1,500 orbits were obtained following orbit-circularization in mid-1993. These data exist as a 75? by 75? harmonic field.

  8. A bulk cloud parameterization in a Venus General Circulation Model

    OpenAIRE

    LEE, C; Lewis, SR; Read, PL

    2010-01-01

    A condensing cloud parameterization is included in a super-rotating Venus General Circulation Model. A parameterization including condensation, evaporation and sedimentation of mono-modal sulfuric acid cloud particles is described. Saturation vapor pressure of sulfuric acid vapor is used to determine cloud formation through instantaneous condensation and destruction through evaporation, while pressure dependent viscosity of a carbon dioxide atmosphere is used to determine sedimentation rates ...

  9. Evidence for dust accumulation just outside the orbit of Venus

    OpenAIRE

    Leinert, Ch.; Moster, B.

    2007-01-01

    To contribute to the knowledge of dynamics of interplanetary dust we are searching for structures in the spatial distribution of interplanetary dust near the orbit of Venus. To this end we study the radial gradient of zodiacal light brightness, as observed by the zodiacal light photometer on board the Helios space probes on several orbits from 1975 to 1979. The cleanest data result from Helios B (= Helios 2) launched in January 1976. With respect to the general increase of z...

  10. Venus Atmosphere Profile from a Maximum Entropy Principle

    OpenAIRE

    L. N. Epele; H. Fanchiotti; García Canal, C. A.; A.F. Pacheco; J. Sañudo

    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 ...

  11. 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...

  12. CO2-Reduction Primary Cell for Use on Venus

    Science.gov (United States)

    West, William; Whitacre, Jay; Narayanan, Sekhanipuram

    2007-01-01

    A document proposes a CO2-reduction primary electrochemical cell as a building block of batteries to supply electric power on the surface of Venus. The basic principle of the proposed cell is similar to that of terrestrial Zn-air batteries, the major differences being that (1) the anode metal would not be Zn and (2) CO2, which is about 96.5 mole percent of the Venusian atmosphere, would be used, instead of O2, as the source of oxygen.

  13. 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...

  14. Rebus-PWR. International programme at the VENUS critical facility

    International Nuclear Information System (INIS)

    The main objective of the REBUS-PWR programme is to establish an experimental benchmark database for validation of reactor physics codes, for the calculation of the loss of reactivity due to burnup for PWR (and BWR) fuel both for UO2 and MOX fuel bundles. In June 2003, an irradiated BR3 MOX bundle was loaded in the VENUS reactor. A complete experimental programme associated with this first irradiated configuration was successfully completed

  15. Crustal thickness and support of topography on Venus

    OpenAIRE

    James, Peter Benjamin; Zuber, Maria; Phillips, Roger J.

    2012-01-01

    The topography of a terrestrial planet can be supported by several mechanisms: (1) crustal thickness variations, (2) density variations in the crust and mantle, (3) dynamic support, and (4) lithospheric stresses. Each of these mechanisms could play a role in compensating topography on Venus, and we distinguish between these mechanisms in part by calculating geoid-to-topography ratios and apparent depths of compensation. By simultaneously inverting for mass anomalies at two depths, we solve fo...

  16. Background heatflow on hotspot planets - Io and Venus

    Science.gov (United States)

    Stevenson, David J.; Mcnamara, Sean C.

    1988-01-01

    It is suggested that there is no simple relationship between lithospheric thickness and heatflow on planets where volcanism dominates the heatflow. This applies locally and globally, even away from regions of volcanic activity. This indicates that there is no basis for the assumption that the Io heatflow is as low as (or lower than) the hotspot component alone would suggest. A model is presented to describe the heatflow on hotspot planets. The model is applied to Io and Venus.

  17. Glory revealed in disk-integrated photometry of Venus

    OpenAIRE

    Muñoz, A. García; Pérez-Hoyos, S.; 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....

  18. Performance of the VENUS lead-glass calorimeter at TRISTAN

    International Nuclear Information System (INIS)

    The initial performance of the VENUS barrel electromagnetic calorimeter at TRISTAN is described. The calorimeter is composed of 5160 lead-glass counters in a semi-tower arrangement. An energy resolution of 3.8% was obtained for 26 GeV Bhabha events. The neutral pions in the hadronic events were reconstructed with a mass resolution of ?=16 MeV. The gain of the lead-glass counters was stable within 2% during a four months operation at TRISTAN. (orig.)

  19. Geologic map of the Pandrosos Dorsa Quadrangle (V-5), Venus

    Science.gov (United States)

    Rosenberg, Elizabeth; McGill, George E.

    2001-01-01

    Introduction The Magellan spacecraft orbited Venus from August 10, 1990, until it plunged into the Venusian atmosphere on October 12, 1994. Magellan had the objectives of (1) improving knowledge of the geologic processes, surface properties, and geologic history of Venus by analysis of surface radar characteristics, topography, and morphology and (2) improving knowledge of the geophysics of Venus by analysis of Venusian gravity. The Magellan spacecraft carried a 12.6-cm radar system to map the surface of Venus. The transmitter and receiver systems were used to collect three datasets: synthetic aperture radar (SAR) images of the surface, passive microwave thermal emission observations, and measurements of the backscattered power at small angles of incidence, which were processed to yield altimetric data. Radar imaging and altimetric and radiometric mapping of the Venusian surface were done in mission cycles 1, 2, and 3, from September 1990 until September 1992. Ninety-eight percent of the surface was mapped with radar resolution of approximately 120 meters. The SAR observations were projected to a 75-m nominal horizontal resolution; these full-resolution data compose the image base used in geologic mapping. The primary polarization mode was horizontal-transmit, horizontal-receive (HH), but additional data for selected areas were collected for the vertical polarization sense. Incidence angles varied from about 20? to 45?. High-resolution Doppler tracking of the spacecraft was done from September 1992 through October 1994 (mission cycles 4, 5, 6). High-resolution gravity observations from about 950 orbits were obtained between September 1992 and May 1993, while Magellan was in an elliptical orbit with a periapsis near 175 kilometers and an apoapsis near 8,000 kilometers. Observations from an additional 1,500 orbits were obtained following orbitcircularization in mid-1993. These data exist as a 75? by 75? harmonic field.

  20. 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.