WorldWideScience
1

Life after Venus Express: Science goals for a European Venus radar orbiter  

Science.gov (United States)

ESA’s Venus Express mission has led to a renaissance of Venus science, following a dearth of Venus missions in the previous 15 years. Venus Express has made many discoveries in atmospheric science, for which its payload was optimised; however it has also provided tantalising hints about the geological activity of the planet. Mesospheric sulphur dioxide abundances vary by 1000% on decadal timescales, in a pattern which suggests episodic volcanic injections [Marcq et al. Nature Geosci 2013; Esposito, Science 1984]; anomalous emissivity near suggest volcanic hotspots implies geologically recent, as-yet-unweathered lava flows [Smrekar et al., Science 2010]; and recent results, if confirmed, show temporal evolution of thermal emission from some regions of the surface may be direct evidence of volcanic activity during the duration of the VEx mission [Shalygin et al., LPSC 2014]. While there are more results to be obtained yet from the Venus Express dataset, further investigation of these phenomena will require a new Venus mission. We therefore propose an orbiter mission focussed on characterising the geological activity of Venus. The key instrument would be a Synthetic Aperture Radar (SAR). Why a radar mission following NASA’s Magellan mission? Radar capabilities are vastly improved in the last 30 years and a modern radar would be capable of spatial resolution approaching two orders of magnitude better than that from Magellan; this enables a wide range of investigations, from detailed study of tectonic, volcanic and Aeolian features, to stratigraphy for better reconstruction of geological epochs. Interferometric SAR could also be used to study the centimetre-scale surface deformations due to current volcanic or tectonic activity. Constraints on interior structure can be obtained not only from improved gravity mapping (from spacecraft tracking) but also by studying the spin state of Venus from high-resolution radar measurements. The radar measurements will be complemented by a further suite of instruments which may include a dedicated surface emission mapper using near-infrared spectral windows; a spectrometer suite to map sulphur dioxide and other possibly volcanic gases; and possibly a subsurface sounding radar to reveal the structure of lava flows and other surface structures. This mission, following on from the 2007 EVE [Chassefière et al., Exp. Astron 2009] and 2010 Envision [Ghail et al., Exp. Astron 2012] proposals, is being developed for proposal to ESA as a “Medium-class” mission in late 2014.

Wilson, Colin; Ghail, Richard

2

Venus Express—The first European mission to Venus  

Science.gov (United States)

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 fields. Venus Express will enable a breakthrough in Venus science after a long period of silence since the period of intense exploration in the 1970s and the 1980s. The payload consists of seven instruments. Five of them were inherited from the Mars Express and Rosetta projects while two instruments were designed and built specifically for Venus Express. The suite of spectrometers and imaging instruments, together with the radio-science experiment, and the plasma package make up an optimised payload well capable of addressing the mission goals to sufficient depth. Several of the instruments will make specific use of the spectral windows at infrared wavelengths in order to study the atmosphere in three dimensions. The spacecraft is based on the Mars Express design with minor modifications mainly needed to cope with the thermal environment around Venus, and so a very cost-effective mission has been realised in an exceptionally short time. The spacecraft was launched on 9 November 2005 from Baikonur, Kazakhstan, by a Russian Soyuz-Fregat launcher and arrived at Venus on 11 April 2006. Venus Express will carry out observations of the planet from a highly elliptic polar orbit with a 24-h period. In 3 Earth years (4 Venus sidereal days) of operations, it will return about 2 Tbit of scientific data. Telecommunications with the Earth is performed by the new ESA ground station in Cebreros, Spain, while a nearly identical ground station in New Norcia, Australia, supports the radio-science investigations.

Svedhem, H.; Titov, D. V.; McCoy, D.; Lebreton, J.-P.; Barabash, S.; Bertaux, J.-L.; Drossart, P.; Formisano, V.; Häusler, B.; Korablev, O.; Markiewicz, W. J.; Nevejans, D.; Pätzold, M.; Piccioni, G.; Zhang, T. L.; Taylor, F. W.; Lellouch, E.; Koschny, D.; Witasse, O.; Eggel, H.; Warhaut, M.; Accomazzo, A.; Rodriguez-Canabal, J.; Fabrega, J.; Schirmann, T.; Clochet, A.; Coradini, M.

2007-10-01

3

Venus express - The first European mission to Venus  

OpenAIRE

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...

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

2007-01-01

4

Venus Atmospheric Circulation: Update after Venus Express  

Science.gov (United States)

Venus Express orbiter has provided new insights into the atmospheric circulation of Venus from its very first observation from the insertion orbit on 12 April 2006 and has continued until now. The very first observation showed the complete vortex organization of the circulation on day and night side in a single image. By summer 2014, the spacecraft will have observed the planet for slightly more than half a solar cycle, during which the strength of this circulation has been observed to vary, suggesting periodic activity. Global cloud morphology, cloud motions from visible and infrared images from Venus Monitoring Camera (VMC) and the Visible InfraRed Imaging Spectrometer (VIRTIS) have yielded information about the variability of the atmospheric superrotation near and slightly below the cloud top level. Deduced balanced flow from the radio occultation temperature profiles indicate high vertical shear in certain layers and faster balanced zonal flow. Gradual increase in the day side cloud latitudinally averaged cloud motions is observed, but it is not known whether this is an artifact of the limited data or actual changes in the atmospheric circulation. Small scale gravity waves have been observed at high latitudes at the cloud tops and show some preferred regions (Ishtar Terra) for their occurrence. Other gravity waves have also been observed in mid-latitude near the peak zonal or angular speed of the clouds. Much remains unknown about the processes that maintain this circulation. Several numerical circulation efforts are making progress, but no confirmation or improved estimates of meridional momentum transport are available from the observations at hand. An effort is being organized to arrive at a synthesis picture of the atmospheric circulation to reflect both Doppler observations of line-of-sight flow above the clouds and the Venus Express observations in the cloud region.

Limaye, Sanjay

5

Europe Goes to the Venus - The Journey of Venus Express  

Science.gov (United States)

On 9th November 2005, a Russian Soyuz-Fregat launcher boosted Venus Express into space from the Baikonur cosmodrome, in Kazakhstan. The spacecraft reached its final destination 5 months later, on 11th April 2006, after a journey of 440 millions of kilometres in the solar system. It fired its main engine during 49 minutes and slowed down to be captured into orbit around the planet. A series of manoeuvres then led the spacecraft to its operational orbit, circling the poles with a period of 24h along a highly elliptical orbit, with an altitude between 250 km and 66,000 km. It has then undertaken the most comprehensive study ever of the Venusian atmosphere, over a period of at least 2 Venus sidereal days (486 days). Venus Express is the first European mission to Earth's twin, only two years after Mars Express, the first ESA mission to Mars. It was developed in less than 4 years from concept to launch, which also makes it the fastest ESA Science mission ever done. The global budget of the mission is 220 millions Euro, covering development of the spacecraft, launch and operations.

Fabrega, J.; Schirmann, T.; McCoy, D.; Sivac, P.

6

Lunar and Planetary Science XXXV: Venus  

Science.gov (United States)

The session "Venus" included the following reports:Preliminary Study of Laser-induced Breakdown Spectroscopy (LIBS) for a Venus Mission; Venus Surface Investigation Using VIRTIS Onboard the ESA/Venus Express Mission; Use of Magellan Images for Venus Landing Safety Assessment; Volatile Element Geochemistry in the Lower Atmosphere of Venus; Resurfacing Styles and Rates on Venus: Assessment of 18 Venusian Quadrangles; Stereo Imaging of Impact Craters in the Beta-Atla-Themis (BAT) Region, Venus; Depths of Extended Crater-related Deposits on Venus ; Potential Pyroclastic Deposit in the Nemesis Tessera (V14) Quadrangle of Venus; Relationship Between Coronae, Regional Plains and Rift Zones on Venus, Preliminary Results; Coronae of Parga Chasma, Venus; The Evolution of Four Volcano/Corona Hybrids on Venus; Calderas on Venus and Earth: Comparison and Models of Formation; Venus Festoon Deposits: Analysis of Characteristics and Modes of Emplacement; Topographic and Structural Analysis of Devana Chasma, Venus: A Propagating Rift System; Anomalous Radial Structures at Irnini Mons, Venus: A Parametric Study of Stresses on a Pressurized Hole; Analysis of Gravity and Topography Signals in Atalanta-Vinmara and Lavinia Planitiae Canali are Lava, Not River, Channels; and Formation of Venusian Channels in a Shield Paint Substrate.

2004-01-01

7

Venus Express Italian Day on 4 October  

Science.gov (United States)

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

2004-09-01

8

Thermal structure of Venus atmosphere from Venus Express observations  

Science.gov (United States)

The thermal structure of Venus atmosphere has been investigated since the early 1960s by several groundbased campaigns and spacecraft missions, such as Pioneer Venus (PV) orbiter [1], PV probes [2], Galileo flyby [3], Venera 15 and 16 [4]. Based on these early and sparse observations, a Venus International Reference Atmosphere (VIRA) model was published in 1983 [5]. The VIRA model splits the atmosphere into three different dynamical regions: (1) the lower atmosphere, from the surface to the upper cloud top (˜ 70 km), (2) the middle atmosphere, extending between the cloud tops and 110 km, and (3) the upper atmosphere, above ~110 km. Vertical temperature profiles below 40 km of altitude are quite similar over the entire planet, with latitudinal and local time variations less than 5 K. On the other hand, the thermal structure of the middle and upper atmosphere shows a significant variability with latitude and local time. The VIRA model presents an atmosphere temperature that decreases from values of ˜ 240 K at the cloud top to 170 K at ˜ 90 ? 100 km altitudes on the dayside of the planet and reaching minimum values of less than 120 K during the nighttime in the upper atmosphere[5]. More recently, several experiments on board the European mission to Venus, Venus Express (VEx) [6], and ground-based campaigns [7,8,9] have extensively studied the thermal structure of Venus upper atmosphere over a long time scale revealing a far more complex situation. Three different methods are used to sound remotely atmospheric temperatures: (1) the VeRa radio occultation instrument studies the upper troposphere/mesosphere (40 - 90 km) of both the north and south hemispheres with a vertical resolution of ~500 m [10,11]; (2) the nightside mesosphere (60 - 90 km) is investigated also by VIRTIS thermal emission spectroscopy [12,13]; (3) finally, SPICAV-SOIR stellar/solar occultations sound Venus upper atmosphere (70 - 150 km altitude) on the nightside and at the terminator [14,15,16]. Together, these three techniques sound Venus atmosphere in the altitude range from 40 km up to 150 km with different altitude coverage, resolution, temporal and spatial sampling. Observations acquired by these experiments will be compared and their differences and similarities will be analyzed with the main goal to improve and update the reference model of Venus atmosphere.

Bertaux, J. L.; Drossart, P.; Grassi, D.; Häusler, B.; Mahieux, A.; Migliorini, A.; Montmessin, F.; Pätzold, M.; Piccialli, A.; Piccioni, G.; Tellmann, S.; Vandaele, A. C.; Wilquet, V.

2014-04-01

9

Scientific goals for the observation of Venus by VIRTIS on ESA/Venus express mission  

OpenAIRE

The Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) on board the ESA/Venus Express mission has technical specifications well suited for many science objectives of Venus exploration. VIRTIS will both comprehensively explore a plethora of atmospheric properties and processes and map optical properties of the surface through its three channels, VIRTIS-M-vis (imaging spectrometer in the 0.3-1 ?m range), VIRTIS-M-IR (imaging spectrometer in the 1-5 ?m range) and VIRTIS-H (aperture hig...

Drossart, P.; Piccioni, G.; Adriani, A.; Angrilli, F.; Arnold, G.; Baines, Kh; Bellucci, G.; Benkhoff, J.; Bezard, B.; Bibring, J-p; Blanco, A.; Blecka, Mi; Carlson, Rw; Coradini, A.; Di Lellis, A.

2007-01-01

10

Venus  

Science.gov (United States)

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

Fegley, B., Jr.

11

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

OpenAIRE

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 ...

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

12

A New Method for the Detection of Small-scale Wave-like Features in the Venusian Atmosphere with the Venus Express Radio Science Experiment VeRa  

Science.gov (United States)

Wave structures are common phenomena in planetary atmospheres. Different kind of waves were observed in the thick Venus atmosphere[1,2,3]. Measurements at high temporal and spatial resolution are needed to identify such structures. The Venus Express Radio Science Experiment VeRa observed about 700 vertical profiles of temperature, pressure and neutral number density in the Venus atmosphere. The profiles cover the altitude range between 40km and 90-100km. Variations in the temperature profiles were interpreted as wave structures down to 60km[1]. One kind of waves are gravity waves which propagate vertically in the Venusian atmosphere. One open question is the contribution of topographical features to their formation. VeRa data may clarify wave formation mechanisms for associated altitude regions in particular using occultation open-loop data. The processing of the open-loop data may reveal a spectrum of wave frequencies with the prospect to detect small-scale atmospheric phenomena. Multipath effects remain still a problem in particular within the cloud layer which can only be addressed with open-loop data.

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

2014-04-01

13

A dynamic atmosphere revealed by the Venus Express mission  

Science.gov (United States)

ESA’s Venus Express orbiter has achieved a mission lifetime of eight years, well in excess of its original nominal science mission duration of 500 days. The science payload was selected to focus on atmospheric investigations from the deep atmosphere - probed using near-infrared spectral windows - up to the mesosphere and exosphere. While initial analyses focussed on first detections and mean atmospheric states, subsequent analyses have revealed variability on timescales ranging from diurnal to seasonal to multiannual. In the upper atmosphere, VEx/VIRTIS shows dramatic maps of O_{2} nightglow spatial distribution changing location on scales of minutes to hours, as well as gravity waves high in polar regions high above the core of the polar vortex. Thermospheric and mesospheric densities, revealed through solar and stellar occultation as well as by the VEx Atmospheric Drag Experiment, are observed to vary by over 100% on a day-to-day basis. The Southern polar vortex was revealed to change shape on a day-to-day basis, taking sometimes the previously observed wavenumber-2 shape (“polar dipole”) but changing rapidly also to wavenumber-1 or wavenumber-3 shapes. In the lower / middle cloud layer Venus Express was able to map the formation and dissipation of regions of thin and thick cloud on timescales of hours to days. But it is the long-term changes on periods of several years which are perhaps the most intriguing. Mean zonal wind speed at low latitudes at cloud-top altitude, as revealed by cloud tracking in UV imagery, is found to have increased by 30% over the period 2007-2013. Mesospheric sulphur dioxide abundances were found to increase fourfold during 2006-2008 followed by a tenfold decrease in 2008-2012, echoing a pattern seen earlier from Pioneer Venus and Hubble observations. There may also be associated long-term changes in the UV albedo of Venus - this is still under investigation. But to date no long-term trend has been observed in the abundance of other trace gas species, notably of water vapour, which might be expected to vary alongside mesospheric sulphur dioxide abundances. Explaining this combination of observations provides constraints and challenges for our understanding of the Venus atmosphere. In this presentation we review the highlights of Venus Express atmospheric science results, with particular focus on temporal variability.

Wilson, Colin; Svedhem, Håkan; Drossart, Pierre; Piccioni, Giuseppe; Markiewicz, Wojciech; Pätzold, Martin; Titov, Dmitrij; Bertaux, Jean-Loup

14

Venus  

Science.gov (United States)

Venus is Earth's nearest planetary neighbor, and has fascinated mankind since the dawn of history. Venus' clouds reflect most of the sunlight shining on the planet and make it the brightest object in the sky after the Sun and Moon. Venus is visible with the naked eye as an evening star until a few hours after sunset, or as a morning star shortly before sunrise. Many ancient civilizations observed and worshipped Venus, which had a different name in each society, e.g., Ishtar to the Babylonians, Aphrodite to the Greeks, Tai'pei to the Chinese, and Venus to the Romans (Hunt and Moore, 1982). Venus has continued to play an important role in myth, literature, and science throughout history. In the early seventeenth century, Galileo's observations of the phases of Venus showed that the geocentric (Ptolemaic) model of the solar system was wrong and that the heliocentric (Copernican) model was correct. About a century later, Edmund Halley proposed that the distance from the Earth to the Sun (which was then unknown and is defined as one astronomical unit, AU) could be measured by observing transits of Venus across the Sun. These transits occur in pairs separated by eight years at intervals of 105.5 yr and 121.5 yr in an overall cycle of 243 yr, e.g., June 6, 1761, June 3, 1769; December 9, 1874, December 6, 1882, June 8, 2004, June 6, 2012, December 11, 2117, and December 8, 2125. The first attempted measurements of the astronomical unit during the 1761 transit were unsuccessful. However, several observers reported a halo around Venus as it entered and exited the Sun's disk. Thomas Bergman in Uppsala and Mikhail Lomonosov in St. Petersburg, independently speculated that the halo was due to an atmosphere on Venus. Eight years later observations of the 1769 solar transit (including those made by Captain Cook's expedition to Tahiti) gave a value of 1 AU=153 million kilometers, ~2.3% larger than the actual size (149.6 million kilometers) of the astronomical unit (Woolf, 1959; Maor, 2000).

Fegley, B., Jr.

2003-12-01

15

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

Science.gov (United States)

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.

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

16

The Surface of Venus After VIRTIS on Venus Express: Laboratory Analogs and the Venus Emissivity Mapper  

Science.gov (United States)

A combination of laboratory work and remote sensing will be able to determine the large-scale compositional variations of the surface of Venus and will provide valuable input for any landing site selections for future Venus lander missions.

Ferrari, S.; Helbert, J.; Maturilli, A.; Dyar, D. M.; Mueller, N.; Elkins-Tanton, L. T.

2014-05-01

17

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

Science.gov (United States)

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

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

2004-01-01

18

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

Science.gov (United States)

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,

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

19

Temporal variations of UV reflectivity of Venus observed by the Venus Monitoring Camera onboard Venus Express.  

Science.gov (United States)

The UV channel of the Venus Monitoring Camera (VMC) onboard Venus Express (VEX) detects dark and bright features at the cloud top level all over the globe. This UV contrast is affected by the abundance of an unknown UV absorber, which is located within the upper cloud layer, and the upper haze above the cloud tops (Pollack et al.,1979; Esposito, 1980). The unknown UV absorber is a major sink of solar energy in the Venus middle atmosphere (Crisp, 1986). The upper haze and clouds take part in sulfur photochemical processes in the Venus mesosphere (Mills et al., 2007). At the cloud top altitude the zonal wind speed is highest, resulting in changes in cloud morphology in a few days. Therefore, the features shown in the UV images are diagnostic for atmospheric dynamics and chemistry. By analyzing VMC UV images, we found there is a clear decreasing trend of the global mean albedo by 20-30% over 2000 orbits (=2000 Earth days) of VEX operation. This decrease is driven by changes at high latitudes. This implies that the typical latitudinal albedo distribution, bright polar hood and dark equatorial region, varies over time. The latitudinal difference in albedo changes from a clear brightness gradient from pole to equator to an almost identical brightness in both regions. Interestingly, this temporal variation is similar to that of the SO2 abundance above the cloud tops, observed in the same period (Marcq et al., 2013). This suggests a reduction of SO2 over the equator decreases the amount of upper haze at high latitudes, as less sulfur is supplied by the meridional circulation. We investigate the phase angle dependence of the latitudinal albedo difference, which reveals that the vertical distribution of the UV absorbers and the upper haze varies in time as well. Our results show large scale variations in Venusian atmospheric dynamics near the cloud tops, represented by temporal changes in the amount of upper haze at high latitudes and/or in the vertical distribution of the unknown UV absorber.

Lee, Yeon Joo; Imamura, Takeshi; Schroder, Stefan

20

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

Science.gov (United States)

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

2005-11-01

21

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

Science.gov (United States)

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.

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

2013-11-01

22

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

Science.gov (United States)

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.

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

2011-10-01

23

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

OpenAIRE

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...

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

2011-01-01

24

Scattering particles in nightside limb observations of Venus' upper atmosphere by Venus Express VIRTIS  

OpenAIRE

Nightside infrared limb spectra of the Venus upper atmosphere, obtained by Venus Express VIRTIS, show strong scattering of thermal radiation. This scattering of upward-going radiation into the line-of-sight is dominant below 82.5. km even at a wavelength of 5 ?m, which is indicative of relatively large particles. We show that 1 ?m-sized sulfuric acid particles (also known as mode 2 particles) provide a good fit to the VIRTIS limb data at high altitudes. We retrieve vertical profiles of the ...

Kok, R.; Irwin, Pgj; Tsang, Ccc; Piccioni, G.; Drossart, P.

2011-01-01

25

Lightning on Venus? Searching for optical evidence with VIRTIS on Venus Express  

Science.gov (United States)

The Venus Express mission has been observing the Venusian Atmosphere continuously since 2006, producing great amounts of hyper-spectral data from the Visible to the Near InfraRed. Although the occurrence of lightning in the Venus atmosphere has been published several times in the past years, always on the basis of detected electromagnetic pulses, the subject is still controversial. It is generally agreed that an optical observation of the phenomenon would settle the issue. We will show here some details of the analysis of the whole data collection of hyperspectral images produced by the VIRTIS instrument in the visible and infrared range, with description of the method and preliminary results.

Cardesín Moinelo, A.; García Muñoz, A.; Piccioni, G.

2013-09-01

26

Variability of CO concentrations in the Venus troposphere from Venus Express/VIRTIS using a Band Ratio Technique  

OpenAIRE

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 ...

Tsang, Ccc; Taylor, Fw; Wilson, Cf; Liddell, Sj; Irwin, Pgj; Piccioni, G.; Drossart, P.; Calcutt, Sb

2009-01-01

27

Venus  

Science.gov (United States)

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…

Martin, Paula; Stofan, Ellen

2004-01-01

28

Results of the Venus Express Aerobraking Campaign  

Science.gov (United States)

After a very successful mission orbiting Venus for more than 8 years, slowly the fuel is running out and the spacecraft will inevitably one day end up in the hot and acid atmosphere of the planet. Being near the end of the mission and in a position to accept some risk to the spacecraft we decided to take the opportunity to dip down deep into the atmosphere, 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 on board accelerometers gave direct measurements of the deceleration which in turn is directly proportional to the local atmospheric density. This provided an excellent way to study both the total density profile throughout the orbital arc in the atmosphere and small scale density variations in the region of the pericentre. The spacecraft behaved perfectly well throughout the whole campaign and provided a wealth of data both on the atmosphere and on the response of the spacecraft to the harsh environment with strong heat loads and some dynamic stress. At the time of the campaign the pericentre was 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.The so called "walk-in" phase started at an altitude of 190 km on 17 May and the campaign ended on 11 July, after having reached a lowest altitude of 129.2 km. Subsequently, a series of orbit control manoeuvres lifted up the pericentre to 460 km altitude and the science activities were resumed after a thorough check-out of the spacecraft. We have detected a highly variable atmosphere, both on a day to day basis and within the individual pericentre passes. The duration of each pass was approximately 100 s and the maximum dynamic pressure achieved was more than 0.75 N/m2, probably a record for a spacecraft that continued its operation afterwards. The orbital period was reduced over the duration of the campaign changing from 24 hours to 22 hours 20 minutes.

Svedhem, Hakan; Müller-Wodarg, Ingo

2014-11-01

29

Venus Express set for launch to the cryptic planet  

Science.gov (United States)

On Wednesday, 26 October 2005, the sky over the Baikonur Cosmodrome, Kazakhstan, will be illuminated by the blast from a Soyuz-Fregat rocket carrying this precious spacecraft aloft. The celestial motion of the planets in our Solar System has given Venus Express the window to travel to Venus on the best route. In fact, every nineteen months Venus reaches the point where a voyage from Earth is the most fuel-efficient. To take advantage of this opportunity, ESA has opted to launch Venus Express within the next ‘launch window’, opening on 26 October this year and closing about one month later, on 24 November. Again, due to the relative motion of Earth and Venus, plus Earth’s daily rotation, there is only one short period per day when it is possible to launch, lasting only a few seconds. The first launch opportunity is on 26 October at 06:43 Central European Summer Time (CEST) (10:43 in Baikonur). Venus Express will take only 163 days, a little more than five months, to reach Venus. Then, in April 2006, the adventure of exploration will begin with Venus finally welcoming a spacecraft, a fully European one, more than ten years after humankind paid the last visit. The journey starts at launch One of the most reliable launchers in the world, the Soyuz-Fregat rocket, will set Venus Express on course for its target. Soyuz, procured by the European/Russian Starsem company, consists of three main stages with an additional upper stage, Fregat, atop. Venus Express is attached to this upper stage. The injection of Venus Express into the interplanetary trajectory which will bring it to Venus consists of three phases. In the first nine minutes after launch, Soyuz will perform the first phase, that is an almost vertical ascent trajectory, in which it is boosted to about 190 kilometres altitude by its three stages, separating in sequence. In the second phase, the Fregat-Venus Express ‘block’, now free from the Soyuz, is injected into a circular parking orbit around Earth heading east. This injection is done by the first burn of the Fregat engine, due to take place at 06:52 CEST (04:52 GMT). At 08:03 CEST, about one hour and twenty minutes after lift-off and after an almost full circle around Earth, the third phase starts. While flying over Africa, Fregat will ignite for a second time to escape Earth orbit and head into the hyperbolic trajectory that will bring the spacecraft to Venus. After this burn, Fregat will gently release Venus Express, by firing a separation mechanism. With this last step, the launcher will have concluded its task. Plenty of ground activities for a successful trip Once separated from Fregat at 08:21 CEST, Venus Express will be awoken from its dormant status by a series of automatic on-board commands, such as the activation of its propulsion and thermal control systems, the deployment of solar arrays and manoeuvres to ‘orient’ itself in space. From this moment the spacecraft comes under the control of ESA’s European Space Operations Centre (ESOC) for the full duration of the mission. The flight control team co-ordinate and manage a network of ESA ground stations and antennas around the globe, to regularly communicate with the spacecraft. The New Norcia station in Australia and the Kourou station in French Guiana will in turn communicate with Venus Express in the initial phase of the mission. The first opportunity to receive a signal and confirm that the spacecraft is in good health will be the privilege of the New Norcia station about two hours after launch. In this early phase of the mission, once ESOC has taken full control of the satellite, the spacecraft will be fully activated. Operations will also include two burns of the Venus Express thrusters, to correct any possible error in the trajectory after separation from Fregat. On 28 October, the newly inaugurated Cebreros station in Spain, with its 35-metre antenna, will start to take an active part in ground network operations to relay information between ESOC and the spacecraft. During the cruise phase and once the spacecraft has arrived at Venus,

2005-10-01

30

CO2 catalogue from SOIR on board Venus Express  

Science.gov (United States)

The SOIR instrument performs solar occultation measurements in the IR region (2.2 - 4.3 µm) at a resolution of 0.12 cm-1, the highest on board Venus Express. It combines an echelle spectrometer and an AOTF (Acousto-Optical Tunable Filter) for the order selection. The wavelength range probed by SOIR allows a detailed chemical inventory of the Venus atmosphere above the cloud layer (65 to 150 km) with an emphasis on vertical distribution of the gases. In particular, measurements of CO2 vertical profiles have been routinely performed. Its isotopologues have also been studied. The detection of the up to then unobserved 01111-00001 absorption band of 12C16O18O [1, 2] initiated a extensive and systematic search of other such unobserved CO2 bands. Here we report the detection of several new absorption bands of different isotopologues of CO2 as observed by SOIR on board the Venus Express mission. 1. Bertaux, J.-L., A.C. Vandaele, V. Wilquet, F. Montmessin, R. Dahoo, E. Villard, O. Korablev, and A. Fedorova, First observation of 628 CO2 isotopologue band at 3.3 mm in the atmosphere of Venus by solar occultation from Venus Express, Icarus, 195(1), 28-33, 2008. 2. Wilquet, V., A. Mahieux, A.C. Vandaele, V.I. Perevalov, S.A. Tashkun, A. Fedorova, O. Korablev, F. Montmessin, R. Dahoo, and J.-L. Bertaux, Line parameters for the 01111-00001 band of 12C16O18O from SOIR measurements of the Venus atmosphere, Journal of Quantitative Spectroscopy and Radiative Transfer, 109, 895-905, 2008.

Borkov, Y.; Perevalov, V.; Tashkun, S.; Vandaele, A. C.; Drummond, R.; Mahieux, A.; Wilquet, V.; Bertaux, J.-L.

2009-04-01

31

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

Directory of Open Access Journals (Sweden)

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.

L. Guicking

2010-04-01

32

Radio sounding of the solar corona with Mars Express, Venus Express and Rosetta  

Science.gov (United States)

The radio sounding technique is a powerful tool to investigate the large-scale structure of the solar corona when a radio transmitter is located near superior solar conjunction. Mars Express, in orbit about Mars, underwent solar conjunctions in August/September 2004, Octo-ber/November 2006 and December/January 2008/09. Venus Express and Rosetta went through solar conjunction in 2006. As part of the Radio Science Experiments MaRS (Mars Express), Vera (Venus Express) and RSI (Rosetta), radio-sounding measurements were recorded using the dual-frequency downlinks of the three spacecraft during their respective solar conjunctions. The transmitted radio signals at X-band (8.4 GHz) and S-band (2.3 GHz) propagated through the dense plasma of the solar corona. Changes in carrier frequency and propagation delay reveal the large-scale coronal structure, the electron content and plasma turbulence as a function of distance from the Sun. MaRS observed several Coronal Mass Ejection (CME) events crossing the radio ray path. A detailed interpretation of these events is presented. A CME-model was developed and adapted to the measured electron content in order to derive information on the electron density, plasma velocity and spatial structure of component CME features. Results of various simulations are presented and compared with SOHO/LASCO data.

Hahn, Matthias; Paetzold, Martin; Haeusler, Bernd; Tyler, G. L.; Bird, Michael; Tellmann, Silvia

33

Composition and chemistry of the Venusian atmosphere after Venus Express  

Science.gov (United States)

The ESA/Venus Express orbiter mission is expected to end before the end of this year (2014), and time has come to summarize its results and examine how they changed our view of this planet. Venus Express instruments (especially the spectrometers VIRTIS and SPICAV/SOIR) have been addressing numerous scientific issues since 2006, among which remote sensing of many minor species from the lower troposphere up to the mesosphere at various latitudes and local solar time, often evidencing spatial or temporal variability. In preparation of a new synthesis of our current knowledge about Venusian atmospheric chemistry and composition to be included in the Venus III book (expected to be published in 2015), we shall present an overview of the most significant updates in this domain. A non-exhaustive list of the sub-topics we would like to address is; (1) Lower tropospheric measurements: Venus Express has been able to study in detail most of the thermal infrared windows, yielding extensive night side measurements of some key minor species (CO, OCS, H_2O, HDO, SO_2) (2) Profiles at an unparalleled vertical resolution of many minor species in the lower mesosphere thanks to stellar and solar occultation techniques. (3) Spatial and temporal variability of minor species at various scales, the most striking example being SO_2 above cloud top. (4) New theoretical understanding and modeling of the interplay between the various chemical cycles (carbon, sulfur, halogens) and the condensed phase particulate matter from the clouds and hazes, based on the newest available observational constraints from Venus Express and ground-based telescopes.

Marcq, Emmanuel

34

Spectral inventory of the SOIR spectra onboard Venus Express  

Science.gov (United States)

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.

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

2013-04-01

35

Study of the nightside Venus upper haze from VIRTIS-M / Venus Express limb observations  

Science.gov (United States)

This work studies the structure of the aerosol in the upper haze of Venus (75-95 km). According to several nightside limb observations made by VIRTIS (IR imaging spectrometer on-board the Venus Express spacecraft) a haze of particles can sometimes be seen on the planet's limb. These observations are also confirmed by the similar results, gained by SPICAV/SOIR, another experiment on the same mission, operating however in a different geometry. By using the model ARS [2], which simulates the radiative transfer in the venusian atmosphere, we were able to create the intensity profiles and to try to fit them (forward modeling) into the experimental data. As a result of these calculations, a lot of particle parameters were found out, including their size distribution, altitude distribution and number density.

Gorinov, D.; Ignatiev, N.; Zasova, L.; Piccioni, G.; Drossart, P.

2014-04-01

36

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

International Nuclear Information System (INIS)

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

37

Venus winds from ultraviolet, visible and near infrared images from the VIRTIS instrument on Venus Express  

Science.gov (United States)

After more than 6 years orbiting Venus the Venus Express mission has provided the largest database of observations of Venus atmosphere at different cloud layers with the combination of VMC and VIRTIS instruments. We present measurements of cloud motions in the South hemisphere of Venus analyzing images from the VIRTIS-M visible channel at different wavelengths sensitive to the upper cloud haze at 65-70 km height (dayside ultraviolet images) and the middle cloud deck (dayside visible and near infrared images around 1 ?m) about 5-8 km deeper in the atmosphere. We combine VIRTIS images in nearby wavelengths to increase the contrast of atmospheric details and measurements were obtained with a semi-automatic cloud correlation algorithm. Both cloud layers are studied simultaneously to infer similarities and differences in these vertical levels in terms of cloud morphologies and winds. For both levels we present global mean zonal and meridional winds, latitudinal distribution of winds with local time and the wind shear between both altitudes. The upper branch of the Hadley cell circulation is well resolved in UV images with an acceleration of the meridional circulation at mid-latitudes with increasing local time peaking at 14-16h. This organized meridional circulation is almost absent in NIR images. Long-term variability of zonal winds is also found in UV images with increasing winds over time during the VEX mission. This is in agreement with current analysis of VMC images (Kathuntsev et al. 2013). The possible long-term acceleration of zonal winds is also examined for NIR images. References Khatuntsev et al. Icarus 226, 140-158 (2013)

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

2013-10-01

38

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

OpenAIRE

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...

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

2012-01-01

39

Spatial variability of carbon monoxide in Venus' mesosphere from Venus Express/Visible and Infrared Thermal Imaging Spectrometer measurements  

OpenAIRE

[1] Observations of Venus' mesosphere by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS)-M instrument of Venus Express have been used to investigate the spatial distribution of CO above Venus' nightside cloud tops by fitting the CO absorption in the (1-0) CO band around 4.7 ?m. We find little spatial variation in the abundance of CO at midlatitudes, with a retrieved abundance of approximately 40 ± 10 ppm just above the cloud tops between 65 and 70 km altitude. Unfortunately, ...

Irwin, Pgj; Kok, R.; Negrao, A.; Tsang, Ccc; Wilson, Cf; Drossart, P.; Piccioni, G.; Grassi, D.; Taylor, Fw

2008-01-01

40

The OH Venus nightglow spectrum: intensity and vibrational composition from VIRTIS-Venus Express observations  

OpenAIRE

Limb spectra of the OH nightglow emission corresponding to the ?v=1 and ?v=2 sequences have been collected with the VIRTIS infrared imaging spectrograph on board Venus Express between April 2006 and October 2008. A detailed statistical analysis shows that the peak intensity and altitude of the two vibrational sequences are significantly correlated, with a mean intensity ratio of the two sequences of 0.38±0.37. The altitude of the maximum of the ?v=2 emission is located ~1 km lower than...

Soret, Lauriane; Ge?rard, Jean-claude; Piccioni, Giuseppe; Drossart, Pierre

2012-01-01

41

Tropospheric carbon monoxide concentrations and variability on Venus from Venus Express/VIRTIS-M observations  

OpenAIRE

[1] We present nightside observations of tropospheric carbon monoxide in the southern hemisphere near the 35 km height level, the first from Venus Express/Visible and Infrared Thermal Imaging Spectrometer (VIRTIS)-M-IR. VIRTIS-M data from 2.18 to 2.50 ?m, with a spectral resolution of 10 nm, were used in the analysis. Spectra were binned, with widths ranging from 5 to 30 spatial pixels, to increase the signal-to-noise ratio, while at the same time reducing the total number of retrievals requ...

Tsang, Ccc; Irwin, Pgj; Wilson, Cf; Taylor, Fw; Lee, C.; Kok, R.; Drossart, P.; Piccioni, G.; Bezard, B.; Calcutt, S.

2008-01-01

42

Understanding of the Venus upper atmosphere dynamics with O2(a1 ) Venus Express observations  

OpenAIRE

The O2(a1 ) nightglow emission at 1.27 m may be used as a tracer of the dynamics prevailing in the Venusian upper mesosphere. This emission has thus been observed with ground-based telescopes and from space with instruments such as VIRTIS on board Venus Express. Observations have shown that the emission maximum is statistically located close to the antisolar point at 96 km. As originally suggested by Connes et al. (1979), such an emission results from the production of oxygen atoms on th...

Soret, Lauriane; Ge?rard, Jean-claude; Piccioni, Giuseppe; Drossart, Pierre

2012-01-01

43

Venus Express Contributions to the Study of Planetary Lightning  

Science.gov (United States)

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.

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

2014-04-01

44

Morphology and dynamics of Venus oxygen airglow from Venus Express/Visible and Infrared Thermal Imaging Spectrometer observations  

OpenAIRE

Images obtained by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS)-M channel instrument onboard Venus Express have been used to retrieve maps and apparent motions of the O[SUB]2[/SUB] ([SUP]1[/SUP]Delta) infrared nightglow on Venus at 1.27 mum. The nightglow distribution is highly inhomogeneous with the regions of brightest emission generally located at low latitudes near the midnight meridian. Unexpectedly some orbits show also intense airglow activity over the south polar reg...

Hueso, R.; Sa?nchez-lavega, A.; Piccioni, G.; Drossart, P.; Ge?rard, Jean-claude; Khatuntsev, I.; Zasova, L.; Migliorini, A.

2008-01-01

45

High latitude gravity waves at the Venus cloud tops as observed by the Venus Monitoring Camera on board Venus Express  

Science.gov (United States)

High resolution images of Venus Northern hemisphere obtained with the Venus Monitoring Camera (VMC/VEx) allow studying small-scale dynamical phenomena at the cloud tops (˜62-70 km altitude) including features like wave trains. A systematic visual search of these waves was performed; more than 1500 orbits were analyzed and wave patterns were observed in more than 300 images. Four types of waves were identified in VMC images on the base of their morphology: long, medium, short and irregular type waves. With the aim to characterize the wave types and their possible excitation source, we retrieved wave properties such as location (latitude and longitude), local time, solar zenith angle, packet length and width, orientation, and wavelength of each wave. The long type waves appear as long and narrow straight features extending more than a few hundreds kilometers and with wavelengths between 7 and 17 km. Medium type waves exhibit irregular wavefronts extending more than 100 km and with wavelengths in the range 8-21 km. Short wave packets have a width of several tens of kilometers and extend to few hundreds kilometers and are characterized by smaller wavelengths (3-16 km). Irregular wave fields appear to be the result of wave interference. The waves are often identified in all VMC filters and are mostly found in the cold collar region at high latitudes (60-80°N) and are concentrated above Ishtar Terra, a continental size highland that includes the highest mountain belts of the planet. The high speed of the Venus Express spacecraft close to the pericentre does not allow to measure phase speed of waves due to the short temporal interval between image pairs. The lack of information on phase velocities does not allow us to establish with absolute confidence the nature of these waves. However, by comparing the morphology and properties of the wave features observed in VMC images to those seen by previous observations it is reasonable to assume that the waves studied here are gravity waves.

Piccialli, A.; Titov, D. V.; Sanchez-Lavega, A.; Peralta, J.; Shalygina, O.; Markiewicz, W. J.; Svedhem, H.

2014-01-01

46

Aerobraking at Venus: A science and technology enabler  

Science.gov (United States)

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.

Hibbard, Kenneth; Glaze, Lori; Prince, Jill

2012-04-01

47

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

OpenAIRE

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...

Barentsen, Geert; Koschny, Detlef

2013-01-01

48

Venus  

Science.gov (United States)

This NASA (National Aeronautics and Space Administration) planet profile provides data and images of the planet Venus. These data include planet size, orbit facts, distance from the Sun, rotation and revolution times, temperature, atmospheric composition, density, surface materials and albedo. Images with descriptions of the planet include many surface features such as halos, craters, ridges, troughs, ticks and other volcano types, lava flows and other tectonic features. Some of the main region images show areas such as Selu Corona, Bright Plains, Gula Mons, Sif Mons, the Ovda Region, Danu Mountains, Akna Mountains, Crater Mead, Golubkina, Lavinia Region, the Eastern Lakshmi Region, Corona Derceto, and Sacajawea Patera. All of these images are from the Magellan Spacecraft.

49

Future Exploration of Venus  

Science.gov (United States)

Venus has been the target of exploration for half a century, before the successful Mariner 2 fly-by in December 1962. The decade after that was marked by growing sophistication in the instruments and spacecraft. During the second decade of Venus exploration (1972 - 1981) the instruments and spacecraft had advanced to make the first detailed survey of the planet and image the surface. During the third decade Venus was explored with more advanced instruments such as synthetic aperture radar and by balloons - the only balloons in another atmosphere ever flown till present. Then came a long pause until 2005 when ESA launched Venus Express, which is still orbiting the planet and returning data. The nearly two-dozen missions flown to Venus have painted a puzzling picture of Venus - we still do not have answers to some key questions. The foremost is why did Venus evolve so differently from Earth? International space agencies and scientists have been considering various approaches to exploring Venus through small and large missions. The Venus Exploration Analysis Group (NASA) has developed a Venus Exploration Roadmap and a comprehensive list of goals, objectives and investigations (www.lpi.usra.edu/vexag), but an international coordinated, comprehensive plan to explore Venus is needed. To fill this void, the COSPAR International Venus Exploration Working Group (IVEWG) has been active in fostering dialog and discussions among the space faring agencies. One small step in the future exploration of Venus is the formation of a joint Science Definition Team (SDT) (NASA and Roscosmos/IKI) for Russia’s Venera-D mission in early 2014. The team is expected to submit a report to respective agencies in early 2015. Towards identifying key surface regions and atmospheric regions of Venus, a workshop is being held in May 2014 by VEXAG to seek community input. It is likely that calls for proposals for missions will also be announced under the M class by ESA and under the Discovery Program by NASA during 2014. Given that the science questions about Venus are many - ranging from the surface and interior and extending into the atmosphere to 120 km and beyond, it is likely that there will be opportunities for other efforts to contribute to the comprehensive exploration of Venus. If undertaken in a coordinated and collaborative manner, we may make substantial progress in understanding Venus, why and/or how it evolved differently from Earth. This knowledge will help us understand Earth-like rocky planets around other stars that are being discovered at a rapid pace now.

Limaye, Sanjay

50

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

OpenAIRE

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 an...

Peralta, Javier; Luz, David; Berry, David; Piccioni, Giuseppe; Drossart, Pierre; Hueso, Ricardo; Sa?nchez-lavega, Agustin

2011-01-01

51

Venus thermal evolution and outgassing history: constraints from numerical simulations and Venus Express observations  

Science.gov (United States)

The Venus Express mission has revealed areas of high emissivity that are indicative of recent volcanism [1]. These areas are also characterized by gravity and topography signatures typical of the presence of active plumes. In an effort to understand the characteristics of these plumes, numerical simulations of heat transfer in a 3D spherical shell have been carried out [2]. These numerical simulations can handle large viscosity variations [3]. We have examined 16 cases with Temperature differences from 1140 to 2280°K, non dimensional internal heating of 0 to 10, and mantle viscosities of 10**20 and 10**21 Pa.s. The equivalent activation energy is ~485 kJ/mole. Convective Rayleigh numbers range from 10**5 to 3x10**7. Increasing internal heating increases the number of hot plumes. The limit occurs when the mantle temperature becomes so large that the temperature difference across the hot thermal boundary layer drops below the viscous temperature scale [4], at which point there is insufficient buoyancy to give rise to plumes. Such a case contradicts the observations. Including a lower mantle viscosity value of 10**20 Pa.s allows for larger values of internal heating that permit hot plumes. However, the highest non-dimensional heating rate in cases with mantle plumes achieved to date (HS = 10) is lower than the value of 50 than predicted by scaling internal heating from Earth to Venus. Partitioning of radiogenic elements into the crust would lower the mantle concentration, but is inconsistent with retaining volatiles in the mantle. Thus our simulations suggest that the mantle is heating up at a rate of about 100 K/byr. In half of the cases, the hot plumes produce pressure release melting over several 100s km beneath the conductive lid, intersecting the wet solidus, but not the dry solidus. Wet melting throughout much of the upper mantle suggests that it may be lacking in light elements and more fully outgassed than the lower mantle. Over time the upper mantle may have lost significant volatiles. Assuming 50 ppm water in the mantle, 10 plumes with a buoyancy flux of 500 kg/s erupting for 4 m.y. will outgas approximately the amount of water in the lower atmosphere [5]. Volcanism may have gone through a transition from more wide-spread, wet melting in the upper mantle to more localized melting in mantle plumes carrying unmelted, volatile rich material from depth. Part of this work has been performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract to NASA. Government sponsorship acknowledged.

Sotin, C.; Choblet, G.; Smrekar, S. E.

2012-04-01

52

Upper haze on the night side of Venus from VIRTIS-M / Venus Express limb observations  

Science.gov (United States)

Night side limb observations of Venus made by VIRTIS mapping spectrometer onboard Venus Express revealed a thermal emission scattered at the right angle by the upper haze above the cloud tops. This emission comes from the cloud tops in the spectral range of 4-5 microns and from the hot deep subcloud atmosphere and the surface in several spectral transparency windows between 1 and 2.5 mum. De Kok et al. (2011, Icarus 211, 51) first demonstrated that the spectra of this emission can be used to retrieve the density of the upper haze and estimate its particle size. In particular they obtained vertical profiles of the haze density from the spectra of the thermal emission from the cloud in the interval of 4-5 mum for 4 orbits and two narrow latitudinal bands of 20-30N and 47-50. We extend this study to other spectral windows and analyzed a wide set of measurements obtained in 2006-2009. We analyzed the vertical profiles of the scattered emission at 1.18, 1.7 and 2.3 microns to retrieve the upper haze density between 75 and 90 km with the vertical resolution of 3 km. In low latitudes the retrieved extinction at 85 km is equal to 0.001-0.003 km (-1) at wavelength 1.75 mum, and the equivalent mode 2 density equals 0.1-0.3 cm (-3) , which is generally in agreement with the results by deKok et al. (2011) and Wilquet et al. (2009, JGR 114, E00B42; 2012, Icarus 217, 875) obtained for similar conditions. The upper haze is subjected to a considerable temporal variability, which is difficult to systematize due to very non-uniform limb observation sequence. The variability can be illustrated by the altitude of the apparent limb boundary in the IR limb images: in most cases it is located at altitudes of 79-83 km, being systematically lower at higher latitudes, but sometimes extends up to 89 km. Detached layers are sometimes observed at 75-85 km.

Ignatiev, Nikolay; Drossart, Pierre; Piccioni, Giuseppe; Zasova, Ludmila; Gorinov, Dmitry

53

Venus winds at cloud level from UV, visible and near infrared observations from VIRTIS on Venus Express over 2006-2012  

Science.gov (United States)

After more than 6 years orbiting Venus the Venus Express mission (VEX) has provided the largest database of observations of Venus atmosphere at different cloud layers with the combination of VMC and VIRTIS instruments. We present measurements of cloud motions in the South hemisphere of Venus analyzing images from the VIRTIS-M visible channel at different wavelengths sensitive to the upper cloud haze at 65-70 km height (dayside ultraviolet images) and the middle cloud deck (dayside visible and near infrared images around 1 mm) about 5-8 km deeper in the atmosphere.

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

2014-04-01

54

A dynamic upper atmosphere of Venus as revealed by VIRTIS on Venus Express.  

OpenAIRE

The upper atmosphere of a planet is a transition region in which energy is transferred between the deeper atmosphere and outer space. Molecular emissions from the upper atmosphere (90-120 km altitude) of Venus can be used to investigate the energetics and to trace the circulation of this hitherto little-studied region. Previous spacecraft and ground-based observations of infrared emission from CO2, O2 and NO have established that photochemical and dynamic activity controls the structure of th...

Drossart, P.; Piccioni, G.; Ge?rard, Jc; Lopez-valverde, Ma; Sanchez-lavega, A.; Zasova, L.; Hueso, R.; Taylor, Fw; Be?zard, B.; Adriani, A.; Angrilli, F.; Arnold, G.; Baines, Kh; Bellucci, G.; Benkhoff, J.

2007-01-01

55

Radio sounding of the solar corona with Mars Express, Venus Express and Rosetta from 2004 to 2011  

Science.gov (United States)

The radio sounding technique is a powerful tool to investigate the large-scale structure of the solar corona when a radio transmitter is located near superior solar conjunction. Mars Express, in orbit about Mars, underwent solar conjunctions in August/September 2004, October/November 2006, December/January 2008/09 and December to March 2010/2011. Venus Express went through solar conjunction in 2006 and Rosetta in 2006 and 2010. Thus, the declining phase and the start of the new solar activity cycle could be covered. As part of the Radio Science Experiments MaRS (Mars Express), Vera (Venus Express) and RSI (Rosetta), the solar corona was sounded using coherent dual-frequency downlinks of the three spacecraft during their respective solar conjunctions. The transmitted radio signals at X-band (8.4 GHz) and S-band (2.3 GHz) propagated through the dense plasma of the solar corona. Changes in carrier frequency and propagation delay reveal the largescale coronal structure, the electron content and plasma turbulence as a function of distance from the Sun. It could be observed that the level of frequency fluctuations follows the solar cycle in general. Extreme variations were observed when the signal path crossed large-scale structures like coronal mass ejections and streamers. Observed variations in electron content are correlated with SOHO/LASCO white light images. Complementary to coronagraph mapping, radio sounding provides a high temporal resolution. Thus, the fine-scale structures of a CME are identified in the data. The observed total electron content as a function of distance follows the relation which was derived from the Ulysses solar conjunction in 1991 and which is obviously not changing over the solar cycles.

Hahn, M.; Pätzold, M.; Bird, M. K.; Häusler, B.; Tellmann, S.; Tsurutani, B.; Tyler, G. L.

2011-10-01

56

Venus OH nightglow distribution based on VIRTIS limb observations from Venus Express  

OpenAIRE

The full set of VIRTIS?M limb observations of the OH Venus nightglow has been analyzed to determine its characteristics. Based on 3328 limb profiles, we find that the mean peak intensity along the line of sight of the OH(deltaV = 1 sequence) is 0.35 MR and is located at 96.4 ± 5 km. The emission is highly variable and no dependence of the airglow layer altitude versus the antisolar angle is observed. The peak brightness appears to decrease away from the antisolar point even if the varia...

Soret, Lauriane; Ge?rard, Jean-claude; Piccioni, Giuseppe; Drossart, Pierre

2010-01-01

57

A dynamic upper atmosphere of Venus as revealed by VIRTIS on Venus Express.  

Science.gov (United States)

The upper atmosphere of a planet is a transition region in which energy is transferred between the deeper atmosphere and outer space. Molecular emissions from the upper atmosphere (90-120 km altitude) of Venus can be used to investigate the energetics and to trace the circulation of this hitherto little-studied region. Previous spacecraft and ground-based observations of infrared emission from CO2, O2 and NO have established that photochemical and dynamic activity controls the structure of the upper atmosphere of Venus. These data, however, have left unresolved the precise altitude of the emission owing to a lack of data and of an adequate observing geometry. Here we report measurements of day-side CO2 non-local thermodynamic equilibrium emission at 4.3 microm, extending from 90 to 120 km altitude, and of night-side O2 emission extending from 95 to 100 km. The CO2 emission peak occurs at approximately 115 km and varies with solar zenith angle over a range of approximately 10 km. This confirms previous modelling, and permits the beginning of a systematic study of the variability of the emission. The O2 peak emission happens at 96 km +/- 1 km, which is consistent with three-body recombination of oxygen atoms transported from the day side by a global thermospheric sub-solar to anti-solar circulation, as previously predicted. PMID:18046396

Drossart, P; Piccioni, G; Gérard, J C; Lopez-Valverde, M A; Sanchez-Lavega, A; Zasova, L; Hueso, R; Taylor, F W; Bézard, B; Adriani, A; Angrilli, F; Arnold, G; Baines, K H; Bellucci, G; Benkhoff, J; Bibring, J P; Blanco, A; Blecka, M I; Carlson, R W; Coradini, A; Di Lellis, A; Encrenaz, T; Erard, S; Fonti, S; Formisano, V; Fouchet, T; Garcia, R; Haus, R; Helbert, J; Ignatiev, N I; Irwin, P; Langevin, Y; Lebonnois, S; Luz, D; Marinangeli, L; Orofino, V; Rodin, A V; Roos-Serote, M C; Saggin, B; Stam, D M; Titov, D; Visconti, G; Zambelli, M; Tsang, C; Ammannito, Eleonora; Barbis, Alessandra; Berlin, Rainer; Bettanini, Carlo; Boccaccini, Angelo; Bonnello, Guillaume; Bouyé, Marc; Capaccioni, Fabrizio; Cardesin, Alejandro; Carraro, Francesco; Cherubini, Giovanni; Cosi, Massimo; Dami, Michele; De Nino, Maurizio; Del Vento, Davide; Di Giampietro, Marco; Donati, Alessandro; Dupuis, Olivier; Espinasse, Sylvie; Fabbri, Anna; Fave, Agnès; Veltroni, Iacopo Ficai; Filacchione, Gianrico; Garceran, Katia; Ghomchi, Yamina; Giustizi, Maurizio; Gondet, Brigitte; Hello, Yann; Henry, Florence; Hofer, Stefan; Huntzinger, Gerard; Kachlicki, Juergen; Knoll, René; Kouach, Driss; Mazzoni, Alessandro; Melchiorri, Riccardo; Mondello, Giuseppe; Monti, Francesco; Neumann, Christian; Nuccilli, Fabrizio; Parisot, Jérôme; Pasqui, Claudio; Perferi, Stefano; Peter, Gisbert; Piacentino, Alain; Pompei, Carlo; Réess, Jean-Michel; Rivet, Jean-Pierre; Romano, Antonio; Russ, Natalie; Santoni, Massimo; Scarpelli, Adelmo; Sémery, Alain; Soufflot, Alain; Stefanovitch, Douchane; Suetta, Enrico; Tarchi, Fabio; Tonetti, Nazzareno; Tosi, Federico; Ulmer, Bernd

2007-11-29

58

South polar dynamics of the Venusian atmosphere from VIRTIS/Venus Express mapping in the thermal range  

OpenAIRE

We report on measurements of Venus cloud velocities from VIRTIS/Venus Express observations of the south polar region of Venus. Cloud tracking has been performed using a method of automated digital correlation. Tracking has been performed on pairs of monochromatic VIRTIS images selected mainly in the 5 ?m window, but also at 1.74, 2.3, 3.93 micrometers. Wind measurements from vector retrievals based on automated feature tracking show high variability, indicating the presence of important tran...

Luz, David; Berry, David L.; Peralta, Javier; Drossart, Pierre; Piccioni, Giuseppe

2010-01-01

59

Gravity waves study from the nighglow emissions in the Venus upper atmosphere observed by VIRTIS-Venus Express  

Science.gov (United States)

The O _{2} nightglow emissions in the infrared spectral range are important features to investigate dynamics at the mesospheric altitudes, in the Venus atmosphere. We analyzed the profiles obtained at limb by the VIRTIS spectrometer on board the Venus Express mission, acquired during the mission period from 2006-07-05 to 2008-08-15. Several profiles present double peaked structures that can be interpreted as due to gravity waves. In analogy to the Earth’s and Mars cases, we use a well-known theory to model the O _{2} nightglow emissions affected by gravity waves propagation, in order to support this thesis and derive the waves properties. In the present work, we discus the gravity waves characteristics, namely vertical wavelength and wave amplitude, with respect to local time and latitude. The method is applied to about 30 profiles showing double peaked structures. On average, the double peaked profiles are compatible with the effects of gravity waves with a vertical wavelength ranging between 7 and 16 km, and wave amplitude of 3-14%. A comparison with gravity waves properties in the Mars and Earth’s atmospheres, using the same theory, is also proposed.

Migliorini, Alessandra; Piccioni, Giuseppe; Zasova, Ludmila; Shakun, Alexey; Altieri, Francesca; Bellucci, Giancarlo

60

Mars Express and Venus Express Data Retention In-Flight Performance  

Science.gov (United States)

Venus, Mars and Earth, three out of the four inner or 'rocky' planets of the Solar System, have a lot in common: a solid surface you could walk on, a comparable surface composition, an atmosphere and a weather system. European Space Agency (ESA) Mars Express (MEx) and Venus Express (VEx) pioneer scientific missions aim at exploring these two neighbours of the Earth, in order to enrich our knowledge of our planet and of the Solar System. Both projects are based on the same spacecraft bus, and in particular on 'sister' Solid State Mass Memory (SSMM) units, in charge of the acquisition, storage and retrieval of all on board data, relevant both to the platform and to the instruments. This paper recalls the common SSMM design and the inner fault tolerant memory array module architecture based on Computer Off The Shelf (COTS) Samsung 64 Mbit Synchronous Dynamic Random Access Memory (SDRAM) chips, and presents the comparative in-flight data retention performance for both MEx and Vex units, since their respective June 2003 and November 2005 launches. Both units have shown to successfully withstand the radiative deep space environment, including during the outstanding October 2003 solar flare, and no uncorrectable data corruption was ever reported. Beyond this stable retention performance over time, the memory scrubbing correctable error accounting feedback allows evaluating the deep space Single Event Upset (SEU) rates, to be compared with the theoretical SSMM radiation assessment as well as with other previous missions in-flight qualitative reference performance records, and finally enables to derive a couple of recommendations from the lessons' learnt.

Lebrédonchel, J.; Rombeck, F.-J.

2007-08-01

61

Atomic oxygen distribution in the Venus mesosphere from observations of O[SUB]2[/SUB] infrared airglow by VIRTIS-Venus Express  

OpenAIRE

This VIRTIS instrument on board Venus Express has collected spectrally resolved images of the Venus nightside limb that show the presence of the (0,0) band of the Deltag1-->Sigmag3 infrared atmospheric system of O[SUB]2[/SUB] at 1.27 mum. The emission is produced by three-body recombination of oxygen atoms created by photodissociation of CO[SUB]2[/SUB] on the dayside. It is consistently bright so that emission limb profiles can be extracted from the images. The vertical distribution of O[SUB]...

Ge?rard, Jean-claude; Saglam, Adem; Piccioni, Giuseppe; Drossart, Pierre; Montmessin, Frank; Bertaux, Jean-loup

2009-01-01

62

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)

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.

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

63

Time-series analysis of temperature profiles from VIRTIS Venus Express data  

Science.gov (United States)

Nighttime infrared observations of the VIRTIS instrument on board Venus Express have already demonstrated their potential in the study of air temperature fields of the Venusian mesosphere. The entire available dataset acquired by the VIRTIS-M IR channel was processed at moderate spatial resolution (i.e. averaging pixels in 8x8 boxes) to derive an unprecedented dataset of air temperature profiles in the pressure range 100-0.1 mbar, covering mostly the latitudes south of 45S. We presented in Grassi et al. (2010, doi:10.1029/2009JE003553) an analysis of the mean properties of temperature profiles, once binned in the latitude/local time/pressure space. Here we discuss the preliminary findings of time-series analysis of data from individual bins. Despite the sparsity of most series, Lomb-Scargle periodogram can be effectively applied in the regions south of 70S, where better coverage is made possible by specific properties of Venus Express orbit. Here the algorithm is able to extract a clear signature related to a period of about 115-120 Earth days, i.e. one Venus solar day, particularly strong at the level around 10 mbar. Further analysis of average temperature fields in the latitude - longitude space demonstrated, for different local times during night, that air temperatures east of Lada Terra (most specifically in a region centered around 130°E and about 60° wide) are about 10K warmer than in other longitudes at 75S.

Grassi, D.; Migliorini, A.; Politi, R.; Montabone, L.; Piccioni, G.; Drossart, P.

2012-04-01

64

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

CERN Document Server

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...

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

2015-01-01

65

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

OpenAIRE

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...

Aspaas, Per Pippin

2012-01-01

66

The 2004 Transit of Venus as a Space Science Education Opportunity  

Science.gov (United States)

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

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

2003-12-01

67

Thermal structure of Venusian nighttime mesosphere as observed by VIRTIS-Venus Express  

OpenAIRE

The mapping IR channel of the Visual and Infrared Thermal Imaging Spectrometer (VIRTIS-M) on board the Venus Express spacecraft observes the CO2 band at 4.3 ?m at a spectral resolution adequate to retrieve the atmospheric temperature profiles in the 65-96 km altitude range. Observations acquired in the period June 2006 to July 2008 were used to derive average temperature fields as a function of latitude, subsolar longitude (i.e., local time, LT), and pressure. Coverage presented here is limi...

Grassi, D.; Migliorini, A.; Montabone, L.; Lebonni?ois, S.; Cardesi?n-moinelo, A.; Piccioni, G.; Drossart, P.; Zasova, Lv

2010-01-01

68

Venus Exploration opportunities within NASA's Solar System Exploration roadmap  

Science.gov (United States)

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.

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

2006-01-01

69

First observation of 628 CO 2 isotopologue band at 3.3 ?m in the atmosphere of Venus by solar occultation from Venus Express  

Science.gov (United States)

The new ESA Venus Express orbiter is the first mission applying the probing technique of solar and stellar occultation to the atmosphere of Venus, with the SPICAV/SOIR instrument. SOIR is a new type of spectrometer used for solar occultations in the range 2.2-4.3 ?m. Thanks to a high spectral resolving power R˜15,000-20,000 (unprecedented in planetary space exploration), a new gaseous absorption band was soon detected in the atmospheric transmission spectra around 2982 cm -1, showing a structure resembling an unresolved Q branch and a number of isolated lines with a regular wave number pattern. This absorption could not be matched to any species contained in HITRAN or GEISA databases, but was found very similar to an absorption pattern observed by a US team in the spectrum of solar light reflected by the ground of Mars [Villanueva, G.L., Mumma, M.J., Novak, R.E., Hewagama, T., 2008. Icarus 195 (1), 34-44]. This team then suggested to us that the absorption was due to an uncatalogued transition of the 16O 12C 18O molecule. The possible existence of this band was soon confirmed from theoretical considerations by Perevalov and Tashkun. Some SOIR observations of the atmospheric transmission are presented around 2982 cm -1, and rough calculations of line strengths of the Q branch are produced, based on the isotopic ratio measured earlier in the lower atmosphere of Venus. This discovery emphasizes the role of isotopologues of CO 2 (as well as H 2O and HDO) as important greenhouse gases in the atmosphere of Venus.

Bertaux, Jean-Loup; Vandaele, Ann Carine; Wilquet, Valérie; Montmessin, F.; Dahoo, R.; Villard, E.; Korablev, O.; Fedorova, A.

2008-05-01

70

Zonal winds at high latitudes on Venus: An improved application of cyclostrophic balance to Venus Express observations  

OpenAIRE

Recent retrievals of zonal thermal winds obtained in a cyclostrophic regime on Venus are generally consistent with cloud tracking measurements at mid-latitudes, but become unphysical in polar regions where the values obtained above the clouds are often less than or close to zero. Using a global atmospheric model, we show that the main source of errors that appear in the polar regions when retrieving the zonal thermal winds is most likely due to uncertainties in the zonal wind intensity in the...

Mendonca, Jm; Read, Pl; Wilson, Cf; Lewis, Sr

2012-01-01

71

Concurrent observations of the ultraviolet nitric oxide and infrared O[SUB]2[/SUB] nightglow emissions with Venus Express  

OpenAIRE

Two prominent features of the Venus nightside airglow are the nitric oxide delta and gamma bands produced by radiative association of O and N atoms in the lower thermosphere and the O[SUB]2[/SUB] infrared emission generated by three-body recombination of oxygen atoms in the upper mesosphere. The O[SUB]2[/SUB] airglow has been observed from the ground, during the Cassini flyby, and with VIRTIS on board Venus Express. It now appears that the global structure of the two emissions shows some simi...

Ge?rard, Jean-claude; Cox, Ce?dric; Soret, Lauriane; Saglam, Adem; Piccioni, G.; Bertaux, J. -l; Drossart, P.

2009-01-01

72

The Scientific Exploration of Venus  

Science.gov (United States)

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

Taylor, Fredric W.

2014-12-01

73

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

International Nuclear Information System (INIS)

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

74

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

Science.gov (United States)

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.

Martin Taylor, S.

2009-04-01

75

Characterizing atmospheric waves on Venus, Earth, and Mars  

OpenAIRE

Atmospheric Waves Workshop; Noordwijk, Netherlands, 9-10 November 2011 Experts in observations and modeling of atmospheric waves from the Earth and planetary atmospheric science communities came together at a November 2011 workshop held at the European Space Agency's (ESA) European Space Research and Technology Centre (ESTEC) site in the Netherlands to discuss the nature of waves observed in Venus's atmosphere and their comparison to those on Earth and Mars. ESA's Venus Express (VEx) satellit...

Wilson, Cf; Piccialli, A.

2012-01-01

76

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

Science.gov (United States)

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

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

77

Vertical structure of Venus polar thermosphere from in-situ data of the Venus Express Atmospheric Drag Experiment (VExADE)  

Science.gov (United States)

The Venus Express Atmospheric Drag Experiment (VExADE) has enabled first ever in-situ measurements of the density of the near-polar thermosphere of Venus above an altitude of 165 km. The measured values have been compared with existing models such as VTS3, which has been built mainly with the Pioneer Venus Orbiter Mass Spectrometer (PV-ONMS) data taken near 16? latitude, but extrapolated globally. The VExADE density values have been derived from the Precise Orbit Determination (POD) of the VEx spacecraft using both navigation and dedicated tracking data around pericenter passes during several VExADE campaigns. The last campaign has also benefited from the Planetary Radio Interferometry and Doppler Experiment (PRIDE) tracking. The combination of POD techniques has provided 46 reliable estimates of the polar thermosphere density. An independent set of density measurements was also taken by inferring the torque of the VEx spacecraft exerted by Venus’ upper atmosphere on the spacecraft during pericenter passes. This method has provided more than 120 density values in remarkably good agreement with the density values provided by the POD method. To date, the VExADE data have probed a range of 160 to 185 km in altitude, 80 to 90 degrees North in latitude and 5 to 20 hours in local time. While sampling in these ranges is insufficient to establish detailed horizontal density structures of the polar thermosphere a set of important properties can be inferred. First, the densities are lower by a factor of around 1.5 than the densities predicted by VTS3. At the same time, we find the density scale heights of VExADE and VTS3 to be consistent. Second, the density values exhibit strong variability, which is not taken into account in the VTS3 model. In order to investigate this dynamical behavior of the polar thermosphere, the ratio between the VExADE and VTS3 density has been analyzed. The latitude, altitude and local time trends are tentatively identified, but the sparse sampling provided by the VExADE data prevents us from drawing any definitive conclusions. We tentatively interpret the measured densities by a vertical wave-like pattern in the thermosphere with the amplitude of about 40% of the mean density value and a vertical wavelength of about 15 km. The causes of this vertical structure are as yet unknown. In order to improve sampling in this altitude range and thereby advance our understanding of the behavior of the polar thermosphere, further measurements are needed. An opportunity will be offered by the forthcoming aerobraking campaign scheduled for June-July 2014. The altitude of the spacecraft will decrease down to 130 km where the sensitivity of the accelerometer will enable density measurements. Tracking data and torque data may still be used to provide reliable density measurements at higher altitudes (150 to 185 km range).

Mueller-Wodarg, Ingo; Svedhem, Håkan; Bruinsma, Sean; Gurvits, Leonid; Cimo, Giuseppe; Molera Calves, Guifre; Bocanegra Bahamon, Tatiana; Rosenblatt, Pascal; Duev, Dmitry; Marty, Jean-Charles; Progebenko, Sergei

78

Scientists are from Mars, educators are from Venus: Relationships in the ecosystem of science teacher preparation  

Science.gov (United States)

Great problems exist in science teaching from kindergarten through the college level (NRC, 1996; NSF, 1996). The problem may be attributed to the failure of teachers to integrate their own understanding of science content with appropriate pedagogy (Shulman, 1986, 1987). All teachers were trained by college faculty and therefore some of the blame for these problems rests on those faculty. This dissertation presents three models for describing secondary science teacher preparation. Two Programs, Two Cultures adapts C. P. Snow's classic work (1959) to describe the work of a science teacher candidate as that of an individual who navigates between two discrete programs: one in college science and the second in teacher education. The second model, Scientists Are from Mars, Educators Are from Venus adapts the popular work of John Gray to describe the system of science teacher education as hobbled by the dysfunctional relationships among the major players and describes the teacher as progeny from this relationship. The third model, The Ecosystem of Science Teacher Preparation reveals some of the deeper complexities of science teacher education and posits that the traditional college science approach treats students as a monoculture when great diversity in fact exists. The three models are described in the context of a large Midwestern university's teacher education program as that program is construed for future biology teachers. Four undergraduate courses typically taken by future biology teachers were observed and described: an introductory biology course; an introductory teacher education course; an upper division course in biochemistry and a senior level science teaching methods course. Seven second semester seniors who were biological Science majors were interviewed. All seven students had taken all of the courses observed. An organization of scientists and educators working together to improve science teaching from kindergarten through graduate school is also described in a case study. The three models described in the dissertation build upon one another and the third model, that of the ecosystem is recognized as both the most accurate portrayal and most complex and therefore most difficult to apply. The system of science teacher preparation is in many ways a system under stress and that stress will result in system evolution. Through better understanding Complex Adaptive Systems and applying that understanding to the system of science teacher education, individuals may be able to influence the nature of system evolution.

Duggan-Haas, Don Andrew

2000-10-01

79

Comparative analysis of airglow emissions in terrestrial planets, observed with VIRTIS-M instruments on board Rosetta and Venus Express  

Science.gov (United States)

Airglow emissions are optimal processes to investigate the chemistry and dynamics in planetary atmospheres. In this study, we focus on the O2 and OH airglow emissions in Venus, Earth, and Mars atmospheres, which are controlled by chemical reactions common to the three planets. By studying these phenomena on Venus, Earth, and Mars using similar instruments, we are able to derive information about their photochemistry and the physical conditions of the atmospheres, but also to constrain the dynamics responsible for transport of atomic oxygen, ozone and other minor species. After a review of the nightglow emissions observed in the Venus atmosphere, we analyze the O2 and OH airglow emissions in the Earth’s atmosphere observed during the 3 swing-bys of our planet by the Rosetta spacecraft. We also report the detection of the O2 nightglow emission in the Mars atmosphere, observed in February 2007 during the Rosetta fly-by of the planet. The airglow characteristics are in agreement with the measurements obtained from sensors on board Mars Express.

Migliorini, A.; Piccioni, G.; Capaccioni, F.; Filacchione, G.; Tosi, F.; Gérard, J.-C.

2013-09-01

80

INPOP08, a 4-D planetary ephemeris: From asteroid and time-scale computations to ESA Mars Express and Venus Express contributions  

CERN Document Server

The latest version of the planetary ephemerides developed at the Paris Observatory and at the Besancon Observatory is presented here. INPOP08 is a 4-dimension ephemeris since it provides to users positions and velocities of planets and the relation between TT and TDB. Investigations leading to improve the modeling of asteroids are described as well as the new sets of observations used for the fit of INPOP08. New observations provided by the European Space Agency (ESA) deduced from the tracking of the Mars Express (MEX) and Venus Express (VEX) missions are presented as well as the normal point deduced from the Cassini mission. We show the huge impact brought by these observations in the fit of INPOP08, especially in terms of Venus, Saturn and Earth-Moon barycenter orbits.

Fienga, A; Morley, T; Manche, H; Kuchynka, P; Poncin-Lafitte, C Le; Budnik, F; Gastineau, M; Somenzi, L

2009-01-01

81

Winds and cloud morphology in the southern polar region of Venus  

OpenAIRE

Spinning on average 60 times faster than the surface, the atmosphere of Venus is superrotational, a state in which the averaged angular momentum is much greater than that corresponding to co-rotation with the solid globe. The rapid mean flow, which is main- tained by momentum transports in the deep atmo- sphere, presents a puzzle to the atmospheric and plan- etary sciences[1]. After previous missions revealed a bright polar feature at the north pole[9, 10], the Venus Express spacecraft discov...

Luz, David; Berry, David L.; Peralta, Javier; Piccioni, Giuseppe; Drossart, Pierre; VIRTIS-Venus Express Team

2010-01-01

82

Venus - summary and review of science research activities 1983-87  

International Nuclear Information System (INIS)

The geology, geomorphology, and atmosphere of Venus are characterized on the basis of observations obtained with the Soviet Venera 15 and 16 spacecraft (including two international Vega balloon experiments), the Pioneer Venus Orbiter, and the Arecibo radio telescope during the period 1983-1986. Features discussed include impact craters, evidence of tectonic and volcanic activity, the high average age of the Venusian surface (apparently over 1 Gyr, indicating resurfacing rates much lower than on earth), and atmospheric temperature differences across the equator. 85 references

83

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

Science.gov (United States)

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.

Haus, Rainer; Kappel, David; Arnold, Gabriele

2015-01-01

84

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  

OpenAIRE

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 hi...

Fedorova, A.; Be?zard, B.; Bertaux, J-l; Korablev, O.; Wilson, C.

2014-01-01

85

Venus's southern polar vortex reveals precessing circulation.  

OpenAIRE

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...

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

2011-01-01

86

Venus Syndrome  

Science.gov (United States)

We use three alternative avenues to investigate climate sensitivity on Earth and the conditions that could lead to extermination of human life on the planet or even a Venus-like runaway greenhouse effect.

Hansen, J.; Kharecha, P.; Lacis, A.; Russell, G.; Sato, M.

2012-06-01

87

Chasing Venus  

Science.gov (United States)

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

88

Variable Venus  

Science.gov (United States)

This is an activity about the phases of Venus and the planet’s variance in angular size as seen from Earth. Learners will use an online program such as Solar System Live to determine Venus’s distance from Earth for one half of its cycle. This activity requires access to the Solar System Update software and a computer with Internet access. This is Solar System Activity 6 in a larger resource, Space Update.

2012-08-03

89

Ice On Venus  

Science.gov (United States)

This resource is part of the Science Education Gateway (SEGway) project, funded by NASA, which is a national consortium of scientists, museums, and educators working together to bring the latest science to students, teachers, and the general public. Is there ice on Venus? If so, what kind of ice is it? In this activity, students find the answers to these questions by using internet resources. The teacher's page contains teaching strategies, vocabulary, homework ideas, and assessment possibilities.

90

Venus Atmospheric Maneuverable Platform (VAMP)  

Science.gov (United States)

Over the past years we have explored a possible new approach to Venus upper atmosphere exploration by applying recent Northrop Grumman (non-NASA) development programs to the challenges associated with Venus upper atmosphere science missions. Our concept is a low ballistic coefficient (explore the Venus upper atmosphere. VAMP targets the global Venus atmosphere between 55 and 70 km altitude and would be a platform to address VEXAG goals I.A, I.B, and I.C. We will discuss the overall mission architecture and concept of operations from launch through Venus arrival, orbit, entry, and atmospheric science operations. We will present a strawman concept of VAMP, including ballistic coefficient, planform area, percent buoyancy, inflation gas, wing span, vehicle mass, power supply, propulsion, materials considerations, structural elements, subsystems, and packaging. The interaction between the VAMP vehicle and the supporting orbiter will also be discussed. In this context, we will specifically focus upon four key factors impacting the design and performance of VAMP: 1. Science payload accommodation, constraints, and opportunities 2. Characteristics of flight operations and performance in the Venus atmosphere: altitude range, latitude and longitude access, day/night performance, aircraft performance, performance sensitivity to payload weight 3. Feasibility of and options for the deployment of the vehicle in space 4. Entry into the Venus atmosphere, including descent profile, heat rate, total heat load, stagnation temperature, control, and entry into level flight We will discuss interdependencies of the above factors and the manner in which the VAMP strawman's characteristics affect the CONOPs and the science objectives. We will show how the these factors provide constraints as well as enable opportunities for novel long duration scientific studies of the Venus upper atmosphere that support VEXAG goals I.A, I.B, and I.C.. We will also discuss how the VAMP platform itself can facilitate some of these science measurements.

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

2014-04-01

91

Sampling the Cloudtop Region on Venus  

Science.gov (United States)

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

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

2014-05-01

92

Venus Transit  

Science.gov (United States)

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

93

The Venus oxygen nightglow and density distributions  

OpenAIRE

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 Ve...

Soret, Lauriane; Ge?rard, Jean-claude; Montmessin, Franck; Piccioni, Giuseppe; Drossart, Pierre; Bertaux, Jean-loup

2010-01-01

94

The Venus environment  

International Nuclear Information System (INIS)

Attention is given to noble gases in planetary atmospheres, the photochemistry of the stratosphere of Venus, the chemistry of metastable species in the Venusian ionosphere, the Venus ionosphere at grazing incidence of solar radiation, disappearing ionospheres on the nightside of Venus, and the observed composition of the ionosphere of Venus. Other investigations considered are concerned with the predicted electrical conductivity between 0 and 80 km in the Venusian atmosphere, sulfuric acid vapor and other cloud-related gases in the Venus atmosphere, the composition and vertical structure of the lower cloud deck on Venus, amorphous sulfur as the ultraviolet absorber on Venus, and polarization studies of the Venus UV contrasts. A description is provided of topics related to temporal variability of ultraviolet cloud features in the Venus stratosphere, zonal mean circulation at the cloud level on Venus, the influence of thermospheric winds on exospheric hydrogen on Venus, and an analysis of Venus gravity data

95

Dynamics and chemistry of Venus' large and complex cloud system : a science case for an in-situ long-term chemical laboratory  

Science.gov (United States)

The planet Venus is the closest to the planet Earth both geographically and geometrically, with an average solar distance only 0.3AU smaller than that of Earth and an equatorial radius that is only 5% smaller than Earth's. But the similarities appear to end there. How did the environments of Venus and Earth become so divergent? The answer to this question relies upon an understanding of Venus' origins, the nature of its present atmosphere, and the role that the clouds have played in evolution and current state of Venus. Venus' clouds are composed of highly concentrated solutions of sulfuric acid and water. The sulfuric acid is produced photochemically from reactions involving water vapor and various sulfur species such as SO2 in the upper atmosphere around 62 km. The region from 50-60 km altitude is convectively unstable, suggesting that most of the cloud formation here is convectively driven, as are cumulus clouds on Earth but with sulfuric acid taking the place of water as the main condensable species. The clouds of Venus are ubiquitous, play a significant role in the radiative balance of the planet, are used as tracers to probe the atmospheric circulation, and are a key part of a global sulfurohydrological cycle that redistributes key greenhouse gasses such as SO2 and H2O. Thus understanding the clouds of Venus holds the key to understanding how Venus itself came to be the world of extremes that it is today. ESA's Venus Express mission, launched in Nov. 2005, has significantly improved our knowledge about the atmosphere of Venus by providing global long-term remote sensing observations with complete coverage in latitude and local solar time. However major questions remain about key minor species and how they vary throughout the major atmospheric regimes in the upper atmosphere, near the cloud tops where photolysis and condensation processes occur, near the surface where coupling and interchange with the atmosphere occurs, and in the middle atmosphere where they combine through meso-scale convection. In situ sampling of these aerosols represents a key measurement for constraining their properties, and identifying their role in the sulfurohydrological cycle by means of microphysical models of steadily increasing complexity. A probe/lander making a single descent will lack the spatial, temporal and local time coverage to address the coupling of compositional variations with radiative and dynamical properties of the atmosphere at cloud level, requiring a long duration flight. Establishing a long-term chemical laboratory in the cloud layer which would measure the detailed composition of both gas and liquid phases, and their latitudinal, diurnal and vertical variability using a combination of mass spectrometry, gas chromatography, tunable laser transmission spectrometry, and polar nephelometry would significantly address all of these objectives. It would allow the determination of the size distribution, shape, and real and imaginary refractive indices of the cloud particles, and the measurement of intensity and polarization phase functions. Our target species would include those known to be associated with cloud formation (e.g. H2SO4, SO3, SO2, H2O), as well as species important in stratospheric chemistry (e.g. CO, ClCOx, Ox, HCl, HF) and surface-atmosphere buffering (e.g. CO, OCS, SOx, Ox, H2S).

Widemann, Thomas; Määttänen, Anni; Wilquet, Valérie; McGouldrick, Kevin; Jessup, Kandis Lea; Wilson, Colin; Limaye, Sanjay; EuroVenus Consortium, the

2014-05-01

96

Spatial correlation of OH Meinel and O2 Infrared Atmospheric nightglow emissions observed with VIRTIS-M on board Venus Express  

OpenAIRE

We present the two-dimensional distribution of the O2 a1?-X3? (0-0) band at 1.27 µm and the OH ?v=1 Meinel airglow measured simultaneously with the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) on board Venus Express. We show that the two emissions present very similar spatial structures. A cross-correlation analysis indicates that the highest level of correlation is reached with only very small relative shifts of the pairs of images. In spite of the strong spatial correlat...

Ge?rard, Jean-claude; Soret, Lauriane; Piccioni, G.; Drossart, P. D.

2012-01-01

97

Mars Express Science Results and Goals for the Extended Mission  

Science.gov (United States)

The ESA Mars Express mission was successfully launched on 02 June 2003 from Baikonur, Kazakhstan, onboard a Russian Soyuz rocket with a Fregat upper stage. The mission comprises an orbiter spacecraft, which has been placed in a polar martian orbit, and the small Beagle-2 lander, due to land in Isidis Planitia but whose fate remains uncertain. In addition to global studies of the surface, subsurface and atmosphere of Mars, with an unprecedented spatial and spectral resolution, the unifying theme of the mission is the search for water in its various states everywhere on the planet. A summary of scientific results from all experiments after more than one Martian year in orbit (687 days) will be presented. Mars Express is already hinting at a quantum leap in our understanding of the planet's geological evolution, to be complemented by the ground truth being provided by the American MER rovers. The nominal mission lifetime of one Martian year for the orbiter spacecraft has already been extended by another Martian year. During the extended mission, priority will be given to fulfill the remaining goals of the nominal mission (e.g., gravity measurements and seasonal coverage), to catch up with delayed MARSIS measurements during the nominal mission, to complete global coverage of high-resolution imaging and spectroscopy, as well as subsurface sounding with the radar, to observe atmospheric and variable phenomena, and to revisit areas where discoveries were made. Also, an effort to enlarge the scope of existing cooperation will be made, in particular with respect to other missions to Mars (such as MGS, MER, MRO) and also missions to other planets carrying the same instruments as Mars Express (i.e. Venus Express). For further details on the Mars Express mission and its science, see the web site: http://sci.esa.int/marsexpress/

Chicarro, A. F.

2006-08-01

98

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

OpenAIRE

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...

Mun?oz, A. Garci?a; Hueso, R.; Sa?nchez-lavega, A.; Markiewicz, W. J.; Titov, D. V.; Witasse, O.; Opitz, A.

2013-01-01

99

Hot Flow Anomalies at Venus  

Science.gov (United States)

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.

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

100

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

101

Solar Wind Interaction with Venus  

Science.gov (United States)

Venus Express, which was inserted into orbit in mid-2006, has added significantly to the knowledge gained from Pioneer Venus from 1978 to 1992. This observational database interpreted in terms of modern multi-fluid codes and hybrid simulations has deepened our understanding of Earth's very different twin sister planet. Furthermore, the very different orbits of VEX and PVO has allowed the more complete mapping of the volume of space around the planet. Now the bow shock has been probed over its full surface, the ionosphere mapped everywhere, and the tail studied from the ionosphere to 12 Venus radii. Some unexpected discoveries have been made. The exospheric hydrogen at Venus, unlike that at Mars,does not produce ion-cyclotron waves, perhapsbecause the stronger gravity of Venus produces a smaller geocorona. The solar wind interaction drapes the magnetic field around the planet, and a strong layer of magnetic field builds up at low altitudes. While the layer does not appear to penetrate into the dayside atmosphere (perhaps diffusing only slowly through the low atmosphere), it does appear to dip into the atmosphere at night. Surprisingly, over the poles, this layer is most strongly seen when the IMF BY component has a positive Y-component in Venus- Solar-Orbital coordinates. Multi-fluid simulations show that this result is consistent with the pressure of significant ion densities of ions with quite different mass which causes magnetic polarity control of the ion flow over the terminators. Reconnection is found in the tail close to the planet, and the structure of the outer tail found by PVO is confirmed to exist in the inner tail by VEX. When combined, the VEX and PVO Data provide a very comprehensive picture of the physics of the solar wind interaction with the ionosphere of Venus.

Russell, C. T.; Luhmann, J. G.; Ma, Y. J.; Villarreal, M. N.; Zhang, T. L.

2014-04-01

102

Three-dimensional modelling of Venus photochemistry  

Science.gov (United States)

We have developed a new code of the Venus atmospheric chemistry based on our photochemical model already in use for Mars (e.g., Lefèvre et al., J. Geophys. Res., 2004). For Venus, the code also includes a parameterized treatment of cloud microphysics that computes the composition of sulphuric acid droplets and their number density based on a given droplet size distribution in altitude. We coupled this photochemical-microphysical package to the LMD general circulation model of Venus (Lebonnois et al., J. Geophys. Res., 2010) with a sedimentation module recently added. We will describe preliminary results obtained with this first three-dimensional model of the Venus photochemistry. The space and time distribution of key chemical species as well as the modelled clouds characteristics will be detailed and compared to observations performed from Venus Express and from the Earth (e.g. Knollenberg and Hunten, J. Geophys. Res., 1980 ; Wilquet et al., J. Geophys. Res., 2009 ; Sandor et al., Icarus, 2012).

Stolzenbach, Aurélien; Lefèvre, Franck; Lebonnois, Sébastien; Määttänen, Anni; Bekki, Slimane

2014-05-01

103

Robotic Technology for Exploration of Venus  

Science.gov (United States)

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.

Landis, Geoffrey A.

2003-01-01

104

Solar wind driven plasma fluxes from the Venus ionosphere  

OpenAIRE

Measurements conducted with the ASPERA-4 instrument and the magnetometer of the Venus Express spacecraft show that the dynamic pressure of planetary O+ ion fluxes measured in the Venus wake can be significantly larger than the local magnetic pressure and, as a result, those ions are not being driven by magnetic forces but by the kinetic energy of the solar wind. Beams of planetary O+ ions with those properties have been detected in several orbits of the Venus Express through...

Perez-de-tejada, H.; Lundin, R.; Barabash, S.; Zhang, T. L.; Sauvaud, J. A.; Durand-manterola, H. J.; Reyes-ruiz, M.

2012-01-01

105

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)

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.

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

106

Studying Venus' atmosphere and ionosphere with Planetary Radio Interferometry and Doppler Experiment (PRIDE)  

Science.gov (United States)

The Planetary Radio Interferometry and Doppler Experiment (PRIDE) is a technique that can provide a multi-disciplinary enhancement of the science return of planetary missions. By performing precise Doppler tracking of a spacecraft carrier radio signal, at Earth-based radio telescopes, and VLBI-style processing of these signals in phase-referencing mode, the technique allows the determination of the radial velocity and lateral coordinates of the spacecraft with very high accuracy[1]. Because of the 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 planetary research. The application of this technique for atmospheric studies has been assessed by observing ESA's Venus Express (VEX) during Venus occultation events in 2012 and 2014, and by participating in one of the Venus Express Atmospheric Drag Experiment (VExADE) campaigns in 2012. Both studies are contributing to the characterization efforts of the atmosphere and ionosphere of Venus. During the Venus Express Atmospheric Drag Experiment (VExADE) campaigns VEX's orbit pericenter was 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]. In the December 2012 campaign 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. Next to that, the PRIDE-team was involved in the tracking of VEX during ingress and egress occultation events. During two sessions of radio occultation experiments in April 2012 and March 2014, VEX was tracked with several telescopes from the European VLBI Network (EVN) at X-band. From these experiments, radio occultation profiles of neutral density and electron density of the dayside upper atmosphere and ionosphere of Venus were obtained from ingress and egress occultation tracking. These activities serve as demonstration of the applicability of the PRIDE technique for radio occultation studies, and provides a benchmark against the traditional Doppler tracking, for the same purposes.

Bocanegra-Bahamon, T. M.; Cimo, G.; Duev, D. A.; Gurvits, L. I.; Marty, J. Ch.; Pogrebenko, S. V.; Rosenblatt, P.

2014-04-01

107

Velocities of Venus clouds derived from VIRTIS observations  

OpenAIRE

Retrograde superrotation is a well known feature of the atmosphere of Venus, with Venus’ cloud tops rotating in only 4.4 days, much faster than the 243-day rotation period of the solid globe. A good characterization of the circulation of the venusian atmosphere is essential in order to understand the mechanisms controlling superrota- tion. VIRTIS, onboard ESA’s Venus Express, is one of the most flexible instruments for such a characterization. The VIRTIS-M imaging spectrometer, operating ...

Luz, David; Berry, David L.; Piccioni, Giuseppe; Drossart, Pierre

2008-01-01

108

Mirror mode structures near Venus and Comet P/Halley  

OpenAIRE

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 ...

Schmid, D.; Volwerk, M.; Plaschke, F.; Vo?ro?s, Z.; Zhang, T. L.; Baumjohann, W.; Narita, Y.

2014-01-01

109

About the various contributions in Venus rotation rate and LOD  

OpenAIRE

% 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...

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

2011-01-01

110

Current Sheets and Substroms in Venus' Magnetotail  

Science.gov (United States)

We investigate 2 years of Venus Express FGM data when the spacecraft is crossing Venus' magnetotail. Using only data when the IMF is within ± 20° of the nominal Parker spiral ~ 37° and little variation of the field before and after the tail crossing, we obtain a quiet-time magnetic field profile along the orbit of the spacecraft. There is an Earth-like tail field in the region less then 3 RV downstream from Venus and the current sheet is in the XYVSO-plane, with an estimated current density of 3 nA/m2. We also investigate two cases, one for a quiet tail and one for an acitive tail, using both FGM and ASPERA data. Increased but constant pressure of the solar wind is shown to increase the esitmated cross- tail current. Most importantly, strongly varying solar wind magnetic field is shown to lead to observations that can be interpreted as reconnection in Venus' magnetotail.

Volwerk, M.; Delva, M.; Futaana, Y.; Vörös, Z.; Zhang, T.; Baumjohann, W.; Barabash, S.

2008-12-01

111

Interaction of Venus and Titan with their Plasma Environments  

Science.gov (United States)

The ionospheres of Titan, Venus and Mars are magnetized by their interactions with flowing magnetized plasma corotating with Saturn in the former case and convected by the supersonic solar wind in the latter two cases. At solar maximum, the Venus ionosphere was found to be generally field-free by the PVO eccentric orbiter, albeit threaded with twisted flux ropes. Venus Express is now orbiting Venus at solar minimum and detects a largely magnetized ionosphere. Similarly, the repeated low altitude passes of Cassini through the Titan atmosphere reveal a "strongly" magnetized ionosphere. We compare the features of these two magnetized ionospheres to illustrate the differences associated with subsonic and supersonic flow.

Weil, H. Y.; Russell, C. T.; Dougherty, M. K.; Luhmann, J. G.; Zhang, T. L.; Delva, M.; Ma, Y. J.

2007-08-01

112

Solar wind interaction with Venus and impact on its atmosphere  

Science.gov (United States)

We present a review of the solar wind interaction with Venus and how the interaction affects the Venusian atmosphere. The Venus Express observations for more than 8 years (2005-present) and quantitatively new simulation codes substantially advanced physical understanding of the plasma processes in the near-Venus space since the Pioneer Venus Orbiter (PVO) mission (1978-1992). The near-Venus space can be divided into several plasma domains: the magnetotail with the plasmasheet, induced magnetosphere, and magnetosheath. The bow shock separates the undisturbed solar wind from the Venus-affected environment. We review the shapes and positions of the boundaries enveloping the main domains and discuss how they are formed by the current systems and pressure balance. In particular, we discuss the morphology and dynamics of the near-Venus magnetotail that was not accessible by PVO. Using the unique Venus Express measurements we discuss the ion acceleration processes and their links to the ionosphere. The focus is given to the Venus' atmosphere erosion associated with the solar wind interaction, both through the energy (ion acceleration) and momentum (atmospheric sputtering) transfer. We review the measurements of the escape rates, their variability with the upstream solar wind conditions and the solar cycle. We emphasize the measurements duirng extreme solar wind conditions as an analogue with nominal conditions for the young Sun. The modeling efforts in this area are also reviewed as they provide a quantitatively approach to understand the impact of the solar wind interaction on the atmospheric evolution. Finally, we compare Venus with other planets of the terrestrial planet group, the Earth and Mars. The Earth, a twin planet of the similar size, is magnetized. Mars, an unmagnetized planet like Venus, possesses by far weaker gravitation to hold its atmospheric gasses. This comparative magnetosphere approach based on the natural solar system laboratory of experiments gives a clearer perspective on physics and processes, which forms the near-Venus space.

Barabash, S.; Futaana, Y.; Wieser, G. S.; Luhmann, J.

2014-04-01

113

Synoptic Regional-scale Air Temperature Fields in the Venusian Mesosphere as Observed by Venus Express VIRTIS-M  

Science.gov (United States)

The recent reprocessing of the entire night-time VEX VIRTIS-M dataset according a full Bayesian method (Grassi et al., 2013, submitted) has eventually allowed the production of large scale synoptic air temperature fields in the Venusian Mesosphere from the mosaicking of several cubes acquired during a given orbit. While average fields as a function of latitude and local time suggest a semi-diurnal tide dominating at mid-latitudes and a diurnal tide dominating at high latitudes, synoptic fields reveals a much more complex picture. At the lowest level probed by VIRTIS-M (98.4 mbar, about 65 km above the surface), the cold collar region appears rich in small scale features. Namely, long (exceeding 90° in longitude) but narrow (less than 5° in latitude) patterns of alternate warm and cold air, apparently originating from the extremes of polar dipole, are over posed to a general trend that shows a minimum in the early hours after midnight. Similar patterns persist also at higher altitude (34.0 mbar, about 70 km above the surface), but their shapes appear more blurred. Noticeably, relative air temperature maxima and minima are anticorrelated at the two levels of 98.4 and 34.0 for the small scale features, while a similar anticorrelation does not hold true in more smoothed areas. Moving to even higher altitude than 70 km, the high-frequency patterns become less prominent but are still seen up to 1.4 mbar level (84.5 km) while large scale features seen just above the cloud level (dipole and cold collar) have completely disappeared. In general, we confirm that the region of the Venus South presents general trends well distinct at different levels between 65 and 85 km, but hosts small scale perturbations extended over at least 20 km in latitude, likely induced by dynamical phenomena.

Grassi, Davide; Politi, Romolo; Ignatiev, Nikolai; Plainaki, Christina; Lebonnois, Sèbastien; Wolkenberg, Paulina; Montabone, Luca; Migliorini, Alessandra; Piccioni, Giuseppe; Drossart, Pierre

2014-05-01

114

Hypothetical flora and fauna of Venus  

Science.gov (United States)

Hypothetical habitability of some of extrasolar planets is a fundamental question of science. Some of exoplanets possess physical conditions close to those of Venus. Therefore, the planet Venus, with 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 in the 1970s and 1980s. 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). There have not been any similar missions to Venus in the subsequent 39 and 32 years. In the absence of new landing missions to Venus, the VENERA panoramas have been re-processed. 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. Their emergence by chance could hardly be explained by noise. Certain unusual findings that have similar structure were found in different areas of the planet. This paper presents the last results obtained of a search for hypothetical flora and fauna of Venus.

Ksanfomality, L. V.

2014-12-01

115

The Planet Venus  

Science.gov (United States)

This resource covers early and modern views of Venus; the general features of Venus; its cloud layer, including high velocity winds, the absence of water vapor, and the different wavelengths used to analyze the Venusian atmosphere; properties of the Venusian atmosphere; a runaway greenhouse effect (where oceans would boil and rocks would sublimate), caused by radiation trapping by greenhouse gases; surface features of Venus, including different hemispheric views, mountains, volcanoes, lava flows, rift valleys and meteor craters; and a comparison of Venus and Earth.

116

Venus - Mead Crater  

Science.gov (United States)

This Magellan image mosaic shows the largest (275 kilometers in diameter [170 miles]) impact crater known to exist on Venus at this point in the Magellan mission. The crater is located north of Aphrodite Terra and east of Eistla Regio at latitude 12.5 degrees north and longitude 57.4 degrees east, and was imaged during Magellan orbit 804 on November 12, 1990. The Magellan science team has proposed to name this crater Mead, after Margaret Mead, the American Anthropologist (1901- 1978). All Magellan-based names of features on Venus are, of course, only proposed until final approval is given by the International Astronomical Union-Commission on Planetary Nomenclature. Mead is classified as a multi-ring crater with its innermost, concentric scarp being interpreted as the rim of the original crater cavity. No inner peak-ring of mountain massifs is observed on Mead. The presence of hummocky, radar-bright crater ejecta crossing the radar-dark floor terrace and adjacent outer rim scarp suggests that the floor terrace is probably a giant rotated block that is concentric to, but lies outside of, the original crater cavity. The flat, somewhat brighter inner floor of Mead is interpreted to result from considerable infilling of the original crater cavity by impact melt and/or by volcanic lavas. To the southeast of the crater rim, emplacement of hummocky ejecta appears to have been impeded by the topography of preexisting ridges, thus suggesting a very low ground-hugging mode of deposition for this material. Radar illumination on this and all other Magellan image products is from the left to the right in the scene.

1991-01-01

117

Bursty escape fluxes in plasma sheets of Mars and Venus  

Science.gov (United States)

High resolution measurements of plasma in the plasma sheets of Mars and Venus performed by almost identical plasma instruments ASPERA-3 on the Mars Express spacecraft and ASPERA-4 on Venus Express reveal similar features of bursty fluxes of escaping planetary ions. A period of bursts lasts about 1-2 min. Simultaneous magnetic field measurements on Venus Express show that these burst-like features arise due to flapping motions of the plasma sheet. Their occurrence can be related to large-amplitude waves propagating on the plasma sheet surface and launched by reconnection in the magnetic tails.

Dubinin, E.; Fraenz, M.; Woch, J.; Zhang, T. L.; Wei, J.; Fedorov, A.; Barabash, S.; Lundin, R.

2012-01-01

118

Venus's southern polar vortex reveals precessing circulation.  

Science.gov (United States)

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 drifts around the pole with a period of 5 to 10 Earth days. This is indicative of a nonsymmetric and varying precession of the polar atmospheric circulation with respect to the planetary axis. PMID:21474710

Luz, D; Berry, D L; Piccioni, G; Drossart, P; Politi, R; Wilson, C F; Erard, S; Nuccilli, F

2011-04-29

119

Mars Express - Science summary after four years in orbit  

Science.gov (United States)

The ESA Mars Express mission, launched on 02 June 2003 from Baikonur, Kazakhstan, onboard a Russian Soyuz rocket, includes an orbiter spacecraft which was placed in a polar martian orbit. In addition to global studies of the surface, subsurface and atmosphere of Mars, with an unprecedented spatial and spectral resolution, the unifying theme of the mission is the search for water in its various states everywhere on the planet by all instruments using different techniques. A summary of scientific results from all experiments after more than four terrestrial years in orbit is given below. The High-Resolution Stereo Colour Imager (HRSC) has shown breathtaking views of the planet from both hemispheres, pointing to very young ages for both glacial and volcanic processes, from hundreds of thousands to a few million years old, respectively. The IR Mineralogical Mapping Spectrometer (OMEGA) has provided unprecedented maps of H2O ice and CO2 ice in the polar regions, and determined that the alteration products (phyllosilicates) in the early history of Mars correspond to abundant liquid water, while the post-Noachian products (sulfates and iron oxides) suggest a colder, drier planet with only episodic water on the surface. The Planetary Fourier Spectrometer (PFS) has confirmed the presence of methane for the first time, which would indicate current volcanic activity and/or biological processes. The UV and IR Atmospheric Spectrometer (SPICAM) has provided the first complete vertical profile of CO2 density and temperature, and has discovered the existence of nightglow, as well as that of auroras over mid-latitude regions with paleomagnetic signatures and very high-altitude CO2 clouds. The Energetic Neutral Atoms Analyser (ASPERA) has identified solar wind scavenging of the upper atmosphere down to 270 km altitude as one of the main culprits of atmospheric degassing and determine the current rate of atmospheric escape. The Radio Science Experiment (MaRS) has studied the surface roughness by pointing the spacecraft high-gain antenna to the Martian surface. Also, the martian interior has been probed by studying the gravity anomalies affecting the orbit, and a transient ionospheric layer due to meteors burning in the atmosphere, was identified by MaRS. Finally, results of the subsurface sounding radar (MARSIS) indicate strong echoes coming from the surface and the subsurface allowing to identify buried impact craters and tectonic structures, as well as the very fine structure of the polar caps. The Northern crust appears thus just as old as the Southern one, owing to the large number of impact basins being recognized. Also, probing of the ionosphere reveals a variety of echoes originating in areas of remnant magnetism. Mars Express is already hinting at a quantum leap in our understanding of the planet's geological evolution, to be complemented by the ground truth being provided by the American MER rovers. The nominal mission lifetime of one Martian year for the orbiter spacecraft has already been extended by another Martian year (687 days). During the extended mission, priority was given to fulfill the remaining goals of the nominal mission (e.g., gravity measurements and seasonal coverage), to catch up with delayed MARSIS measurements during the nominal mission, to complete global coverage of high-resolution imaging and spectroscopy, as well as subsurface sounding with the radar, to observe atmospheric and variable phenomena, and to revisit areas where discoveries were made. Also, an effort to enlarge the scope of existing cooperation is being made, in particular with respect to other missions at Mars (such as MER and MRO) and also missions to other planets carrying the same instruments as Mars Express (i.e. Venus Express). Finally, Mars Express is providing valuable data for the preparation of ESA's Aurora Exploration Programme first mission to Mars (called ExoMars and including a capable rover to perform astrobiological, geophysical and climatological investigations), in terms of helping identifying potential landing sites on Mars, e

Chicarro, Agustin

120

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

121

The Nine Planets: Venus  

Science.gov (United States)

This page contains details about the planet Venus. Information includes planet mass, distance from the Sun, diameter, orbit, and mythology. Also covered is planet composition, surface features, atmosphere and magnetic field data, temperature on the planet, and results of exploration spacecraft. Includes links to images, movies, and additional facts. Discusses unanswered questions about Venus as well.

Bill Arnett

122

Exploring the Planets: Venus  

Science.gov (United States)

This site contains most of the up-to-date information known about the planet Venus, including mean distance from Sun, length of year, rotation period, mean orbital velocity, inclination of axis, average temperature (day and night), and diameter. Many discoveries about Venus have been made using Earth-based radio telescopes, however the images of Venus in this exhibit were collected by the Magellan spacecraft. Magellan used radar to produce the first high-resolution global map of Venus. Since Venus has no water erosion and little wind, volcanic eruptions are a major force reshaping the landscape. Geologic forces at work beneath the crust create mountains, rifts, and patterns of fractures, while the sluggish winds sculpt the surface in subtler ways but many mysteries remain. This site includes numerous images of the planet.

123

Scientists Identify Exploration Goals for Venus  

Science.gov (United States)

Since the turn of the millennium, a large proportion of NASA's planetary science missions—including spacecraft and payloads on four orbiting missions and three rovers—has targeted Mars in preparation for future human missions to the red planet. Less studied, however, is Venus.

Kumar, Mohi

2014-04-01

124

Venus Ionosphere and Solar Wind Interaction  

Science.gov (United States)

Venus Express, which was inserted into orbit in mid-2006, has added significantly to the knowledge gained from Pioneer Venus from 1978 to 1992. This observational database interpreted in terms of modern multi-fluid codes and hybrid simulations has deepened our understanding of Earth’s very different twin sister planet. Furthermore, the very different orbits of VEX and PVO has allowed the more complete mapping of the volume of space around the planet. Now the bow shock has been probed over its full surface, the ionosphere mapped everywhere, and the tail studied from the ionosphere to 12 Venus radii. Some unexpected discoveries have been made. The exospheric hydrogen at Venus, unlike that at Mars, does not produce ion-cyclotron waves, perhaps because the stronger gravity of Venus produces a smaller geocorona. The solar wind interaction drapes the magnetic field around the planet, and a strong layer of magnetic field builds up at low altitudes. While the layer does not appear to penetrate into the dayside atmosphere (perhaps diffusing only slowly through the low atmosphere), it does appear to dip into the atmosphere at night. Surprisingly, over the poles, this layer is most strongly seen when the IMF BY component has a positive Y-component in Venus-Solar-Orbital coordinates. Multi-fluid simulations show that this result is consistent with the pressure of significant ion densities of ions with quite different mass which causes magnetic polarity control of the ion flow over the terminators. Reconnection is found in the tail close to the planet, and the structure of the outer tail found by PVO is confirmed to exist in the inner tail by VEX. When combined, the VEX and PVO Data provide a very comprehensive picture of the physics of the solar wind interaction with the ionosphere of Venus.

Russell, C. T.; Luhmann, Janet G.; Ma, Yingjuan; Zhang, Tielong; Villarreal, M.

125

Salt tectonics on Venus?  

International Nuclear Information System (INIS)

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

126

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

Science.gov (United States)

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

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

2013-01-01

127

The atmosphere of Venus  

International Nuclear Information System (INIS)

The last expeditions to Venus carried out in 1978 - American (Pioneer-Venus) and Soviet (Venera 11 and 12) - brought much news and it is interesting to sum up the results just now. The contents of this review are: 1. The planet Venus - basic astronomical data. 2. Chemical composition. 3. Temperature, pressure, density (from 0 to 100 km). 4. Clouds. 5. Thermal regime and greenhouse effect. 6. Dynamics. 7 Chemical processes. 8. Upper atmosphere. 9. Origin and evolution. 10. Problems for future studies. (orig./WL)

128

Studying the surface composition of Venus from orbit  

Science.gov (United States)

The atmosphere of Venus allows observations of the surface only in very narrow spectral windows around 1 micron. These have been successfully used by the VenusExpress, Galileo and Cassini spacecrafts as well as by ground-based observers. For any other planetary body this spectral range would be observed in reflectance. However for Venus we can obtain useful data only during nighttime using the thermal emission of the surface. So far no systematic studies have been done on the emissivity of Venus analog materials at high temperatures in this wavelength range due to the significant technical challenges of such experiments. At the Planetary Emissivity Laboratory (PEL) we started 6 years ago to extend our laboratory capabilities to support specifically missions to Venus and Mercury. Both planets exhibit surface temperatures up to 500°C and this extreme temperature range affects the spectral characteristics of the surface minerals. We are systematically studying different Venusian analogs to obtain spectra in the 1 microns region at Venus surface temperatures. First measurements of a carbonatite and an ijolite sample as analogs for low viscosity lavas clearly indicating changes of the emissivity signature at 1 micron with temperature. One of the next steps is to study tesserae analog materials to determine how the diagnostic the 1 micron region is for different compositions. We are currently developing a new instrument concept for future Venus missions designed specifically to observe Venus's surface in segments of the near-IR (NIR) spectrum that penetrate the atmosphere with minimal absorption. The Venus Emissivity Mapper (VEM) builds on experience from analysis of data from Galileo/NIMS, Cassini/VIMS, and especially VIRTIS on Venus Express. Unlike those general-purpose imaging spectrometers, VEM is a hyperspectral mapper focused on observing the surface. It will map the surface in five atmospheric windows between 0.85 and 1.18 microns. In addition, several other bands are used to observe the clouds and water vapor at 0-15 km altitude.

Helbert, J.; Mueller, N. T.; Maturilli, A.; D'Incecco, P.; Smrekar, S. E.; Nadalini, R.

2013-12-01

129

Transits of Venus and Mercury as muses  

Science.gov (United States)

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

Tobin, William

2013-11-01

130

Venus Transit 2004  

Science.gov (United States)

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

131

Magellan Mission to Venus  

Science.gov (United States)

The Magellan Mission to Venus Home is now available at NASA's Jet Propulsion Lab. The Magellan mission ended with a dramatic plunge into the atmosphere of Venus, the first time an operating spacecraft has ever been intentionally crashed into a planet. On October 11, 1994, Magellan's thrusters were fired in four sequences to lower its orbit into the atmosphere of Venus for its final experiment -- to gather data on Venus' high atmosphere. Within two days after these maneuvers, the spacecraft became caught in the atmosphere and plunged to the surface. Although most of Magellan will be vaporized during the fiery descent, some sections of the spacecraft will probably hit the planet's surface. The latest updates on Magellan's status -- as well as a comprehensive gallery of images and information from the five-year mission -- are available on the home page.

132

Resurfacing on Venus  

OpenAIRE

The resurfacing evolution of Venus has beene valuated through Monte Carlo simulations. Forthefirst time, the size sof volcanic flows in the models were generated using the frequency–size distribution of volcanic units measured on Venus. Anon-homogeneous spatial generation of volcanic units was included in the models reproducing the Beta–Alta–Themis volcanic anomaly. Crater modification is simulated using a 3 Dapproach. The final number of modified craters and randomnes sof...

Romeo Briones, Ignacio; Turcotte, Donald L.

2010-01-01

133

Mercury, Venus, and Earth!  

Science.gov (United States)

You will compare and contrast Mercury, Venus, and Earth. While looking at these different websites, use the information to fill in your handout of a column chart and on the back answer the questions you are asked on here. First view this website and record on your chart the distance from the sun Mercury,Venus, and Earth are. Now, learn about Mercury! What is the surface ...

bschiffer

2009-10-21

134

Venus Cloud Patterns (colorized and filtered)  

Science.gov (United States)

This picture of Venus was taken by the Galileo spacecrafts Solid State Imaging System on February 14, 1990, at a range of almost 1.7 million miles from the planet. A highpass spatial filter has been applied in order to emphasize the smaller scale cloud features, and the rendition has been colorized to a bluish hue in order to emphasize the subtle contrasts in the cloud markings and to indicate that it was taken through a violet filter. The sulfuric acid clouds indicate considerable convective activity, in the equatorial regions of the planet to the left and downwind of the subsolar point (afternoon on Venus). They are analogous to 'fair weather clouds' on Earth. The filamentary dark features visible in the colorized image are here revealed to be composed of several dark nodules, like beads on a string, each about 60 miles across. The Galileo Project is managed for NASA's Office of Space Science and Applications by the Jet Propulsion Laboratory; its mission is to study Jupiter and its satellites and magnetosphere after multiple gravity assist flybys at Venus and Earth. These images of the Venus clouds were taken by Galileo's Solid State Imaging System February 13, 1990, at a range of about 1 million miles. The smallest detail visible is about 20 miles. The two right images show Venus in violet light, the top one at a time six hours later than the bottom one. They show the state of the clouds near the top of Venus's cloud deck. A right to left motion of the cloud features is evident and is consistent with westward winds of about 230 mph. The two left images show Venus in near infrared light, at the same times as the two right images. Sunlight penetrates through the clouds more deeply at the near infrared wavelengths, allowing a view near the bottom of the cloud deck. The westward motion of the clouds is slower (about 150 mph) at the lower altitude. The clouds are composed of sulfuric acid droplets and occupy a range of altitudes from 30 to 45 miles. The images have been spatially filtered to bring out small scale details and de-emphasize global shading. The filtering has introduced artifacts (wiggly lines running north/south) that are faintly visible in the infrared image. The Galileo Project is managed for NASA's Office of Space Science and Applications by the Jet Propulsion Laboratory; its mission is to study Jupiter and its satellites and magnetosphere after multiple gravity assist flybys at Venus and Earth.

1990-01-01

135

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

Directory of Open Access Journals (Sweden)

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.

Shibata Shinsuke

2010-10-01

136

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

CERN Document Server

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

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

2013-01-01

137

Study of Venus cloud layers with polarimetric data from SPICAV/VEx  

Science.gov (United States)

The study of Venus's cloud layers is important in order to understand the structure, radiative balance and dynamics of the Venusian atmosphere. The main cloud layers between 50 and 70km are thought to consist in ~ 1 ?m radius droplets of a H2SO4-H2O solution. Nevertheless, the composition and the size distribution of the droplets are difficult to constrain more precisely. Polarization measurements have given great results in the determination of the constituents of the haze. In the early 1980s, Kawabata et al.(1980) used the polarization data from the OCPP instrument on the spacecraft Pioneer Venus to constrain the properties of the haze. They obtained a refractive index of 1.45 ± 0.04 at ? = 550nm effective radius of 0.23 ± 0.04?m, with a normalized size distribution variance of 0.18 ± 0.1. We introduce here new polarimetric measurements from 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 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. Our analysis is based on a polarized radiative transfer code similar to the one used by Hansen and Hovenier (1974). Using the particle size distribution from Kawabata et al.(1980) and a simple two-layered cloud model, we try to retrieve particle size and refrative index from nadir observations. We are interested in particular by the glory which is also visible in polarization and whose linear degree of polarization as a function of observation geometry is dependent on the cloud parameters. The polarization measured at higher latitudes provides constrains on the hazes, in particular their optical thickness. We will discuss the first results of our modeling of the glory. In the future we aim to characterize the cloud droplets on the planet along with their temporal and spatial variability. A comparison with the photometric observations of the glory from VMC could also provide stronger constrains on the size and composition of the cloud particles. References: HANSEN, J. E. AND HOVENIER, J. W., Interpretation of the polarization of Venus., Journal of Atmospheric Sciences, 1974. KAWABATA et al., Cloud and haze properties from Pioneer Venus Polarimetry, Journal of Geophysical Research, 1980

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

2014-05-01

138

Global scale concentrations of volcanic activity on Venus: A summary of three 23rd Lunar and Planetary Science Conference abstracts. 1: Venus volcanism: Global distribution and classification from Magellan data. 2: A major global-scale concentration of volcanic activity in the Beta-Atla-Themis region of Venus. 3: Two global concentrations of volcanism on Venus: Geologic associations and implications for global pattern of upwelling and downwelling  

Science.gov (United States)

As part of the analysis of data from the Magellan Mission, we have compiled a global survey of the location, dimensions, and subsidiary notes of all identified volcanic features on Venus. More than 90 percent of the surface area was examined and the final catalog comprehensively identifies 1548 individual volcanic features larger than approximately 20 km in diameter. Volcanic features included are large volcanoes, intermediate volcanoes, fields of small shield volcanoes, calderas, large lava channels, and lava floods as well as unusual features first noted on Venus such as coronae, arachnoids, and novae.

Crumpler, L. S.; Aubele, Jayne C.; Head, James W.; Guest, J.; Saunders, R. S.

1992-01-01

139

Solar wind driven plasma fluxes from the Venus ionosphere  

CERN Document Server

Measurements conducted with the ASPERA-4 instrument and the magnetometer of the Venus Express spacecraft show that the dynamic pressure of planetary O+ ion fluxes measured in the Venus wake can be significantly larger than the local magnetic pressure and, as a result, those ions are not being driven by magnetic forces but by the kinetic energy of the solar wind. Beams of planetary O+ ions with those properties have been detected in several orbits of the Venus Express through the wake as the spacecraft traverses by the noon-midnight plane along its near polar trajectory. The momentum flux of the O+ ions leads to superalfvenic flow conditions. It is suggested that such O+ ion beams are produced in the vicinity of the magnetic polar regions of the Venus ionosphere where the solar wind erodes the local plasma leading to plasma channels that extend downstream from those regions.

Perez-de-Tejada, H; Barabash, S; Zhang, T L; Sauvaud, J A; Durand-Manterola, H J; Reyes-Ruiz, M

2012-01-01

140

Rare gases on the Venus  

International Nuclear Information System (INIS)

Methods and equipment and results of a mass spectrometry of rare gases on the Venus are described. The dynamic radio-frequency mass analyzer used in the ''Venus-11, 12, 13, 14'' space probes is described. Primary (unprocessed) mass spectra obtained using the ''Venus-13, 14'' space probes under the consitions of analysis of rare gases are presented. Unexpectedly high content of argon-36 and argon-38 isotopes, observed on the Venus as compared to the Earth is indicated

141

A conceptual venus rover mission using advanced radioisotope power system  

Science.gov (United States)

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.

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

2006-01-01

142

The venus kinase receptor (VKR) family: structure and evolution.  

OpenAIRE

BACKGROUND: Receptor tyrosine kinases (RTK) form a family of transmembrane proteins widely conserved in Metazoa, with key functions in cell-to-cell communication and control of multiple cellular processes. A new family of RTK named Venus Kinase Receptor (VKR) has been described in invertebrates. The VKR receptor possesses a Venus Fly Trap (VFT) extracellular module, a bilobate structure that binds small ligands to induce receptor kinase activity. VKR was shown to be highly expressed in the la...

Vanderstraete, Mathieu; Gouignard, Nade?ge; Ahier, Arnaud; Morel, Marion; Vicogne, Je?ro?me; Dissous, Colette

2013-01-01

143

Global cloud properties on Venus from orbital infrared spectroscopy  

OpenAIRE

This thesis describes the derivation of Venusian global cloud properties from infrared remote sensing data obtained by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) on the European Space Agency Venus Express satellite. A computationally-efficient retrieval method is designed to exploit the dataset, which provides coverage of the entire nightside southern hemisphere of Venus. Spatially-resolved near-infrared spectra have been used to derive improved models of the vertical stru...

Barstow, Joanna Katy; Taylor, Fredric W.

2012-01-01

144

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.

145

Hybrid simulations of Venus' ionospheric magnetization states  

Science.gov (United States)

The solar wind interaction with the plasma environment of Venus is studied with focus on ionospheric magnetization states using a 3D hybrid simulation code. The plasma environment of Venus was investigated mainly by Pioneer Venus Orbiter (PVO) and the still ongoing Venus Express (VEX) mission. Unlike many other planets, Venus' ionosphere is not shielded by a strong magnetosphere. Hence, data measured by spacecraft like PVO and VEX close to the planet are highly sensitive to solar wind and IMF upstream conditions, which cannot be measured while the spacecraft is inside the magnetosheath region about one hour before and after the closest approach. However, solar wind and IMF are known to change within minutes; ionospheric magnetization states, found by PVO and VEX, are highly dependent on the solar wind upstream pressure and also the magnetic field direction may change rapidly in case of a magnetic sector boundary crossing. When these solar wind induced transition effects occur, the causal change in the solar wind cannot be determined from ionospheric in-situ data. Additionally, with an orbital period of 24 hours, measuring transition timescales of solar wind triggered events is not possible. Our self-consistent simulations aim to provide a global picture of the solar wind interaction with Venus focusing on the effects of upstream fluctuations to the magnetic field in the vicinity of the planet. We use the A.I.K.E.F. (Adaptive Ion Kinetic Electron Fluid) 3D hybrid simulation code to model the entire Venus plasma environment. The simulation grid is refined within the ionosphere in order to resolve strong small-scale gradients of the magnetic field and ion density, a necessity to describe the magnetic field depletion inside the Venus' ionosphere. In contrast to other simulation studies, we apply no boundary conditions for the magnetic field at the planetary surface. Furthermore, we include varying upstream conditions like solar wind velocity and density as well as IMF strength and direction by adjusting these parameters after a first, quasi-stationary state has been reached. This allows for a simulation of dynamic processes like the transition between the magnetized and unmagnetized ionospheric state and fossil fields.

Wiehle, Stefan; Motschmann, Uwe; Fränz, Markus

2013-04-01

146

Lightning Occurrence in the Venus Atmosphere: Statistics from Venus Explorer Observations of ELF Emissions  

Science.gov (United States)

Venus Express has now recorded ELF emissions (up to 64 Hz) in the low-altitude Venus ionosphere since mid-2006. These signals are most prevalent when the ionosphere magnetic field dips into the atmosphere, enabling the electromagnetic signal to enter the ionosphere. The signals can extend over the full bandwidth of the instrument, up to 64 Hz. The waves are nearly circularly polarized and are right-hand polarized, as expected for whistler-mode propagation generated by lightning. When isolated bursts of signal occur, frequently dispersion is seen in which the high-frequency waves arrive first. This is the expected signature generated by impulsive electric discharges. These observations suggest that the rate of lightning occurrence on Venus is not unlike the terrestrial rate where atmosphere chemistry is affected measurably by these discharges. Here we report on the latest results of our studies.

Hart, Richard; Russell, Christopher; Zhang, Tielong

2014-05-01

147

Project Venus 2004  

Science.gov (United States)

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

148

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

Science.gov (United States)

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.

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

2014-11-01

149

Ice caps on venus?  

Science.gov (United States)

The data on Venus obtained by Mariner V and Venera 4 are interpreted as evidence of giant polar ice caps holding the water that must have come out of the volcanoes with the observed carbon dioxide, on the assumption that Earth and Venus are of similar composition and volcanic history. The measurements by Venera 4 of the equatorial surface temperature indicate that the microwave readings were high, so that the polar ice caps may be allowed to exist in the face of the 10-centimeter readings of polar temperature. Life seems to be distinctly possible at the edges of the ice sheets. PMID:17775046

Libby, W F

1968-03-01

150

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

Science.gov (United States)

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.

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

2011-01-01

151

Observing the surface of Venus after VIRTIS on VEX: new concepts and laboratory work  

Science.gov (United States)

The permanent cloud cover of Venus prohibits observation of the surface with traditional imaging techniques most of the visible spectral range. Venus' CO2 atmosphere is transparent in small spectral windows near 1 micron. These windows have been successfully used from ground observers, during the flyby of the Galileo mission at Jupiter and most recently by the VMC and VIRTIS instruments on the ESA VenusExpress spacecraft. Studying surface composition based on only a small number of spectral channels in a very narrow spectral range is very challenging. The task is further complicated by the fact that Venus has an average surface temperature of 460°C. Spectral signatures of minerals are affected by temperature and therefore a comparison with mineral spectra obtained at room temperature can be misleading. We report here about first laboratory measurements of Venus analog materials obtained at Venus surface temperatures. The spectral signatures show clear temperature dependence. Based on the experience gained from using the VIRTIS instrument to observe the surface of Venus combined with the high temperature laboratory experiments we have developed the concept for the Venus Emissivity Mapper (VEM). VEM is a multi-spectral mapper dedicated to the task of multi-spectral mapping the surface of Venus. VEM imposes minimal requirements on the spacecraft and mission design and can therefore added to any future Venus mission. Ideally the VEM instrument is combined with a high resolution radar mapper to provide accurate topographic data.

Helbert, Jörn; Müller, Nils; Maturilli, Alessandro; Nadalini, Riccardo; Smrekar, Suzanne; D'Incecco, Piero; D'Amore, Mario

2013-09-01

152

The Pioneer Venus Missions.  

Science.gov (United States)

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…

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

153

Mercury and Venus  

Science.gov (United States)

Students explore Mercury and Venus, the first and second planets nearest the Sun. They learn about the planets' characteristics, including their differences from Earth. Students also learn how engineers are involved in the study of planets by designing equipment and spacecraft to go where it is too dangerous for humans.

Integrated Teaching and Learning Program,

154

Is Venus alive?  

Science.gov (United States)

Apart from the earth, the near environment of only one other planet, Venus, has been the subject of sustained in situ investigations from space. Owing to the similarity in the physical characteristics of the two bodies, this is most appropriate in that it provides the opportunity to test the credo that through comparative analysis, planetary exploration holds the promise for better understanding of our earth environment.The Pioneer Venus Orbiter was placed into orbit about Venus in December 1978 and has provided a wealth of observations of the planet surface, its atmosphere and clouds, the ionosphere, and the interaction of the solar wind and interplanetary magnetic field with the planetary environment. Among these observations, perhaps the most potentially significant and yet controversial result has been the claimed evidence of extensive lightning and the coupled assertion that the lightning is stimulated by volcanic activity. This lightning- volcanism scenario has become widely publicized in films, books, and numerous journal and magazine articles. Also, these results have had considerable influence in stimulating ongoing research on the basis that active volcanic output might explain otherwise unanswered questions in wide-ranging disciplines, including atmospheric and cloud physics, geology, and plasma physics. Quite naturally, the question of whether Venus is geologically either living or dead is fundamentally significant for comparative planetary analysis.

Taylor, Harry A., Jr.

155

Transit of Venus  

Science.gov (United States)

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

156

Aeolian processes on Venus  

International Nuclear Information System (INIS)

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

157

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

Science.gov (United States)

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.

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

158

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

Science.gov (United States)

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

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

2013-06-01

159

Thermal Control Technology Developments for a Venus Lander  

Science.gov (United States)

The thermal control system for a Venus Lander is critical to mission success and the harsh operating environment presents significant thermal design and implementation challenges. A successful thermal architecture draws heavily from previous missions to the Venus surface such as Pioneer Venus and the Soviet Venera Landers. Future Venus missions will require more advanced thermal control strategies to allow greater science return than previous missions and will need to operate for more than one or two hours as previous missions have done. This paper describes a Venus Lander thermal architecture including the technology development of a phase change material system for absorbing the heat generated within the Lander itself and an insulation system for resisting the heat penetrating the Lander from the Venus environment. The phase change energy storage system uses lithium nitrate that can absorb twice the amount of energy per unit mass in comparison to paraffin based systems. The insulation system uses a porous silica material capable of handling a high temperature and high pressure gas environment while maintaining low thermal conductivity.

Pauken, Mike; Emis, Nick; van Luvender, Marissa; Polk, Jay; Del Castillo, Linda

2010-01-01

160

On the Frequency of Potential Venus Analogs from Kepler Data  

Science.gov (United States)

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

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

2014-10-01

161

Present Status of Janaese Venus Climate Orbiter  

Science.gov (United States)

The start of the Japanese Venus Exploration program was in 2001, and last year (2006) we moved it to Phase C after PDR in August.We would like to report the present status of our Venus Climate Orbiter. Planet-C is the project name in ISAS/JAXA. The launch vehicle is changed from M-V to H-IIA. It will be launched from Tanegashima Space Center (TNSC) in Kagoshima. With this modification, we changed some minor design of the spacecraft and the total weight is slightly heavier than before, but the basic design has not been modified. The launch window will be kept in summer in 2010 and it will arrive at Venus in December 2010. The spacecraft will be directly put into the interplanetary orbit. Now we are preparing the Mechanical and Thermal engineering Model (MTM) which will end in middle of 2007 and will shake it and do the thermal vacuum test. Later this model will be modified to the flight model and the final integration test will be in 2009 which takes 1 year. Development of all the science instruments are going well. The first integration test of science instruments will be in August this year. We can report the results of it in the meeting.

Nakamura, M.; Imamura, T.; Ishii, N.; Satoh, T.; Abe, T.; Ueno, M.; Suzuki, M.; Yamazaki, A.

2007-08-01

162

Perspectives of the bistatic radar and occultation studying of the Venus atmosphere and surface  

Science.gov (United States)

Studying the physical properties of Venus surface and subsurface structures is an important direction in the space research. The first aim of this contribution is to present some results of reanalysis of the bistatic radar and occultation experiments provided using Venera-9, 10 and 15, 16 satellites. Comparison is made with Magellan and Venus Express bistatic radar missions. Bistatic radio images of the Venus surface is compared with monostatic radio images obtained by the Soviet and USA orbiters. The second aim consists in introducing new methods for investigation of the layered structure of the Venus atmosphere and measuring parameters of Venus surface and subsurface structures using the bistatic radar technology. The first bistatic radar measurements with spatial resolution ~ 10-20 km have been carried out during autumn of 1975 year in the five Venus equatorial regions using the Venera-9 and 10 satellites. Small roughness and, in general, plain character of relief in the investigated regions have been revealed. In 1983, the satellites Venera 15 and 16 have carried out new bistatic radar experiments with spatial resolution in the interval 5 - 10 km. New information on the large-scale topography and roughness of small-scale relief has been obtained in Northern polar areas of the planet. Some features have been detected. 1. The significant variations of the reflectivity ~ 2-4 times were found in the first region. The second area of reflectivity magnitude was far below (by three - four times) the previously measured values in the equatorial regions of Venus. These significant reflectivity variations may be related to changes in the conductivity of the ground. 2. Extremely small values roughness with rms of slopes ~ 0.20 were recorded in the northern area. 3. Both the bending angle and the reflection coefficient were determined in the experiment from the measured frequency difference between the direct and the reflected signals as a function of time, using the orbital data. New methods developed by analysis of the experimental data obtained using high-stability radio fields of the Earth's navigational satellites are introduced. For investigations of the layered structures of the Venus atmosphere a new eikonal acceleration/intensity technique is proposed. This technique allows: (1) one frequency high-precision measuring the total absorption of radio waves in the atmosphere; (2) estimating vertical gradients of the refractivity, and determining the height, slope, and horizontal displacement of the atmospheric and ionospheric layers; (3) a criterion is introduced for identification of the internal waves in the Venus atmosphere. To obtain the information on the planetary subsurface structure up to depth 1 km it is necessary to use radio waves in the Low Frequency (LF), Medium Frequency (MF), or High Frequency (HF) bands with wavelength from 1 m up 300 m. The depth of radio sounding is proportional to the wavelength, the intensity of the radio-emission source, and depends on the conductivity of the ground. The bistatic subsurface remote sensing of the planet can be achieved using powerful Earth based transmitters, and/or sporadic radio emission of the Sun and other space radio sources. The work was partly supported by Program 22 of Presidium of Russian Academy of Sciences.

Pavelyev, Alexander; Gubenko, Vladimir; Matyugov, Stanislav; Yakovlev, Oleg

2013-04-01

163

Venus, Earth, Xenon  

Science.gov (United States)

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.

Zahnle, K. J.

2013-12-01

164

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

Science.gov (United States)

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

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

2014-05-01

165

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)

166

Status of the VENUS ECR ion source  

International Nuclear Information System (INIS)

The status and future developments of the 28-GHz VENUS (Versatile ECR for Nuclear Science) Electron Cyclotron Resonance (ECR) ion source after the two years repair are presented. The fully superconducting ECR ion source VENUS serves as prototype injector for the Facility for Rare Isotope Beams (FRIB) project at Michigan State University (MSU) as well as injector ion source for the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory (LBNL). As such the source has produced many record beams of high charge state ions as well as high-intensity, medium charge state ions. As the FRIB project has now entered the preliminary design phase, LBNL is involved in the design of two new VENUS-like ECR injector ion sources for the FRIB facility. This paper will review the design changes for the FRIB injector, which will allow the installation of the FRIB injector source on a 100 kV platform. In support of the FRIB ion sources design systematic measurements of the heat load due to Bremsstrahlung from the plasma for different magnetic fields have been performed and are presented. Finally, a possible future upgrade path for the FRIB injector using an advanced Nb3Sn magnet structure is described. The paper is followed by the slides of the presentation. (authors)

167

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

168

The transit of Venus enterprise in Victorian Britain  

CERN Document Server

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.

Ratcliff, Jessica

2008-01-01

169

Pioneer Venus gas chromatography of the lower atmosphere of Venus  

Science.gov (United States)

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.

Oyama, V. I.; Carle, G. C.; Woeller, F.; Pollack, J. B.; Reynolds, R. T.; Craig, R. A.

1980-01-01

170

Pioneer Venus gas chromatography of the lower atmosphere of Venus  

Science.gov (United States)

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.

Oyama, V. I.; Carle, G. C.; Woeller, F.; Pollack, J. B.; Reynolds, R. T.; Craig, R. A.

1980-12-01

171

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

172

Stagnation Point Radiative Heating Relations for Venus Entry  

Science.gov (United States)

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.

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

2012-01-01

173

On the Frequency of Potential Venus Analogs from Kepler Data  

CERN Document Server

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...

Kane, Stephen R; Domagal-Goldman, Shawn D

2014-01-01

174

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

Science.gov (United States)

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

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

2015-01-01

175

Mars Express: Mission and Science Goals (Invited)  

Science.gov (United States)

The ESA Mars Express mission includes an orbiter spacecraft and a small lander module to be launched in 2003 by a Soyuz rocket. The scientific objectives of the orbiter spacecraft include: global high-resolution photogeology at 10 m resolution, global mineralogical mapping at 100 m resolution, global atmospheric circulation and mapping of the atmospheric composition, subsurface structure at km scale down to the permafrost, surface-atmosphere interactions and interaction of the atmosphere with the interplanetary medium. For the lander module, the objectives include: geology, geochemistry, meteorology and exobiology (i.e. search for signatures of life) of the landing site. Design estimates allow for an orbiter scientific payload of about 106 kg and 60 kg total lander mass (at launch) compatible with the approved mission scenario. The Beagle small lander, dedicated to geochemistry and exobiology with a number of robotic devices, will deploy a sophisticated robotic-sampling arm , which could manipulate different types of tools and retrieve samples to be analyzed by the geochemical instruments mounted on the lander platform. One of the tools to be deployed by the arm is a 'mole' capable of subsurface sampling to reach soil unaffected by solar-UV radiation. The orbiter will be 3-axis stabilised and will be placed in an elliptical martian orbit (250 ( 10142 km)of 86.35 degrees inclination and 6.75 hours period. The nominal mission lifetime of one martian year (687 days) for the orbiter investigations will be extended by another martian year for lander relay communications with the European Netlanders to be launched in 2005 and to complete global coverage. ESA will provide the launcher, the orbiter and the operations, while the lander module as well as the instruments are to be delivered by the scientific community. International collaboration is very much valued to diversify the scope and enhance the scientific return of the mission, and in particular close cooperation between Nozomi and Mars Express within a joint ESA-ISAS programme of Mars exploration.

Chicarro, A. F.

1999-09-01

176

The 2010 European Venus Explorer (EVE) mission proposal  

Science.gov (United States)

The European Venus Explorer (EVE) mission described in this paper was proposed in December 2010 to ESA as an `M-class' mission under the Cosmic Vision programme. It consists of a single balloon platform floating in the middle of the main convective cloud layer of Venus at an altitude of 55 km, where temperatures and pressures are benign (˜25°C and ˜0.5 bar). The balloon float lifetime would be at least 10 Earth days, long enough to guarantee at least one full circumnavigation of the planet. This offers an ideal platform for the two main science goals of the mission: study of the current climate through detailed characterization of cloud-level atmosphere, and investigation of the formation and evolution of Venus, through careful measurement of noble gas isotopic abundances. These investigations would provide key data for comparative planetology of terrestrial planets in our solar system and beyond.

Wilson, Colin Frank; Chassefière, Eric; Hinglais, Emmanuel; Baines, Kevin H.; Balint, Tibor S.; Berthelier, Jean-Jacques; Blamont, Jacques; Durry, Georges; Ferencz, Csaba S.; Grimm, Robert E.; Imamura, Takeshi; Josset, Jean-Luc; Leblanc, François; Lebonnois, Sebastien; Leitner, Johannes J.; Limaye, Sanjay S.; Marty, Bernard; Palomba, Ernesto; Pogrebenko, Sergei V.; Rafkin, Scot C. R.; Talboys, Dean L.; Wieler, Rainer; Zasova, Liudmila V.; Szopa, Cyrill

2012-04-01

177

Variable winds on Venus mapped in three dimensions  

OpenAIRE

We present zonal and meridional wind measurements at three altitude levels within the cloud layers of Venus from cloud tracking using images taken with the VIRTIS instrument on board Venus Express. At low latitudes, zonal winds in the Southern hemisphere are nearly constant with latitude with westward velocities of 105 ms-1 at cloud-tops (altitude ? 66 km) and 60-70 ms-1 at the cloud-base (altitude ? 47 km). At high latitudes, zonal wind speeds decrease linearly with latitude with no dete...

Sanchez-lavega, A.; Hueso, R.; Piccioni, G.; Drossart, P.; Peralta, J.; Perez-hoyos, S.; Wilson, Cf; Taylor, Fw; Baines, Kh; Luz, D.; Erard, S.; Lebonnois, S.

2008-01-01

178

Gravity waves in the upper mesosphere of Venus  

Science.gov (United States)

Gravity waves are common features in planetary atmospheres. They can manifest through fluctuations on temperature and density fields, and hence on airglow intensities. In analogy to the Earth's and Mars' cases, we apply a well-known theory to investigate the gravity waves influence in shaping the O2 nightglow emissions in the infrared in the Venus atmosphere. We use VIRTIS/Venus Express observations at limb, acquired during the mission period from 2006-07-05 to 2008-08-15. We present wave properties, like vertical wavelength ?z and wave amplitude GW. Other parameters, like for example horizontal wavelength, are inferred and discussed.

Migliorini, A.; Altieri, F.; Shakun, A.; Zasova, L.; Piccioni, G.; Bellucci, G.

2014-04-01

179

Short Large-Amplitude Magnetic Structures (SLAMS) at Venus  

Science.gov (United States)

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.

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

180

Progress report on VENUS  

International Nuclear Information System (INIS)

The construction of VENUS, a next generation superconducting Electron Cyclotron Resonance ion source designed to operate at 28 GHz, is complete. The cryostat including the superconducting magnet assembly was delivered in September 2001. During acceptance tests, the superconducting magnets produced an axial magnetic field strength of 4T at injection, 3T at extraction, and a radial field strength of 2T at the plasma chamber wall without any quenches. These fields are sufficient for optimum operation at 28 GHz. The cryogenic system for VENUS has been designed to operate at 4.2 K with two cryocoolers each providing up to 45 W of cooling at 50 K and 1.5 W at 4 K in a closed loop mode without further helium transfers. However, during the acceptance tests an excessive heat leak of about 3W was measured. In addition, the liquid helium heat exchanger did not work properly and had to be redesigned. The cryogenic system modifications will be described. In addition, an update on the installation of the ion source and its beam line components will be given

181

Recent hotspot volcanism on Venus from VIRTIS emissivity data.  

Science.gov (United States)

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

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

2010-04-30

182

A full Earth orbit as viewed from Venus  

Science.gov (United States)

The Earth has been monitored from Venus orbit in both reflected sunlight and thermal emission with the VIRTIS instrument on Venus Express. The spectra, obtained between April 2007 and October 2008, show clear evidence of some of the most abundant gases in the planet's atmosphere, namely O2, CO2, CH4, and H2O. From Venus orbit, the Earth is seen within a limited range of phase angles ~0-46o, which means that the fraction of the Earth's illuminated disk is always ~80% or more. We have set out to interpret the collected spectra and their relevance in the context of the prospective characterization of an Earth-twin orbiting a Sun-like star in a remote solar system.

García Muñoz, A.; Cardesin Moinelo, A.; Piccioni, G.

2013-09-01

183

Temporal variations observed in the clouds of Venus from Venus Monitoring Camera  

Science.gov (United States)

The Venus Monitoring Camera (VMC) on Venus Express [1] has been collecting images of the planet since orbit insertion in April 2006 through four narrow band pass (50 nm halfwidth) with center wavelengths of 365, 550, 950 and 1050 nm [2]. With varying range to the planet during the spacecraft's elliptical, near polar orbit, VMC obtains views of the day side southern hemisphere ( ~ 72,500 km) and the limb when it is furthest away from the planet, and can see a fraction of the planet's sun-lit limb northern latitudes when the spacecraft is closer to the planet ( >~ 25,000 km). We use these images to look at the temporal behavior of the normalized intensity and unit slant optical depth (location of the bright limb) at four wavelengths during April 2006 - March 2014. We detect correlated changes in the normalized brightness and the altitude of the unit optical depth over this period.

Limaye, S. S.; Markiewicz, W. J.; Krauss, R. J.

2014-04-01

184

Interpretation of Venus gravitational anomalies  

International Nuclear Information System (INIS)

The Venus gravity field anomalies are interpreted from three harmonics of potential expansion. Masses and depths of the anomaly centers in three regions: the Aphrodita land, the Ishtar land and in the South of the planet, are defined from the Venus geoid height, pure anomaly of attractive force, and plumb deviation. These depths are determined to be 930-1140 km. Analogous Earth anomalies in the field smoothing from 16 to 3 harmonics are characterized by depth overestimation. 1.4-times. Because of this, depths of the Venus anomaly sources reduced to 16 harmonics lie approximately in the range of 700-800 km, that is they correspond to the depth of bedding of the Venus mantle second phase boundary

185

Venus näitas lillekleite / Regina Hansen  

Index Scriptorium Estoniae

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"

Hansen, Regina

2001-01-01

186

Circulation of Venus upper mesosphere.  

Science.gov (United States)

Observation of the O2 1.27 ?m airglow intensity distribution on the night side of Venus is one of the methods of study of the circulation in upper mesosphere 90-100 km. VIRTIS-M on board Venus Express made these observations in nadir and limb modes in Southern and Northern hemispheres respectively. Global map of the O2 night glow is published (Piccioni et al. 2009). In this work we use for analysis only data, obtained with exposure > 3 s to avoid high noisy data. It was found that intensity of emission decreases to poles and to terminators (similar to Piccioni et al.2009) in both hemispheres, which gives evidence for existence of SS-AS circulation with transport of the air masses through poles and terminators with ascending/descending flows at SS/AS areas. However, asymmetry of distribution of intensity of airglow is observed in both hemispheres. Global map for southern hemisphere (from nadir data) has good statistics at ? > 10-20° S and pretty poor at low latitude. Maximum emission is shifted from midnight by 1 - 2 hours to the evening (22-23h) and deep minimum of emission is found at LT=2-4 h at ? > 20° S. This asymmetry is extended up to equatorial region, however statistic is poor there. No evident indication for existence of the Retrograde Zonal Superrotation (RZS) is found: maximum emission in this case, which is resulting from downwards flow, should be shifted to the morning. The thermal tides, gravity waves are evidently influence on the night airglow distribution. VIRTIS limb observations cover the low northern latitudes and they are more sparse at higher latitudes. Intensity of airglow at ? = 0 - 20° N shows wide maximum, which is shifted by 1- 2 h from midnight to morning terminator. This obviously indicates that observed O2 night glow distribution in low North latitudes is explained by a superposition of SS-AS flow and RZS circulation at 95-100 km. This behavior is similar to the NO intensity distribution, obtained by SPICAV.

Zasova, Ludmila; Gorinov, Dmitry; Shakun, Alexey; Altieri, Francesca; Migliorini, Alessandra; Piccioni, Giuseppe; Drossart, Pierre

2014-05-01

187

Clouds and aerosols on Venus: an overview  

Science.gov (United States)

The past decade demonstrated significant progress in understanding of the Venus cloud system. This paper gives a summary of new observations and modelling efforts that will form the basis for a relevant chapter in the Venus III book. Venus Express observations reveal significant latitudinal variations and temporal changes in the global cloud top morphology [1]. 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 [2, 3]. 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 [4]. 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 [5]. Based on 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 midwavelength IR (SPICAV-SOIR), the size distribution of aerosols in the upper haze of Venus was retrieved, assuming H2SO4/water composition of the droplets [6]. 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 & 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 [7]. 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, the acidity of the cloud particles is found to be higher near the polar collar and in regions of optically thick cloud [8]. 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 [9]. Radio occultation from Venus Express confirms that the atmosphere is in convective equilibrium from 50-60 km [10]. Sulphuric acid vapour profiles calculated from the absorption of the radio signals show an atmosphere saturated with sulphuric acid in the cloud layer [11]. 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 variabilit

Titov, D. V.; Ignatiev, N. I.; McGouldrick, K.; Wilquet, V.; Wilson, C. F.

2014-04-01

188

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

189

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

190

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Mexico | Language: English Abstract in spanish 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.

Changbom, Park; Heajoo, Chung.

191

A Conceptual Venus Rover Mission Using Advanced Radioisotope Power Systems  

Science.gov (United States)

This concept study demonstrates that a long lived Venus rover mission could be enabled by a novel application of advanced RPS technology. General Purpose Heat Source (GPHS) modules would be employed to drive an advanced thermoacoustic Stirling engine, pulse tube cooler and linear alternator that provides electric power and cooling for the rover. The Thermoacoustic Stirling Heat Engine (TASHE) is a system for converting high-temperature heat into acoustic power which then drives linear alternators and a pulse tube cooler to provide both electric power and coolin6g for the rover. A small design team examined this mission concept focusing on the feasibility of using the TASHE system in this hostile environment. A rover design is described that would provide a mobile platform for science measurements on the Venus surface for 60 days, with the potential of operating well beyond that. A suite of science instruments is described that collects 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 at under 50 °C.

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

2006-01-01

192

Atomic oxygen on the Venus nightside: Global distribution deduced from airglow mapping  

OpenAIRE

The Visible and Infra-Red Thermal Imaging Spectrometer (VIRTIS) instrument on board the Venus Express spacecraft has measured the O2(a1[Delta]) nightglow distribution at 1.27 [mu]m in the Venus mesosphere for more than two years. Nadir observations have been used to create a statistical map of the emission on Venus nightside. It appears that the statistical 1.6 MR maximum of the emission is located around the antisolar point. Limb observations provide information on the altitude and on the ...

Soret, Lauriane; Ge?rard, Jean-claude; Montmessin, Franck; Piccioni, Giuseppe; Drossart, Pierre; Bertaux, Jean-loup

2012-01-01

193

Hot-spot tectonics of Eistla Regio, Venus: Results from Magellan images and Pioneer Venus gravity  

Science.gov (United States)

Eistla Regio (ER) is a broad, low, discontinuous topographic rise striking roughly EW at low northern latitudes of Venus. Some 2000 x 7000 km in dimensions, it is the third largest rise in planform on Venus after Aphrodite Terra and Beta Phoebe Regiones. These rises are the key physiographic elements in a hot spot model of global tectonics including transient plume behavior. Since ER is the first such rise viewed by Magellan and the latitude is very favorable for Pioneer Venus gravity studies, some of the predictions of a time dependent hot spot model are tested. Western ER is defined as the rise including Gula and Sif Mons and central ER as that including Sappho Patera. Superior conjunction prevented Magellan from returning data on eastern ER (Pavlova) during the first mapping cycle. It is concluded that the western and central portions of ER, while part of the same broad topographic rise and tectonic framework, have distinctly different surface ages and gravity signatures. The western rise, including Gula and Sif Mons, is the expression of deep seated uplift with volcanism limited to the individual large shields. The eastern portion has been widely resurfaced more recently by thermal anomalies in the mantle.

Grimm, Robert E.; Phillips, Roger J.

1991-06-01

194

The 2012 Transit of Venus for Cytherean Atmospheric Studies and as an Exoplanet Analog  

Science.gov (United States)

We worked to assemble as complete a dataset as possible for the Cytherean atmosphere in collaboration with Venus Express in situ and to provide an analog of spectral and total irradiance exoplanet measurements. From Haleakala, the whole transit was visible in coronal skies; our B images showed the evolution of the visibility of Venus's atmosphere and of the black-drop effect, as part of the Venus Twilight Experiment's 9 coronagraphs distributed worldwide with BVRI. We imaged the Cytherean atmosphere over two minutes before first contact, with subarcsecond resolution, with the coronagraph and a separate refractor. The IBIS imaging spectrometer at Sacramento Peak Observatory at H-alpha and carbon-dioxide also provided us high-resolution imaging. The NST of Big Bear Solar Observatory also provided high-resolution vacuum observations of the Cytherean atmosphere and black drop evolution. Our liaison with UH's Mees Solar Observatory scientists provided magneto-optical imaging at calcium and potassium. Spaceborne observations included the Solar Dynamics Observatory's AIA and HMI, and the Solar Optical Telescope (SOT) and X-ray Telescope (XRT) on Hinode, and total-solar-irradiance measurements with ACRIMSAT and SORCE/TIM, to characterize the event as an exoplanet-transit analog. Our expedition was sponsored by the Committee for Research and Exploration/National Geographic Society. Some of the funds for the carbon-dioxide filter for IBIS were provided by NASA through AAS's Small Research Grant Program. We thank Rob Lucas, Aram Friedman, and Eric Pilger '82 for assistance with Haleakala observing, Rob Ratkowski of Haleakala Amateur Astronomers for assistance with equipment and with the site, Stan Truitt for the loan of his Paramount ME, and Steve Bisque/Software Bisque for TheSky X controller. We thank Joseph Gangestad '06 of Aerospace Corp., a veteran of our 2004 expedition, for assistance at Big Bear. We thank the Lockheed Martin Solar and Astrophysics Laboratory and Hinode science and operations teams for planning and support.

Pasachoff, Jay M.; Schneider, G.; Babcock, B. A.; Lu, M.; Reardon, K. P.; Widemann, T.; Tanga, P.; Dantowitz, R.; Willson, R.; Kopp, G.; Yurchyshyn, V.; Sterling, A.; Scherrer, P.; Schou, J.; Golub, L.; Reeves, K.

2012-10-01

195

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

Science.gov (United States)

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.

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

196

Correlations between cloud thickness and sub-cloud water abundance on Venus  

OpenAIRE

Past spacecraft observations of Venus have found considerable spatial and temporal variations of water vapour abundance above the clouds. Previous searches for variability below the clouds at 30–45 km altitude found no large scale latitudinal gradients, but lacked the spatial resolution to detect smaller scale variations. Here we interpret results from the VIRTIS imaging spectrometer on Venus Express, remotely sounding at near-infrared ‘spectral window’ wavelengths, as indicating that t...

Tsang, Ccc; Wilson, Cf; Barstow, Jk; Irwin, Pgj; Taylor, Fw; Mcgouldrick, K.; Piccioni, G.; Drossart, P.; Svedhem, H.

2010-01-01

197

Venera-D -the future Russian mission to Venus  

Science.gov (United States)

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.

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.

198

Lada Terra: A 'new' hotspot on Venus  

Science.gov (United States)

On Earth, areas called 'hotspots' form above mantle plumes and are defined by their topographic swells, volcanism, and large positive gravity anomalies. Hawaii is a classic example. Venus has ~10 such highland regions that are analogous to terrestrial hotspots and are approximately 2000 km in diameter. Modeling of their gravity and topography provides evidence for compensation beneath the thermal lithosphere, which is interpreted to indicate the presence of a hot mantle plume. Analysis of data from the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS, see Drossart et al. 2007) on the Venus Express mission reveals surface thermal emissivity anomalies in the southern hemisphere that are interpreted as compositional variations (Helbert et al., 2008; Mueller et al., 2008). Most high emissivity anomalies occur in regions previously interpreted as hotspots: Imdr, Themis, and Dione Regiones. The evidence for plumes at depth, the correlation of high emissivity anomalies to stratigraphically young volcanic flows, and analysis of the likely emissivity of weathered and unweathered basalt on Venus lead Smrekar et al. (2010) to interpret the high emissivity flows as evidence of geologically recent, relatively unweathered volcanic flows. Lada Terra also contains volcanic flows with high emissivity anomalies. This region had not been studied using gravity data previously due to the locally low resolution (65-70 spherical harmonic degree and order). Further, the radar data have a high look angle, making it harder to interpret. The high emissivity anomalies inspired Ivanov and Head (2010) to reexamine this region. Their analysis of the geologic setting along with the high emissivity anomalies and the positive gravity anomaly provide evidence that Lada Terra is likely to be recently active. Here we use the spherical harmonic gravity and topography data from Magellan to calculate a geoid-to-topography ratio (GTR) of 23.5±1.6 m/km. This value is in the range of the GTRs previously found for highlands interpreted as hotspots on Venus and provides evidence of a mantle plume at depth. This brings the number of likely hotspots in the southern hemisphere to 4. Although VIRITS did not acquire 1 micron data in the northern hemisphere, the gravity and topography data for the 7 northern hemisphere hotspots indicate active plumes. The similarity of geologic and gravity signatures between northern and southern hemisphere hotspots suggests that all of them may be sites of currently or recently active volcanism. This brings the hotspot count on Venus to 11. Such hotspots could be plausible sources of lower atmospheric water (Smrekar and Sotin, 2012). The presence of ~10 plumes from the core-mantle-boundary on Venus suggests that the mantle may be heating up (Sotin and Smrekar, 2012 - this meeting). (Drossart et al., PSS, 2007; Helbert et al., GRL, 2008; Mueller et al., JGR-P, 2008; Smrekar et al., Sci., 2010; Ivanov and Head, PSS, 2010; Smrekar and Sotin, Icarus, 2012) This research was conducted at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

Smrekar, S. E.; Brown, N.

2012-12-01

199

Undercloud aerosol in Venus 'atmosphere  

International Nuclear Information System (INIS)

Parameters of finely dispersed undercloud aerosol detected from the results of spectrophotometric measurements at descent capsules of Venus - 9, 10, 11 and 12 have been considered. The aerosol is mainly at heights H > or approximately 30 km but sometimes it is also observed at lower heights. Particle size r amounts to 0.05-0.1 ?m. Particles of large sizes (r=0.1+-0.3 ?m) were discovered in the place of Venus 12 landing. Particle concentration and relative-in-mass aerosol content have been evaluated, identification of aerosol particle substance was attemped. Altitudinal dependences of the extinction coefficient have been obtained. The aerosol parameters obtained for the places of Venus 9, 10, 11 and 12 landings agree well between themselves

200

Spaceborne radar studies of Venus  

International Nuclear Information System (INIS)

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

201

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

202

Analysis of MESSENGER/MASCS data during second Venus flyby  

Science.gov (United States)

In June 2007, the MESSENGER spacecraft performed its second Venus flyby during its travel to Mercury. The spacecraft acquired several spectra of the reflected sunlight from the equatorial region of the planet and covering from the middle ultraviolet (195nm) to the near infrared (1450 nm) using the MASCS instrument (MUV-UVVS and VIRS channels). In this work we present an analysis of the data and their spectral and spatial variability following the mission footprint on the Venus disk. In order to reproduce the observed reflectivity and obtain information on the upper clouds and the unknown UV absorber, we use XtraRT, a radiative transfer code based on DISORT and the HITRAN database, which includes SO, SO2, CO2 and H2O absorption together with absorption and scattering by mode-1 and mode-2 cloud particles. We discuss the sensitivity of our models to key atmospheric parameters and some preliminary results. The MASCS observations of Venus mean a valuable opportunity for cross-calibration with VIRTIS, the spectrometer on board the Venus Express mission.

Perez-Hoyos, S.; Garcia-Muñoz, A.; Sánchez-Lavega, A.; McClintock, W. M.

2013-09-01

203

How to Electrically Sound the Size of the Venus Core  

Science.gov (United States)

When the solar wind interacts with the Venus ionosphere, the interplanetary magnetic field can diffuse into the ionosphere at a rate dependent on the collision frequency at the ionopause. The magnetic field is carried downward by the ionospheric circulation that is downward near the subsolar point. This magnetic flux is deposited at low altitudes building up a magnetic layer at about 200 km altitude, which, at most, slowly diffuses into the neutral atmosphere below. The dayside low latitude layer has been mapped by Pioneer Venus around the planet, across the terminators, and to midnight. At the terminator, the field begins to dip into the atmosphere, and at midnight, the field rises out of the atmosphere almost vertically. Venus Express measurements complement those of PVO with data at low altitudes solely over the north pole, increasing the coverage in the region in which the field begins to dip into the atmosphere. To the accuracy in which we can determine the geometry of the field relative to the radial direction over the bottom of the ionosphere, we should be able to determine the size of the core of Venus. If this is not possible to the required accuracy, measurements in the ionosphere and from balloons beneath the ionosphere could be combined to provide the needed measurements.

Russell, C. T.; Luhmann, Janet G.; Zhang, Tielong; Chi, Peter; Villarreal, M.

204

Chemical Weathering Kinetics of Basalt on Venus  

Science.gov (United States)

The purpose of this project was to experimentally measure the kinetics for chemical weathering reactions involving basalt on Venus. The thermochemical reactions being studied are important for the CO2 atmosphere-lithosphere cycle on Venus and for the atmosphere-surface reactions controlling the oxidation state of the surface of Venus. These reactions include the formation of carbonate and scapolite minerals, and the oxidation of Fe-bearing minerals. These experiments and calculations are important for interpreting results from the Pioneer Venus, Magellan, Galileo flyby, Venera, and Vega missions to Venus, for interpreting results from Earth-based telescopic observations, and for the design of new Discovery class (e.g., VESAT) and New Millennium missions to Venus such as geochemical landers making in situ elemental and mineralogical analyses, and orbiters, probes and balloons making spectroscopic observations of the sub-cloud atmosphere of Venus.

Fegley, Bruce, Jr.

1997-01-01

205

The present status of Japanese Venus Climate Orbiter (AKATSUKI: PLANET-C) after the launch  

Science.gov (United States)

The Venus Climate Orbiter mission (PLANET-C), one of the planetary missions of Japan, aims at understanding the atmospheric circulation of Venus. Meteorological information will be obtained by globally mapping clouds and minor constituents successively with 4 cameras at ultraviolet and infrared wavelengths, detecting lightning with a high-speed imager, and ob-serving the vertical structure of the atmosphere with radio science technique. The equatorial elongated orbit with westward revolution fits the observation of the movement and temporal variation of the atmosphere which rotates westward. The systematic, continuous imaging ob-servations will provide us with an unprecedented large dataset of the Venusian atmospheric dynamics. Planet-C is launched from Kagoshima Space Center and will reach Venus in Dec, 2010. Nominal operation period is 2 earth years. It is now in the transfer orbit to Venus We will report the present status of the spacecraft after the launch.

Nakamura, Masato

206

Pancakelike domes on Venus  

Science.gov (United States)

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

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

1992-01-01

207

Formation of plasma vortices in the interaction of the Solar Wind with the ionosphere of Venus  

Science.gov (United States)

Recent in-situ measurements from the Venus Express spacecraft indicate the existence of large-scale vortex-like motions in the combined plasma flow, solar wind H+ and ionospheric O+ ions, in the Venus plasma tail (Lundin et al. 2012, Pérez-de-Tejada et al., 2012). We present results of three-dimensional numerical simulations of the fluid-like interaction of the solar wind with the ionosphere of Venus. The formation of vortical flows in the near wake of Venus plasma environment is naturally explained in the context of such scenario due to the advection and stretching of structures resulting from the development of the Kelvin-Helmholtz instability at the ionopause. The consequent erosion rate of ionospheric material predicted by our results is also quantified.

Reyes-Ruiz, M.; Perez De Tejada, H. A.; Aceves, H.

2013-05-01

208

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

Science.gov (United States)

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.

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

2009-01-01

209

Silkworm expression system as a platform technology in life science.  

Science.gov (United States)

Many recombinant proteins have been successfully produced in silkworm larvae or pupae and used for academic and industrial purposes. Several recombinant proteins produced by silkworms have already been commercialized. However, construction of a recombinant baculovirus containing a gene of interest requires tedious and troublesome steps and takes a long time (3-6 months). The recent development of a bacmid, Escherichia coli and Bombyx mori shuttle vector, has eliminated the conventional tedious procedures required to identify and isolate recombinant viruses. Several technical improvements, including a cysteine protease or chitinase deletion bacmid and chaperone-assisted expression and coexpression, have led to significantly increased protein yields and reduced costs for large-scale production. Terminal N-acetyl glucosamine and galactose residues were found in the N-glycan structures produced by silkworms, which are different from those generated by insect cells. Genomic elucidation of silkworm has opened a new chapter in utilization of silkworm. Transgenic silkworm technology provides a stable production of recombinant protein. Baculovirus surface display expression is one of the low-cost approaches toward silkworm larvae-derived recombinant subunit vaccines. The expression of pharmaceutically relevant proteins, including cell/viral surface proteins, membrane proteins, and guanine nucleotide-binding protein (G protein) coupled receptors, using silkworm larvae or cocoons has become very attractive. Silkworm biotechnology is an innovative and easy approach to achieve high protein expression levels and is a very promising platform technology in the field of life science. Like the "Silkroad," we expect that the "Bioroad" from Asia to Europe will be established by the silkworm expression system. PMID:19830419

Kato, Tatsuya; Kajikawa, Mizuho; Maenaka, Katsumi; Park, Enoch Y

2010-01-01

210

Mars is close to venus--female reproductive proteins are expressed in the fat body and reproductive tract of honey bee (Apis mellifera L.) drones.  

Science.gov (United States)

Vitellogenin (Vg) and lipophorin (Lp) are lipoproteins which play important roles in female reproductive physiology of insects. Both are actively taken up by growing oocytes and especially Vg and its receptor are considered as female-specifically expressed. The finding that the fat body of in honey bee (Apis mellifera) drones synthesizes Vg and is present in hemolymph has long been viewed as a curiosity. The recent paradigm change concerning the role played by Vg in honey bee life history, especially social division of labor, has now led us to investigate whether a physiological constellation similar to that seen in female reproduction may also be represented in the male sex. By means of Western blot analysis we could show that both Vg and Lp are present in the reproductive tract of adult drones, including the accessory (mucus) glands, but apparently are not secreted. Furthermore, we analyzed the transcript levels of the genes encoding these proteins (vg and lp), as well as their putative receptors (Amvgr and Amlpr) in fat body and accessory glands. Whereas lp, vg and Amlpr transcript levels decreased with age in both tissues, Amvgr mRNA levels increased with age in fat body. To our knowledge this is the first report that vitellogenin and its receptor are co-expressed in the reproductive system of a male insect. We interpret these findings as a cross-sexual transfer of a social physiological trait, associated with the rewiring of the juvenile hormone/vitellogenin circuitry that occurred in the female sex of honey bees. PMID:20600084

Colonello-Frattini, Nínive Aguiar; Guidugli-Lazzarini, Karina Rosa; Simões, Zilá Luz Paulino; Hartfelder, Klaus

2010-11-01

211

Non-Cooled Power System for Venus Lander  

Science.gov (United States)

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.

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

2014-01-01

212

Earth/Venus Rotation Movie  

Science.gov (United States)

This movie shows Venus and Earth as they rotate. The images are superimposed on each other so that differences in rotation speed and tilt of axes can be seen. Links to documents describing the physical properties and characteristics of the two planets are provided.

2005-09-01

213

Comparative Climate Studies of Earth, Venus and Mars  

Science.gov (United States)

One of the most promising area in Solar System science is the comparative study of the three terrestrial planets (Venus, Earth, Mars). Why did the three planets evolve in such different ways, from relatively comparable initial states? The small size of Mars, favoring atmospheric escape, certainly played a role in making the present Mars so inhospitable. Venus has almost the same size and density as the Earth, and was probably initially endowed with similar amounts of volatile material. The absence of water in significant amounts on Venus, generally explained by intense primitive atmospheric escape, remains poorly constrained and understood. Two specific problems, related to Mars and Venus climate evolution, will be discussed in this talk. One major challenge of Mars studies is to determine the nature of the present Martian atmosphere: is it the residual of an old atmosphere, progressively lost by escape, or is it young, at steady state equilibrium between outgassing and escape? The possible detection of methane in Martian atmosphere suggests that methane currently is being produced, possibly signing outgassing, since methane is the thermodynamically favoured form of carbon, as released by potential volcanism or hydrothermalism, at low Martian temperature and pressure. Although no typical volcanic gas, like SO2, has ever been detected on Mars, the existence of recent lava flows (a few million years old) shows that a residual volcanism is still episodically active. Another possible tracer of outgassing, that is radon 222, seems promising, and could have been detected (although indirectly) in the Martian atmosphere from recent APXS (MER rovers) and Gamma Ray Spectrometer (Mars- Odyssey) measurements. The lack of any isotopic fractionation of carbon and oxygen in Martian CO2, as shown by existing measurements, suggests that the atmosphere of Mars is young, since it should have been fractionated by escape if it is old. This possibility of a young Martian atmosphere, permanently supplied from the planetary interior, will be discussed. Concerning Venus, we will focus on the question of the fate of its primitive ocean. The possibility that Venus was born 'dry', massively losing its atmosphere to space during the first ten million years of its life, will be assessed. It will be shown that massive primitive escape doesn"t necessarily result in strong isotopic fractionation of atmospheric species, and that the few existing information about noble gas isotopic ratios in Venus atmosphere (Ne, Ar) are consistent with a primitive episode of intense hydrodynamic escape.

Chassefiere, E.

2008-12-01

214

Ion heating near the ion composition boundary at Venus  

Science.gov (United States)

In this study we focus on the boundary layer above the ionopause of Venus. The first measurements which demonstrated the existence of such a boundary layer were those of the electron energy spectra obtained by the Pioneer Venus Orbiter Retarding Potential Analyser (ORPA) [Spenner et al., 1980, JGR]. The measurements of the ASPERA-4 electron spectrometer on board Venus Express (VEX) confirmed the existence of such a layer [Coates et al. 2008, Planetary and Space Sci.]. The upper end of the interaction layer, where planetary ions disappear, is called ion composition boundary (ICB). Due to the interaction of the two plasma populations near the ICB - the shocked solar wind and planetary ions - instabilities are excited. Significant collisionless momentum and energy exchange takes place because of wave-particle interaction, creating a highly turbulent layer. In earlier works we proposed that modified two stream instabilities (MTSI) excited there (see e.g. Dobe et al., 1999, Phys. Rev. Lett., 83, pp. 260-263) might explain the 100-Hz waves observed by the electric field detector (OEFD) on board PVO in the dayside of Venus. The instability also heats the ions. PVO data covered only partially the energy range of the particles in question. Using the much better 3-D energy and spatial coverage of the Analyser of Space Plasmas and Energetic Atoms (ASPERA-4) instrument suite on board VEX, we compare here with data the charged particle heating due to the MTSI. The first data set is for average solar wind conditions, the second one is for a case when a strong solar storm hit Venus. This analysis will be expanded in the future to have a broader picture on planetary space weather effects. After having summarised the properties of the modified two stream instability, and the ion heating and ion acceleration mechanism in the framework of a numerical hybrid model which retains electron inertia, we show that MTSI works effectively. We also discuss the limits of this approach.

Szegö, Karoly; Dobe, Zoltan; Bebesi, Zsofia; Coates, Andrew; Foldy, Lajos; Fraenz, Markus; Opitz, Andrea; Vech, Daniel

2014-05-01

215

Transits of Venus in Public Education and Contemporary Research  

Science.gov (United States)

Transits of Venus are among the rarest predictable astronomical event that humans can enjoy, and the 2012 transit will be visible by almost all the people on Earth. It is our job as educators to bring out the thrill of being able to see the tiny dot of Venus silhouetted against the solar disk even with just a simple eye-protection filter. My Website at http://www.transitofvenus.info brings together not only historical information about the five previous transits of Venus that were observed through the 20th century--1639, 1761, 1769, 1874, and 1882--but also the scientific work carried out at the 2004 transit and at recent transits of Mercury. Based on space observations of the 1999 transit of Mercury with NASA's Transition Region and Coronal Explorer (TRACE), Glenn Schneider and I provided proof of the contemporary explanation of the black-drop effect as an amalgam of instrumental point-spread and solar limb-darkening [1]. Based on observations of the changes in the total solar irradiance during the transit, we provided an analysis of this solar-system analogue to exoplanet transits [2]. High-resolution (0.5 arcsec pixels) observations of ingress and egress with TRACE during the 2004 transit provided information about the visibility of Venus's atmosphere through its refraction of sunlight, interpreted with Venus Express observations [3]. We anticipate observing the 2012 transit with groundbased facilities of the University of Hawaii at Haleakala, and of the National Solar Observatory at Sacramento Peak, and Kitt Peak, as well as with NASA and JAXA spacecraft, including Solar Dynamics Observatory, ACRIMsat, and Hinode. The Program Group on Public Education on the Occasions of Eclipses and Transits of Commission 46 on Education and Development of the International Astronomical Union, which I chair, looks forward to participating in Education and Public Outreach efforts related to the 2012 transit.

Pasachoff, J. M.

2011-10-01

216

Pioneer Venus and Galileo entry probe heritage  

Science.gov (United States)

Beginning in the late 1960s, NASA began planning for its first program to explore Venus. Although planetary entry probes had been flown to Venus by the Soviets beginning in 1967, NASA had not previously flown this type of mission. The Space and Communications Group of Hughes Aircraft Company, now owned by Boeing and called Boeing Satellite Systems, worked with NASA to perform initial studies that culminated with a contract for the Pioneer Venus program in early 1974. Pioneer Venus was an ambitious program that included four planetary entry probes, transported to Venus by a Multiprobe Bus, and a Venus Orbiter. This paper focuses on the engineering aspects of the probes and the challenges overcome in accommodating the various scientific instruments. The second NASA planetary entry program was the Galileo Mission that began with initial studies in the early 1970s. This mission to Jupiter included both an Orbiter and a Probe. Although the Galileo Probe planetary entry program was begun as the Pioneer Venus probes were heading towards Venus, there were significant engineering differences between the Pioneer Venus probe designs and the Galileo Probe. These differences, dictated by a number of factors, are discussed. The paper concludes with a summary of lessons learned by Boeing and NASA in designing, manufacturing and ultimately flying the Venus and Jupiter planetary entry probes.

Bienstock, Bernard J.

2004-02-01

217

Circulation in upper mesosphere of Venus in the Southern and Northern hemispheres from the O2 1.27 ?m night glow (VIRTIS-M/VEX data)  

Science.gov (United States)

Mapping spectrometer VIRTIS-M on board Venus Express [1] made observations of the O2 1.27 ?m airglow intensity distribution on the night side of Venus in nadir and limb modes in Southern and Northern hemispheres respectively. The work is devoted to comparison of the results, obtained for both hemispheres.

Zasova, L.; Shakun, A.; Khatuntsev, I.; Gorinov, D.; Migliorini, A.; Altieri, F.; Piccioni, G.; Drossart, P.

2014-04-01

218

The Transit of Venus: an Opportunity to Promote Astronomy  

Science.gov (United States)

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”

Ros, R. M.

219

BOOK REVIEW: June 8, 2004: Venus in Transit  

Science.gov (United States)

A transit of Venus is a relatively rare astronomical event in which the silhouette of Venus is seen to move across the face of the Sun. The phenomenon typically lasts several hours, during which Venus is seen as a small dot against the half-degree angular diameter of the solar disc. The last transit of Venus occurred in 1882; the next will be 8 June 2004. Such transits were once of great importance in astronomy. By observing a transit simultaneously from well separated points on the Earth's surface, astronomers were able to measure, with some degree of accuracy, the crucially important separation of the Earth and the Sun. Knowing this enabled them to convert the relative spacings of the planets indicated by Kepler's laws into absolute interplanetary distances expressed in miles or kilometres. Eli Maor's book presents the general reader with a full account of Venusian transits that covers the history of their observation as well as their significance and the reasons for their rarity. The book is a light and enjoyable read that opens well with an imaginative description of observing the 2004 transit from the hills outside Jerusalem. Following an account of Kepler's prediction of a transit of Mercury in 1631 and its observation by Gassendi, the book moves on to describe the transit of Venus in 1639, giving particular emphasis to the prescient work of Jeremiah Horrocks, the extraordinary young English curate and astronomer who died just two years later at the age of 21. The story, however, really takes off with Edmond Halley's realization, in 1677, that transits of Venus might provide the key to determining distances within the solar system. The details of Halley's method are confined to an appendix, but the central chapters of the book detail the increasingly elaborate efforts that astronomers made to observe transits of Venus up to the time of the 1882 transit, when, due to the impact of new photographic methods, interest in transit observations was waning. By that time the distance to the Sun was known to be about 93 000 000 miles and observations of Mars or the asteroids seemed to offer a better prospect of improved accuracy than further observations of Venus. The story is rounded off by a chapter that describes spurious transit observations (such as that of Vulcan, a planet that was supposed to orbit closer to the Sun than Mercury) and a chapter concerning transits of the Earth seen from Mars, Jupiter and the other outer planets. Maor, who is also the author ofe: The Story of a Number, and various other books, writes clearly and well, but Venus in Transit is not uniformly interesting throughout. The early chapters are generally very good, as is the account of Captain James Cook and theEndeavour's voyage to observe the 1761 transit. But after that I felt my interest flagging somewhat, just as the astronomers of the time seemed to find their own interest diminishing. The closing chapters helped to re-engage my interest, but I did feel that the discussion of the 19th century transits was rather perfunctory and that it would have benefited from more space. Still, these are minor criticisms of a book that I am personally very glad to have read. Venus in Transit will obviously appeal most to those with an interest in astronomy, particularly in its historical aspects. But there is also much that physicists can enjoy in the book and I can easily imagine it as a useful though non-essential addition to many school and college libraries. Robert Lambourne

Maor, Eli

2000-09-01

220

Venus Data Analysis Program: Directory of Research Projects (1993-1994)  

Science.gov (United States)

This directory provides information about the scientific investigations funded by the NASA Venus Data Analysis Program (VDAP) during fiscal year 1993. The VDAP Directory consists of summary sheets from the proposals that were selected by NASA for funding in FY 93. Each summary sheet indicates the title, principal investigator, institution of the investigation, and information related to the objectives of the research activities proposed for FY 93. The objective of the VDAP Program is to advance our understanding of the nature and evolution of Venus. VDAP supports scientific investigation using data obtained from the Magellan, Pioneer Venus, and other Venus missions, as well as earth-based observations that contribute to understanding the physical and evolutionary properties of Venus. The program intends to enhance the scientific return from these missions by broadening the participation in the analysis of Venus data. Categories of research funded by VDAP are atmosphere, ionosphere, geology, geophysics, and mapping. The directory is intended to provide the science community with an overview of the research projects supported by this program. Research activities identified in this directory were selected for funding in FY 93 on the basis of scientific peer review conducted by the VDAP Review Panel.

221

A Venus Rover Capable of Long Life Surface Operations  

Science.gov (United States)

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.

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

2005-12-01

222

Abstracts for the Venus Geoscience Tutorial and Venus Geologic Mapping Workshop  

Science.gov (United States)

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.

1989-01-01

223

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 resuGHz 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

224

Hotspots on Venus: Possible recent activity at Themis Regio  

Science.gov (United States)

Themis Regio, Venus is a 2300 x 1700 km topographic rise, with an average height of about 0.5 km. It is one of the ~10 hotspots on Venus, thought to be underlain by a mantle plume (e.g., Stofan and Smrekar, 2005). Thirteen coronae are located on the rise, with an additional six in the surrounding region (Stofan and Brian, 2012). In addition, six volcanoes with diameters > 100 km are found on and near the rise, along with numerous intermediate and smaller volcanoes. The Themis rise lies at the western end of the Parga Chasma rift system. Flows associated with Themis coronae, volcanoes and plains both superpose and are cut by Parga fractures and graben. Recent mapping of Themis Regio reveals a complex history of corona, volcano and rift formation that has overlapped in time and space (Stofan and Brian, 2012). Smrekar and Stofan (1999) found that gravity data for Themis was best fit by a bottom-loading model with an elastic thickness estimate of 22 km, a crustal thickness of 10 km, and an apparent depth of compensation of 80-110 km. The observed range in morphologies of the Themis coronae indicating a range in stages of evolution, along with the delamination signal seen in the gravity data, and the broad topographic swell indicate that Themis is likely to be underlain by an active plume with ongoing surface deformation due to delamination. In addition, the complex sequence of corona formation observed at Themis suggests that a series of small-scale upwellings over time are responsible for corona formation, rather than nearly simultaneously from the break-up of a single large-scale mantle plume (Stofan and Smrekar, 2005). VIRTIS data from the Venus Express mission has provided evidence that relatively recent volcanic activity may have occurred in the region (Smrekar et al., 2010). Fifteen locations on or near the Themis rise have elevated values of emissivity in the VIRTIS data. We investigate all of these regions, and find them to be correlated with areas of volcanic activity, associated with either coronae or volcanoes. While a few of the high emissivity spots are associated with steep-sided domes, most are associated with flows that are likely to be basaltic in origin. The anomalies occur on both topographically elevated terrain as well as on relatively low-lying plains. Based on their morphology and stratigraphic relations with surrounding units, we interpret all of the features to provide evidence of volcanic activity that likely occurred within the last 250,000 years (e.g., Smrekar et al., 2010). References: Smrekar, S.E. and E.R. Stofan, Icarus 139, 100, 1999; Smrekar, S.E. et al., Science 328, 305, 2010; Stofan, E.R. and A.W. Brian, U.S.G.S. SIM- 3165, 2012; Stofan, E.R. and S.E. Smrekar, GSA Spec. Paper 388, 841, 2005.

Stofan, E. R.; Smrekar, S. E.; Helbert, J.; Mueller, N. T.

2012-12-01

225

Pioneer Venus Sounder Probe gas chromatograph  

Science.gov (United States)

The design logic, construction, function, and data processing of the Pioneer Venus Sounder Probe gas chromatograph instrument are discussed. A gas chromatograph for the analysis of the chemical composition of the lower atmosphere of Venus was included in the Sounder Probe of the Pioneer Venus mission. This paper describes the design logic of the gas chromatograph as constrained by the mission; attention is given to instrument construction, function, and data reduction.

Oyama, V. I.; Carle, G. C.; Woeller, F.; Rocklin, S.; Vogrin, J.; Potter, W.; Rosiak, G.; Reichwein, C.

1980-01-01

226

Mid-day naked-eye Venus  

Science.gov (United States)

It is generally believed that Venus may be seen with the naked eye in daylight at any time of the day. However, I could not actually find any documents indicating that Venus had been seen in the middle of the day! We now wish to correct that omission: my 4th-year students and I, on Wednesday 2004 April 28, succeeded in observing Venus at noon with the naked eye. It happened in Sana'a the capital city of Yemen.

Sultan, A. H.

2004-10-01

227

Upstream proton cyclotron waves at Venus near solar maximum  

Science.gov (United States)

magnetometer data of Venus Express are analyzed for the occurrence of waves at the proton cyclotron frequency in the spacecraft frame in the upstream region of Venus, for conditions of rising solar activity. The data of two Venus years up to the time of highest sunspot number so far (1 Mar 2011 to 31 May 2012) are studied to reveal the properties of the waves and the interplanetary magnetic field (IMF) conditions under which they are observed. In general, waves generated by newborn protons from exospheric hydrogen are observed under quasi- (anti)parallel conditions of the IMF and the solar wind velocity, as is expected from theoretical models. The present study near solar maximum finds significantly more waves than a previous study for solar minimum, with an asymmetry in the wave occurrence, i.e., mainly under antiparallel conditions. The plasma data from the Analyzer of Space Plasmas and Energetic Atoms instrument aboard Venus Express enable analysis of the background solar wind conditions. The prevalence of waves for IMF in direction toward the Sun is related to the stronger southward tilt of the heliospheric current sheet for the rising phase of Solar Cycle 24, i.e., the "bashful ballerina" is responsible for asymmetric background solar wind conditions. The increase of the number of wave occurrences may be explained by a significant increase in the relative density of planetary protons with respect to the solar wind background. An exceptionally low solar wind proton density is observed during the rising phase of Solar Cycle 24. At the same time, higher EUV increases the ionization in the Venus exosphere, resulting in higher supply of energy from a higher number of newborn protons to the wave. We conclude that in addition to quasi- (anti)parallel conditions of the IMF and the solar wind velocity direction, the higher relative density of Venus exospheric protons with respect to the background solar wind proton density is the key parameter for the higher number of observable proton cyclotron waves near solar maximum.

Delva, M.; Bertucci, C.; Volwerk, M.; Lundin, R.; Mazelle, C.; Romanelli, N.

2015-01-01

228

Towards a Self Consistent Model of the Thermal Structure of the Venus Atmosphere  

Science.gov (United States)

Nearly three decades ago, an international effort led to the adoption of the Venus International Reference Atmosphere (VIRA) was published in 1985 after the significant data returned by the Pioneer Venus Orbiter and Probes and the earlier Venera missions (Kliore et al., 1985). The vertical thermal structure is one component of the reference model which relied primarily on the three Pioneer Venus Small Probes, the Large Probe profiles as well as several hundred retrieved temperature profiles from the Pioneer Venus Orbiter radio occultation data collected during 1978 - 1982. Since then a huge amount of thermal structure data has been obtained from multiple instruments on ESA’s Venus Express (VEX) orbiter mission. The VEX data come from retrieval of temperature profiles from SPICAV/SOIR stellar/solar occultations, VeRa radio occultations and from the passive remote sensing by the VIRTIS instrument. The results of these three experiments vary in their intrinsic properties - altitude coverage, spatial and temporal sampling and resolution and accuracy An international team has been formed with support from the International Space Studies Institute (Bern, Switzerland) to consider the observations of the Venus atmospheric structure obtained since the data used for the COSPAR Venus International Reference Atmosphere (Kliore et al., 1985). We report on the progress made by the comparison of the newer data with VIRA model and also between different experiments where there is overlap. Kliore, A.J., V.I. Moroz, and G.M. Keating, Eds. 1985, VIRA: Venus International Reference Atmosphere, Advances in Space Research, Volume 5, Number 11, 307 pages.

Limaye, Sanjay; Vandaele, Ann C.; Wilson, Colin

229

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

230

Investigating gravity waves evidences in the Venus upper atmosphere  

Science.gov (United States)

We present a method to investigate gravity waves properties in the upper mesosphere of Venus, through the O2 nightglow observations acquired with the imaging spectrometer VIRTIS on board Venus Express. Gravity waves are important dynamical features that transport energy and momentum. They are related to the buoyancy force, which lifts air particles. Then, the vertical displacement of air particles produces density changes that cause gravity to act as restoring force. Gravity waves can manifest through fluctuations on temperature and density fields, and hence on airglow intensities. We use the O2 nightglow profiles showing double peaked structures to study the influence of gravity waves in shaping the O2 vertical profiles and infer the waves properties. In analogy to the Earth's and Mars cases, we use a well-known theory to model the O2 nightglow emissions affected by gravity waves propagation. Here we propose a statistical discussion of the gravity waves characteristics, namely vertical wavelength and wave amplitude, with respect to local time and latitude. The method is applied to about 30 profiles showing double peaked structures, and acquired with the VIRTIS/Venus Express spectrometer, during the mission period from 2006-07-05 to 2008-08-15.

Migliorini, Alessandra; Altieri, Francesca; Shakun, Alexey; Zasova, Ludmila; Piccioni, Giuseppe; Bellucci, Giancarlo; Grassi, Davide

2014-05-01

231

A migratory mantle plume on Venus: Implications for Earth?  

Science.gov (United States)

A spatially fixed or at least internally rigid hotspot reference frame has been assumed for determining relative plate motions on Earth. Recent 1:5,000,000 scale mapping of Venus, a planet without terrestrial-style plate tectonics and ocean cover, reveals a systematic age and dimensional progression of corona-like arachnoids occurring in an uncinate chain. The nonrandom associations between arachnoids indicate they likely formed from a deep-seated mantle plume in a manner similar to terrestrial hotspot features. However, absence of expected convergent "plate" margin deformation suggests that the arachnoids are the surface expression of a migratory mantle plume beneath a stationary surface. If mantle plumes are not stationary on Venus, what if any are the implications for Earth?

Chapman, M.G.; Kirk, R.L.

1996-01-01

232

Solar wind alpha particle capture at Mars and Venus  

Science.gov (United States)

Helium is detected in the atmospheres of both Mars and Venus. It is believed that radioactive decay of uranium and thorium in the interior of the planets' is not sufficient to account for the abundance of helium observed. Alpha particles in the solar wind are suggested to be an additional source of helium, especially at Mars. Recent hybrid simulations show that as much as 30% of the alpha particles can be lost from the solar wind due to charge-exchange processes associated with the Mars/solar wind interaction. We use ion data from the ASPERA-3 and ASPERA-4 instruments on Mars and Venus Express to estimate how efficient solar wind alpha particles are captured in the atmospheres of the two planets.

Stenberg, Gabriella; Barabash, Stas; Nilsson, Hans; Fedorov, Andrei; Brain, Dave

2010-05-01

233

Substorm activity in Venus's magnetotail  

Directory of Open Access Journals (Sweden)

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.

M. Volwerk

2009-06-01

234

Latitudinal - local time distribution of the O2 and OH infrared nightglows and O density in the Venus lower thermosphere  

OpenAIRE

Atomic oxygen has been measured in situ only above 145 km on both the day and the night sides of Venus. Limb observations obtained with the Venus Infrared Thermal Imaging Spectrometer (VIRTIS) on board Venus Express show that the O2 infrared nightglow peaks at ~97 km [1, 2], with a mean intensity value of about 1 MR. Yet, the distribution is largely inhomogeneous, with an enhanced region of ~3 MR statistically located near the midnight meridian at low latitude [3]. The oxygen density can ...

Soret, Lauriane; Ge?rard, Jean-claude; Saglam, Adem; Piccioni, Giuseppe; Drossart, Pierre

2009-01-01

235

The Venus Tablet and Refraction  

OpenAIRE

It is shown that the refraction near the horizon is introducing an additional bias into the Venus Tablet of Ammisaduqa, which is able to influence the interpretation of the data. We then discuss the attempts to link certain solar eclipses to the birth of Shamshi-Adad and conclude that a record of a single solar eclipse without description of details and/or unambiguous historical links, can hardly act as a reliable anchor.

Gurzadyan, V. G.

2003-01-01

236

An unusual volcano on Venus  

Science.gov (United States)

Materials that issued from an unusual Venusian volcano produced (1) a complex domical structure about 100 km across with thick, broad flow lobes up to 41 wide, (2) an extensive sheet of thick flows, and (3) radar-bright surfaces that extend to 360-400 km from the volcano. Altimetry indicates that the relief of the domical structure is about 0.5-1.1 km. The lobes and flows have prominant regularly spaced ridges about 686-820 m apart. Thick flows with large ridge separations and broad lobes are rare on Venus. The viscosities of these flows were larger than those of most lava flows on Venus. Comparisons of the dimensions of the volcano's lobes with lava flows on earth suggest that the Venusian lavas may have large silica contents. Radar-bright surfaces around the volcano may represent the result of an explosive eruption or very thin deposits of low-viscosity lavas. Thus, the radar-bright surfaces and lavas of the volcano were derived from a magma that differentiated within the crust or mantle of Venus. The differentiation produced (1) a gas-rich low-viscosity phase, (2) high-viscosity lavas, and (3) a residual primary magma.

Moore, H. J.; Plaut, J. J.; Schenk, P. M.; Head, J. W.

1992-08-01

237

Memristors in the Venus flytrap.  

Science.gov (United States)

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:25763613

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

2014-08-01

238

An unusual volcano on Venus  

Science.gov (United States)

Materials that issued from an unusual Venusian volcano produced (1) a complex domical structure about 100 km across with thick, broad flow lobes up to 41 wide, (2) an extensive sheet of thick flows, and (3) radar-bright surfaces that extend to 360-400 km from the volcano. Altimetry indicates that the relief of the domical structure is about 0.5-1.1 km. The lobes and flows have prominant regularly spaced ridges about 686-820 m apart. Thick flows with large ridge separations and broad lobes are rare on Venus. The viscosities of these flows were larger than those of most lava flows on Venus. Comparisons of the dimensions of the volcano's lobes with lava flows on earth suggest that the Venusian lavas may have large silica contents. Radar-bright surfaces around the volcano may represent the result of an explosive eruption or very thin deposits of low-viscosity lavas. Thus, the radar-bright surfaces and lavas of the volcano were derived from a magma that differentiated within the crust or mantle of Venus. The differentiation produced (1) a gas-rich low-viscosity phase, (2) high-viscosity lavas, and (3) a residual primary magma.

Moore, H. J.; Plaut, J. J.; Schenk, P. M.; Head, J. W.

1992-01-01

239

Two-dimensional time-dependent model of the transport of minor species in the Venus night side upper atmosphere  

OpenAIRE

We present a numerical tool developed to quantify the role of processes controlling the spatio-temporal distribution of the NO ultraviolet and O2 infrared nightglows in the Venus night side upper atmosphere, observed with the VIRTIS and SPICAV instruments on board Venus Express. This numerical tool consists in a two-dimensional chemical-transport time-dependent model which computes in a hypothetical rectangular solving domain the spatio-temporal distributions of the number densities of the fo...

Collet, Arnaud; Cox, Ce?dric; Ge?rard, Jean-claude

2010-01-01

240

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)

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

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

241

Topic in Depth - Transit of Venus  

Science.gov (United States)

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

242

Helium on Mars and Venus: EUVE observations and modeling  

Science.gov (United States)

Long-exposure spectroscopy of Mars and Venus with the Extreme Ultraviolet Explorer (EUVE) has revealed emissions of He 584 Å on both planets and He 537 Å/O + 539 Å and He + 304 Å on Venus. Our knowledge of the solar emission at 584 Å, eddy diffusion in Mars' upper atmosphere, electron energy distributions above Mars' ionopause, and hot oxygen densities in Mars' exosphere has been significantly improved since our analysis of the first EUVE observation of Mars [Krasnopolsky, Gladstone, 1996, Helium on Mars: EUVE and Phobos data and implications for Mars' evolution, J. Geophys. Res. 101, 15,765-15,772]. These new results and a more recent EUVE observation of Mars are the motivation for us to revisit the problem in this paper. We find that the abundance of helium in the upper atmosphere, where the main loss processes occur, is similar to that in the previous paper, though the mixing ratio in the lower and middle atmosphere is now better estimated at 10±6 ppm. Our estimate of the total loss of helium is almost unchanged at 8×10 s, because a significant decrease in the loss by electron impact ionization above the ionopause is compensated by a higher loss in collisions with hot oxygen. We neglect the outgassing of helium produced by radioactive decay of U and Th because of the absence of current volcanism and a very low upper limit to the seepage of volcanic gases. The capture of solar wind ?-particles is currently the only substantial source of helium on Mars, and its efficiency remains at 0.3. A similar analysis of EUV emissions from Venus results in a helium abundance in the upper atmosphere which is equal to the mean of the abundances measured previously with two optical and two mass spectrometers, and a derived helium mixing ratio in the middle and lower atmosphere of 9±6 ppm. Helium escape by ionization and sweeping out of helium ions by the solar wind above the ionopause is smaller than that calculated by Prather and McElroy [1983, Helium on Venus: implications for uranium and thorium, Science 220, 410-411] by a factor of 3. However, charge exchange of He + ions with CO 2 and N 2 between the exobase and ionopause and collisions with hot oxygen ignored previously add to the total loss which appears to be at the level of 10 6 cm -2 s -1 predicted by Prather and McElroy [1983, Science 220, 410-411]. The loss of helium is compensated by outgassing of helium produced by radioactive decay of U and Th and by the capture of the solar wind ?-particles with an efficiency of 0.1. We also compare our derived ?-particle capture efficiencies for Mars and Venus with observed X-ray emissions resulting from the charge exchange of solar wind heavy ions with the extended atmospheres on both planets [Dennerl et al., 2002, Discovery of X-rays from Venus with Chandra, Astron. Astrophys. 386, 319-330; Dennerl, 2002, Discovery of X-rays from Mars with Chandra, Astron. Astrophys. 394, 1119-1128]. The emissions from both disk and halo on Mars agree with our calculated values; however, we do not see a reasonable explanation for the X-ray halo emission on Venus. The ratio of the charge exchange efficiencies derived from the disk X-ray emissions of Mars and Venus is similar to the ratio of the capture efficiencies for these planets. The surprisingly bright emission of He + at 304 Å observed by EUVE and Venera 11 and 12 suggests that charge exchange in the flow of the solar wind ?-particles around the ionopause is much stronger than in the flow of ?-particles into the ionosphere.

Krasnopolsky, Vladimir A.; Gladstone, G. Randall

2005-08-01

243

Recent progress on the superconducting ion source VENUS  

Energy Technology Data Exchange (ETDEWEB)

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

Benitez, J. Y.; Franzen, K. Y.; Hodgkinson, A.; Loew, T.; Lyneis, C. M.; Phair, L.; Saba, J.; Strohmeier, M. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Tarvainen, O. [Accelerator Laboratory, Department of Physics, University of Jyvaeskylae, FIN-40014 (Finland)

2012-02-15

244

Recent progress on the superconducting ion source VENUS.  

Science.gov (United States)

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

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

2012-02-01

245

Recent progress on the superconducting ion source VENUS  

International Nuclear Information System (INIS)

The 28 GHz Ion Source VENUS (versatile ECR for nuclear science) is back in operation after the superconducting sextupole leads were repaired and a fourth cryocooler was added. VENUS serves as an R and D device to explore the limits of electron cyclotron resonance source performance at 28 GHz with its 10 kW gryotron and optimum magnetic fields and as an ion source to increase the capabilities of the 88-Inch Cyclotron both for nuclear physics research and applications. The development and testing of ovens and sputtering techniques cover a wide range of applications. Recent experiments on bismuth demonstrated stable operation at 300 e?A of Bi31+, which is in the intensity range of interest for high performance heavy-ion drivers such as FRIB (Facility for Rare Isotope Beams). In addition, the space radiation effects testing program at the cyclotron relies on the production of a cocktail beam with many species produced simultaneously in the ion source and this can be done with a combination of gases, sputter probes, and an oven. These capabilities are being developed with VENUS by adding a low temperature oven, sputter probes, as well as studying the RF coupling into the source.

246

Magma vesiculation and pyroclastic volcanism on Venus  

Science.gov (United States)

Theoretical consideration of the magma vesiculation process under observed and inferred venusian surface conditions suggests that vesicles should form in basaltic melts, especially if CO2 is the primary magmatic volatile. However, the high surface atmospheric pressure (about 90 bars) and density on Venus retard bubble coalescence and disruption sufficiently to make explosive volcanism unlikely. The products of explosive volcanism (fire fountains, convecting eruption clouds, pyroclastic flows, and topography-mantling deposits of ash, spatter, and scoria) should be rare on Venus, and effusive eruptions should dominate. The volume fraction of vesicles in basaltic rocks on Venus are predicted to be less than in chemically similar rocks on earth. Detection of pyroclastic landforms or eruption products on Venus would indicate either abnormally high volatile contents of Venus magmas (2.5-4 wt%) or different environmental conditions (e.g., lower atmospheric pressure) in previous geologic history.

Garvin, J. B.; Head, J. W.; Wilson, L.

1982-01-01

247

Venus Atmospheric Circulation from Digital Tracking of VMC Images  

Science.gov (United States)

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).

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

2008-09-01

248

The loss of ions from Venus through the plasma wake  

Science.gov (United States)

Venus, unlike Earth, is an extremely dry planet although both began with similar masses, distances from the Sun, and presumably water inventories. The high deuterium-to-hydrogen ratio in the venusian atmosphere relative to Earth's also indicates that the atmosphere has undergone significantly different evolution over the age of the Solar System. Present-day thermal escape is low for all atmospheric species. However, hydrogen can escape by means of collisions with hot atoms from ionospheric photochemistry, and although the bulk of O and O2 are gravitationally bound, heavy ions have been observed to escape through interaction with the solar wind. Nevertheless, their relative rates of escape, spatial distribution, and composition could not be determined from these previous measurements. Here we report Venus Express measurements showing that the dominant escaping ions are O+, He+ and H+. The escaping ions leave Venus through the plasma sheet (a central portion of the plasma wake) and in a boundary layer of the induced magnetosphere. The escape rate ratios are Q(H+)/Q(O+) = 1.9; Q(He+)/Q(O+) = 0.07. The first of these implies that the escape of H+ and O+, together with the estimated escape of neutral hydrogen and oxygen, currently takes place near the stoichometric ratio corresponding to water.

Barabash, S.; Fedorov, A.; Sauvaud, J. J.; Lundin, R.; Russell, C. T.; Futaana, Y.; Zhang, T. L.; Andersson, H.; Brinkfeldt, K.; Grigoriev, A.; Holmström, M.; Yamauchi, M.; Asamura, K.; Baumjohann, W.; Lammer, H.; Coates, A. J.; Kataria, D. O.; Linder, D. R.; Curtis, C. C.; Hsieh, K. C.; Sandel, B. R.; Grande, M.; Gunell, H.; Koskinen, H. E. J.; Kallio, E.; Riihelä, P.; Säles, T.; Schmidt, W.; Kozyra, J.; Krupp, N.; Fränz, M.; Woch, J.; Luhmann, J.; McKenna-Lawlor, S.; Mazelle, C.; Thocaven, J.-J.; Orsini, S.; Cerulli-Irelli, R.; Mura, M.; Milillo, M.; Maggi, M.; Roelof, E.; Brandt, P.; Szego, K.; Winningham, J. D.; Frahm, R. A.; Scherrer, J.; Sharber, J. R.; Wurz, P.; Bochsler, P.

2007-11-01

249

Outgassing history of Venus and the absence of water on Venus  

Science.gov (United States)

Similarities in the size and mean density of Earth and Venus encourage the use of Earth-analogue models for the evolution of Venus. However, the amount of water in the present Venus atmosphere is miniscule compared to Earth's oceans. The 'missing' water is thus one of the most significant problems related to the origin and evolution of Venus. Other researchers proposed that Venus accreted with less water, but this was challenged. The high D/H ratio in Venus' atmosphere is consistent with an earlier water mass more than 100 times higher than at present conditions and is often cited to support a 'wet' Venus, but this amounts to only 0.01 to 0.1 percent of the water in terrestrial oceans and the high D/H ratio on Venus could easily reflect cometary injection. Nevertheless, many authors begin with the premise that Venus once had an oceanlike water mass on its surface, and investigate the many possible mechanisms that might account for its loss. In this paper we propose that Venus degassed to lower degree than the Earth and never had an oceanlike surface water mass.

Zhang, Youxue; Zindler, Alan

1992-01-01

250

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

Science.gov (United States)

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.

Hansen, Vicki L.

2009-01-01

251

Transmission spectrum of Venus as a transiting exoplanet  

Science.gov (United States)

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 ?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 ?m by Mie extinction (~5 ppm at 0.8 ?m) caused by droplets of sulfuric acid composing an upper haze layer above the main deck of clouds. These features are not expected for a terrestrial exoplanet and could help discriminating an Earth-like habitable world from a cytherean planet. Appendix A is available in electronic form at http://www.aanda.orgFull Table A.1 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/537/L2

Ehrenreich, D.; Vidal-Madjar, A.; Widemann, T.; Gronoff, G.; Tanga, P.; Barthélemy, M.; Lilensten, J.; Lecavelier Des Etangs, A.; Arnold, L.

2012-01-01

252

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

Science.gov (United States)

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.

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

2013-12-01

253

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 dese 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

254

Distant interplanetary wake of Venus: plasma observations from pioneer Venus  

International Nuclear Information System (INIS)

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

255

The Mars Express Orbiter Radio Science Experiment (MaRS)  

Science.gov (United States)

The Mars Express Orbiter Radio Science experiment (MaRS) will employ radio occultation (i) to sound the neutral Martian atmosphere to derive vertical density, pressure and temperature profiles as a function of height to better than 100 meter), and (ii) the ionosphere to derive vertical ionospheric electron density profiles and a description of the Martian ionosphere through its diurnal and seasonal variations depending also on solar wind conditions, (iii) to determine the dielectric and scattering properties of the Martian surface in specific target areas by a bistatic radar experiment, (iv) to determine gravity anomalies for the investigation of the structure and evolution of the Martian crust and lithosphere in conjunction with observations of the High Resolution Stereo Camera (HRSC) as a base for three dimensional (3D) topography, and (v) to sound the solar corona during the superior conjunction of the planet Mars with the Sun. The radio carrier links of the spacecraft Telemetry, Tracking and Command (TTC) subsystem between the orbiter and the Earth will be used for these investigations. Simultaneous and coherent dual-frequency downlinks at X-band (8.4 GHz) and S-band (2.3 GHz) via the High Gain Antenna (HGA) permit separation of contributions from the classical Doppler shift and the dispersive media effects caused by the motion of the spacecraft with respect to the Earth and the propagation of the signals through the dispersive media, respectively. The investigation relies on the observation of the phase, amplitude, polarization and propagation times of radio signals transmitted from the spacecraft and received with ground station antennas on Earth. The radio signals are affected by the medium through which the signals propagate (atmospheres, ionospheres, interplanetary medium, solar corona), by the gravitational influence of the planet on the spacecraft and finally by the performance of the various systems involved both on the spacecraft and on ground.

Paetzold, M.

256

The Mars Express Radio Science Experiment (MaRS)  

Science.gov (United States)

The Mars Express Orbiter Radio Science experiment (MaRS) will employ radio occultation (i) to sound the neutral Martian atmosphere to derive vertical density, pressure and temperature profiles as a function of height to better than 100 meter, and (ii) sound the the ionosphere to derive vertical ionospheric electron density profiles and a description of the Martian ionosphere through its diurnal and seasonal variations depending also on solar wind conditions. MaRS will also (iii) determine the dielectric and scattering properties of the Martian surface in specific target areas by a bistatic radar experiment, (iv) determine gravity anomalies for the investigation of the structure and evolution of the Martian crust and lithosphere in conjunction with observations of the High Resolution Stereo Camera (HRSC) as a base for three dimensional (3D) topography, and (v) sound the solar corona during the superior conjunction of the planet Mars with the Sun. The radio carrier links of the spacecraft Telemetry, Tracking and Command (TT&C) subsystem between the orbiter and the Earth will be used for these investigations. Simultaneous and coherent dual-frequency downlinks at X-band (8.4 GHz) and S-band (2.3 GHz) via the High Gain Antenna (HGA) permit separation of contributions from the classical Doppler shift and the dispersive media effects caused by the motion of the spacecraft with respect to the Earth and the propagation of the signals through the dispersive media, respectively. The investigation relies on the observation of the phase, amplitude, polarization and propagation times of radio signals transmitted from the spacecraft and received with ground station antennas on Earth. The radio signals are affected by the medium through which the signals propagate (atmospheres, ionospheres, interplanetary medium, solar corona), by the gravitational influence of the planet on the spacecraft and finally by the performance of the various systems involved both on the spacecraft and on ground.

Pätzold, M.; Mars Team

2003-04-01

257

MaRS: Mars Express Orbiter Radio Science  

Science.gov (United States)

The Mars Express Orbiter Radio Science (MaRS) experiment will employ radio occultation to (I) sound the neutral martian atmosphere to derive vertical density, pressure and temperature profiles as functions of height to resolutions better than 100 m, (II) sound the ionosphere to derive vertical ionospheric electron density profiles and a description of the ionosphere through its diurnal and seasonal variations with solar wind conditions; MaRS will also (III) determine the dielectric and scattering properties of the martian surface in target areas by a bistatic radar experiment, (IV) determine gravity anomalies for the investigation of the structure and evolution of the martian crust and lithosphere in conjunction with observations of the High Revolution Stereo Camera as a base for 3D topography, and (V) sound the solar corona during the superior conjunction of Mars with the Sun. The radio carrier links of the spacecraft Telemetry, Tracking and Command subsystem between the Orbiter and Earth will be used for these investigations. Simultaneous and coherent dual-frequency downlinks at X-band (8.4 GHz) and S-band (2.3 GHz) via the High Gain Antenna will permit separation of contributions from the classical Doppler shift and the dispersive media effects caused by the motion of the spacecraft with respect to the Earth and the propagation of the signals through the dispersive media, respectively. The investigation relies on the observation of the phase, amplitude, polarisation and propagation times of radio signals transmitted from the spacecraft and received with antennas on Earth. The radio signals are affected by the medium through which they propagate (atmospheres, ionospheres, interplanetary medium, solar corona), by the gravitational influence of the planet on the spacecraft and, finally, by the performances of the various systems aboard the spacecraft and on Earth.

Pätzold, M.; Neubauer, F. M.; Carone, L.; Hagermann, A.; Stanzel, C.; Häusler, B.; Remus, S.; Selle, J.; Hagl, D.; Hinson, D. P.; Simpson, R. A.; Tyler, G. L.; Asmar, S. W.; Axford, W. I.; Hagfors, T.; Barriot, J.-P.; Cerisier, J.-C.; Imamura, T.; Oyama, K.-I.; Janle, P.; Kirchengast, G.; Dehant, V.

2004-08-01

258

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

Science.gov (United States)

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.

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

2012-04-01

259

Venus III: The Atmosphere, Climate, Surface, Interior And Near-space Environment Of An Earth-like Planet  

Science.gov (United States)

The new knowledge that has been acquired about Venus since the publication of the books Venus I (1982) and Venus II (1997) will form the basis for a new volume, Venus III in 2013/14. Although stimulated by Venus Express, and timed to incorporate results from the Japanese Akatsuki mission, contributions from any source including theory, models, and future mission planning will be included, and authorship is open to all subject only to the usual editorial process and review. Cambridge University Press has expressed a strong interest in publishing the volume and we plan to make a formal proposal in January 2011. An essential part of this will be an outline of the likely chapters, authors, and total number of pages. We invite interested Venus scientists to propose or suggest topics for chapters and to indicate whether they would personally be interested in leading or contributing to them. Chapter proposals and enquiries or comments of any kind can be sent to any of the editors, and/or to fwt@atm.ox.ac.uk if possible before the end of December 2010. All contributions will be reviewed and incorporated into a draft contents list by the editors, with consultation as necessary to resolve any gaps, overlaps, or conflicts, and this will be circulated for approval before submission to the publisher.

Taylor, Fredric W.; Russell, C. T.; Satoh, T.; Svedhem, H.; Titov, D. V.

2010-10-01

260

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

Science.gov (United States)

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

2004-11-01

261

Mitigating Extreme Environments for In-Situ Jupiter and Venus Missions  

Science.gov (United States)

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.

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

2006-01-01

262

The Ancient Mariner and the transit of Venus.  

Science.gov (United States)

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

Griffin-Short, Rita

2003-12-01

263

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

OpenAIRE

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.

Soret, Lauriane; Ge?rard, Jean-claude; Piccioni, Giuseppe; Drossart, Pierre

2010-01-01

264

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

OpenAIRE

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 appr...

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

2012-01-01

265

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

OpenAIRE

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 s...

Peralta, Javier; Luz, David; Berry, David; Tsang, Constantine; Sa?nchez-lavega, Agusti?n; Huelso, Ricardo; Piccioni, Giuseppe; Drossart, Pierre

2012-01-01

266

Signs of possible volcanism on Venus  

International Nuclear Information System (INIS)

In this paper the author discusses some independent facts established by exploration of Venus, and endeavors to clarify the origin of such phenomena as the electrical activity of the atmosphere, the bimodal particle distribution in the clouds on Venus, and the variable properties of the upper cloud deck, all discovered by polarimetric and radiometric techniques. Analysis of recent spacecraft data suggests that the frequent electrical discharges in the surface layers of the Venus atmosphere, the variable density of the submicron haze above the clouds and certain properties of the cloud microphysics can jointly be explained if the planetary surface is undergoing volcanic eruptions

267

Carbon dioxide opacity of the Venus' atmosphere  

Science.gov (United States)

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

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

2014-11-01

268

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.)

269

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%

270

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

Science.gov (United States)

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.

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

2007-01-01

271

Novel Architecture for a Long-Life, Lightweight Venus Lander  

Science.gov (United States)

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

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

2009-03-01

272

Novel Architecture for a Long-Life, Lightweight Venus Lander  

International Nuclear Information System (INIS)

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

273

Mantle flow tectonics and the origin of Ishtar Terra, Venus  

International Nuclear Information System (INIS)

It is proposed that western Ishtar Terra formed due to compression and crustal thickening above a cylindrical mantle downwelling. A model for crustal deformation due to downwelling successfully reproduces many observed characteristics of western Ishtar. Although axisymmetric downwellings occur in numerical models of constant-viscosity mantle convection, there is no evidence for their existence in Earth's mantle, where downwellings are sheet-like. Either modes of downflow in Venus and Earth are fundamentally different, or differences in near-surface conditions and material behavior selectively emphasize surface expressions of the different downwelling modes

274

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

Science.gov (United States)

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

Goebel, Camille A.

275

On Combining Radar Altimetry and Near-Infrared Imaging for an Estimate of Venus Surface Emissivity  

Science.gov (United States)

Venus Express is an ESA spacecraft orbiting Venus since April 2006. The instrument VIRTIS acquires multispectral images in the range from 0.2 to 5 ?m wavelength. An analysis of VIRTIS images of the atmospheric windows at 1.02, 1.10 and 1.18 ?m shows evidence for variation of surface emissivity on the southern hemisphere. The emissivity of rock or soil in the NIR range is sensitive to its mineral composition and grain size distribution. The surface is subject to weathering, which may alter both mineral composition and grain sizes. Therefore the surface emissivity has the potential to give evidence of original rock composition as well as weathering processes and their effective duration. Mapping the emissivity might give clues about rock forming processes or surface age. Bands 0, 8, 17 and 30 of VIRTIS -M IR image cubes, accessible at the ESA planetary science archive PSA (http://www.rssd.esa.int/psa), are corrected for stray-sunlight and limb-darkening to retrieve flux of radiation emitted through the windows. Cloud transmittance is determined from 1.31 ?m and applied to 1.02, 1.10 and 1.18 ?m while accounting for multiple reflections between lower atmosphere and clouds. The remaining surface thermal emission is highly correlated with Magellan altimetry. Owing to the greenhouse climate the surface temperature can assumed to be constant temporally albeit steadily decreasing with surface elevation. The residual of emission after removal of the global trend with Magellan altimetry is positively correlated with emissivity variation and is used as basis for surface studies. The signal of emissivity is small compared to the signal of surface temperature represented by Magellan altimetry. While the nominal vertical error of Magellan data of 50 m is sufficient for NIR emissivity estimation there are still some uncertainties due to the topography data. In an initial estimates a bias of higher apparent emissivity to the western flanks of topographic elevations was found. This is might be indicative of an offset of longitude of 0.15° between the VIRTIS images and the Magellan data set. Estimates of the period of rotation of Venus from different radar observations disagree outside of their formal errors. The possible error in angular velocity accumulated over the 16 years between Magellan and Venus Express might account for the apparent offset. Comparison of VIRTIS and Magellan data does not provide unambiguous evidence on the rotation period since an actual bias of NIR emissivity or surface temperature with respect to direction of slope can not be ruled out yet. On the other side there is no compelling argument for such a bias and we will use a shift in coordinates for surface emissivity studies, effectively assuming a period of rotation 0.0014 % longer than the value currently recommended by the IAU.

Mueller, N. T.; Helbert, J.

2009-12-01

276

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

Science.gov (United States)

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 data from the balloon and descent probe, and perform science observations. The balloon type preferred for scientific goals is one which oscillates in altitude through the cloud deck. To achieve this flight profile, the balloon envelope contains a phase change fluid, which results in a flight profile which oscillates in height. The nominal balloon lifetime is 7 days—enough for one full circumnavigation of the planet. The descent probe’s fall through the atmosphere takes 60 min, followed by 30 min of operation on the surface. The key measurement objectives of EVE are: (1) in situ measurement from the balloon of noble gas abundances and stable isotope ratios, to study the record of the evolution of Venus; (2) in situ balloon-borne measurement of cloud particle and gas composition, and their spatial variation, to understand the complex cloud-level chemistry; (3) in situ measurements of environmental parameters and winds (from tracking of the balloon) for one rotation around the planet, to understand atmospheric dynamics and radiative balance in this crucial region. The portfolio of key measurements is complemented by the Russian descent probe, which enables the investigation of the deep atmosphere and surface.

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.; Michaud, J.; Bertrand, R.; Charbonnier, J.-M.; Carbonne, D.; Raizonville, P.

2009-03-01

277

Bimodal Distribution of Sulfuric Acid Aerosols in the Atmosphere of Venus  

Science.gov (United States)

Observations by the SPICAV/SOIR instruments aboard Venus Express have revealed that the upper haze of Venus, between 70 and 90 km, is variable on the order of days and that it is populated by two particle modes. In this work, we posit that the observed phenomena are caused by the transient mixing of the clouds and the haze, as well as another source of sulfuric acid aerosols in the upper haze that nucleate on meteoric dust. We test this hypothesis by simulating a column of the Venus atmosphere from 40 to 100 km above the surface using a model based upon the Community Aerosol and Radiation Model for Atmospheres and consider the effects of meteoric dust and polysulfur acting as condensation nuclei in the upper haze and upper cloud, respectively, as well as transient winds at the cloud tops caused by subsolar convection. Our aerosol number density results are consistent with Pioneer Venus data from Knollenberg and Hunten (1980), while our gas distribution results match the Magellan radio occultation data as analyzed by Kolodner and Steffes (1998) below 55 km. The size distribution of cloud particles shows two distinct modes in the upper clouds region and three distinct modes in the middle and lower clouds regions, qualitatively matching the observations of Pioneer Venus. The UH size distribution shows one distinct mode that is likely an upwelled cloud particle population with which an in situ meteoric dust condensation particle population has coagulated. The results of the transient wind simulations yield a variability timescale that is consistent with Venus Express observations, as well as a clear bimodal size distribution in the UH.

Gao, Peter; Zhang, X.; Crisp, D.; Bardeen, C. G.; Yung, Y. L.

2013-10-01

278

The development of studies of Venus  

Science.gov (United States)

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.

Cruikshank, D. P.

1983-01-01

279

The Rarest Eclipse: Transit of Venus  

Science.gov (United States)

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

280

High Temperature, Wireless Seismometer Sensor for Venus  

Science.gov (United States)

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.

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

281

IR spectrometers for Venus and Mars measurements  

Science.gov (United States)

The SOIR spectrometer [1] is an infra-red spectrometer that has performed over 500 solar occultation measurements of the Venus atmosphere, profiling major and minor constituents and studying aerosol absorption, temperature and pressure effects. NOMAD is a 3-channel spectrometer for Mars occultation, limb and nadir measurements. 2 channels are infra-red, the other UV-visible. We will present the technology that enables SOIR and NOMAD to get to parts per billion mixing ratio sensitivities for trace atmospheric components and highlight the improvements made to the SOIR design to enable nadir viewing with NOMAD. Key components include the Acousto-Optical Tunable Filter with radio frequency driver that allows these spectrometers to select the wavelength domain under observation with no need for mechanical moving parts. It also allows background measurements because it is opaque when no RF is applied. The grating with 4 grooves/mm is a very hard to manufacture optical component, and suppliers were very difficult to find. The detector-cooler combination (working at 90K) is from Sofradir/Ricor and the model on board Venus Express is still working after 6 years in space (more on/off cycles that ON hour lifetime problem). The detector MCT mix is slightly altered for nadir observation, in order to reduce thermal background noise and the nadir channel spectrometer is cooled down to 173K by a large V-groove radiator. All the optical components have been enlarged to maximise signal throughput and the slit (that determines spatial and spectral resolution) has also been increased. The spacecraft attitude control system switches from yaw steering for nadir to inertial pointing for solar occultations. 1. Nevejans, D., E. Neefs, E. Van Ransbeeck, S. Berkenbosch, R. Clairquin, L. De Vos, W. Moelans, S. Glorieux, A. Baeke, O. Korablev, I. Vinogradov, Y. Kalinnikov, B. Bach, J.P. Dubois, and E. Villard, 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, 45(21), 5191-5206 (2006)

Drummond, Rachel; Neefs, Eddy; Vandaele, Ann C.

2012-07-01

282

225 years of the Venus atmosphere investigations  

International Nuclear Information System (INIS)

Historical review of investigation into the Venus atmosphere is given. It begins from the discovery of planetary atmosphere made by a great Russian scientist Lomonosov in 1761 till the latest atmosphere investigations by means of the Vega-1 and Vega-2 descent vehicles in 1985 within the framework of the international project for studying. The Venus planet and Halley comet. Results of investigation into physical properties and chemical composition of the planetary atmosphere and surface are present in short

283

A global traveling wave on Venus  

Science.gov (United States)

The dominant large-scale pattern in the clouds of Venus has been described as a 'Y' or 'Psi' and tentatively identified by earlier workers as a Kelvin wave. A detailed calculation of linear wave modes in the Venus atmosphere verifies this identification. Cloud feedback by infrared heating fluctuations is a plausible excitation mechanism. Modulation of the large-scale pattern by the wave is a possible explanation for the Y. Momentum transfer by the wave could contribute to sustaining the general circulation.

Smith, Michael D.; Gierasch, Peter J.; Schinder, Paul J.

1993-01-01

284

Geology of Maxwell Montes, Venus  

Science.gov (United States)

Maxwell Montes represent the most distinctive topography on the surface of Venus, rising some 11 km above mean planetary radius. The multiple data sets of the Pioneer missing and Earth based radar observations to characterize Maxwell Montes are analyzed. Maxwell Montes is a porkchop shaped feature located at the eastern end of Lakshmi Planum. The main massif trends about North 20 deg West for approximately 1000 km and the narrow handle extends several hundred km West South-West WSW from the north end of the main massif, descending down toward Lakshmi Planum. The main massif is rectilinear and approximately 500 km wide. The southern and northern edges of Maxwell Montes coincide with major topographic boundaries defining the edge of Ishtar Terra.

Head, J. W.; Campbell, D. B.; Peterfreund, A. R.; Zisk, S. A.

1984-01-01

285

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  

Science.gov (United States)

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 statistical study treats all of the plasma spectra containing pickup ions in the vicinity of the Venus tail. A hemispheric asymmetry is found in the pickup of ionospheric ions, with approximately four times more O(+) events observed in the 'northern' magnetic hemisphere (where the induced electric field points outward) than in the 'southern' magnetic hemisphere. Out of a total of 167 large O(+) events, 125, or 75 percent, occurred in the northern hemisphere when position is calculated in terms of Venus radii, and 129 or 77 percent occurred in the 'northern' hemisphere when position is expressed in gyroradii. This hemispheric 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.

Intriligator, Devrie S.

1989-01-01

286

Generation of a Tlx1(CreER-Venus) knock-in mouse strain for the study of spleen development.  

Science.gov (United States)

The spleen is a lymphoid organ that serves as a unique niche for immune reactions, extramedullary hematopoiesis, and the removal of aged erythrocytes from the circulation. While much is known about the immunological functions of the spleen, the mechanisms governing the development and organization of its stromal microenvironment remain poorly understood. Here we report the generation and analysis of a Tlx1(Cre) (ER) (-Venus) knock-in mouse strain engineered to simultaneously express tamoxifen-inducible CreER(T2) and Venus fluorescent protein under the control of regulatory elements of the Tlx1 gene, which encodes a transcription factor essential for spleen development. We demonstrated that Venus as well as CreER expression recapitulates endogenous Tlx1 transcription within the spleen microenvironment. When Tlx1(Cre) (ER) (-Venus) mice were crossed with the Cre-inducible reporter strain, Tlx1-expressing cells as well as their descendants were specifically labeled following tamoxifen administration. We also showed by cell lineage tracing that asplenia caused by Tlx1 deficiency is attributable to altered contribution of mesenchymal cells in the spleen anlage to the pancreatic mesenchyme. Thus, Tlx1(Cre) (ER) (-Venus) mice represent a new tool for lineage tracing and conditional gene manipulation of spleen mesenchymal cells, essential approaches for understanding the molecular mechanisms of spleen development. PMID:25283275

Nakahara, Ryo; Kawai, Yasuhiro; Oda, Akihisa; Nishimura, Miyuki; Murakami, Akikazu; Azuma, Takachika; Kaifu, Tomonori; Goitsuka, Ryo

2014-11-01

287

To the problem of the Venus magnetic barrier  

International Nuclear Information System (INIS)

The analytical description of the Venus magnetic barrier on the basis of mathematical models of body flow-around with plasma is suggested. Calculated characteristics of the magnetic barrier and experimental data are compared. Expressions obtained for the thickness of the magnet+c barrier and magnetic field depend on an angle between vectors of field intensity and planet velocity in an undisturbed flow and on the place of a considered point inside the magnetic barrier. The evaluation performed shows that the condition of the magnetic barrier existence is met at Msub(A)sup(2) > or approximately 10 (Msub(A) - Mach Alvfen number) and in that case the dissipation processes affect the height of an upper boundary of the magnetic barrier and size of magnetic field in it. The upper boundary of the Venus magnetic barrier according to the expressions obtained is at a height h approximately 0.1 R=600 km relative to ionopause which, apparently, does not contradict the experimental data

288

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

Science.gov (United States)

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

Bannister, Roger A.; Hansen, Vicki L.

2010-01-01

289

Closing of Venus Flytrap by Electrical Stimulation of Motor Cells  

OpenAIRE

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...

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

2007-01-01

290

Concept study for a Venus Lander Mission to Analyze Atmospheric and Surface Composition  

Science.gov (United States)

We present a concept-level study of a New Frontiers class, Venus lander mission that was developed during Session 1 of NASA's 2011 Planetary Science Summer School, hosted by Team X at JPL. Venus is often termed Earth's sister planet, yet they have evolved in strikingly different ways. Venus' surface and atmosphere dynamics, and their complex interaction are poorly constrained. A lander mission to Venus would enable us to address a multitude of outstanding questions regarding the geological evolution of the Venusian atmosphere and crust. Our proposed mission concept, VenUs Lander for Composition ANalysis (VULCAN), is a two-component mission, consisting of a lander and a carrier spacecraft functioning as relay to transmit data to Earth. The total mission duration is 150 days, with primary science obtained during a 1-hour descent through the atmosphere and a 2-hour residence on the Venusian surface. In the atmosphere, the lander will provide new data on atmospheric evolution by measuring dominant and trace gas abundances, light stable isotopes, and noble gas isotopes with a neutral mass spectrometer. It will make important meteorological observations of mid-lower atmospheric dynamics with pressure and temperature sensors and obtain unprecedented, detailed imagery of surface geomorphology and properties with a descent Near-IR/VIS camera. A nepholometer will provide new constraints on the sizes of suspended particulate matter within the lower atmosphere. On the surface, the lander will quantitatively investigate the chemical and mineralogical evolution of the Venusian crust with a LIBS-Raman spectrometer. Planetary differentiation processes recorded in heavy elements will be evaluated using a gamma-ray spectrometer. The lander will also provide the first stereo images for evaluating the geomorphologic/volcanic evolution of the Venusian surface, as well as panoramic views of the sample site using multiple filters, and detailed images of unconsolidated material and rock textures from a microscopic imager. Our mission proposal will enable the construction of a unique Venus test facility that will attract a new generation of scientists to Venus science. With emphasis on flight heritage, we demonstrate our cost basis and risk mitigation strategies to ensure that the VULCAN mission can be conducted within the requirements and constraints of the New Frontiers Program.

Kumar, K.; Banks, M. E.; Benecchi, S. D.; Bradley, B. K.; Budney, C. J.; Clark, G. B.; Corbin, B. A.; James, P. B.; O'Brien, R. C.; Rivera-Valentin, E. G.; Saltman, A.; Schmerr, N. C.; Seubert, C. R.; Siles, J. V.; Stickle, A. M.; Stockton, A. M.; Taylor, C.; Zanetti, M.; JPL Team X

2011-12-01

291

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

292

VENUS superconducting thin solenoid magnet  

International Nuclear Information System (INIS)

The VENUS solenoid magnet was constructed, and tested successfully at KEK on February 1986. The magnet has a warm bore diameter of 3.4 m, an outer diameter of the cryostat of 3.8 m, and a total length of the cryostat of 5.6 m. It is the largest one at present of several thin solenoid magnets for colliding beam detectors, and furthermore it has a very short radiation thickness of 0.52. For the purpose of better cooling, Kapton insulators between the coil-case and the winding were cured under expansion pressure, and the helium shield of 2 mm thick aluminum cylinder was set up inside the coll. The conductor jointing method without extra space in the winding was invented to obtain a uniform magnetic field distribution, and an aluminum stabilized NbTi-Cu conductor of 10 km unit length was fabricated. The magnet was first cooled and excited to 2000 A without an iron yoke at the factory. It was assembled with the iron yoke at KEK, and cooled to 4.6 K in 14 days. The first excitation to the rated current of 3978 A was performed without quench. The magnetic field was 0.75 T. Several forced quench tests were made to investigate the stability of the magnet and to check the safety of operation

293

Can Venus magnetosheath plasma evolve into turbulence?  

Science.gov (United States)

The present work aims to understand turbulence properties in planetary magnetosheath regions to obtain physical insight on the energy transfer from the larger to smaller scales, in spirit of searching for power-law behaviors in the spectra which is an indication of the energy cascade and wave-wave interaction. We perform a statistical analysis of energy spectra using the Venus Express spacecraft data in the Venusian magnetosheath. The fluxgate magnetometer data (VEXMAG) calibrated down to 1 Hz as well as plasma data from the ion mass analyzer (ASPERA) aboard the spacecraft are used in the years 2006-2009. Ten-minute intervals in the magnetosheath are selected, which is typical time length of observations of quasi-stationary fluctuations avoiding multiple boundaries crossings. The magnetic field data are transformed into the mean-field-aligned (MFA) coordinate system with respect to the large-scale magnetic field direction and the energy spectra are evaluated using a Welch algorithm in the frequency range between 0.008 Hz and 0.5 Hz for 105 time intervals. The averaged energy spectra show a power law upto 0.3 Hz with the approximate slope of -1, which is flatter than the Kolmogorov slope, -5/3. A slight hump in the spectra is found in the compressive component near 0.3 Hz, which could possibly be realization of mirror mode in the magnetosheath. A spectral break (sudden change in slope) accompanies the spectral hump at 0.4 Hz, above which the spectral curve becomes steeper. The overall spectral shape is reminiscent of turbulence. The low-frequency part with the slope -1 is interpreted as realization of the energy containing range, while the high-frequency part with the steepening is interpreted either as the beginning of energy cascade mediated by mirror mode or as the dissipation range due to wave-particle resonance processes. The present research work is fully supported by FP7/STORM (313038).

Dwivedi, Navin; Schmid, Daniel; Narita, Yasuhito; Volwerk, Martin; Delva, Magda; Voros, Zoltan; Zhang, Tielong

2014-05-01

294

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

OpenAIRE

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

Aspaas, Per Pippin; Sterken, Christiaan

2013-01-01

295

Sapphire Viewports for a Venus Probe  

Science.gov (United States)

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.

Bates, Stephen

2012-01-01

296

The Magellan Venus radar mapping mission  

Science.gov (United States)

The NASA Magellan Venus Radar Mapper spacecraft, which will be placed into orbit around Venus on August 10, 1990, is described and its mission is discussed. The orbiter's 12-cm wavelength, multimode radar system is examined and the applications of its modes are addressed. In the SAR mode, it can image most of the Venus surface at a resolution of better than 300 m, approaching 120 m over more than half the planet. In the altimeter mode, the radar will determine topographic relief to a vertical accuracy of better than 50 m averaged over a surface resolution cell approximately 10 km in diameter. In the radiometer mode, the radar receiver can determine the surface radio emission brightness temperature with an absolute accuracy of 20 K, at a resolution of 2 K. The nature of the data products and the archiving plans are also considered.

Saunders, R. S.; Sjogren, W. L.; Johnson, W. T. K.; Pieri, L.; Pettengill, G. H.; Arvidson, R. E.

1990-01-01

297

Venus - Radar determination of gravity potential.  

Science.gov (United States)

We describe a method for the determination of the gravity potential of Venus from multiple-frequency radar measurements. The method is based on the strong frequency dependence of the absorption of radio waves in Venus' atmosphere. Comparison of the differing radar reflection intensities at several frequencies yields the height of the surface relative to a reference pressure contour; combination with measurements of round-trip echo delays allows the pressure, and hence the gravity potential contour, to be mapped relative to the mean planet radius. Since calibration data from other frequencies are unavailable, the absorption-sensitive Haystack Observatory data have been analyzed under the assumption of uniform surface reflectivity to yield a gravity equipotential contour for the equatorial region and a tentative upper bound of .0006 on the fractional difference of Venus' principal equatorial moments of inertia.

Shapiro, I. I.; Pettengill, G. H.; Sherman, G. N.; Rogers, A. E. E.; Ingalls, R. P.

1973-01-01

298

Venus: radar determination of gravity potential.  

Science.gov (United States)

We describe a method for the determination of the gravity potential of Venus from multiple-frequency radar measurements. The method is based on the strong frequency dependence of the absorption of radio waves in Venus' atmosphere. Comparison of the differing radar reflection intensities at several frequencies yields the height of the surface relative to a reference pressure contour; combination with measurements of round-trip echo delays allows the pressure, and hence the gravity potential contour, to be mapped relative to the mean planet radius. Since calibration data from other frequencies are unavailable, the absorption-sensitive Haystack Observatory data have been analyzed under the assumption of uniform surface reflectivity to yield a gravity equipotential contour for the equatorial region and a tentative upper bound of 6 x 10(-4) on the fractional difference of Venus' principal equatorial moments of inertia. The minima in the equipotential contours appear to be associated with topographic minima. PMID:17739140

Shapiro, I I; Pettengill, G H; Sherman, G N; Rogers, A E; Ingalls, R P

1973-02-01

299

Isostatic compensation of equatorial highlands on Venus  

Science.gov (United States)

Spherical harmonic models for Venus' global topography and gravity incorporating Magellan data are used to test isostatic compensation models in five 30 deg x 30 deg regions representative of the main classes of equatorial highlands. The power spectral density for the harmonic models obeys a power-law scaling with spectral slope Beta approximately 2 (Brown noise) for the topography and Beta approximately 3 (Kaula's law) for the geoid, similar to what is observed for Earth. The Venus topography spectrum has lower amplitudes than Earth's which reflects the dominant lowland topography on Venus. Observed degree geoid to topography ratios (GTRs) on Venus are significantly smaller than degree GTRs for uncompensated topography, indicative of substantial compensation. Assuming a global Airy compensation, most of the topography is compensated at depths greater than 100 km, suggesting a thick lithosphere on Venus. For each region considered we obtain a regional degree of compensation C from a linear regression of Bouguer anomaly versus Bouguer gravity data. Geoid anomaly (N) versus topography variation (h) data for each sample were compared, in the least-squares sense, to theoretical correlations for Pratt, Airy, and thermal thinning isostasy models yielding regional GTR, zero-elevation crustal thickness (H), and zero elevation thermal lithosphere thickness (y(sub L(sub 0)), respectively. We find the regional compensation to be substantial (C approximately 52-80%), and the h, N data correlations in the chosen areas can be explained by isostasy models applicable on the Earth and involving variations in crustal thickness (Airy) and/or lithospheric (thermal thinning) thickness. However, a thick crust and lithosphere (y(sub L(sub 0)) approximately 300 km) must be assumed for Venus.

Kucinskas, Algis B.; Turcotte, Donald L.

1994-01-01

300

Characterization of the lower layer in the dayside Venus ionosphere  

Science.gov (United States)

The dayside Venus ionosphere consists of two layers: the V2 layer at 141 km, produced by solar extreme ultraviolet (EUV) photons, and the V1 layer at 127 km, produced by solar soft X-rays. The influence of solar zenith angle (SZA) and solar irradiance has been well characterized for the V2 layer, but not the V1 layer, where previous efforts were limited by data scarcity and incomplete SZA coverage. Here we use over 200 radio occultation profiles from Venus Express 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 do not vary with SZA, and both peak electron densities vary with SZA in a Chapman-like manner. These results imply that the thermal structures of the atmosphere and ionosphere between 141 km and 127 km vary little with SZA. Also, the V1 peak density increases more with solar activity than the V2 peak density and the V1 morphology can change much 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.

Girazian, Zachary; Withers, Paul; Paetzold, Martin; Tellmann, Silvia; Peter, Kerstin

2014-11-01

301

A Survey for Satellites of Venus  

OpenAIRE

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...

Sheppard, Scott S.; Trujillo, Chadwick A.

2009-01-01

302

Emplacement Scenarios for Volcanic Domes on Venus  

Science.gov (United States)

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.

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

2012-01-01

303

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

Directory of Open Access Journals (Sweden)

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.

T. L. Zhang

2009-11-01

304

Planetary Core Sounding with the Solar Wind Interaction: Application to Venus  

Science.gov (United States)

When the solar wind interacts with a planetary ionosphere, the interplanetary magnetic field can diffuse into the ionosphere at a rate dependent on the collision frequency if the ionopause is sufficiently low. The magnetic field is carried by the ionospheric circulation, which is downward near the subsolar point for these conditions. This magnetic flux is deposited at low altitudes building up a magnetic layer at about 170 km altitude, which, at most, slowly diffuses into the neutral atmosphere below. Pioneer Venus has also mapped this Venus dayside low latitude layer near the midnight equatorial region. Venus Express measurements complement those of PVO with data at low altitudes solely over the north pole, providing coverage between the subsolar and wake regions. At the terminator, the field begins to dip into the atmosphere, with the tilt increasing toward midnight, and if the PVO holes are connected, the field rises out of the atmosphere almost vertically in the wake region (Figures 1 and 2). When we compare these observations with MHD models, we can improve the models where we find inaccuracies and improve our understanding of both the observations and the models. To the accuracy in which we can determine the geometry of the field relative to the radial direction over the bottom of the ionosphere, we should be able to determine the size of the core of Venus. If this is not possible to the required accuracy, measurements in the ionosphere and from balloons beneath the ionosphere could be combined to provide the needed measurements.

Russell, C. T.; Villarreal, M. N.; Chi, P. J.; Zhang, T. L.; Luhmann, J. G.; Ma, Y. J.

2014-04-01

305

Measurements of turbulence in the Venus atmosphere deduced from Pioneer Venus multiprobe radio scintillations  

Science.gov (United States)

The 2.3-GHz log-amplitude fluctuations observed in the radio links of the Pioneer Venus entry probes during Venus encounter have been used to study turbulence in the Venus atmosphere. The deduced estimates of the upper bound of the structure constant of the refractive index fluctuations (less than approximately 4 x 10 to the -8th/cu root cm) are inconsistent with similar entry probe measurements by Veneras 4 to 8 but are consistent with the radio occultation measurements by flyby (Mariners 5 and 10) and orbiting (Venera 9) spacecraft. The Pioneer Venus measurements therefore provide a resolution of the long-standing order of magnitude discrepancy between these earlier measurements of the structure constant.

Woo, R.; Armstrong, J. W.; Kendall, W. B.

1979-01-01

306

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

OpenAIRE

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...

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

1998-01-01

307

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

Science.gov (United States)

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.

Chin, Gordon

2011-01-01

308

Analysis of thermal emission from the nightside of Venus at 1.51 and 1.55 microns  

OpenAIRE

Abstract We present radiative transfer modelling of thermal emission from the nightside of Venus in two ‘spectral window’ regions at 1.51 and 1.55 ?m. The first discovery of these windows, reported by Erard et al. 2009, was achieved using a principal component analysis of data from the VIRTIS instrument on Venus Express. These windows are spectrally narrow, with a full-width at half-maximum of ?20 nm, and less bright than the well-known 1.7 and 2.3 ?m spectral windows by tw...

Wilson, C. F.; Tsang, C. C. C.; Irwin, P. G. J.; Taylor, F. W.; Be?zard, B.; Erard, S.; Carlson, R. W.; Drossart, P.; Piccioni, G.; Holmes, R. C.

2009-01-01

309

Analysis of thermal emission from the nightside of Venus at 1.51 and 1.55 mu m  

OpenAIRE

We present radiative transfer modelling of thermal emission from the nightside of Venus in two 'spectral window' regions at 1.51 and 1.55 ?m. The first discovery of these windows, reported by Erard et al. [Erard, S., Drossart, P., Piccioni, G., 2009. J. Geophys. Res. Planets 114, doi:10.1029/2008JE003116. E00B27], was achieved using a principal component analysis of data from the VIRTIS instrument on Venus Express. These windows are spectrally narrow, with a full-width at half-maximum of ?...

Wilson, Cf; Tsang, Ccc; Irwin, Pgj; Taylor, Fw; Bezard, B.; Erard, S.; Carlson, Rw; Drossart, P.; Piccioni, G.; Holmes, Rc

2009-01-01

310

Nanoscale organization of b2-adrenergic receptor-Venus fusion protein domains on the surface of mammalian cells  

OpenAIRE

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 b2-adrenergic receptors (b2AR) fused to the GFP analogue Venus at the nanoscale on HEK293 cells. The expression of the b2AR-Venus fusion protein was tightly controlled using a tetracycline-induced promoter. Both the size and density of the observed nanoscale...

Vobornik, Dusan; Rouleau, Yanouchka; Haley, Jennifer; Bani-yaghoub, Mahmud; Taylor, Rod; Johnston, Linda J.; Pezacki, John Paul

2009-01-01

311

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)

312

Collection of Magellan Venus radar mapping results  

Science.gov (United States)

Through computer animation several geological features of Venus are presented in this video. The Sif Mons, a 1.2 mile high volcano and the Gula Mons, a 1.8 mile high volcano are shown. Also, radar images of a rift valley, several impact craters, and a corona can be seen. The video ends with a northeast view of Eistla Regio.

1991-03-01

313

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

314

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

Energy Technology Data Exchange (ETDEWEB)

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%.

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

315

Communications Transceivers for Venus Surface Missions  

Science.gov (United States)

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.

Force, Dale A.

2004-01-01

316

Origin and evolution of the atmosphere of Venus  

Science.gov (United States)

Implications for the origin and evolution of the terrestrial planets are drawn from a comparison of the Venus, earth and Mars atmosphere volatile inventories. Attention is given to the possible loss of an appreciable amount of water from Venus, in light of recent evidence for a 100-fold deuterium enrichment. Ar-40 and He-4 abundances suggest that outgassing has been inefficient for much of Venus's lifetime, in keeping with evidence for a lower level of tectonic activity on Venus than on the earth. Attention is also given to Venus's CO2 geochemistry. The picture now emerging is that of a Venus that began to evolve along a path similar to that of the earth, but suffered a catastrophic, runaway greenhouse effect early in its lifetime. How early the castastrophe occurred may be suggested by the presently low inventories of radiogenic argon and helium in its atmosphere.

Donahue, T. M.; Pollack, J. B.

1983-01-01

317

Solar wind interaction with comets - lessons from Venus  

International Nuclear Information System (INIS)

Data on the solar wind interaction with Venus are examined for the purpose of comparison with similar processes that may occur in comets. Attention is given to bow shock, magnetosheath, ionopause, ionosphere, and magnetotail of Venus. These features are compared with, respectively, the bow shock, magnetosheath, contact surface, coma, and plasma tail of a comet. It is concluded that observations of the solar wind interaction with Venus should provide new insight into the solar wind interaction with comets

318

A 360-Degree and -Order Model of Venus Topography  

Science.gov (United States)

This report presents the most recent spherical harmonic topography model of Venus developed at Jet Propulsion Laboratory. It was produced by a spherical harmonic analysis of the most complete set of Magellan altimetry data, augmented by Pioneer Venus and Venera data. The harmonic coefficients of the topography were computed to degree and order 360. Compared to previous topography models, this one has the highest correlation with the gravity field of Venus.

Rappaport, Nicole; Plaut, Jeffry J.

1996-01-01

319

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

Science.gov (United States)

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.

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

2015-03-01

320

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

Science.gov (United States)

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.

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

2011-03-01

321

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

Directory of Open Access Journals (Sweden)

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.

M. Yamauchi

2011-03-01

322

First stage of cosmic expedition Vega: Venus investigations  

International Nuclear Information System (INIS)

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

323

An Improved 360 Degree and Order Model of Venus Topography  

Science.gov (United States)

We present an improved 360 degree and order spherical harmonic solution for Venus' topography. The new model uses the most recent set of Venus altimetry data with spacecraft positions derived from a recent high resolution gravity model. Geometric analysis indicates that the offset between the center of mass and center of figure of Venus is about 10 times smaller than that for the Earth, the Moon, or Mars. Statistical analyses confirm that the RMS topography follows a power law over the central part of the spectrum. Compared to the previous topography model, the new model is more highly correlated with Venus' harmonic gravity field.

Rappaport, Nicole J.; Konopliv, Alex S.; Kucinskas, Algis B.; Ford, Peter G.

1999-01-01

324

Linelist of HD16O for study of atmosphere of terrestrial planets (Earth, Venus and Mars)  

Science.gov (United States)

Studies of water vapor in the atmospheres of Venus, Mars and Earth by spectroscopic techniques are being made routinely with different instruments on board of interplanetary missions like Mars-Express, Venus-Express and many others as well as with a lot of spacecrafts on the Earth’ orbit. Accessibility of detailed spectroscopic information in a wide range is then of crucial importance to retrieve reliable results with these instruments. Unlike Earth, Mars and Venus have the CO2-rich planetary atmospheres that require line shape parameters for HDO-CO2 broadening. In this paper a new linelist for HD16O is presented. This linelist covers the range of 0.00065-25,660 cm-1 and is significantly more complete than other databases presently available. All lines with intensities (for 100% abundance) greater than 10-30 cm/molecule at 296 K are included. Wavenumbers for 43% (about 300,000) of all lines were evaluated at a level of the best experimental accuracy. For each transition the line shape parameters such as halfwidth and temperature exponent are provided for the case of HDO-air, HDO-HDO, and HDO-CO2 broadening. The final linelist contains more than 700,000 HD16O lines and is presented in HITRAN-compatible format.

Lavrentieva, N. N.; Voronin, B. A.; Naumenko, O. V.; Bykov, A. D.; Fedorova, A. A.

2014-07-01

325

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

Science.gov (United States)

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

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

2013-01-01

326

Comparison of measurements of electromagnetic induction in the magnetosphere of Venus with laboratory simulations  

International Nuclear Information System (INIS)

Analysis of Venera 9 and 10 data suggest a comingled excitation of the ionosphere of Venus by the time dependent component of the interplanetary magnetic field, upon which may be superimposed a contribution from the interplanetary electric field. The inductive contributions correspond respectively to generation of eddy currents and to unipolar induction, i.e., the TE and TM modes of classical electromagnetism. The former is suggested when the interplanetary magnetic field exhibits significant changes in intensity or orientation, but could also have contributions from fluctuations in plasma pressure expressed through the frozen-in field. The magnetic field measured near Venus by Venera 9 and 10 is considered within this framework and with respect to laboratory simulation using both conducting and insulated (but internally conducting) spheres. (Auth.)

327

Development of the Kelvin-Helmholtz instability at the ionopause of Venus  

Science.gov (United States)

We present the result of the numerical simulation of the interaction of the solar wind with the ionosphere of Venus assuming that both plasmas behave as ideal fluids. We find that the Kelvin-Helmhotz instability easily develops at midlatitudes in the dayside ionopause for typical solar wind flow and ionospheric plasma conditions. The end result of the process, once the system reaches a quasi-steady state, is that multiple waves and vortices are found travelling downstream across the ionopause to the planet's nightside. As the flow expands past the terminator of the planet, the ionopause vortices also expand leading to a complex plasma flow in the near wake that could explain the vortical motions measured by the Venus Express spacecraft in the region.

Reyes-Ruiz, M.; Perez De Tejada, H. A.; Aceves, H.

2013-12-01

328

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

OpenAIRE

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...

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

2012-01-01

329

The change of resurfacing regimes on Venus  

Science.gov (United States)

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.

Ivanov, M. A.

2015-01-01

330

Venus y el fin del mundo  

Directory of Open Access Journals (Sweden)

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.

Gonzalo Munévar

2006-01-01

331

Plasma channels in the Venus upper ionosphere  

Directory of Open Access Journals (Sweden)

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.

H. Pérez de Tejada

2001-05-01

332

La Hieroglyphica y el Nacimiento de Venus  

Directory of Open Access Journals (Sweden)

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

González de Zarate, Jesús maría

2003-09-01

333

NITRO: Understanding the Earth-Venus-Mars difference in Nitrogen  

Science.gov (United States)

Nitrogen is a key element for life as an inevitable part of the amino acids and proteins. While nitrogen is abundant on the Earth (the amount in the soil, crust, and ocean are small compared to the atmospheric amount) and on Venus (only 3% but pressure is 90 times that of the Earth, resulting in three times more nitrogen than on the Earth), Martian atmosphere has very little nitrogen, about only 0.01% that of the Earth or Venus (with 10% of planetary mass). This contrasts the oxygen abundance, which is found in all three planets (Martian case, it is now believed to exist in the crust as oxidized rocks because the observed escape rate is equivalent only 10 m deep water). Considering the fact that nitrogen is much more difficult to be ionized than oxygen, due to triple chemical binding, absence of the nitrogen only on Mars is a mystery, while this absence might explain the absence of life at the present knowledge. From these viewpoints, it is important to understand the dynamics of nitrogen at different solar conditions, e.g., its difference from the oxygen dynamics for any planet. Such a study requires a dedicated space mission. We have recently proposed a small satellite mission to study this problem, NITRO. This mission will analyze the atmospheric escape and circulation in the inner magnetosphere of the Earth of heavy ions such as N+ and N2+, and will rely on a high mass resolution ion spectrometry instrumentation, capable of separationg nitrogen from oxygen ions. The science objectives and the instrumentation of the NITRO mission will be presented.

Yamauchi, M.; Dandouras, I.

2012-12-01

334

Atmospheric Chemistry of Venus-like Exoplanets  

OpenAIRE

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 ...

Schaefer, Laura; Fegley Jr, Bruce

2010-01-01

335

Venus 1882 and Jean-Charles Houzeau  

Science.gov (United States)

This paper focuses on one particular type of telescope - the heliometer - designed for solving one specific basic problem in astronomy: the scale factor of the solar system. One very special instrument of this type was the ``heliometer with unequal focal lengths'' designed by the Belgian astronomer Jean-Charles Houzeau for the 1882 transit of Venus. We also draw attention to the most interesting personality of Houzeau, and to his social engagement that went much beyond his work as a scientist.

Sterken, C.

2009-06-01

336

VENUS meets SEMAT : How do they compare?  

OpenAIRE

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...

Geihs, Kurt; Evers, Christoph; Niemczyk, Stefan

2014-01-01

337

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 thethe 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

338

Solar diameter with 2012 Venus transit  

OpenAIRE

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...

Sigismondi, Costantino

2012-01-01

339

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.

340

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

Science.gov (United States)

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.

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

2012-01-01

341

Average configuration of the induced venus magnetotail  

International Nuclear Information System (INIS)

In this paper we discuss the interaction of the solar wind flow with Venus and describe the morphology of magnetic field line draping in the Venus magnetotail. In particular, we describe the importance of the interplanetary magnetic field (IMF) X-component in controlling the configuration of field draping in this induced magnetotail, and using the results of a recently developed technique, we examine the average magnetic configuration of this magnetotail. The derived J x B forces must balance the average, steady state acceleration of, and pressure gradients in, the tail plasma. From this relation the average tail plasma velocity, lobe and current sheet densities, and average ion temperature have been derived. In this study we extend these results by making a connection between the derived consistent plasma flow speed and density, and the observational energy/charge range and sensitivity of the Pioneer Venus Orbiter (PVO) plasma analyzer, and demonstrate that if the tail is principally composed of O+, the bulk of the plasma should not be observable much of the time that the PVO is within the tail. Finally, we examine the importance of solar wind slowing upstream of the obstacle and its implications for the temperature of pick-up planetary ions, compare the derived ion temperatures with their theoretical maximum values, and discuss the implications of this process for comets and AMPTE-type releases

342

Average configuration of the induced venus magnetotail  

Energy Technology Data Exchange (ETDEWEB)

In this paper we discuss the interaction of the solar wind flow with Venus and describe the morphology of magnetic field line draping in the Venus magnetotail. In particular, we describe the importance of the interplanetary magnetic field (IMF) X-component in controlling the configuration of field draping in this induced magnetotail, and using the results of a recently developed technique, we examine the average magnetic configuration of this magnetotail. The derived J x B forces must balance the average, steady state acceleration of, and pressure gradients in, the tail plasma. From this relation the average tail plasma velocity, lobe and current sheet densities, and average ion temperature have been derived. In this study we extend these results by making a connection between the derived consistent plasma flow speed and density, and the observational energy/charge range and sensitivity of the Pioneer Venus Orbiter (PVO) plasma analyzer, and demonstrate that if the tail is principally composed of O/sup +/, the bulk of the plasma should not be observable much of the time that the PVO is within the tail. Finally, we examine the importance of solar wind slowing upstream of the obstacle and its implications for the temperature of pick-up planetary ions, compare the derived ion temperatures with their theoretical maximum values, and discuss the implications of this process for comets and AMPTE-type releases.

McComas, D.J.; Spence, H.E.; Russell, C.T.

1985-01-01

343

Venus tectonics - Initial analysis from Magellan  

Science.gov (United States)

The styles of lithospheric deformation, the inferred mechanical properties of the lithosphere, and their implications for the tectonic history of Venus are discussed on the basis of radar imaging and altimetry data from Magellan. Observations of the planet plains reveal a superposition of different episodes of deformation and volcanism, strain both distributed and concentrated into zones of extension and shortening, and features reflecting a crustal response to mantle dynamic processes. Lithospheric shortening and crustal thickening are represented by ridge belts and mountain belts. The latter show the evidence for extension and collapse both during and following crustal compression. Venus displays quasi-circular coronae and broad rises with linear rift zones, associated with significant volcanism. Large-offset strike-slip faults have not been observed, although horizontal shear is accommodated across broad zones of crustal shortening. On Venus strain is distributed across zones that are one to a few hundred kilometers wide, and separated by stronger and less deformed blocks hundreds of kilometers in width, as in actively deforming continental regions on earth.

Solomon, Sean C.; Head, James W.; Kaula, William M.; Schubert, Gerald; Mckenzie, Dan

1991-01-01

344

Secreted major Venus flytrap chitinase enables digestion of Arthropod prey.  

Science.gov (United States)

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

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

345

Carbonate-sulfate volcanism on Venus?  

Science.gov (United States)

Venusian canali, outflow channels, and associated volcanic deposits resemble fluvial landforms more than they resmeble volcanic features on Earth and Mars. Some canali have meandering habits and features indicative of channel migration that are very similar to meandering river channels and flood plains on Earth, venusian outflow channels closely resemble water-carved outflow channels on Mars and the Channeled Scabland in Washington, collapsed terrains at the sources of some venusian channels resemble chaotic terrains at the sources of martian outflow channels, venusian lava deltas are similar to bird's-foot deltas such as the Mississippi delta, and venusian valley networks indicate sapping. We have developed an alternative possibility that the lava had a water-like rheology and a melting point slightly greater than Venus' surface temperature, thus accounting for the unusual behavior of the lava. Unlike silicate lavas, some carbonatites (including carbonate-sulfate-rich liquids) have these properties; thus they can flow great distances while retaining a high fluidity, significant mechanical erosiveness, and substantial capacity to transport and deposit sediment. Venusian geochemistry and petrology are consistent with extensive eruptions of carbonatite lavas, which could have crustal and/or mantle origins. Venus' atmosphere (especially CO2, HCl, and HF abundances) and rocks may be in local chemical equilibrium, which suggests that the upper crust contains large amounts of calcite, anhydrite, and other salts. Chemical analyses indicate, according to some models, that Venusian rocks may contain 4-19% calcite and anhydrite. Mixtures of crustal salts could melt at temperatures a few tens to a few hundred Kelvins higher than Venus' surface temperature; hence, melting may be induced by modest endogenetic or impact heating. Salts may have many of the same geologic roles on Venus as water and ice have on Mars. A molten salt (carbonatite) 'aquifer' may exist beneath a few hundred meters to several kilometers of solidified salt-rich 'permafrost.' Many geologic features can be explained by carbonatite magmatism: (1) impact melting of crustal salts can explain crater outflows, (2) small, sustained eruptions from molten salt aquifers can explain sapping valleys, (3) large, sustained eruptions may explain canali and their flood plans, and (4) catastrophic outbursts amy have formed outflow channels and chaotic terrain. Landforms created by carbonate-rich lavas would be thermally stable on Venus' surface, though some minerals may weather to other solid substances.

Kargel, Jeffrey S.; Kirk, Randolph L.; Fegley, Bruce, Jr.

1994-01-01

346

Atmospheric and water loss from early Venus  

Science.gov (United States)

Previous interpretations of the Pioneer Venus mass spectrometer data of the deuterium to hydrogen (D/H) ratio of 1.9×10-2 or 120±40 times the terrestrial value indicate that Venus may have had at least an H2O content of the order of about 0.3% of a terrestrial ocean (TO), and even much more during and shortly after the accretion period of ?300Myr, depending on the unknown ratio of a continuous supply of H2O by comets to a hydrogen blow-off loss and impact erosion of the early atmosphere. In view of the low H2O abundance in the present atmosphere, several studies suggest that the planet should have lost most of its H2O during the early high X-ray, EUV and solar wind period of the active young Sun. Because oxygen did not accumulate in Venus' atmosphere it is commonly believed that a part of the oxygen from dissociated H2O vapor was dragged off to space along with the escaping hydrogen during a blow-off period, or could have oxidized the surface minerals to produce FeO and Fe2O3 to the depths of a few kilometers to tens of kilometers depending on the initial amount of H2O. We use in the present study, for the first time, multi-wavelength X-ray and EUV (XUV) observations by the ASCA, ROSAT, EUVE, FUSE and IUE satellites and stellar winds inferred from mass loss observations by the Hubble Space Telescope of solar proxies with ages inventory due to the removal of oxygen picked up by the solar wind. For modelling the Venusian thermosphere over the planetary history we apply a diffusive-gravitational equilibrium and thermal balance model and investigate the heating of the early thermosphere by photodissociation and ionization processes, due to exothermic chemical reactions and cooling by CO2 IR emission in the 15?m band. Our model simulations result in expanded thermospheres with exobase levels between about 200 km at present and about 2200 km 4.5 Gyr ago. Moreover, our results yield high exospheric temperatures during the active phase of the young Sun even if we assume a "dry" CO2 atmosphere with similar composition that is observed on present Venus of more than 8000 K after the Sun arrived at the zero-age-main-sequence (ZAMS). Exospheric temperatures above about 4000 K lead to diffusion-limited escape and high loss rates for atomic hydrogen. The duration of this blow-off phase for atomic hydrogen essentially depends on the mixing ratios of CO2, N2 and H2O in the early Venusian atmosphere and could last between about 150 to several hundred Myr, which could result in a large thermal loss of hydrogen from Venus. For studying how much of the H2O-related oxygen could have been lost to space by the ion pick up process due to the stronger solar wind and higher XUV fluxes of the young Sun we used our modelled atmospheric density profiles and studied the loss of O+ ion pick up from the upper atmosphere of Venus over the planet's history by applying a numerical test particle model. Depending on the used solar wind parameters, our model simulations show that ion pick up by a strong early solar wind on a non-magnetized Venus could erode during 4.6 Gyr more than about 250 bar of O+ ions, that corresponds to an equivalent amount of one terrestrial ocean. Finally, we discuss the implications of our findings for the formation of the Venusian atmosphere and discuss our results in the frame of previous studies.

Kulikov, Yu. N.; Lammer, H.; Lichtenegger, H. I. M.; Terada, N.; Ribas, I.; Kolb, C.; Langmayr, D.; Lundin, R.; Guinan, E. F.; Barabash, S.; Biernat, H. K.

2006-11-01

347

Carbonate-Sulfate Volcanism on Venus?  

Science.gov (United States)

Venusian canali, outflow channels, and associated volcanic deposits resemble fluvial landforms more than they resemble volcanic features on Earth and Mars. Some canali have meandering habits and features indicative of channel migration that are very similar to meandering river channels and flood plains on Earth, venusian outflow channels closely resemble water-carved outflow channels on Mars and the Channeled Scabland in Washington, collapsed terrains at the sources of some venusian channels resemble chaotic terrains at the sources of martian outflow channels, venusian lava deltas are similar to bird's-foot deltas such as the Mississippi delta, and venusian valley networks indicate sapping. The depositional fluvial-type features (deltas, braided bars, and channeled plains) are generally among the smoothest terrains at the Magellan radar wavelength (12.6 cm) on Venus. These features suggest the involvement of an unusual lava, unexpected processes, and/or extraordinary eruption conditions. Possibly the lava was an ordinary silicate lava such as basalt or a less common type of silicate lava, and conditions unique to Venus or to those particular eruptions may have caused an unusual volcanological behavior. We have developed the alternative possibility that the lava had a water-like rheology and a melting point slightly greater than Venus' surface temperature, thus accounting for the unusual behavior of the lava. Unlike silicate lavas, some carbonatites (including carbonate-sulfate-rich liquids) have these properties; thus they can flow great distances while retaining a high fluidity, significant mechanical erosiveness, and substantial capacity to transport and deposit sediment. Venusian geochemistry and petrology are consistent with extensive eruptions of carbonatite lavas, which could have crustal and/or mantle origins. Venus' atmosphere (especially CO2, HCl, and HF abundances) and rocks may be in local chemical equilibrium, which suggests that the upper crust contains large amounts of calcite, anhydrite, and other salts. Chemical analyses indicate, according to some models, that Venusian rocks may contain 4-19% calcite and anhydrite. Mixtures of crustal salts could melt at temperatures a few tens to a few hundred Kelvins higher than Venus' surface temperature; hence, melting may be induced by modest endogenetic or impact heating. Salts may have many of the same geologic roles on Venus as water and ice have on Mars. A molten salt (carbonatite) "aquifer" may exist beneath a few hundred meters to several kilometers of solidified salt-rich "permafrost." Many geologic features can be explained by carbonatite magmatism: (1) impact melting of crustal salts can explain crater outflows, (2) small, sustained eruptions from molten salt aquifers can explain sapping valleys, (3) large, sustained eruptions may explain canali and their flood plans, and (4) catastrophic outbursts may have formed outflow channels and chaotic terrain. Landforms created by carbonate-rich lavas would be thermally stable on Venus' surface, though some minerals may weather to other solid substances. ?? 1994 Academic Press. All rights reserved.

Kargel, J.S.; Kirk, R.L.; Fegley, B., Jr.; Treiman, A.H.

1994-01-01

348

Revised upper limit on the internal magnetic moment of Venus  

Science.gov (United States)

Over four Venus years of low altitude nightside PVO magnetometer observations are used to establish a new upper limit for the magnetic moment of Venus. Improvements over previous studies include data coverage and new instrument calibration information. The upper limit on an internal dipole moment is determined to be 8.4 x 10 to the 10th T cu m.

Phillips, J. L.; Russell, C. T.

1987-01-01

349

Helium on Venus - Implications for uranium and thorium  

Science.gov (United States)

Helium is removed at an average rate of 10 to the 6th atoms per square centimeter per second from Venus's atmosphere by the solar wind following ionization above the plasmapause. The surface source of helium-4 on Venus is similar to that on earth, suggesting comparable abundances of crustal uranium and thorium.

Prather, M. J.; Mcelroy, M. B.

1983-01-01

350

VERITAS: A Mission Concept for the High Resolution Topographic Mapping and Imaging of Venus  

Science.gov (United States)

Magellan, a NASA mission to Venus in the early 1990's, mapped nearly the entire surface of Venus with an S-band (12 cm) synthetic aperture radar and microwave radiometer and made radar altimeter measurements of the topography. These measurements revolutionized our understanding of the geomorphology, geology and geophysical processes that have shaped the evolution of the surface of Venus. The Magellan spacecraft had an elliptical orbit with an apoapsis of approximately 8000 km and a periapsis of 257 km and an orbital inclination of 86°. In this way the radar was able to collect long strips of data approximately 10000 km in length running north to south with altitudes varying from 3000 km to 257 km. During the remainder of the orbit the collected data was down linked to earth. The SAR mode operated in burst mode fashion whereby it transmitted a small string of pulses up to a couple of hundred pulses in length followed by a quiescent period when the radar ceased transmission and allowed interleaved operation of the altimeter and radiometer modes. This mode of operation allowed for a significant reduction in downlinked SAR imaging data at the expense of azimuth (i.e. along-track) resolution. However, the lack of finer resolution imagery and topography of the surface than that obtained by the Magellan mission has hampered the definitive answer to key questions concerning the processes and evolution of the surface of Venus. The Venus Emissivity, Radio Science, InSAR Topography And Spectroscopy (VERITAS) Mission is a proposed mission to Venus designed to obtain high resolution imagery and topography of the surface using an X-band radar configured as a single pass radar interferometer coupled with a multispectral NIR emissivity mapping capability. VERITAS would map surface topography with a spatial resolution of 250 m and 5 m vertical accuracy and generate radar imagery with 30 m spatial resolution. These capabilities represent an order of magnitude or better improvement of the Magellan system and are expected to reveal definitive information on processes not possible with the Magellan data. The combination of surface topography and image data provide unprecedented knowledge of Venus' tectonic and impact history, the timing and mechanisms of volcanic resurfacing, and the mantle processes responsible for them. The combination of instruments on VERITAS, and in particular the InSAR instrument, is designed to address a series of focused hypothesis driven questions left unresolved by the Magellan mission for example: 1) Is there evidence for a past tectonic or cratered surface beneath the plains? and 2) How and when did Venus resurface? This talk will present an overview of the proposed VERITAS mission, the radar instrument design and trade options and the projected performance as well as a brief overview of some of the major science objectives. This research was conducted at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

Hensley, S.; Smrekar, S. E.; Pollard, B.

2012-12-01

351

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

Science.gov (United States)

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.

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

2014-01-01

352

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

Science.gov (United States)

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.

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

2011-01-01

353

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

Science.gov (United States)

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

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

2005-12-01

354

Giant radiating dyke swarms on Earth and Venus  

Science.gov (United States)

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

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

1995-09-01

355

Venus transit 2004: Illustrating the capability of exoplanet transmission spectroscopy  

Science.gov (United States)

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.

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

2011-09-01

356

Venus transit 2004: Illustrating the capability of exoplanet transmission spectroscopy  

CERN Document Server

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.

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

2011-01-01

357

The solar wind interaction with Venus - Pioneer Venus observations of bow shock location and structure  

Science.gov (United States)

Pioneer Venus observations are used in carrying out a study of the location and structure of the Venus bow shock. The trace of the shock in the solar wind aberrated terminator plane is almost circular at an altitude of 1.38 Venus radii independent of interplanetary magnetic field orientation with an extrapolated subsolar height of 0.38 Venus radii. Gas dynamic relations and scaling of the terrestrial analogue are used in determining the effective impenetrable obstacle altitude from the mean shock surface with the conclusion that it lies beneath the observed height of the ionopause. The short-term variability in shock position is similar to that found at the earth; over the long-term bow shock, altitude varies by up to approximately 35% in phase with the solar cycle for reasons other than changing solar wind Mach number. In contrast to ionopause position, which is shown to be well determined by external pressure measurements, it is found that bow shock altitude is only weakly dependent on ionopause height and solar wind dynamic pressure.

Slavin, J. A.; Elphic, R. C.; Russell, C. T.; Scarf, F. L.; Wolfe, J. H.; Mihalov, J. D.; Intriligator, D. S.; Brace, L. H.; Taylor, H. A.; Daniell, R. E.

1980-12-01

358

The near-infrared nitric oxide nightglow in the upper atmosphere of Venus.  

Science.gov (United States)

The v' = 0 progressions of the C --> X and A --> X band systems of nitric oxide dominate the middle-UV spectrum of the night-time upper atmospheres of the Earth, Mars, and Venus. The C(0) --> A(0)+h nu radiative transition at 1.224 mum, the only channel effectively populating the A(0) level, must therefore occur also. There have been, however, no reported detections of the C(0) --> A(0) band in the atmospheres of these or any other planets. We analyzed all available near-infrared limb observations of the dark-side atmosphere of Venus by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) instrument on the Venus Express spacecraft and found 2 unambiguous detections of this band at equatorial latitudes that seem to be associated with episodic events of highly enhanced nightglow emission. The discovery of the C(0) --> A(0) band means observations in the 1.2-1.3 microm region, which also contains the a(0) --> X(0) emission band of molecular oxygen, can provide a wealth of information on the high-altitude chemistry and dynamics of the Venusian atmosphere. PMID:19164595

García Muñoz, A; Mills, F P; Piccioni, G; Drossart, P

2009-01-27

359

The influence of lithospheric flexure on magma ascent at large volcanoes on Venus  

Science.gov (United States)

volcanoes on Venus exert large vertical loads on the lithosphere, which responds by deflecting downward. Stresses induced by this lithospheric flexure can have a strong influence on magma ascent pathways from the mantle source region to the surface. Here we propose that flexural stresses exert control over the shapes of volcanic edifices on Venus, applying criteria for magma ascent expressed in terms of stress orientations (can vertical dikes form?) and gradients (is magma squeezed upward or downward in a vertical dike?) to determine favored magma ascent paths and locations. For conical edifices emplaced on lithosphere with high elastic thickness Te, (e.g., > 40 km) both sets of magma ascent criteria are satisfied over the entire lithosphere, allowing essentially unimpeded ascent of magma to the surface and the formation of relatively steep edifices. However, for lower values of Te, high adverse stress gradients tend to cut off magma ascent beneath the summit, instead favoring lateral transport of magma at depth to distal regions with gentler stress gradients, resulting in domical edifice shapes. At the lowest values of Te (< 10 km), large short-wavelength deflections of the lithosphere tend to produce narrow and widely spaced zones of magma ascent: Such zones may produce annular ridges of volcanic material, thereby generating forms characteristic of a subset of features known as "coronae" on Venus. Another subset of coronae may form by intrusive-based generation of annular fractures at the edge of the summit region of domical edifices, as proposed for Alba Mons on Mars.

McGovern, Patrick J.; Rumpf, M. Elise; Zimbelman, James R.

2013-11-01

360

Stereo-Derived Magellan Topography, VIRTIS Emissivity Estimates, and Tesserae on Venus  

Science.gov (United States)

The VIRTIS instrument aboard the Venus Express spacecraft has allowed for emissivity estimates of surface materials for a variety of terrains in the southern latitudes of Venus. In the case of tesserae, such as Alpha Regio, emissivity signatures tend to be relatively low and suggest a possibly more evolved, Si-rich composition [Mueller et al, 2008]. If confirmed for tesserae, such a composition would imply crustal recycling, a locally depressed solidus and weaker crust. This would not only help constrain our understanding of tessera formation, whether it is due to crustal contraction or volcanic underplating over 1 Gyr ago, but also the environmental conditions prevailing on Venus then. A more silicic composition would imply a wetter, and therefore cooler (more habitable?) Venus and a dramatically different planet from the one we see today. The significance of such a climatic transition would be profound. Correcting for topography is a key step in deriving emissivity from the surface brightness obtained by VIRTIS at 1.02 ?m. Magellan altimetry suffers from large errors at tessera because the rough relief caused surface returns that were more complex than those in the templates used in the processing of the Magellan altimetry data. We are working to produce a high-accuracy DEM from Magellan stereo SAR coverage for a patch of tessera present that is also present in the VIRTIS dataset. Our technique [Hensley and Shaffer, 1994] uses a hierarchical scheme that applies a 2-D normalized correlation function to determine offsets between two images with formal error calculation, which is of crucial importance in constraining emissivity values. Our preliminary results have lateral resolution of 600 m and vertical resolutions of less than 100 m. First estimates of vertical error lie in the 0 to 40 m range.

Nunes, D. C.; Mitchell, K. L.; Hensley, S.; Shaffer, S.; Mueller, N. T.; Smrekar, S. E.

2013-12-01

361

Temperature fields in the Venus mesosphere as observed by VIRTIS-M on Venus Express  

Science.gov (United States)

The entire dataset of nighttime observations of the VIRTIS-M instrument has recently been reprocessed according a new Bayesian algorithm (Grassi et al., 2014, submitted), allowing us to achieve a full self-consistent modelling of the 5.1-4.3 mum spectral region. Retrieved fields include the average cloud deck height, the mean CO mixing ratio at the top of the clouds and the air temperatures between the indicative levels of 65 and 80 km. We review here the main assumptions and uncertainties related to the method, with a discussion on derived retrieval errors. We present also the average fields as a function of latitude and local time, as well as a selection of large synoptic mosaics of temperature fields, derived from several acquisitions during individual orbits.

Grassi, Davide; Drossart, Pierre; Lebonnois, Sebastien; Politi, Romolo; Montabone, Luca; Piccioni, Giuseppe; Migliorini, Alessandra; Ignatiev, Nikolay; Plainaki, Christina; Wolkenberg, Paulina

362

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.

363

Chemical composition of Earth, Venus, and Mercury  

OpenAIRE

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...

Morgan, John W.; Anders, Edward

1980-01-01

364

The sulfur cycle and clouds of Venus  

Science.gov (United States)

The clouds of Venus play a central role in governing its meteorology and climate. These clouds contain concentrated sulfuric acid and an ultraviolet absorbing material which is probably elemental sulfur; their existence depends on the working of complex chemical cycles on the planet. In this paper, the overall chemical cycle responsible for the maintenance of significant amounts of the lithophilic element sulfur in the atmosphere, and the photochemical and thermochemical reactions involved in formation and destruction of the cloud particles themselves are elucidated. The susceptibility of these processes to change (e.g., due to episodic volcanism) with concomitant feedacks to the Venusian climate is emphasized.

Prinn, R. G.

365

Mars, Venus and Gray: Gender Communication  

OpenAIRE

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

Kamarul Zaman Ahmad; Kalaiselvee Rethinam

2010-01-01

366

Venus Unveiled: How Warm is Too Warm  

Science.gov (United States)

This classroom activity has students think about and debate two models of the greenhouse effect: small temperature increase and large temperature increase. Information is provided about the two models and each team is assigned one side of the argument. Students are given time to gather information from outside resources to support their arguments. After discussing the issues, the challenges the scientists face as they try to determine the process by which Venus loses heat is reviewed. After the debate, the influences, assumptions, and interpretations of data that affected students opinions is also reviewed.

367

Venus mapping delayed by Magellan problem  

Science.gov (United States)

The start of full-scale radar mapping of Venus by NASA's Magellan spacecraft has been delayed until at least September 15 while a task force of mission personnel investigates the cause of two communication losses with the spacecraft during its first week in orbit.The task force, headed by Frank McKinney of the Martin-Marietta spacecraft operations division, convened August 28 at the Jet Propulsion Laboratory in Pasadena, Calif., to review possible causes of the signal losses experienced by Magellan. “The investigation group is looking at all possible causes, including both software and hardware,” said JPL spokesman Jim Doyle.

Cole, Steven

368

Transit of Venus Culture: A Celestial Phenomenon Intrigues the Public  

Science.gov (United States)

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.

Bueter, Chuck

2012-01-01

369

Venus Length-of-Day Variations  

Science.gov (United States)

Since 2004 we have been monitoring the instantaneous spin state of Venus with the goals of measuring the precession of the rotation axis and of quantifying daily, seasonal, and secular changes in length-of-day. We use the Goldstone and Green Bank Telescopes for these observations. The spin period of Venus is thought to be set by a delicate balance between solid-body tides and atmospheric torques that must vary as insolation and orbital parameters change [Bills 2005]. Our measurements to date reveal length-of-day (LOD) variations of 50 ppm. None of the models can be reconciled with the Magellan 500-day-average spin period of 243.0185 +/- 0.0001 days [Davies et al 1992], nor with a 16-year-average estimate of 243.023 +/- 0.002 days [Mueller et al 2012], nor with any other constant spin period. With our nominal solution we can rule out a constant spin period with over 99.9% confidence. When allowances are made for uncertainties in spin axis orientation and instantaneous spin measurement epochs, the confidence is reduced but remains higher than 99%. We attribute the LOD variations primarily to angular momentum exchange between the atmosphere and solid planet. Because there are so few constraints on the internal dynamical structure of the Venusian atmosphere, a time history of atmospheric angular momentum changes can be used to address questions related to the dynamics of the atmosphere, including its super-rotation, and climatic variations.

Margot, Jean-Luc; Campbell, D. B.; Peale, S. J.; Ghigo, F. D.

2012-10-01

370

Evaluation of Long Duration Flight on Venus  

Science.gov (United States)

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.

Landis, Geoffrey A.; Colozza, Anthony J.

2006-01-01

371

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)

372

The clouds of Venus. [physical and chemical properties  

Science.gov (United States)

The physical and chemical properties of the clouds of Venus are reviewed, with special emphasis on data that are related to cloud dynamics. None of the currently-popular interpretations of cloud phenomena on Venus is consistent with all the data. Either a considerable fraction of the observational evidence is faulty or has been misinterpreted, or the clouds of Venus are much more complex than the current simplistic models. Several lines of attack are suggested to resolve some of the contradictions. A sound understanding of the clouds appears to be several years in the future.

Young, A. T.

1975-01-01

373

Chemistry of atmosphere-surface interactions on Venus and Mars  

Science.gov (United States)

Earth-based, earth-orbital, and spacecraft observational data are used in the present evaluation of Venus atmosphere-surface interactions to quantitatively characterize the reactions between C, H, S, Cl, F, and N gases and plausible surface minerals. Calculation results are used to predict stable minerals and mineral assemblages on the Venus surface, in order to ascertain which (if any) of the atmospheric gases are buffeted by mineral assemblages. Chemical equilibrium calculations using extant thermodynamic data on scapolite minerals predict that carbonate-bearing scapolite and sulfate meionite are unstable on the surface of Venus, while chloride-bearing scapolite is stable.

Fegley, Bruce, Jr.; Treiman, Allan H.

1992-01-01

374

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

375

Asteroid 2012 XE133: a transient companion to Venus  

OpenAIRE

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 ...

Marcos, C. La Fuente; Marcos, R. La Fuente

2013-01-01

376

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)

377

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.)

378

Line parameters for the 01111-00001 band of 12C16O18O from SOIR measurements of the Venus atmosphere  

International Nuclear Information System (INIS)

CO2 is the major constituent of the atmosphere of Venus. Absorption lines due to its 12C16O18O isotopologue have been observed for the first time in Venus spectra in the 2930-3015 cm-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

379

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)

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.

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

380

Mantle-flow tectonics and the origin of Ishtar Terra, Venus  

Science.gov (United States)

It is proposed that western Ishtar Terra formed due to compression and crustal thickening above a cylindrical mantle downwelling. A model for crustal deformation due to downwelling successfully reproduces many observed characteristics of western Ishtar. Although axisymmetric downwelling occur in numerical models of constant-viscosity mantle convection, there is no evidence for their existence in earth's mantle, where downwellings are sheet-like. Either modes of downflow in Venus and earth are fundamentally different, or differences in near-surface conditions and material behavior selectively emphasize surface expressions of the different downwelling modes.

Bindschadler, D. L.; Schubert, G.; Kaula, W. M.

1990-08-01

381

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)

382

Deuterium on Venus - model comparisons with Pioneer Venus observations of the predawn bulge ionosphere  

International Nuclear Information System (INIS)

A self-consistent model of the Venus ionosphere in the predawn bulge region where the mass-two ion density is observed to be maximum was prepared in order to examine the question of mass-two ion identification in detail. The model calculations are compared to the Pioneer Venus observations of ion composition and structure in the 153-250 km altitude range. The observed densities of major ions O2(+) and O(+) are used to constrain the source of ionization. Once the source is determined, the density distribution of D(+) and H2(+) is calculated for various values of D and H2 in the atmosphere. It is found that mass-two ion is clearly due to deuterium and that the H2 contribution to the mass-two ion is small, if present at all. 34 references

383

On properties of the Venus ionosphere and its sources  

International Nuclear Information System (INIS)

Properties of the day- and nighttime venus ionosphere and some possible sources of its ionization are considered. Differences in measurement results of different experiments carried out at space probes and results of upper ionosphere observations by radioeclipse methods are discussed. It is shown that the satisfactory quantitative description of the Venus ionosphere as a whole is impossible. As for as the fact of the existence of ionizing flows of electrons with energies of an order of several tens of electronvolts in the nighttime Venus ionosphere is reliably established both by the Soviet and American measurements, and the value of these flows is sufficient for creation in the surroundings of the main ionization maximum electron concentrations compared with the observed ones, than any model of the nighttime Venus ionosphere should take into account the effect of the given electron flows

384

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)