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Sample records for venus express mission

  1. Venus Express - the First European Mission to Venus

    NASA Astrophysics Data System (ADS)

    Titov, D. V.; Svedhem, H.; Venus Express Team

    2005-08-01

    The ESA Venus Express mission is based on reuse of the Mars Express spacecraft and the payload available from the Mars Express and Rosetta missions. In less than 3 years the spacecraft was rebuilt with modifications to cope with harsh environment at Venus and fully tested. The Venus Express will be launched in the end of October 2005 from Baykonur (Kazakhstan) by the Russian Sojuz-Fregat rocket. In the beginning of April 2006 the spacecraft will be inserted in a polar orbit around Venus with pericenter of 250 km and apocentre of 66,000 km and a period of 24 hours. The planned mission duration is two Venus sidereal days ( 500 Earth days) with possibility to extend the mission for two more Venus days. The Venus Express aims at a global investigation of the Venus atmosphere and the plasma environment, and addresses some important aspects of the surface physics. The science goals comprise investigation of the atmospheric structure and composition, cloud layer and hazes, global circulation and radiative balance, plasma and escape processes, and surface properties. These topics will be addressed by seven instruments onboard the satellite: Analyzer of Space Plasma (ASPERA), Magnetometer (MAG), IR Fourier spectrometer (PFS), spectrometer for solar and stellar occultation (SPICAV), radio science experiment (VeRa), visible and IR imaging spectrometer (VIRTIS), and Venus Monitoring Camera (VMC). Scientific operations will include observations in pericentre, off-pericentre and apocentre sessions, limb scans, solar and stellar occultation, radio occultation, bi-static radar, and solar corona sounding.

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

    NASA Astrophysics Data System (ADS)

    Drossart, Pierre; Montmessin, Franck

    2015-11-01

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

  3. Missions to Venus

    NASA Astrophysics Data System (ADS)

    Titov, D. V.; Baines, K. H.; Basilevsky, A. T.; Chassefiere, E.; Chin, G.; Crisp, D.; Esposito, L. W.; Lebreton, J.-P.; Lellouch, E.; Moroz, V. I.; Nagy, A. F.; Owen, T. C.; Oyama, K.-I.; Russell, C. T.; Taylor, F. W.; Young, R. E.

    2002-10-01

    Venus has always been a fascinating objective for planetary studies. At the beginning of the space era Venus became one of the first targets for spacecraft missions. Our neighbour in the solar system and, in size, the twin sister of Earth, Venus was expected to be very similar to our planet. However, the first phase of Venus spacecraft exploration in 1962-1992 by the family of Soviet Venera and Vega spacecraft and US Mariner, Pioneer Venus, and Magellan missions discovered an entirely different, exotic world hidden behind a curtain of dense clouds. These studies gave us a basic knowledge of the conditions on the planet, but generated many more questions concerning the atmospheric composition, chemistry, structure, dynamics, surface-atmosphere interactions, atmospheric and geological evolution, and the plasma environment. Despite all of this exploration by more than 20 spacecraft, the "morning star" still remains a mysterious world. But for more than a decade Venus has been a "forgotten" planet with no new missions featuring in the plans of the world space agencies. Now we are witnessing the revival of interest in this planet: the Venus Orbiter mission is approved in Japan, Venus Express - a European orbiter mission - has successfully passed the selection procedure in ESA, and several Venus Discovery proposals are knocking at the doors of NASA. The paper presents an exciting story of Venus spacecraft exploration, summarizes open scientific problems, and builds a bridge to the future missions.

  4. A dynamic atmosphere revealed by the Venus Express mission

    NASA Astrophysics Data System (ADS)

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

    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.

  5. Venus winds at cloud level from VIRTIS during the Venus Express mission

    NASA Astrophysics Data System (ADS)

    Hueso, Ricardo; Peralta, Javier; Snchez-Lavega, Agustn.; Prez-Hoyos, Santiago; Piccioni, Giuseppe; Drossart, Pierre

    2010-05-01

    The Venus Express (VEX) mission has been in orbit to Venus for almost four years now. The VIRTIS instrument onboard VEX observes Venus in two channels (visible and infrared) obtaining spectra and multi-wavelength images of the planet. Images in the ultraviolet range are used to study the upper cloud at 66 km while images in the infrared (1.74 ?m) map the opacity of the lower cloud deck at 48 km. Here we present our latest results on the analysis of the global atmospheric dynamics at these cloud levels using a large selection over the full VIRTIS dataset. We will show the atmospheric zonal superrotation at these levels and the mean meridional motions. The zonal winds are very stable in the lower cloud at mid-latitudes to the tropics while it shows different signatures of variability in the upper cloud where solar tide effects are manifest in the data. While the upper clouds present a net meridional motion consistent with the upper branch of a Hadley cell the lower cloud present almost null global meridional motions at all latitudes but with particular features traveling both northwards and southwards in a turbulent manner depending on the cloud morphology on the observations. A particular important atmospheric feature is the South Polar vortex which might be influencing the structure of the zonal winds in the lower cloud at latitudes from the vortex location up to 55S. Acknowledgements This work has been funded by the Spanish MICIIN AYA2009-10701 with FEDER support and Grupos Gobierno Vasco IT-464-07.

  6. Post-Venus Express exploration of Venus : an in-situ mission to characterize Venus climate evolution

    NASA Astrophysics Data System (ADS)

    Chassefiere, E.; Aplin, K.; Ferencz, C.; Lopez-Moreno, J.; Leitner, J.; Marty, B.; Roos-Serote, M.; Titov, D.; Wilson, C.; Witasse, O.; Vep Team

    The planet Venus - our neighbour in the solar system and twin sister of the Earth - was once expected to be very similar to the Earth. However the space missions to the planet discovered a world completely different from ours. The fundamental mysteries in the physics of Venus are related to the composition and dynamics of the atmosphere, physics of the cloud layer and greenhouse effect, surface mineralogy, evolution of the surface and volatile inventory. Despite the fact that both Earth and Venus were formed in the same region of the solar system, the planets followed dramatically different evolutionary paths. Understanding the reasons for this divergence would shed a light on the processes of origin and evolution of all terrestrial planets including Earth. A new mission to Venus is under study. It consists of a set of probes (balloon probe, descent probes) devoted to the characterization of atmospheric chemical cycles, atmospheric electrical/ electromagnetic activity, low atmosphere dynamics, surface/ atmosphere thermo-chemical interactions, surface mineralogy and geology, with an emphasis on past climate evolution (noble gas/ isotope composition of the atmosphere). Some orbital science is planned, in complement to in-situ science. An atmosphere sample return is also considered. Information about current activity may be found at http://www.aero.jussieu.fr/VEP/, together with documents describing the present state of thoughts about scientific priorities and possible mission scenarios.

  7. Venus 2000 Mission Design

    NASA Technical Reports Server (NTRS)

    Folta, David; Marr, Greg; Vaughn, Frank; Houghton, Martin B.

    1997-01-01

    As part of the Discovery Program, National Aeronautics and Space Administration (NASA) has solicited proposals for inter-planetary research to conduct solar system exploration science investigations. A mission, called Venus 2000 (V2k), has been proposed for exploration of the Venus Atmosphere. This is NASAs first voyage to Venus to investigate key science objectives since Magellan and will be launched in summer 2002. In keeping with discovery program requirements to reduce total mission cost and utilize new technology, V2k mission design and control will focus on the use of innovative and proven trajectory analysis programs and control systems provided by the Goddard Space Flight Center (GSFC).

  8. Venus Aerobot Multisonde Mission

    NASA Technical Reports Server (NTRS)

    Cutts, James A.; Kerzhanovich, Viktor; Balaram, J. Bob; Campbell, Bruce; Gershaman, Robert; Greeley, Ronald; Hall, Jeffery L.; Cameron, Jonathan; Klaasen, Kenneth; Hansen, David M.

    1999-01-01

    Robotic exploration of Venus presents many challenges because of the thick atmosphere and the high surface temperatures. The Venus Aerobot Multisonde mission concept addresses these challenges by using a robotic balloon or aerobot to deploy a number of short lifetime probes or sondes to acquire images of the surface. A Venus aerobot is not only a good platform for precision deployment of sondes but is very effective at recovering high rate data. This paper describes the Venus Aerobot Multisonde concept and discusses a proposal to NASA's Discovery program using the concept for a Venus Exploration of Volcanoes and Atmosphere (VEVA). The status of the balloon deployment and inflation, balloon envelope, communications, thermal control and sonde deployment technologies are also reviewed.

  9. The Pioneer Venus Missions.

    ERIC Educational Resources Information Center

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

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

  10. The Pioneer Venus Missions.

    ERIC Educational Resources Information Center

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

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

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

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

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

  12. Future Venus exploration: mission Venera-D

    NASA Astrophysics Data System (ADS)

    Zasova, Ludmila

    Venus was actively studied by Soviet and US missions in 60-90-th years of the last century. The investigations carried out both from the orbit and in situ were highly successful. After a 15-year break in space research of Venus, the ESA Venus Express mission, launched in 2005, successfully continues its work on orbit around Venus, obtaining spectacular results. However, many questions concerning the structure and evolutions of the planet Venus, which are the key questions of comparative planetology and very essential for understanding the possible evolution of the terrestrial climate, cannot be solved by observations only from an orbit. Venera-D includes orbiter, lander, subsatellite, long living station on the surface. Venera-D is focused for both in situ and remote investigations of Venus of surface and atmosphere, as well plasma environment and solar wind interaction. Practically all experiments for Venera-D, will be provided by international teams. A Russia-US Venera-D Joint Science Definition Team has been formed in February 2014 to recommend a possible collaborative and coordinated implementation by considering the common aspects of Venera-D mission as presently defined, as well as the Venus Climate Mission recommended by the US Academies Decadal Survey of Planetary Science and the Venus Flagship mission studied by NASA in 2009. The team will provide its report by March 2015 and will likely lead to a coordinated or joint call for instruements and/or mission elements.

  13. The Magellan Venus mapping mission

    NASA Technical Reports Server (NTRS)

    Cutting, E.; Fordyce, J.; Licata, S.; Lyons, D.

    1989-01-01

    The April 1989 Magellan (MGN) Mission to Venus will initiate a new phase in the exploration of the solar system. In addition to being the first U.S. planetary mission in 10.5 years, it will also be the first such mission to use the Space Shuttle and IUS 2-Stage as launch vehicles. Upon arrival at Venus the spacecraft will begin a systematic mapping of the surface of that planet using side-looking SAR. This paper discusses some of the interesting trade-offs in mission design for this mission in the areas of launch and injection, interplanetary cruise, Venus Orbit insertion, and mapping. The Magellan mapping strategy is discussed briefly along with a few special experiments being considered for the MGN extended mission.

  14. Mars and Venus - The Express Way : Evolution and Heritage in Flexi Type Missions Concerning Model Philosophy and Environmental Test Design

    NASA Astrophysics Data System (ADS)

    Rustichelli, S.; McCoy, D.; Florino, T.; Pereira, J.; Pendaries, M.

    2004-08-01

    Mars Express is the first example of ESA's "Flexible Missions", a new and more economic way of building space science missions based on maximum use of existing technology that is either 'off-the-shelf' or technology that has already been developed for other programs. The high level of recurrence in the design, the re-use of existing hardware and the implementation of new project management practices made possible to Mars Express to meet the objective of shortening the time from original concept to launch, being built unusually quickly to meet its narrow launch window in June 2003. The objective of being assembled, fully tested and prepared for launch in a record time, 30% faster than other comparable missions and with reduced financial funding, could be achieved only with a thorough re- thinking of the model philosophy and environmental test design. The encouraging results obtained with Mars Express are the basis of the AIV program of the second ESA's Flexible Mission, Venus Express. Highly recurrent of Mars Express, even if with important peculiarities due to the different mission and planetary environment, this Project will benefit of the qualifications achieved on its predecessor, allowing a single module approach where the AIT campaign will start directly on the PFM. This paper presents the innovative concepts implemented in the definition of Mars Express Model Philosophy and Environmental Test campaigns, showing the influence of the adopted solutions on the in-flight performances. An overview of Venus Express Test Campaign is also given, focusing on the effects of the previous experience and the lessons learned as well as the peculiarities of the new mission.

  15. Venus Express: Answered and unanswered questions on Venus (Invited)

    NASA Astrophysics Data System (ADS)

    Svedhem, H.; Titov, D.

    2013-12-01

    After having orbited our sister planet for more than seven Earth years Venus Express has collected a very large data set allowing a great number of fundamental scientific questions to be addressed and answered. Most of the questions included in the mission's science requirement, as formulated in the mission proposal, have been answered. These include topics in atmospheric dynamics, structure and chemistry, clouds and hazes, surface and interior, radiation balance and greenhouse, induced magnetosphere and plasma environment, and planetary evolution. Solid results have been achieved in all these fields but with some weakness in the radiation balance measurements, mostly due to the early loss of the planetary Fourier spectrometer providing data at the mid infrared wavelengths. Naturally, due to the limited scope and budget of the Venus Express mission a number of important questions had to be left unaddressed and to be taken up by future missions. This talk will summarise the major results of Venus Express and discuss a number of questions where additional data will be needed in order to provide answers. A wish list for future missions will be provided.

  16. The Venusian induced magnetosphere: A case study of plasma and magnetic field measurements on the Venus Express mission

    NASA Astrophysics Data System (ADS)

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

    2008-05-01

    Plasma and magnetic field measurements made onboard the Venus Express on June 1, 2006, are analyzed and compared with predictions of a global model. It is shown that in the orbit studied, the plasma and magnetic field observations obtained near the North Pole under solar minimum conditions were qualitatively and, in many cases also, quantitatively in agreement with the general picture obtained using a global numerical quasi-neutral hybrid model of the solar wind interaction (HYB-Venus). In instances where the orbit of Venus Express crossed a boundary referred to as the magnetic pileup boundary (MPB), field line tracing supports the suggestion that the MPB separates the region that is magnetically connected to the fluctuating magnetosheath field from a region that is magnetically connected to the induced magnetotail lobes.

  17. Investigation of planetary space weather effects at Venus observed by the ASPERA-4 particle analyzer and the magnetometer flying onboard of Venus Express Mission

    NASA Astrophysics Data System (ADS)

    Vech, Daniel; Szego, Karoly; Opitz, Andrea; Fraenz, Markus

    2014-05-01

    In this study we identified several coronal mass-ejections (CME's) interacting with the induced magnetosphere of Venus during 2010 and 2011 using STEREO observations and ENLIL simulations. Our purpose is to analyze the response of the induced magnetosphere and the ionosphere to these extreme conditions based on measurements made by the ASPERA-4 and MAG instruments on Venus Express. The parameters of the interplanetary magnetic field (IMF) during these solar events are also discussed. Previously we investigated the effects of the May 2007 solar eruption on the induced magnetosphere of Venus in a poster publication (EPSC2013-266). During the analyzed solar event large scale rotation of the interplanetary magnetic field was observed and in the polar region, the altitude where planetary ions were present decreased compared to the average cases. Polarity reversal of the induced magnetosphere also took place, similar to the cases discussed by Edberg et. al (2011). Several CME's interacted with Venus in November 2011. One of the largest lifted off on 3rd November and reached Venus on 5th November. The solar wind parameters showed large variations: the velocity peaked over 900 km/s, and the magnitude of the IMF suddenly increased threefold. The magnetic field reached 240 nT inside the induced magnetosphere, which is extremely high compared to normal conditions. The heavy ion density measured by VEX peaked over 1000 1/cm3 providing clear evidence for ionosphere crossing. Due to the orbit parameters it is possible to investigate the magnetic structure in the tail. The other selected solar eruptions caused similar changes including the sudden increase in the solar wind velocity and magnitude of the magnetic field in the magnetic barrier but due to the different orbital parameters other regions of the induced magnetosphere were investigated as well. In conclusion the observed planetary space weather effects include that in the shocked solar wind we observed Increased velocity, ion density and thermal pressure. As a consequence of those, the ion outflow flux increased at the ion composition boundary; a stronger than usual magnetic barrier was observed. In the tail the magnetic field structure was modified and higher than usual ion outflow was indicated but these require further study. References: Edberg, N. J. T., et al. (2011), Atmospheric erosion of Venus during stormy space weather, J. Geophys. Res., 116, A09308, doi:10.1029/2011JA016749. Vech et. al (2013), The effects of the May 2007 solar eruption on the induced magnetosphere of Venus, European Planetary Science Congress 2013, London, EPSC2013-266

  18. Europe Goes to the Venus - The Journey of Venus Express

    NASA Astrophysics Data System (ADS)

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

    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.

  19. Venus Express ready for lift-off

    NASA Astrophysics Data System (ADS)

    2005-10-01

    Venus Express is Europe’s first mission to Venus, a place of many mysteries that scientists are still eager to solve. Principal among those mysteries is why a planet so similar to the Earth in size, mass, and composition has evolved so differently over the course of the last 4.6 billion years. ESA’s ESOC establishment, the Space Operations Centre in Darmstadt, Germany will control the mission and organise a launch event from 06:00 to 12:00. A live televised transmission of the launch will bring images from Baikonur to broadcasters and the general public. ESA senior management and specialists will be on hand at ESOC and at other ESA establishments for explanations and interviews. All live transmissions are carried free-to-air. For broadcasters, complete details of the various satellite feeds (on Eutelsat W2) are listed at http://television.esa.int. For the general public, a launch transmission via Astra 1G has again been organised, with all schedule and transmission details online at http://television.esa.int/photos/Astra.pdf On the occasion of the launch of Venus Express, the Planetary Society has teamed up with ESA to invite youths and adults worldwide to enter a Venus Express Art Contest. The theme of the contest is "Postcards from Venus". Entrants are invited to imagine the surface of Venus from an above-ground perspective. The winner will be invited to follow the Venus Orbit Insertion event at ESA's control centre in Darmstadt, Germany, on 6 April 2006. More on the constest at http://planetary.org/postcards_from_venus/ Media representatives wishing to follow the event at ESA/ESOC, or the retransmission at other ESA establishments, are requested to fill in the attached registration form and fax it back to the place of their choice.

  20. Mission concepts for Venus surface investigation

    NASA Astrophysics Data System (ADS)

    Hoffman, S. J.; Feingold, H.; Friedlander, A.

    1981-08-01

    Mission concepts for the in situ investigation of the Venus atmosphere and surface in the period following the VOIR mission are discussed. The science issues in Venus exploration and possible means of meeting the scientific objectives are considered, including global mapping, surface composition determination, atmospheric composition determination and surface-atmosphere interactions. Particular attention is then given to the feasibility of buoyant stations for atmospheric observation, balloon-tether combinations for surface observations, and the active thermal control by a reversed Brayton cycle or a vapor compression cycle of a long-lived Venus lander. Of the concepts examined, it is found that only the balloon-tether system would be impractical for the mission outlined for it, while the other two concepts appear feasible.

  1. A Venus Flagship Mission: Exploring a World of Contrasts

    NASA Astrophysics Data System (ADS)

    Senske, D.; Bullock, M.; Balint, T.; Benz, A.; Campbell, B.; Chassefiere, E.; Colaprete, A.; Cutts, J.; Glaze, L.; Gorevan, S.; Grinspoon, D.; Hall, J.; Hasimoto, G.; Head, J.; Hunter, G.; Johnson, N.; Kiefer, W.; Kolawa, E.; Kremic, T.; Kwok, J.; Limaye, S.; Mackwell, S.; Marov, M.; Peterson, C.; Schubert, G.; Spilker, T.; Stofan, E.; Svedhem, H.; Titov, D.; Treiman, A.

    2008-12-01

    Results from past missions and the current Venus Express Mission show that Venus is a world of contrasts, providing clear science drivers for renewed exploration of this planet. In early 2008, NASA's Science Mission Directorate formed a Science and Technology Definition Team (STDT) to formulate science goals and objectives, mission architecture and a technology roadmap for a flagship class mission to Venus. This 3- to 4 billon mission, to launch in the post 2020 timeframe, should revolutionize our understanding of how climate works on terrestrial planets, including the close relationship between volcanism, tectonism, the interior, and the atmosphere. It would also more clearly elucidate the geologic history of Venus, including the existence and persistence of an ancient ocean. Achieving these objectives will provide a basis to understand the habitability of extra solar terrestrial planets. To address a broad range of science questions this mission will be composed of flight elements that include an orbiter that is highlighted by an interferometric SAR to provide surface topographic and image information at scales one to two orders of magnitude greater than that achieved by any previous spacecraft to Venus. Two balloons with a projected lifetime of weeks will probe the structure and dynamics of the atmosphere at an altitude of 50 to 70-km. In addition, two descent probes will collect data synergistic to that from the balloon and analyze the geochemistry of surface rocks over a period of hours. The technology road map focuses on key areas of science instruments and enabling engineering to provide greater in situ longevity in the hostile Venus environment.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

  3. Experimental Aerobraking with Venus Express

    NASA Astrophysics Data System (ADS)

    Svedhem, Hakan

    2013-10-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    Venus is completely enveloped by clouds. The main cloud layers stretch from altitudes of 48 -75 km, with additional tenuous hazes found at altitudes 30 -100 km. Clouds play a crucial role in governing atmospheric circulation, chemistry and climate on all planets, but particularly so on Venus due to the optical thickness of the atmosphere. The European Space Agency's Venus Express (VEx) satellite has carried out a wealth of observations of Venus clouds since its arrival at Venus in April 2006. Many VEx observations are relevant to cloud science -from imagers and spectrometers to solar, stellar and radio occultation -each covering different altitude ranges, spectral ranges and atmospheric constituents

  5. Geochemistry of Venus: Progress, Prospects and New Missions

    NASA Astrophysics Data System (ADS)

    Treiman, A. H.

    2009-04-01

    Available geochemical data on Venus' surface materials are limited and of poor precision. Those data were obtained by the Venera and VEGA lander missions, which were engineering and scientific triumphs of their days. However, their chemical analyses of the Venus surface do not permit detailed geochemical interpretations, such as are routine for terrestrial analyses and MER APXS rover analyses from Mars. In particular, the Venera and VEGA analyses of major elements (by XRF) did not return abundances of Na, and their data on Mg and Al are little more than detections at the 2s level. Their analyses for K, U, and Th (by gamma rays) are imprecise, except for one (Venera 8) with extremely high K contents (~4% K2O) and one (Venera 9) with a non-chondritic U/Th abundance ratio. In addition, the Venera and VEGA landers sampled only materials from the Venus lowlands - they did not target sites in any of the highland areas: shield volcanoes, tesserae, nor the unique plateau construct of Ishtar Terra. The Virtis imaging spectrometer on Venus Express has provided new global data of likely geochemical importance - maps of surface emittance at near 1.2 m - but it remains unclear just what causes its observed variations in emittance. The limitations of the available data on Venus' surface rock compositions and mineralogy highlight the huge opportunities in additional chemical and mineralogical analyses of Venus' surface. In geochemistry, currently available instruments could provide much more precise analyses for major and minor elements, even within the engineering constraints of the Venera / VEGA lander systems. Such precise analyses would be welcome for basalts of Venus' lowland plains, but would be especially desirable for the highland tesserae and for Ishtar Terra. The tesserae may well represent ancient crust that predates the most recent volcanic resurfacing event and so provide a geochemical look into Venus' distant past. Ishtar Terra may be composed (at least in part) of granitic rocks like Earth's continental crust, which required abundant water to form. So, Ishtar Terra could possibly yield evidence on whether Venus once had an ocean, and thus the possibility of life. The mineralogy of Venus' surface materials will reflect not only its rocks, but also their chemical weathering in the hot, dense, corrosive Venus atmosphere. Mineralogical instruments at the Venus surface (like XRD or Raman) could test various theories of surface atmosphere interactions, like carbonate buffering of atmospheric CO2, sulfide/sulfate buffering of SO2, and origin of Venus' low emissivity highlands as iron sulfide or as metallic tellurium frost. The geochemistry of Venus' surface would be learned best in lander missions, which are under consideration from several agencies. Current mission concepts are severely limited durations at Venus' surface before they succumb to its high temperature. However, high-temperature electronics and power systems are under development. Surface-atmosphere interactions, and hence surface mineralogy, can be constrained indirectly by probes of Venus' lower atmosphere (with or without soft landing). And improved radar imagery and altimetry can provide crucial indirect constraints on surface mineralogy and geology via emissivity and geophysical constraints (e.g., whether Ishtar Terra could be a granitic continent).

  6. The Magellan Venus radar mapping mission

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

    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.

  7. The Magellan Venus radar mapping mission

    NASA Astrophysics Data System (ADS)

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

    1990-06-01

    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.

  8. Systems Analysis for a Venus Aerocapture Mission

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

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

  10. Magnetic observations of Venus ionosphere during Venus Express aerobraking campaign

    NASA Astrophysics Data System (ADS)

    Zhang, Tielong; Baumjohann, Wolfgang; Russell, Christopher; Luhmann, Janet

    2015-04-01

    During the late days of the Venus Express mission, an aerobraking campaign was performed in May - July 2014. The altering of the spacecraft orbit allows the pericenter went to as low as 129.7 km in altitude, which is well below the main peak ionosphere altitude of ~140 km. Magnetic observations during aerobraking campaign shows that the Venus ionosphere exhibits the same magnetic properties as observed by Pioneer Venus Orbiter (PVO) during solar maximum for altitude above 150 km which was the lowest altitude reached by PVO: magnetized ionosphere with large-scale horizontal magnetic field; or unmagnetized ionosphere with numerous small-scale thin structures, so-called flux ropes. However, around or below main peak ionosphere altitude, we find only very low background magnetic field of several nanotesla, without any large magnetic belt or larger spikes of fields, the so-called flux ropes. Apparently the magnetization of the ionosphere or the penetration of the magnetic ropes stops at main peak ionosphere altitude.

  11. Densities and temperatures in the Venus mesosphere and lower thermosphere retrieved from SOIR on board Venus Express: Carbon dioxide measurements at the Venus terminator

    NASA Astrophysics Data System (ADS)

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

    2012-07-01

    SOIR is a high-resolution spectrometer flying on board the ESA Venus Express mission. It performs solar occultations of the Venus high atmosphere, and so defines unique vertical profiles of many of the Venus key species. In this paper, we focus on the Venus main constituent, carbon dioxide. We explain how the temperature, the total density, and the total pressure are derived from the observed CO2 density vertical profiles. A striking permanent temperature minimum at 125 km is observed. The data set is processed in order to obtain a Venus Atmosphere from SOIR measurements at the Terminator (VAST) compilation for different latitude regions and extending from 70 up to 170 km in altitude. The results are compared to many literature results obtained from ground-based observations, previous missions, and the Venus Express mission. The homopause altitude is also determined.

  12. Communications Transceivers for Venus Surface Missions

    NASA Technical Reports Server (NTRS)

    Force, Dale A.

    2004-01-01

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

  13. The final year of Venus Express

    NASA Astrophysics Data System (ADS)

    Svedhem, Håkan

    2015-04-01

    The Venus Express mission ended in December 2014 after having run out of fuel after 8.5 years of continuous operation in orbit around our sister planet. The last year in operation was characterised by a number of dedicated science campaigns and the aerobraking in June-July, and the subsequent special operations in the new 22.5 hour orbit post aerobraking. This talk will summarise the activities and the main results of the last year in operation, including the aerobraking, and discuss the events leading up to the declaration of end of mission following the end of fuel condition.

  14. Venus Atmospheric Maneuverable Platform Science Mission

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    Over the past several years, we have explored a possible new approach to Venus upper atmosphere exploration by applying recent Northrop (non-NASA) development programs and have come up with a new class of exploration vehicle: an atmospheric rover. We will discuss a possible suite of instruments and measurements to study the current climate through detailed characterization of cloud level atmosphere and to understand the processes that control climate on Earth-like planets.Our Venus atmospheric rover concept, the Venus Atmospheric Maneuverable Platform (VAMP), is a hypersonic entry vehicle with an ultra-low ballistic coefficient that transitions to a semi-buoyant air vehicle (AV) after entering the Venus atmosphere. Prior to entry, the AV fully deploys to enable lifting entry and eliminates the need for an aeroshell. The mass savings realized by eliminating the aeroshell allows VAMP to accommodate significantly more instruments compared to previous Venus in situ exploration missions. VAMP targets the global Venus atmosphere between 50-65 km altitudes and would be an ideal, stable platform for atmospheric and surface interaction measurements. We will present a straw man concept of VAMP, including its science instrument accommodation capability and platform’s physical characteristics (mass, power, wingspan, etc). We will discuss the various instrument options.VAMP’s subsonic flight regime starts at ~94 km and after <1 hour, the AV will reach its cruise altitude of ~65 km. During this phase of flight, the VAMP sensor suite will acquire a pre-defined set of upper atmosphere measurements. The nominal VAMP lifetime at cruise altitude is several months to a year, providing numerous circumnavigation cycles of Venus at mid-latitude. The stability of the AV and its extended residence time provide the very long integration times required for isotopic mass analysis. VAMP communicates with the orbiter, which provides data relay and possibly additional science measurements complementing the in situ measurements from the AV. We will specifically focus upon key factors impacting the design and performance of VAMP science.

  15. Venus Express set for launch to the cryptic planet

    NASA Astrophysics Data System (ADS)

    2005-10-01

    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, Cebreros will be the main information relay point between ESOC and Venus Express. Reaching for Venus During its 163 day journey to Venus, Venus Express will cover about 400 million kilometres at an average speed of some 28 kilometres per second with respect to the Sun. After an initial commissioning period, the spacecraft will cruise peacefully with no specific operations planned, besides routine checks of its subsystems and scientific instruments, and minor trajectory corrections if needed. The thrills will start again on 6 April 2006, at the end of the cruise, when the spacecraft will have to perform a delicate manoeuvre to brake and be captured into orbit around Venus. The energy required for Venus Orbit Insertion (VOI) is very high, and will need the main engine to fire (burn) for approximately 51 minutes. This manoeuvre will place the spacecraft in a highly elliptical ‘capture’ orbit around the planet, with a pericentre (closest point to the Venusian surface) of 250 kilometres near the north pole, and an apocentre (furthest distance from the surface) at 350 000 kilometres roughly at the south pole. At the end of this initial 10-day ‘capture’ orbit, Venus Express will ignite its main engine again. About six days later, after a series of other minor orbit adjustments, the spacecraft will have been positioned in its final operational orbit. This will be an elliptical polar orbit, lying between 250 and 66 000 kilometres above Venus, and will last 24 hours. The capture orbit could already provide the first opportunity for scientific observations, but the nominal science phase will start on 4 July 2006, after the spacecraft and instruments commissioning phase has been concluded. The set of seven instruments on board Venus Express represents an unprecedented diagnostic package to study the thick and enigmatic atmosphere of Venus - an atmosphere so dense and so intimately coupled with the planet’s surface, that studying it will help provide clues about the features, status and evolution of the entire planet. Note to editors Venus Express is an almost identical twin spacecraft to Mars Express, but adapted to operate in the hot and harsh environment around Venus. It was built by EADS Astrium, Toulouse (France), leading a group of industrial partners throughout Europe. Completing the spacecraft took less than four years from concept to launch, making it the fastest-built ESA scientific satellite ever. Besides the spacecraft manufacturing and testing, industry will still be involved during the mission on a collaboration and consultancy basis for the ESA Venus Express Project team, led by the Project Manager, and for the Venus Express ground control team, led by the Spacecraft Operations Manager. On 4 July 2006, when the nominal science phase begins, the Venus Express Project Manager will hand over responsibility for the mission to an ESA Venus Express Mission Manager, leading the Venus Express Science Operations Centre (VSOC) in ESA’s European Space Research and Technology Centre (ESTEC) in the Netherlands. The VSOC performs the routine planning for scientific observations, in co-ordination with the Project Scientist and the instrument Principal Investigators. ESA’s investment in Venus Express amounts to about 220 million Euros, covering development of the spacecraft, launch and operations. This figure also includes 15 million Euros for instrument development, including support to several research institutes (Principal Investigators) for building the instruments. Venus Express is one of a family of missions in which costs are shared, the others being Rosetta and Mars Express.

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

    NASA Astrophysics Data System (ADS)

    Wilson, Colin; Ghail, Richard

    ESAs 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 NASAs 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 [Chassefire 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.

  17. ASTROD I: Mission concept and Venus flybys

    NASA Astrophysics Data System (ADS)

    Ni, Wei-Tou; Bao, Yun; Dittus, Hansjrg; Huang, Tianyi; Lmmerzahl, Claus; Li, Guangyu; Luo, Jun; Ma, Zhen-Guo; Franois Mangin, Jean; Nie, Yu-Xin; Peters, Achim; Rdiger, Albrecht; Samain, tienne; Schiller, Stephan; Shiomi, Sachie; Sumner, Timothy; Tang, Chien-Jen; Tao, Jinhe; Touboul, Pierre; Wang, Haitao; Wicht, Andreas; Wu, Xue-Jun; Xiong, Yaoheng; Xu, Chongming; Yan, Jun; Yao, Da-Zhi; Yeh, Hsien-Chi; Zhang, Shu-Lian; Zhang, Yuan-Zhong; Zhou, Ze-Bing

    2006-10-01

    ASTROD I is the first step of ASTROD (Astrodynamical Space Test of Relativity using Optical Devices). This mission concept has one spacecraft carrying a payload of a telescope, five lasers, and a clock together with ground stations (ODSN: Optical Deep Space Network) to test the optical scheme of interferometric and pulse ranging and yet give important scientific results. These scientific results include a better measurement of the relativistic parameters, a better sensitivity in using optical Doppler tracking method for detecting gravitational waves, and measurement of many solar system parameters more precisely. The weight of this spacecraft is estimated to be about 300 350 kg with a payload of about 100 120 kg. The spacecraft is to be launched with initial period about 290 days and to pass by Venus twice to receive gravity-assistance for achieving shorter periods. For a launch on August 4, 2010, after two encounters with Venus, the orbital period can be shortened to 165 days. After about 370 days from launch, the spacecraft will arrive at the other side of the Sun for the determination of relativistic parameters.

  18. The face of Venus. The Magellan radar-mapping mission.

    NASA Astrophysics Data System (ADS)

    Roth, Ladislav E.; Wall, Stephen D.

    1995-06-01

    This book presents radar images of Venus' surface taken with Magellan. The chapters are arranged according to missions to Venus, surface structures (impact craters, volcanoes, flows and channels) surface processes, and tectonism. Appendices give a glossary, nomenclature of Venusian features, identification of Magellan images, and availability of Magellan data products.

  19. ESA's Venus Express to reach final destination

    NASA Astrophysics Data System (ADS)

    2006-04-01

    First step: catching Venus To begin to explore our Earths hot and hazy sister planet, Venus Express must complete a critical first step, the most challenging one following launch. This involves a set of complex operations and manoeuvres that will inject the spacecraft into orbit. The Venus Orbit Insertion (VOI) manoeuvre allows the spacecraft to reduce its speed relative to Venus, so that it can be captured by the planets gravitation. The manoeuvre is a critical one which must proceed at precisely the right place and time. The VOI phase officially started on 4 April and will not be completed until 13 April. It is split into three main sub-phases. The first consists in preparing or initialising the spacecraft for the actual capture manoeuvre so as to avoid the risk of the spacecraft going into safe mode, should parameters unrelated to VOI go off-range. The capture manoeuvre itself consists of a main-engine burn lasting about 50 minutes on the morning of 11 April starting at 09:17 (Central European Summer Time). This is the second main VOI sub-phase. The final sub-phase will be restoring all spacecraft functions, notably resuming communications with Earth and uplinking the commands to be executed during the preliminary capture orbit. Orbital capture is controlled by an automatic sequence of predefined commands, uploaded to the spacecraft four days prior to VOI. This sequence is the minimum set needed to perform the main-engine burn. All spacecraft operations are controlled and commanded by the ground control team located at ESAs European Spacecraft Operations Centre (ESOC) in Darmstadt, Germany. Timeeline of major VOI events (some times subject to change) 4 Aprilacecraft transmitter connected to low gain antenna is switched on. During its interplanetary cruise and during the scientific part of the mission to come, Venus Express communicates with Earth by means of its two high gain antennas. However, during the orbit capture phase (11 April), these two antennas become unusable because of the spacecrafts required orientation at that time. The low gain antenna, carrying a feeble but instantly recognisable signal, will be transmitting throughout all VOI manoeuvres. This will allow ground controllers to monitor the velocity change during the burn, using NASAs Deep Space Networks 70-metre antenna near Madrid, Spain. No other means of communication with the Earth is possible during the capture burn. 5 and 9 April, targeting control manoeuvres. Two time slots are available to adjust course if needed. Given the high accuracy of the course correction performed end of March, Venus Express is currently on the right trajectory for a successful capture into orbit and it is therefore unlikely that either of these two extra slots will be required. 10 to 11 April, final preparations for VOI manoeuvre. 24 to 12 hours before VOI, spacecraft controllers will command Venus Express into its final configuration for the burn. Over the final 12 hours, they will monitor its status, ready to deal with any contingencies requiring last-minute trajectory correction or any revising of the main-engine burn duration. 11 April, 08:03 (CEST), slew manoeuvre. This manoeuvre lasts about half an hour and rotates Venus Express so that the main engine faces the direction of motion. Thanks to this, the burn will slow down (rather than accelerate) the spacecraft. 11 April, 09:17 (CEST), main-engine burn starts. A few minutes after firing of the spacecraft thrusters to make sure the propellant settles in the feed lines to the main engine, the latter will begin its 50-minute long burn, ending at 10:07. This thrust will reduce the initial velocity of 29 000 kilometres per hour (in relation to Venus) by 15 percent, allowing capture. Venus Express will settle into its preliminary, elongated nine-day orbit. On capture, it will be at about 120 million kilometres from the Earth and, at its nearest point, within 400 km of the surface of Venus. During the burn, at 09:45 (CEST), Venus Express will disappear behind the planet and will not be visi

  20. Reassessment of planetary protection requirements for Venus missions

    NASA Astrophysics Data System (ADS)

    Szostak, J.; Riemer, R.; Smith, D.; Rummel, J.

    In 2005 the US Space Studies Board SSB was asked by NASA to reexamine the planetary protection requirements for spacecraft missions to Venus In particular the SSB was tasked to 1 Assess the surface and atmospheric environments of Venus with respect to their ability to support the survival and growth of Earth-origin microbial contamination by future spacecraft missions and 2 Provide recommendations related to planetary protection issues associated with the return to Earth of samples from Venus The task group established by the SSB to address these issues assessed the known aspects of the present-day environment of Venus and the ability of Earth organisms to survive in the physical and chemical conditions found on the planet s surface or in the clouds in the planet s atmosphere As a result of its deliberations the task group found compelling evidence against there being significant dangers of forward or reverse biological contamination as a result of contact between a spacecraft and the surface of Venus or the clouds in the atmosphere of Venus regardless of the current unknowns The task group did however conclude that Venus is a body of interest relative to the process of chemical evolution and the origin of life As a result the task group endorses NASA s current policy of subjecting missions to Venus to the requirements imposed by planetary protection Category II rather than the less restrictive Category I recommended by COSPAR

  1. Characterizing the low-altitude magnetic belt at Venus: Complementary observations from the Pioneer Venus Orbiter and Venus Express

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    Using Venus Express, Zhang et al. (2012b) identified strong magnetic field enhancements at low altitudes over the north polar region of Venus as giant flux ropes. Strong fields at low altitudes were also observed during the Pioneer Venus Orbiter mission, but at low latitudes near the subsolar and midnight regions. We examine the possibility that the Venus Express observations are not giant flux ropes, but part of a low-altitude magnetic belt that builds up in the subsolar region, passes over the terminator, and extends to the nightside. Our analysis indicates the magnetic belt is dominantly horizontal over the dayside and gains a radial component nightward. The peak magnetic field strength of the belt and the altitude at which it peaks also varies around the planet, with the lowest altitude and strongest field strength in the subsolar region, consistent with the idea of the belt forming on the dayside. Zhang et al. (2012b) also noted the fields in the polar region had a bias in the +By direction in Venus Solar Orbital coordinates. The multifluid magnetohydrodynamic simulation we present shows an asymmetry in the plasma flow from the subsolar region to the poles due to the oxygen ion and proton mass ratio. This causes the magnetic field to preferentially accumulate in the north for a +By interplanetary magnetic field direction, providing an explanation for this bias.

  2. The Venus electromagnetic wave environment as observed by Venus Express

    NASA Astrophysics Data System (ADS)

    Russell, C. T.; Zhang, T. L.; Wei, H. Y.; Delva, M.

    Free energy for the generation of waves in the plasma environment surrounding Venus can be supplied in a variety of ways. In the region upstream of the bow shock particles reflected from and accelerated at the bow shock counterstream into the incoming solar wind flow. This generates a large number of waves that are convected back toward the shock. Waves are also generated at the shock. Some can move upstream against the shock, while others are carried downstream. Pickup protons from the interaction of the solar wind with the hot hydrogen exosphere also can generate electromagnetic proton cyclotron waves. These are seen mainly in the magnetosheath at Venus. Deep in the magnetosheath the magnetic field increases, plasma beta drops and the wave amplitudes drop. At the inner edge of this magnetic barrier the spacecraft crosses the ionopause current layer in which the electric component of waves were seen on Pioneer Venus, but we do not know if these waves have a magnetic component. The atmosphere also is capable of generating electromagnetic waves through electric current discharges between regions of different electric potential. Electromagnetic waves generated by this process are refracted vertically by the rapid increase in the index of refraction with altitude. If the magnetic field is horizontal these waves will not escape the atmosphere at the frequencies measured by Venus Express. However, on the nightside there are often regions of vertical, strong magnetic fields (called ionospheric holes because of their lower density). In these regions we expect to detect whistler mode waves generated by lightning. At solar minimum when Venus Express arrives this strongly magnetized region may be even more pervasive. This talk will summarize the EM wave findings by Venus Express, concentrating on the regions closest to the planet.

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

    Electrical activity in a planetary atmosphere enables chemical reactions that are not possible under conditions of local thermodynamic equilibrium. In both the Venus and terrestrial atmospheres, lightning forms nitric oxide. Despite the existence of an inventory of NO at Venus like the Earths, 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    The thermal structure of Venus upper atmosphere (90-140 km) was investigated using stellar occultation measurements acquired by the SPICAV experiment on board Venus Express. The SPICAV ultraviolet channel provides CO2 local density and temperature vertical profiles with a vertical resolution of < 7 km of both the southern and the northern hemispheres on the nightside (18:00-06:00 h local time). A permanent layer of warm air is observed at the mesopause in the altitude range 90-100 km. Temperature then decreases with increasing altitude reaching a minimum value around 125 km. Spatial and temporal changes in the thermal structure have been analyzed. Local time variations dominate the structure of Venus atmosphere at these altitudes: temperatures show an increase of ~ 20 K on the morning side compared to the evening side. The homopause altitude was also determined; it varies between 119 and 138 km of altitude, increasing from the evening side to the morning side. SPICAV temperature profiles were compared to several literature results from ground-based observations, previous spacecraft missions and the Venus Express mission.

  6. Mapping Venus: Modeling the Magellan Mission.

    ERIC Educational Resources Information Center

    Richardson, Doug

    1997-01-01

    Provides details of an activity designed to help students understand the relationship between astronomy and geology. Applies concepts of space research and map-making technology to the construction of a topographic map of a simulated section of Venus. (DDR)

  7. The Venus electromagnetic wave environment as observed by Venus Express

    NASA Astrophysics Data System (ADS)

    Russell, C. T.; Zhang, T. L.; Wei, H. Y.; Delva, M.

    Free energy for the generation of waves in the plasma environment surrounding Venus can be supplied in a variety of ways In the region upstream of the bow shock particles reflected from and accelerated at the bow shock counterstream into the incoming solar wind flow This generates a large number of waves that are convected back toward the shock Waves are also generated at the shock Some can move upstream against the shock while others are carried downstream Pickup protons from the interaction of the solar wind with the hot hydrogen exosphere also can generate electromagnetic proton cyclotron waves These are seen mainly in the magnetosheath at Venus Deep in the magnetosheath the magnetic field increases plasma beta drops and the wave amplitudes drop At the inner edge of this magnetic barrier the spacecraft crosses the ionopause current layer in which the electric component of waves were seen on Pioneer Venus but we do not know if these waves have a magnetic component The atmosphere also is capable of generating electromagnetic waves through electric current discharges between regions of different electric potential Electromagnetic waves generated by this process are refracted vertically by the rapid increase in the index of refraction with altitude If the magnetic field is horizontal these waves will not escape the atmosphere at the frequencies measured by Venus Express However on the nightside there are often regions of vertical strong magnetic fields called ionospheric holes because of their lower density In these regions we expect to detect whistler

  8. Venus O + pickup ions: Collected PVO results and expectations for Venus Express

    NASA Astrophysics Data System (ADS)

    Luhmann, J. G.; Ledvina, S. A.; Lyon, J. G.; Russell, C. T.

    2006-11-01

    Observations of oxygen pickup ions by the plasma analyzer on the Pioneer Venus Orbiter (PVO) Mission arguably launched broad interest in solar wind erosion of unmagnetized planet atmospheres, and its potential evolutionary effects. Oxygen pickup ions may play key roles in the removal of the oxygen excess left behind from the photodissociation of water vapor by enabling direct escape, additional sputtering of oxygen when they impact the exobase, and escape as energetic neutrals produced in charge exchange reactions with the ambient exospheric oxygen and hydrogen. Although the PVO observations were compromised by an 8 keV energy limit for O + detection, a lack of ion composition capability, and the limited sampling and data rate of the plasma analyzer which was designed for solar wind monitoring, these measurements provide our best information about the extended O + exosphere and wake at Venus. Here we show the full picture of the spatial distribution and energies of the O + ion observations collected by the plasma analyzer during PVO's 5000 orbit tour. A model of O + test particles launched in the circum-Venus fields described by an MHD simulation of the solar wind interaction is used to help interpret the PVO observations and to anticipate the expanded view of Venus O + escape that will be provided by the ASPERA-4 experiment on Venus Express.

  9. The 2010 European Venus Explorer (EVE) mission proposal

    NASA Astrophysics Data System (ADS)

    Wilson, Colin Frank; Chassefire, 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, Franois; 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

    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 (25C 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.

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

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

  12. Dynamics of the Venus upper atmosphere: Outstanding problems and new constraints expected from Venus Express

    NASA Astrophysics Data System (ADS)

    Bougher, S. W.; Rafkin, S.; Drossart, P.

    2006-11-01

    A consistent picture of the dynamics of the Venus upper atmosphere from 90 to 200 km has begun to emerge [e.g., Bougher, S.W., Alexander, M.J., Mayr, H.G., 1997. Upper Atmosphere Dynamics: Global Circulation and Gravity Waves. Venus II, CH. 2.4. University of Arizona Press, Tucson, pp. 259-292; Lellouch, E., Clancy, T., Crisp, D., Kliore, A., Titov, D., Bougher, S.W., 1997. Monitoring of Mesospheric Structure and Dynamics. Venus II, CH. 3.1. University of Arizona Press, Tucson, pp. 295-324]. The large-scale circulation of the Venus upper atmosphere (upper mesosphere and thermosphere) can be decomposed into two distinct flow patterns: (1) a relatively stable subsolar-to-antisolar (SS-AS) circulation cell driven by solar heating, and (2) a highly variable retrograde superrotating zonal (RSZ) flow. Wave-like perturbations have also been observed. However, the processes responsible for maintaining (and driving variations in) these SS-AS and RSZ winds are not well understood. Variations in winds are thought to result from gravity wave breaking and subsequent momentum and energy deposition in the upper atmosphere [Alexander, M.J., 1992. A mechanism for the Venus thermospheric superrotation. Geophys. Res. Lett. 19, 2207-2210; Zhang, S., Bougher, S.W., Alexander, M.J., 1996. The impact of gravity waves on the Venus thermosphere and O2 IR nightglow. J. Geophys. Res. 101, 23195-23205]. However, existing data sets are limited in their spatial and temporal coverage, thereby restricting our understanding of these changing circulation patterns. One of the major goals of the Venus Express (VEX) mission is focused upon increasing our understanding of the circulation and dynamical processes of the Venus atmosphere up to the exobase [Titov, D.V., Lellouch, E., Taylor, F.W., 2001. Venus Express: Response to ESA's call for ideas for the re-use of the Mars Express platform. Proposal to European Space Agency, 1-74]. Several VEX instruments are slated to obtain remote measurements (2006-2008) that will complement those obtained earlier by the Pioneer Venus Orbiter (PVO) between 1978 and 1992. These VEX measurements will provide a more comprehensive investigation of the Venus upper atmosphere (90-200 km) structure and dynamics over another period in the solar cycle and for variable lower atmosphere conditions. An expanded climatology of Venus upper atmosphere structure and wind components will be developed. In addition, gravity wave parameters above the cloud tops will be measured (or inferred), and used to constrain gravity wave breaking models. In this manner, the gravity wave breaking mechanism (thought to regulate highly variable RSZ winds) can be tested using Venus general circulation models (GCMs).

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

    NASA Astrophysics Data System (ADS)

    2005-11-01

    Venus Express will eventually manoeuvre itself into orbit around Venus in order to perform a detailed study of the structure, chemistry and dynamics of the planet's atmosphere, which is characterised by extremely high temperatures, very high atmospheric pressure, a huge greenhouse effect and as-yet inexplicable "super-rotation" which means that it speeds around the planet in just four days. The European spacecraft will also be the first orbiter to probe the planet's surface while exploiting the "visibility windows" recently discovered in the infrared waveband. The 1240 kg mass spacecraft was developed for ESA by a European industrial team led by EADS Astrium with 25 main contractors spread across 14 countries. It lifted off onboard a Soyuz-Fregat rocket, the launch service being provided by Starsem. The lift-off from the Baikonur Cosmodrome in Kazakstan this morning took place at 09:33 hours local time (04:33 Central European Time). Initial Fregat upper-stage ignition took place 9 minutes into the flight, manoeuvring the spacecraft into a low-earth parking orbit. A second firing, 1 hour 22 minutes later, boosted the spacecraft to pursue its interplanetary trajectory. Contact with Venus Express was established by ESA's European Space Operations Centre (ESOC) at Darmstadt, Germany approximately two hours after lift-off. The spacecraft has correctly oriented itself in relation to the sun and has deployed its solar arrays. All onboard systems are operating perfectly and the orbiter is communicating with the Earth via its low-gain antenna. In three days' time, it will establish communications using its high-gain antenna. Full speed ahead for Venus Venus Express is currently distancing itself from the Earth full speed, heading on its five-month 350 million kilometre journey inside our solar system. After check-outs to ensure that its onboard equipment and instrument payload are in proper working order, the spacecraft will be mothballed, with contact with the Earth being reduced to once daily. If needed, trajectory correction manoeuvres can go ahead at the half-way stage in January. When making its closest approach, Venus Express will face far tougher conditions than those encountered by Mars Express on nearing the Red Planet. For while Venus's size is indeed similar to that of the Earth, its mass is 7.6 times that of Mars, with gravitational attraction to match. To resist this greater gravitational pull, the spacecraft will have to ignite its main engine for 53 minutes in order to achieve 1.3 km/second deceleration and place itself into a highly elliptical orbit around the planet. Most of its 570 kg of propellant will be used for this manoeuvre. A second engine firing will be necessary in order to reach final operational orbit: a polar elliptical orbit with 12-hour crossings. This will enable the probe to make approaches to within 250 km of the planet's surface and withdraw to distances of up to 66 000 km, so as to carry out close-up observations and also get an overall perspective. Exploring other planets to better understand planet Earth "The launch of Venus Express is a further illustration of Europe's determination to study the various bodies in our solar system", stressed Professor David Southwood, the Director of ESA's science programmes. "We started in 2003 with the launch of Mars Express to the Red Planet and Smart-1 to the Moon and both these missions have amply exceeded our expectations. Venus Express marks a further step forward, with a view to eventually rounding off our initial overview of our immediate planetary neighbours with the BepiColombo mission to Mercury to be launched in 2013." "With Venus Express, we fully intend to demonstrate yet again that studying the planets is of vital importance for life here on Earth", said Jean Jacques Dordain, ESA Director General. "To understand climate change on Earth and all the contributing factors, we cannot make do with solely observing our own planet. We need to decipher the mechanics of the planetary atmosphere in general terms. With Mars Express, we are studying the Martian atmosphere. With Huygens, we have explored that of Saturn's satellite Titan. And now with Venus Express, we are going to add a further specimen to our collection. Originally, Venus and the Earth must have been very similar planets. So we really do need to understand why and how they eventually diverged to the point that one became a cradle for life while the other developed into a hostile environment." The Venus Express mission is planned to last at least two Venusian days (486 Earth days) and may be extended, depending on the spacecraft's operational state of health. Twin sister of Mars Express Venus Express largely reuses the architecture developed for Mars Express. This has reduced manufacturing cycles and halved the mission cost, while still targeting the same scientific goals. Finally approved in late 2002, Venus Express was thereby developed fast, indeed in record time, to be ready for its 2005 launch window. However, Venusian environmental conditions are very different to those encountered around Mars. Solar flux is four times higher and it has been necessary to adapt the spacecraft design to this hotter environment, notably by entirely redesigning the thermal insulation. Whereas Mars Express sought to retain heat to enable its electronics to function properly, Venus Express will in contrast be aiming for maximum heat dissipation in order to stay cool. The solar arrays on Venus Express have been completely redesigned. They are shorter and are interspersed with aluminium strips to help reject some solar flux to protect the spacecraft from temperatures topping 250ºC. It has even been necessary to protect the rear of the solar arrays - which normally remain in shadow - in order to counter heat from solar radiation reflected by the planet's atmosphere. An atmosphere of mystery Following on from the twenty or so American and Soviet missions to the planet carried out since 1962, Venus Express will endeavour to answer many of the questions raised by previous missions but so far left unanswered. It will focus on the characteristics of the atmosphere, its circulation, structure and composition in relation to altitude, and its interactions with the planet's surface and with the solar wind at altitude. To perform these studies, it has seven instruments onboard: three are flight-spare units of instruments already flown on Mars Express, two are from comet-chaser Rosetta and two were designed specifically for this mission. The PFS high-resolution spectrometer will measure atmospheric temperature and composition at varying altitudes. It will also measure surface temperature and search for signs of current volcanic activity. The SPICAV/SOIR infrared & ultraviolet spectrometer and the VeRa instrument will also probe the atmosphere, observing stellar occultation and detecting radio signals; the former will in particular seek to detect molecules of water, oxygen and sulphuric compounds thought to be present in the atmosphere. The Virtis spectrometer will map the various layers of the atmosphere and conduct multi-wavelength cloud observation in order to provide images of atmospheric dynamics. Assisted by a magnetometer, the ASPERA 4 instrument will analyse interaction between the upper atmosphere and the solar wind in the absence of magnetospheric protection such as that surrounding the Earth (for Venus had no magnetic field). It will analyse the plasma generated by such interaction, while the magnetometer will study the magnetic field generated by the plasma. And the VMC camera will monitor the planet in four wavelengths, notably exploiting one of the "infrared windows" revealed in 1990 by the Galileo spacecraft (when flying by Venus en route for Jupiter), making it possible to penetrate cloud cover through to the surface. The camera will also be used to monitor atmospheric dynamics, notably to observe the double atmospheric vortex at the poles, the origin of which still remains a mystery.

  14. Nuclear Electric Propulsion Application: RASC Mission Robotic Exploration of Venus

    NASA Technical Reports Server (NTRS)

    McGuire, Melissa L.; Borowski, Stanley K.; Packard, Thomas W.

    2004-01-01

    The following paper documents the mission and systems analysis portion of a study in which Nuclear Electric Propulsion (NEP) is used as the in-space transportation system to send a series of robotic rovers and atmospheric science airplanes to Venus in the 2020 to 2030 timeframe. As part of the NASA RASC (Revolutionary Aerospace Systems Concepts) program, this mission analysis is meant to identify future technologies and their application to far reaching NASA missions. The NEP systems and mission analysis is based largely on current technology state of the art assumptions. This study looks specifically at the performance of the NEP transfer stage when sending a series of different payload package point design options to Venus orbit.

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  16. Venus Cloud Properties from Venus Express VIRTIS Observations

    NASA Astrophysics Data System (ADS)

    Barstow, Joanna; Taylor, F. W.; Tsang, C. C. C.; Wilson, C. F.; Irwin, P. G. J.; Drossart, P.; Piccioni, G.

    2010-10-01

    Near-infrared spectra from the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) on Venus Express have been used to investigate the vertical structure and global distribution of cloud properties on Venus. The spectral range covered by VIRTIS is sensitive on the nightside to absorption by the lower and middle cloud layers, which are back-lit by radiation from the lower atmosphere and surface. The cloud model used to interpret the spectra is based on previous work by Pollack (1993) and others, and assumes a composition for the cloud particles of sulfuric acid and water, with acid concentration as a free parameter to be determined. Other retrieved parameters are the average size of the particles and the altitude of the cloud base in the model. The sensitivity to these variables across the measured spectral range (1.5 to 2.6 m) is investigated, and radiances at suitable pairs of wavelengths are used in model branch plots to recover each variable independently. Spatial variation of sulfuric acid concentration in the cloud particles has been estimated for the first time. This is then used in the determination of other cloud properties and gaseous abundances. Key findings include increased acid concentration and decreased cloud base altitude in regions of optically thick cloud, a peak in cloud base altitude at -50, and an increased average particle size near the pole. These results are being used to develop better models of the structure and variability of the clouds, which are needed to understand the chemistry, meteorology and radiative energy balance on Venus. This research is supported by the Science and Technology Facilities Council (UK) the Centre Nationale d'Etudes Spatiales (France), the Agenzia Spaziale Italiana and ESA.

  17. Plasma Wave Activity Near Venus as Seen by the Venus Express Spacecraft

    NASA Astrophysics Data System (ADS)

    Guicking, L.; Glassmeier, K.; Auster, H.; Zhang, T.; Delva, M.; Fraenz, M.; Martinecz, C.

    2007-12-01

    We present a wave activity map of the Venusian space environment obtained from data of the Venus Express (VEX) magnetometer (MAG). Venus Express is the first European mission to the planet Venus and was inserted in a polar orbit with a duration of 24 hours in April 2006. Due to its different orbit in comparison to the long lasting mission of the Pioneer Venus Orbiter (PVO), it can complete the lack of measurments and leads to a better understanding of the processes occurring within the Venusian magnetosphere and the interaction between the solar wind and the planet's atmosphere. The magnetometer onboard VEX measures the magnetic field vector continously during one orbit. We used for our calculations the data from April to December 2006 with a resolution of four seconds. We made a Fourier Analysis of this data set and determined a mean value of the power spectral densities in different frequency bands. In doing so, we were mainly interested in ultra low frequency (ULF) waves, whose frequencies are less than the gyro-frequencies of the typical species in that region. The wave activity maps show a region of enhanced activity in the magnetosheath between the subsolar point and the terminator. Ion density measurements of the ASPERA-4 instrument onboard VEX shall help to explain these results by determination of the Alfvn velocity, in particular the Alfvn Mach number. We speculate that regions of high wave activity and regions of sub-Alfvn Mach numbers are in general overlapping, because the waves there can propagate in all directions. We discuss this phenomenon, including possible reasons for the occurrence.

  18. Plasma transition at the flanks of the Venus ionosheath: Evidence from the Venus Express data

    NASA Astrophysics Data System (ADS)

    Prez-de-Tejada, H.; Lundin, R.; Barabash, S.; Sauvaud, J.; Coates, A.; Zhang, T. L.; Winningham, D.; Reyes-Ruiz, M.; Durand-Manterola, H.

    2011-01-01

    Measurements conducted with the Analyzer of Space Plasmas and Energetic Atoms (ASPERA-4) instrument in the Venus Express spacecraft reveal the presence of a plasma transition within a boundary layer that extends along at the flanks of the Venus ionosheath and where the solar wind exhibits changes similar to those reported from previous missions (Mariner 5, Venera, and Pioneer Venus). At the plasma transition there is a sharp downstream decrease in the density of the solar wind electrons and a sudden increase in their temperature embedded within the boundary layer where more gradual changes in the speed, temperature, and density of the solar wind ions are observed. The ASPERA-4 data also show important fluxes of planetary ions measured downstream from the plasma transition and whose dominant velocity component is in the Sun-Venus direction. The speed of those ions is slower than the local solar wind speed and thus is different from that expected from the convective electric field acceleration in which both speed values should be comparable. The boundary layer is interpreted as representing a feature that results from the transport of solar wind momentum to the Venus upper ionosphere, and the ASPERA-4 data provide information on the kinetic properties of the eroded planetary ion population that is seen to stream mostly in the Sun-Venus direction. From the comparison of the ASPERA-4 measurements with those of the magnetic field obtained with the magnetometer of the Venus Express, it is found that in the near wake crossing of the plasma transition the magnetic field intensity decreases to lower values with downstream distance from the planet in agreement with measurements conducted with the Mariner 5 and the PVO. From the analysis of data for orbits with evidence of the plasma transition within the boundary layer, it is found that the momentum flux of planetary ions measured in the wake can be accounted for from the incident momentum flux of the solar wind protons implying an approximate balance as would result from the transport of solar wind momentum to the planetary particles.

  19. Composition and chemistry of the Venusian atmosphere after Venus Express

    NASA Astrophysics Data System (ADS)

    Marcq, Emmanuel

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2009-07-01

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

  1. Venus Terminator Temperature Structure: Venus Express SOIR and VTGCM Comparisons

    NASA Astrophysics Data System (ADS)

    Schulte, R.; Bougher, S. W.; Parkinson, C. D.; Brecht, A. S.; Vandaele, A.; Wilquet, V.; Mahieux, A.

    2013-12-01

    Venus Express SOIR terminator profiles of temperatures are organized and presented for 119 selected orbits obtained between 2006-2011. The SOIR instrument measures CO2 absorption across a broad spectral window. The observed atmospheric transmittance spectra are subsequently inverted to obtain vertical CO2 density (and inferred temperature) profiles at the Venusian terminator over approximately 70 to 160 km. These recently recalibrated measurements continue to show a striking permanent temperature minimum (at 125 km) and a weaker temperature maximum (over 100-115 km). These features are reflected in the corresponding CO2 density profiles, and provide detailed constraints for new empirical models and global circulation models of the Venus upper atmosphere. New Venus Thermospheric General Circulation Model (VTGCM) simulations are conducted for conditions appropriate to these SOIR measurements. In particular, solar minimum or moderate fluxes are specified and mean values of eddy diffusion and wave drag parameters are utilized. Recent upgrades to the VTGCM code now include more realistic lower boundary conditions at 70 km near cloud tops. Model temperature profiles are extracted from the terminators that correspond to five latitude bins (0-30, 30-60, 60-70, 70-80, 80-90 latitude) presently used in the SOIR data analysis. Averaging of VTGCM temperature profiles in each of these bins (at morning and evening terminators) is conducted to match SOIR sampling. Comparisons of these SOIR and VTGCM temperature profiles are made. Most notably, the observed temperature minimum near 125 km and the weaker temperature maximum over 100-115 km are generally reproduced by the VTGCM at the correct pressure/altitude levels. However, magnitudes of simulated and measured temperatures are somewhat different. In addition, VTGCM evening terminator (ET) temperatures are simulated to be modestly warmer than corresponding morning terminator (MT) values, a result of stronger ET than MT zonal winds at/above about 130-140 km. The SOIR terminator temperatures thusfar do not reveal any such trend. However, the SOIR temperatures do show latitudinal variations not reproduced by the VTGCM. The incorporation of upward propagating planetary waves (e.g. Kelvin wave) into the VTGCM may introduce additional temperature variability and important latitude variations that are missing in the model.

  2. Science considerations for an orbital radar mapping mission to Venus

    NASA Technical Reports Server (NTRS)

    Wychgram, D. C.

    1974-01-01

    A radar mapping mission to Venus is under consideration by NASA for the 1980s. The science objectives of the mission are to determine the geologic history of the planet; map the major topographic features and provide limited detailed geologic and terrain analysis of potential probe landing sites. Because of the thick Venusian atmosphere, a synthetic-aperture side-looking radar system has been selected as the most practical remote sensing instruments to use. Topographic data are the most useful for achieving the science goals of the mission. The radar system variables and mission parameters must be specified to maximize topographic data returns while being compatible with engineering and cost restraints. A baseline imaging resolution of 100 meters, with ability to obtain some higher-resolution coverage, is acceptable. Total planet coverage is desirable but the primary science objectives can be achieved if at least one entire hemisphere is imaged.

  3. Image processing and products for the Magellan mission to Venus

    NASA Technical Reports Server (NTRS)

    Clark, Jerry; Alexander, Doug; Andres, Paul; Lewicki, Scott; Mcauley, Myche

    1992-01-01

    The Magellan mission to Venus is providing planetary scientists with massive amounts of new data about the surface geology of Venus. Digital image processing is an integral part of the ground data system that provides data products to the investigators. The mosaicking of synthetic aperture radar (SAR) image data from the spacecraft is being performed at JPL's Multimission Image Processing Laboratory (MIPL). MIPL hosts and supports the Image Data Processing Subsystem (IDPS), which was developed in a VAXcluster environment of hardware and software that includes optical disk jukeboxes and the TAE-VICAR (Transportable Applications Executive-Video Image Communication and Retrieval) system. The IDPS is being used by processing analysts of the Image Data Processing Team to produce the Magellan image data products. Various aspects of the image processing procedure are discussed.

  4. An Atmospheric Variability Model for Venus Aerobraking Missions

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

  5. Venus Interior Structure Mission (VISM): Establishing a Seismic Network on Venus

    NASA Technical Reports Server (NTRS)

    Stofan, E. R.; Saunders, R. S.; Senske, D.; Nock, K.; Tralli, D.; Lundgren, P.; Smrekar, S.; Banerdt, B.; Kaiser, W.; Dudenhoefer, J.

    1993-01-01

    Magellan radar data show the surface of Venus to contain a wide range of geologic features (large volcanoes, extensive rift valleys, etc.). Although networks of interconnecting zones of deformation are identified, a system of spreading ridges and subduction zones like those that dominate the tectonic style of the Earth do not appear to be present. In addition, the absence of a mantle low-viscosity zone suggests a strong link between mantle dynamics and the surface. As a natural follow-on to the Magellan mission, establishing a network of seismometers on Venus will provide detailed quantitative information on the large scale interior structure of the planet. When analyzed in conjunction with image, gravity, and topography information, these data will aid in constraining mechanisms that drive surface deformation.

  6. Venus Express Contributions to the Study of Planetary Lightning

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

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

  7. Tracking Clouds on Venus using Venus Express Data

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  8. International Planetary Science Interoperability: The Venus Express Interface Prototype

    NASA Astrophysics Data System (ADS)

    Sanford Bussard, Stephen; Chanover, N.; Huber, L.; Trejo, I.; Hughes, J. S.; Kelly, S.; Guinness, E.; Heather, D.; Salgado, J.; Osuna, P.

    2009-09-01

    NASA's Planetary Data System (PDS) and ESA's Planetary Science Archive (PSA) have successfully demonstrated interoperability between planetary science data archives with the Venus Express (VEX) Interface prototype. Because VEX is an ESA mission, there is no memorandum of understanding to archive the data in the PDS. However, using a common communications protocol and common data standards, VEX mission science data ingested into the PSA can be accessed from a user interface at the Atmospheres Node of the PDS, making the science data accessible globally through two established planetary science data portals. The PSA makes scientific and engineering data from ESA's planetary missions accessible to the worldwide scientific community. The PSA consists of online services incorporating search, preview, download, notification and delivery basket functionality. Mission data included in the archive aside from VEX include data from the Giotto, Mars Express, Smart-1, Huygens, and Rosetta spacecraft and several ground-based cometary observations. All data are compatible to the Planetary Data System data standard. The PDS archives and distributes scientific data from NASA planetary missions, astronomical observations, and laboratory measurements. The PDS is sponsored by NASA's Science Mission Directorate. Its purpose is to ensure the long-term usability of NASA data and to stimulate advanced research. The architecture of the VEX prototype interface leverages components from both the PSA and PDS information system infrastructures, a user interface developed at the New Mexico State University, and the International Planetary Data Alliance (IPDA) Planetary Data Access Protocol (PDAP). The VEX Interoperability Project was a key project of the IPDA, whose objective is to ensure world-wide access to planetary data regardless of which agency collects and archives the data. A follow-on IPDA project will adapt the VEX Interoperability protocol for access in JAXA to the Venus Climate Orbiter "Planet C data.

  9. The Ninevah Mission: A design summary for an unmanned mission to Venus, volume 1

    NASA Technical Reports Server (NTRS)

    1988-01-01

    The design summary for an unmanned mission to the planet Venus, with code name Ninevah, is presented. The design includes a Hohmann transfer trajectory analysis, propulsion trade study, an overview of the communication and instrumentation systems, power requirements, probe and lander analysis, and a weight and cost analysis.

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

    NASA Technical Reports Server (NTRS)

    Yen, C.-W. L.

    1986-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Yen, Chen-Wan Liu

    1989-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Slavin, J. A.; Acua, 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.; Raines, J. M.; Sarantos, M.; Solomon, S. C.; Zhang, T. L.; Zurbuchen, T. H.

    2007-12-01

    At 23:08 UT on 5 June 2007 the MESSENGER spacecraft reached its closest approach altitude (338 km) during its second flyby of Venus en route to its 2011 orbit insertion at Mercury. Whereas no measurements were collected during MESSENGER's first Venus flyby in October 2006, the Magnetometer (MAG) and the Energetic Particle and Plasma Spectrometer (EPPS) operated successfully throughout this second encounter. Venus provides the solar system's best example 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 planetary 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.

  14. Power Conversion with a Stirling Cycle for Venus Surface Mission

    NASA Technical Reports Server (NTRS)

    Mellott, Ken

    2004-01-01

    The light-filtering characteristic of the dense, mostly-CO2 atmosphere of Venus, combined with the high atmospheric cloud cover, relegates the surface mission use of photovoltaic power systems and beckons for the independence and reliability of a nuclear-powered energy source. A multi-faceted Venus mission study was completed at NASA GRC in December of 2003 that resulted in the preliminary design of a helium- charged, kinematic Stirling converter, which is powered by nuclear, General Purpose Heat Source (GPHS) modules. The kinematic, Stirling power converter is configured to drive an electronics and sensor cooler in addition to a generator for electrical power. This paper briefly describes the design process and also describes and summarizes key features of the Stirling power converter preliminary design concept. With an estimated total efficiency of 23.4%, the power converter drives the electronics and sensor cooler, and also produces 100 watts of electricity. The converter rejects waste heat at a hot sink temperature of 500 C.

  15. The thermosphere of Venus and its exploration by a Venus Express Accelerometer Experiment

    NASA Astrophysics Data System (ADS)

    Mller-Wodarg, I. C. F.; Forbes, J. M.; Keating, G. M.

    2006-11-01

    The forthcoming observations by Venus Express provide an ideal opportunity to comprehensively study the atmosphere of Venus for the first time since Pioneer Venus (1978-1992), and for the first time ever in detail at polar latitudes. This article reviews some of our current knowledge from space and ground-based observations about the upper atmosphere of Venus, such as its thermal structure, the global distribution of gases and dynamics. We discuss the processes most likely responsible for phenomena such as the cold nightside cryosphere, the cloud top superrotation and waves, and highlight outstanding scientific challenges for Venus Express measurements. In particular, we describe an experiment to measure atmospheric drag using the on-board accelerometers.

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

    NASA Technical Reports Server (NTRS)

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

    2009-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    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.

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

    NASA Astrophysics Data System (ADS)

    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

    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.

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

    NASA Astrophysics Data System (ADS)

    Chassefiere, Eric

    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 minutes, followed by 30 minutes of operation on the surface. The key measurement objectives of EVE are: (i) in situ measurement from the balloon of noble gas abundances and stable isotope ratios , to study the record of the evolution of Venus; (ii) in situ balloon-borne measurement of cloud particle and gas composition, and their spatial variation, to understand the complex cloud-level chemistry; (iii) 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.

  20. Exploring Venus with high-altitude balloons: Science objectives and mission architectures

    NASA Astrophysics Data System (ADS)

    Baines, Kevin; Limaye, Sanjay; Zahnle, Kevin; Atreya, Sushil K.

    Following the trailblazing flights of the 1985 twin Soviet VEGA balloons, missions to fly in the high atmosphere of Venus near 55 km altitude have been proposed to both NASA's Discovery Program and ESA's Cosmic Vision. Such missions would address a variety of fundamental science issues highlighted in a variety of high-level NASA-authorized science documents in recent years, including the Decadal Study, various NASA roadmaps, and recommendations coming out of the Venus Exploration Analysis Group (VEXAG). Such missions would in particular address key questions of Venus's origin, evolution, and current state, including detailed measurements of (1) trace gases associated with Venus's active photoand thermo-chemistry and (2) measurements of vertical motions and local temperature which characterize convective and wave processes. As an example of what can be done with a small mission (less than 500M US dollars), the Venus Aerostatic-Lift Observatories for in-situ Research (VALOR) Discovery mission will be discussed. This mission would fly twin balloon-borne aerostats over temperate and polar latitudes, sampling rare gases, chemicals and dynamics in two distinct latitude regions for several days. A variety of scenarios for the origin, formation, and evolution of Venus would be tested by sampling all the noble gases and their isotopes, especially the heaviest elements never reliably measured previously: xenon and krypton. Riding the gravity and planetary waves of Venus, the VALOR balloons would sample the chemistry, meteorology and dynamics of Venus's sulfur-cloud region. Tracked by an array of Earth-based telescopes, zonal, meridional, and vertical winds would be measured with unprecedented precision. Such measurements would help to develop a fundamental understanding of (1) the circulation of Venus, especially its enigmatic super-rotation, (2) the nature of Venus's sulfur cycle, key to Venus's current climate, and (3) how Venus formed and evolved over the aeons.

  1. Aerocapture Performance Analysis of A Venus Exploration Mission

    NASA Technical Reports Server (NTRS)

    Starr, Brett R.; Westhelle, Carlos H.

    2005-01-01

    A performance analysis of a Discovery Class Venus Exploration Mission in which aerocapture is used to capture a spacecraft into a 300km polar orbit for a two year science mission has been conducted to quantify its performance. A preliminary performance assessment determined that a high heritage 70 sphere-cone rigid aeroshell with a 0.25 lift to drag ratio has adequate control authority to provide an entry flight path angle corridor large enough for the mission s aerocapture maneuver. A 114 kilograms per square meter ballistic coefficient reference vehicle was developed from the science requirements and the preliminary assessment s heating indicators and deceleration loads. Performance analyses were conducted for the reference vehicle and for sensitivity studies on vehicle ballistic coefficient and maximum bank rate. The performance analyses used a high fidelity flight simulation within a Monte Carlo executive to define the aerocapture heating environment and deceleration loads and to determine mission success statistics. The simulation utilized the Program to Optimize Simulated Trajectories (POST) that was modified to include Venus specific atmospheric and planet models, aerodynamic characteristics, and interplanetary trajectory models. In addition to Venus specific models, an autonomous guidance system, HYPAS, and a pseudo flight controller were incorporated in the simulation. The Monte Carlo analyses incorporated a reference set of approach trajectory delivery errors, aerodynamic uncertainties, and atmospheric density variations. The reference performance analysis determined the reference vehicle achieves 100% successful capture and has a 99.87% probability of attaining the science orbit with a 90 meters per second delta V budget for post aerocapture orbital adjustments. A ballistic coefficient trade study conducted with reference uncertainties determined that the 0.25 L/D vehicle can achieve 100% successful capture with a ballistic coefficient of 228 kilograms per square meter and that the increased ballistic coefficient increases post aerocapture V budget to 134 meters per second for a 99.87% probability of attaining the science orbit. A trade study on vehicle bank rate determined that the 0.25 L/D vehicle can achieve 100% successful capture when the maximum bank rate is decreased from 30 deg/s to 20 deg/s. The decreased bank rate increases post aerocapture delta V budget to 102 meters per second for a 99.87% probability of attaining the science orbit.

  2. Astrod-I: mission concept and Venus flybys

    NASA Astrophysics Data System (ADS)

    Ni, Wei-Tou; Bao, Yun; Dittus, Hansjrg; Huang, Tianyi; Lmmerzahl, Claus; Li, Guangyu; Luo, Jun; Ma, Zhen-Guo; Mangin, Jean Franois; Nie, Yu-Xin; Peters, Achim; Rdiger, Albrecht; Samain, Etienne; Schiller, Stephan; Shiomi, Sachie; Sumner, Timothy; Tang, Chien-Jen; Tao, Jinhe; Touboul, Pierre; Wang, Haitao; Wicht, Andreas; Wu, Xue-Jun; Xiong, Yaoheng; Xu, Chongming; Yan, Jun; Yao, Da-Zhi; Yeh, Hsien-Chi; Zhang, Shu-Lian; Zhang, Yuan-Zhong; Zhou, Ze-Bing

    2003-11-01

    ASTROD I is the first step of ASTROD (Astrodynamical Space Test of Relativity using Optical Devices). This mission concept has one spacecraft carrying a payload of a telescope, five lasers, and a clock together with ground stations (ODSN: Optical Deep Space Network) to test the optical scheme of interferometric and pulse ranging and yet give important scientific results. These scientific results include a better measurement of the relativistic parameters, a better sensitivity in using optical Doppler tracking method for detecting gravitational waves, and measurement of many solar system parameters more precisely. The weight of this spacecraft is estimated to be about 300-350 kg with a payload of about 100-120 kg. The spacecraft is to be launched with initial period about 290 days and to pass by Venus twice to receive gravity-assistance for achieving shorter periods. For a launch on August 4, 2010, after two encounters with Venus, the orbital period can be shortened to 165 days. After about 370 days from launch, the spacecraft will arrive at the other side of the Sun for the determination of relativistic parameters.

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

    NASA Astrophysics Data System (ADS)

    Hunter, C. J.

    2004-10-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  5. Cloud level winds from the Venus Express Monitoring Camera imaging

    NASA Astrophysics Data System (ADS)

    Khatuntsev, I. V.; Patsaeva, M. V.; Titov, D. V.; Ignatiev, N. I.; Turin, A. V.; Limaye, S. S.; Markiewicz, W. J.; Almeida, M.; Roatsch, Th.; Moissl, R.

    2013-09-01

    Six years of continuous monitoring of Venus by European Space Agencys Venus Express orbiter provides an opportunity to study dynamics of the atmosphere our neighbor planet. Venus Monitoring Camera (VMC) on-board the orbiter has acquired the longest and the most complete so far set of ultra violet images of Venus. These images enable a study the cloud level circulation by tracking motion of the cloud features. The highly elliptical polar orbit of Venus Express provides optimal conditions for observations of the Southern hemisphere at varying spatial resolution. Out of the 2300 orbits of Venus Express over which the images used in the study cover about 10 Venus years. Out of these, we tracked cloud features in images obtained in 127 orbits by a manual cloud tracking technique and by a digital correlation method in 576 orbits. Total number of wind vectors derived in this work is 45,600 for the manual tracking and 391,600 for the digital method. This allowed us to determine the mean circulation, its long-term and diurnal trends, orbit-to-orbit variations and periodicities. We also present the first results of tracking features in the VMC near-IR images. In low latitudes the mean zonal wind at cloud tops (67 2 km following: Rossow, W.B., Del Genio, A.T., Eichler, T. [1990]. J. Atmos. Sci. 47, 2053-2084) is about 90 m/s with a maximum of about 100 m/s at 40-50S. Poleward of 50S the average zonal wind speed decreases with latitude. The corresponding atmospheric rotation period at cloud tops has a maximum of about 5 days at equator, decreases to approximately 3 days in middle latitudes and stays almost constant poleward from 50S. The mean poleward meridional wind slowly increases from zero value at the equator to about 10 m/s at 50S and then decreases to zero at the pole. The error of an individual measurement is 7.5-30 m/s. Wind speeds of 70-80 m/s were derived from near-IR images at low latitudes. The VMC observations indicate a long term trend for the zonal wind speed at low latitudes to increase from 85 m/s in the beginning of the mission to 110 m/s by the middle of 2012. VMC UV observations also showed significant short term variations of the mean flow. The velocity difference between consecutive orbits in the region of mid-latitude jet could reach 30 m/s that likely indicates vacillation of the mean flow between jet-like regime and quasi-solid body rotation at mid-latitudes. Fourier analysis revealed periodicities in the zonal circulation at low latitudes. Within the equatorial region, up to 35S, the zonal wind show an oscillation with a period of 4.1-5 days (4.83 days on average) that is close to the super-rotation period at the equator. The wave amplitude is 4-17 m/s and decreases with latitude, a feature of the Kelvin wave. The VMC observations showed a clear diurnal signature. A minimum in the zonal speed was found close to the noon (11-14 h) and maxima in the morning (8-9 h) and in the evening (16-17 h). The meridional component peaks in the early afternoon (13-15 h) at around 50S latitude. The minimum of the meridional component is located at low latitudes in the morning (8-11 h). The horizontal divergence of the mean cloud motions associated with the diurnal pattern suggests upwelling motions in the morning at low latitudes and downwelling flow in the afternoon in the cold collar region.

  6. A Statistical Study of Lightning Occurrence Rates from Venus Express Observations

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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, 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. When Venus Express was inserted into its 24-hour elliptical polar orbit, periapsis was near 80 degrees and later precessed up to 88 degrees. Now in the orbit, Venus Express has precessed over the pole and has reached lower latitudes than on arrival. The spacecraft is in the final stages of its 8 year mission and reaching the lowest latitudes yet. In this study we present statistics of lightning-associated ELF signals from recent observations spanning more than 3 Venus years.

  7. Mariner Venus-Mercury 1973 project. Volume 2: Extended mission-Mercury 2 and 3 encounters

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The Mariner Venus/Mercury 1973 mission operations Extended Mission is described. The activities are summarized from shortly after Mercury I through the end of mission. The operational activities are reported by Mission Operations Systems functions providing a brief summary from each discipline. Based on these experiences recommendations for future projects are made.

  8. Interplanetary mission design handbook. Volume 1, part 1: Earth to Venus ballistic mission opportunities, 1991-2005

    NASA Technical Reports Server (NTRS)

    Sergeyevsky, A. B.; Yin, N. H.

    1983-01-01

    Graphical data necessary for the preliminary design of ballistic missions to Venus is presented. Contours of launch energy requirements, as well as many other launch and arrival parameters, are presented in launch data/arrival date space for all launch opportunities from 1991 through 2005. An extensive text is included which explains mission design methods, from launch window development to Venus probe and orbiter arrival design, utilizing the graphical data in this volume as well as numerous equations relating various parameters.

  9. Ionospheric Modulation of Venus Express Lightning Detection Rates

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  10. First Results from Venus Express Aerobraking Campaign

    NASA Astrophysics Data System (ADS)

    Svedhem, Hkan

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

  11. The Scientific Exploration of Venus

    NASA Astrophysics Data System (ADS)

    Taylor, Fredric W.

    2014-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    This work aims to give a summary of the water vapor at the cloud top of Venus atmosphere using the complete set of observations made using high spectral resolution channel (-H) of Visible and Infrared Thermal Imaging Spectrometer (VIRTIS), on board the ESA Venus Express orbiter, to measure the cloud top altitude and the water vapor abundance near this level. An initial analysis of these measurements by Cottini et al. (2012) was limited to data in 140 orbits in the period 2007-2008. These observations were limited to the Northern hemisphere due to observational geometry in this early part of the mission. In the present paper, the analysis is extended to a larger dataset covering the years 2006-2011, significantly improving the latitudinal coverage. Altitude of the cloud tops, corresponding to unit optical depth at a wavelength of 2.5 ?m, is equal to 691 km at low latitudes, and decreases toward the pole to 62-64 km. The water vapor abundance is equal to 31 ppm in low latitudes and it increases reaching a maximum of 52 ppm at 70-80 of latitude in both hemispheres, with a sharp drop in the polar regions. This can be explained by the specific dynamics of the atmosphere of Venus affecting the distribution of water vapor such as the transfer of water vapor in the Hadley cell and the dynamic in the polar vortex. The average height of the cloud tops and the H2O near this level are symmetric with respect to the equator. As a function of local solar time, the water vapor shows no particular dependence, and the cloud tops exhibit just a weak maximum around noon. Over 5 years of observations the average values of the cloud top altitude and the water vapor were quite stable in low and middle latitudes, while in high latitudes both quantities in 2009-2011 years are systematically higher than in 2006-2008. Short period variations increasing with latitude are observed, from approximately less than 1 km for cloud tops and 1 ppm for water vapor in low latitudes to, respectively, 2 km and 2 ppm in high latitudes. As a rule there is no correlation between variations of the cloud top altitude, the water vapor content, and the UV brightness. However, numerous examples can be found when UV dark features, with a characteristic size of a few degrees of latitude (several hundred kilometers), coincide with regions of higher cloud tops.

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

  14. Mariner Venus-Mercury 1973 mission solar proton environment: fluence and dose

    NASA Technical Reports Server (NTRS)

    Thomas, J. R.

    1972-01-01

    A derivation is presented for proton fluence over the duration of the Mariner Venus-Mercury 1973 (MVM73) mission in terms of a relatively constant, low energy component, the solar wind, and a probabilistic high energy component from discrete solar events. An updated correlation of yearly energetic proton fluence with yearly average sunspot number is presented. This correlation and sunspot cycle forecasts for the period of the MVM73 mission (late 1973 through early 1975) form the basis for the high energy proton fluence estimates with various confidence levels. Uncertainties in the probability estimates and in calculation of the scaling with distance from the Sun are discussed. Selection of a particular 95-percentile model as the design constraint is recommended, and reasons are presented for not using the worst-case model. Interior fluences were calculated and expressed in terms useful for spacecraft design.

  15. Dynamics of Venus' Southern hemisphere and South Polar Vortex from VIRTIS data obtained during the Venus Expres Mission

    NASA Astrophysics Data System (ADS)

    Hueso, R.; Garate-Lopez, I.; Sanchez-Lavega, A.

    2011-12-01

    The VIRTIS instrument onboard Venus Express observes Venus in two channels (visible and infrared) obtaining spectra and multi-wavelength images of the planet. The images have been used to trace the motions of the atmosphere at different layers of clouds [1-3]. We review the VIRTIS cloud image data and wind results obtained by different groups [1-3] and we present new results concerning the morphology and evolution of the South Polar Vortex at the upper and lower cloud levels with data covering the first 900 days of the mission. We present wind measurements of the South hemisphere obtained by cloud tracking individual cloud features and higher-resolution wind results of the polar region covering the evolution of the South polar vortex. The later were obtained by an image correlation algorithm run under human supervision to validate the data. We present day-side data of the upper clouds obtained at 380 and 980 nm sensitive to altitudes of 66-70 km, night-side data in the near infrared at 1.74 microns of the lower cloud (45-50 km) and day and night-side data obtained in the thermal infrared (wavelengths of 3.8 and 5.1 microns) which covers the dynamical evolution of Venus South Polar vortex at the cloud tops (66-70 km). We explore the different dynamics associated to the varying morphology of the vortex, its dynamical structure at different altitudes, the variability of the global wind data of the southern hemisphere and the interrelation of the polar vortex dynamics with the wind dynamics at subpolar and mid-latitudes. Acknowledgements: Work funded by Spanish MICIIN AYA2009-10701 with FEDER support and Grupos Gobierno Vasco IT-464-07. References [1] A. Snchez-Lavega et al., Geophys. Res. Lett. 35, L13204, (2008). [2] D. Luz et al., Science, 332, 577-580 (2011). [3] R. Hueso, et al., Icarus doi:10.1016/j.icarus.2011.04.020 (2011)

  16. A study of an orbital radar mapping mission to Venus. Volume 1: Summary

    NASA Technical Reports Server (NTRS)

    1973-01-01

    A preliminary design of a Venus radar mapping orbiter mission and spacecraft was developed. The important technological problems were identified and evaluated. The study was primarily concerned with trading off alternate ways of implementing the mission and examining the most attractive concepts in order to assess technology requirements. Compatible groupings of mission and spacecraft parameters were analyzed by examining the interaction of their functioning elements and assessing their overall cost effectiveness in performing the mission.

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  18. Ballistic mode Mercury orbiter mission opportunity handbook extension. [interplanetary trajectories for Venus swingbys to Mercury

    NASA Technical Reports Server (NTRS)

    Hollenbeck, G. R.; Lewis, P. S.; Rockenbach, P. C.

    1974-01-01

    Interplanetary trajectory characteristics are presented, for Venus swingbys to Mercury, where multiple revolutions about the Sun are permitted. Additional consideration is given to the use of multiple Venus swingbys and/or to midcourse, near perilhelion, propulsive maneuvers to improve the performance of the mission as measured in terms of payload in Mercury orbit. Missions in 1980, 1983, 1985 and 1988 were analyzed with navigation results also developed. An exploratory investigation established the availability of low energy mission opportunities in 1991, 1994, 1996 and 1999.

  19. PC-403: Pioneer Venus multiprobe spacecraft mission operational characteristics document, volume 2

    NASA Technical Reports Server (NTRS)

    Barker, F. C.

    1978-01-01

    The data handling subsystem, command subsystem, communications subsystem, power subsystem, and mission operations of the Pioneer Venus multiprobe are presented. The multiprobe spacecraft performance in normal operating modes that correspond to the performance of specific functions at the time of specific events in the mission is described.

  20. The thermal balance of Venus in light of the Pioneer Venus mission

    NASA Technical Reports Server (NTRS)

    Tomasko, M. G.; Smith, P. H.; Suomi, V. E.; Sromovsky, L. A.; Revercomb, H. E.; Taylor, F. W.; Martonchik, D. J.; Seiff, A.; Boese, R.; Pollack, J. B.

    1980-01-01

    Pioneer Venus orbiter and probes measured many of the properties of the Venus atmosphere which control its thermal balance and support its high surface temperature. Estimates based on orbiter data yield an effective radiating temperature of Venus of 228 + or - 5 K, corresponding to a solar emission of 153 + or - 13 W/sq cm. A mode of submicron particles is suggested as an important source of thermal opacity near the cloud tops to explain the orbiter and probe thermal flux measurements. A comparison of the measured solar flux profile with thermal fluxes computed from the measured temperature structure and composition shows that the greenhouse mechanism explains essentially all of the 500-K difference between the surface and radiating temperatures of Venus.

  1. VIRTIS on Venus Express: retrieval of real surface emissivity on global scales

    NASA Astrophysics Data System (ADS)

    Arnold, Gabriele E.; Kappel, David; Haus, Rainer; Telléz Pedroza, Laura; Piccioni, Giuseppe; Drossart, Pierre

    2015-09-01

    The extraction of surface emissivity data provides the data base for surface composition analyses and enables to evaluate Venus' geology. The Visible and InfraRed Thermal Imaging Spectrometer (VIRTIS) aboard ESA's Venus Express mission measured, inter alia, the nightside thermal emission of Venus in the near infrared atmospheric windows between 1.0 and 1.2 μm. These data can be used to determine information about surface properties on global scales. This requires a sophisticated approach to understand and consider the effects and interferences of different atmospheric and surface parameters influencing the retrieved values. In the present work, results of a new technique for retrieval of the 1.0 - 1.2 μm - surface emissivity are summarized. It includes a Multi-Window Retrieval Technique, a Multi-Spectrum Retrieval technique (MSR), and a detailed reliability analysis. The MWT bases on a detailed radiative transfer model making simultaneous use of information from different atmospheric windows of an individual spectrum. MSR regularizes the retrieval by incorporating available a priori mean values, standard deviations as well as spatial-temporal correlations of parameters to be retrieved. The capability of this method is shown for a selected surface target area. Implications for geologic investigations are discussed. Based on these results, the work draws conclusions for future Venus surface composition analyses on global scales using spectral remote sensing techniques. In that context, requirements for observational scenarios and instrumental performances are investigated, and recommendations are derived to optimize spectral measurements for Venus' surface studies.

  2. Venus

    NASA Astrophysics Data System (ADS)

    Fegley, B., Jr.

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

  3. Venus

    ERIC Educational Resources Information Center

    Martin, Paula; Stofan, Ellen

    2004-01-01

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

  4. Venus

    ERIC Educational Resources Information Center

    Martin, Paula; Stofan, Ellen

    2004-01-01

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

  5. An orbital radar mapper of venus in the 1980's: Mission design and analysis

    NASA Technical Reports Server (NTRS)

    Asnin, S. K.

    1973-01-01

    The examination of Venus topography, obscured for photographic imaging, is reported in the application of airborne radar mapping systems to an orbiter mission about the planet. Extrapolating the improving capabilities of earth-based radar study of Venus into the 1980's is reported which suggests that only a non-uniform, poorly resolved surface profile will be possible relative to the potential for 100% coverage at 100 meter resolution with an orbital radar. The intent of this paper is: to define mission opportunities favorable for a Venus orbital mapper during the 1980's, to examine orbit design problems associated with mapping radar systems, to establish with flexibility exists for an adaptive mapping strategy, to contribute to the sizing of particular spacecraft systems, and to suggest a reference mission design and demonstrate feasibility.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  7. Pioneer Venus: Report of a study by the Science Steering Group, June 1972. [concerning 1976, 77, 78 and 80 missions

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The 1976/77 multiple probe mission of the Pioneer Venus spacecraft is discussed, along with the 1978 and 1980 missions. Various questions about Venus are answered; velocities and temperatures expected in the atmosphere, atmospheric chemistry, magnetic measurements, and model atmospheres are included.

  8. O+ pickup ions outside of Venus' bow shock: Venus Express observations

    NASA Astrophysics Data System (ADS)

    Wei, Yong; Fraenz, Markus; Dubinin, Eduard; Zhang, Tielong; Jarvinen, Riku; Wan, Weixing; Kallio, Esa; Collinson, Glyn; Barabash, Stars; Norbert, Krupp; Woch, Joachim; Lundin, Rickard; delva, Magda

    2013-04-01

    Pickup ions are ions of planetary origin that become assimilated into the solar wind flow through their interaction with the solar wind magnetic and electric field. The speed of pickup ions varies between zero and twice the underlying plasma flow component perpendicular to magnetic field vector. For the unmagnetized planet Venus and Mars, oxygen (O+) pickup ions are known to be important because they can modify the global configuration of planetary plasma environment and significantly contribute to the atmospheric O+ loss [1]. Since the kinetic energy of an O+ pickup ion can reach 64 times that of a co-moving proton, an instrument must be able to measure O+ ions with energy of at least tens of keV to investigate the O+ pickup ion distribution from planetary ionosphere to solar wind. The in-situ observations and simulations at Mars have shown that the energy of O+ pickup ions can be 55-72 keV outside of the bow shock [2]. For Venus case, the plasma analyzer (OPA) onboard Pioneer Venus Orbiter (PVO), which was designed for solar wind monitoring, has an 8 keV energy limit for O+ detection and the limited sampling and data rate [3]. Therefore, OPA can only measure the O+ pickup ions in the sheath flow or inside the induced magnetosphere where the speed of ambient plasma flow is significantly lower than that of the unshocked solar wind outside of the bow shock. In addition, Galileo also did not capture O+ outside bowshock during its 1-hour Venus flyby though its plasma instrument had ability to cover the energy band of O+ pickup ions [4]. The Ion Mass Analyzer (IMA), included in the Analyzer of Space Plasma and Energetic Atoms (ASPERA-4) package on board Venus Express (VEX), determines the composition, energy, and angular distribution of ions in the energy range ~10 eV/q to 30 keV/q. Note that an O+ ion moving at the typical solar wind speed 400 km/s has kinetic energy 13.4 keV. Therefore, IMA has ability to measure the O+ pickup ions outside of Venus' bow shock. We have examined the IMA data during the solar minimum period 2006-2010, and identified 80 cases with clear signature of O+ pickup ion. With these observations, we can determine the location and the scale height of the source region of O+ pickup ions and describe the relationship between the behavior of these O+ and the upstream solar wind condition. The results would provide new information for numerical simulation of plasma environment near Venus and contribute to estimation of total O+ ion loss from Venus. Reference: [1] Dubinin, E., M. Fränz, J. Woch, E. Roussos, S. Barabash, R. Lundin, J. D. Winningham, R. A. Frahm, and M. Acuña (2006a), Plasma morphology at Mars: Aspera-3 observations, Space Sci. Rev., 126, 209-238, doi:10.1007/s11214-006-9039-4. [2] Cravens, T. E., A. Hoppe, S. A. Ledvina, and S. McKenna-Lawlor (2002), Pickup ions near Mars associated with escaping oxygen atoms, J. Geophys. Res., 107, 1170, doi:10.1029/2001JA000125. [3] Luhmann, J. G., S. A. Ledvina, J. G. Lyon, and C. T. Russell (2006), Venus O+ pickup ions: Collected PVO results and expectations for Venus Express, Planet. Space Sci., 54, 1457-1471, doi:10.1016/j.pss.2005.10.009. [4] Williams, D. J. et al.(1991), Energetic Particles at Venus: Galileo Results. Science 253, 1525-1528.

  9. Navigation Support at JPL for the JAXA Akatsuki (PLANET-C) Venus Orbiter Mission

    NASA Technical Reports Server (NTRS)

    Ryne, Mark S.; Mottinger, Neil A.; Broschart, Stephen B.; You, Tung-Han; Higa, Earl; Helfrich, Cliff; Berry, David

    2011-01-01

    This paper details the orbit determination activities undertaken at JPL in support of the Japanese Aerospace Exploration Agency's (JAXA) Akatsuki (a.k.a. Plan-et-C and/or Venus Climate Orbiter) mission. The JPL navigation team's role was to provide independent navigation support as a point of comparison with the JAXA generated orbit determination solutions. Topics covered include a mis-sion and spacecraft overview, dynamic forces modeling, cruise and approach or-bit determination results, and the international teaming arrangement. Significant discussion is dedicated to the events surrounding recovery from the unsuccessful Venus orbit insertion maneuver.

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

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

    NASA Technical Reports Server (NTRS)

    Bender, D. F.

    1976-01-01

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

  12. Venus Express observations of magnetic field fluctuations in the magnetosheath

    NASA Astrophysics Data System (ADS)

    Du, J.; Wang, C.; Zhang, T. L.; Volwerk, M.; Delva, M.; Baumjohann, W.

    2008-12-01

    Magnetic field fluctuations within a planetary magnetosheath play an important role in the solar wind interaction with the planet, since they can reconfigure the plasma flow and the magnetic field and transfer energy from the bow shock to the lower boundary. Many studies have been presented on the fluctuations in the terrestrial magnetosheath; however, hardly any studies have so far been carried out for Venusian magnetosheath fluctuations, except for Luhmann et al. [1983] and Vörös et al. [2008] who performed some case studies on the magnetosheath fluctuations at Venus. It was shown that the fluctuations are probably convected from the vicinity of the quasi-parallel bow shock along the streamlines. Based on the Venus Express observations in 2006 and 2007, we investigate the spatial distributions of magnetic field fluctuations in the Venus magnetosheath statistically.

  13. O+ pickup ions outside of Venus' bow shock: Venus Express observation

    NASA Astrophysics Data System (ADS)

    Wei, Y.; Fraenz, M.; Dubinin, E.; Zhang, T. L.; Wan, W.; Barabash, S.; Woch, J.; Lundin, R.

    2012-09-01

    Pickup ions are ions of planetary origin that become assimilated into the solar wind flow through their interaction with the solar wind magnetic and electric field. The speed of pickup ions varies between zero and twice the underlying plasma flow component perpendicular to magnetic field vector. For the unmagnetized planet Venus and Mars, oxygen (O+) pickup ions are known to be important because they can modify the global configuration of planetary plasma environment and significantly contribute to the atmospheric O+ loss [1]. Since the kinetic energy of an O+ pickup ion can reach 64 times that of a co-moving proton, an instrument must be able to measure O+ ions with energy of at least tens of keV to investigate the O+ pickup ion distribution from planetary ionosphere to solar wind. The in-situ observations and simulations at Mars have shown that the energy of O+ pickup ions can be 55-72 keV outside of the bow shock [2]. For Venus case, the plasma analyzer (OPA) onboard Pioneer Venus Orbiter (PVO), which was designed for solar wind monitoring, has an 8 keV energy limit for O+ detection and the limited sampling and data rate [3]. Therefore, OPA can only measure the O+ pickup ions in the sheath flow or inside the induced magnetosphere where the speed of ambient plasma flow is significantly lower than that of the unshocked solar wind outside of the bow shock. The Ion Mass Analyzer (IMA), included in the Analyzer of Space Plasma and Energetic Atoms (ASPERA-4) package on board Venus Express (VEX), determines the composition, energy, and angular distribution of ions in the energy range ~10 eV/q to 30 keV/q. Note that an O+ ion moving at the typical solar wind speed 400 km/s has kinetic energy 13.4 keV. Therefore, IMA has ability to measure the O+ pickup ions outside of Venus' bow shock. We have examined the IMA data during the solar minimum period 2006-2010, and identified about ten cases with clear signature of O+ pickup ion. With these observations, we will determine the location and the scale height of the source region of O+ pickup ions and describe the relationship between the behavior of these O+ and the upstream solar wind condition. The results would provide new information for numerical simulation of plasma environment near Venus and contribute to estimation of total O+ ion loss from Venus.

  14. Investigating Climate on Venus with Future Missions (Invited)

    NASA Astrophysics Data System (ADS)

    Grinspoon, D. H.

    2013-12-01

    Venus presents unique opportunities to study climate on a nearby, active planet that is both surprisingly like Earth and startlingly different. Venus is remarkably like Earth in terms of bulk properties such as size, mass and density. And yet its modern climate has evolved to a state which is dramatically divergent from that of Earth. Thus Venus presents a fascinating experimental laboratory for studying and modeling climate processes on an Earth-sized world with a strong atmospheric greenhouse and for exploring the role of heliocentric distance and other initial conditions in determining the outcome of climate evolution on an Earth-like planet. Previous spacecraft investigations of Venus, combined with ground based observations, have confirmed the existence of a dynamic, changeable atmosphere with a deep troposphere extending to an altitude of 65 km, a highly variable globally encompassing cloud deck extending from 48 to 70 km altitude, and a complex pattern of global circulation dominated by superrotating winds which circle the globe at a rate up to 60 times faster than the retrograde rotation of the solid planet, with the peak wind velocities at an altitude of 60 km. Other large scale features of the global circulation include Hadley cells in which air rises at low latitudes and travels poleward at high altitudes; and large, complex vortices at both poles where sinking air from the Hadley circulation intersects with the superrotation. Attempts to model this global circulation using modified terrestrial General Circulation Models (GCMs) have been only partially successful. Such tests have the promise of not only increasing our understanding of the Venus atmosphere and its response to solar radiation, but improving our general knowledge of climate and global circulation on Earth-sized terrestrial planets, including Earth itself. They also serve as a 'reality check' on the current generation of terrestrial GCMs and their ability to accurately model climate and circulation on radically altered versions of Earth's climate. In the framework of comparative planetology, climate models and GCMs in particular have taken on a vital role in understanding and predicting the role of anthropogenic forcing in Earth's climate, and separating human from natural influences. The potential role of new spacecraft observations of Venus in improving our ability to accurately model climate on moderately to severely perturbed variations of Earth's current climate is thus extremely valuable. Several efforts to model climate on Venus using terrestrial GCMs have reproduced the gross properties of the Venusian global circulation. These efforts have also revealed that various components of terrestrial GCMs are 'hard coded' with empirically-derived assumptions that are at best only accurate for the current terrestrial climate. Many of these assumptions are hidden within complex 'black boxes' of code that are not always obvious to the modelers using the code. Thus pushing the codes near to, or beyond, the breaking point by applying them toward the problem of Venus helps to improve the veracity and reliability of these models for terrestrial applications. At this point our ability to greatly improve upon these efforts is hampered by the amount and quality of available data on the Venus atmosphere. In order to understand which model, and which assumptions are correct, improved spacecraft observations from several platforms are required.

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

  16. A Wind-powered Rover for a Low-Cost Venus Mission

    NASA Technical Reports Server (NTRS)

    Benigno, Gina; Hoza, Kathleen; Motiwala, Samira; Landis, Geoffrey A.; Colozza, Anthony J.

    2013-01-01

    Venus, with a surface temperature of 450 C and an atmospheric pressure 90 times higher than that of the Earth, is a difficult target for exploration. However, high-temperature electronics and power systems now being developed make it possible that future missions may be able to operate in the Venus environment. Powering such a rover within the scope of a Discovery class mission will be difficult, but harnessing Venus' surface winds provides a possible way to keep a powered rover small and light. This project scopes out the feasibility of a wind-powered rover for Venus surface missions. Two rover concepts, a land-sailing rover and a wind-turbine-powered rover, were considered. The turbine-powered rover design is selected as being a low-risk and low-cost strategy. Turbine detailed analysis and design shows that the turbine can meet mission requirements across the desired range of wind speeds by utilizing three constant voltage generators at fixed gear ratios.

  17. Spectral inventory of the SOIR spectra onboard Venus Express

    NASA Astrophysics Data System (ADS)

    Robert, Sverine; Mahieux, Arnaud; Wilquet, Valrie; Drummond, Rachel; Carine Vandaele, Ann

    2013-04-01

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

  18. Magellan - Early results from the Venus mapping mission

    NASA Technical Reports Server (NTRS)

    Saunders, R. S.

    1991-01-01

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

  19. Preliminary radar systems analysis for Venus orbiter missions

    NASA Technical Reports Server (NTRS)

    Brandenburg, R. K.; Spadoni, D. J.

    1971-01-01

    A short, preliminary analysis is presented of the problems involved in mapping the surface of Venus with radar from an orbiting spacecraft. Two types of radar, the noncoherent sidelooking and the focused synthetic aperture systems, are sized to fulfill two assumed levels of Venus exploration. The two exploration levels, regional and local, assumed for this study are based on previous Astro Sciences work (Klopp 1969). The regional level is defined as 1 to 3 kilometer spatial and 0.5 to 1 km vertical resolution of 100 percent 0 of the planet's surface. The local level is defined as 100 to 200 meter spatial and 50-10 m vertical resolution of about 100 percent of the surfAce (based on the regional survey). A 10cm operating frequency was chosen for both radar systems in order to minimize the antenna size and maximize the apparent radar cross section of the surface.

  20. The Rationale for a New High-resolution Imaging Radar Mission to Venus

    NASA Astrophysics Data System (ADS)

    Herrick, R. R.; Sharpton, V. L.; Gens, R.; Ghent, R. R.; Gilmore, M. S.; Grimm, R. E.; Johnson, C. L.; McGovern, P. J.; Meyer, F.; Mouginis-Mark, P. J.; Plaut, J. J.; Sandwell, D. T.; Simons, M.; Solomon, S. C.

    2009-12-01

    Magellan, NASAs last geoscience mission to Venus, provided synthetic aperture radar (SAR) images at ~100-m resolution, topography at ~10-km resolution, and the gravity field at ~300-km resolution. Although that mission provided a major advance in our understanding of the planet, basic questions about the geologic history of Venus remain unresolved. For example, hypotheses on the planets surface evolution range from uniformitarian to catastrophic, and assessments of current geologic activity range from earth-comparable levels of volcanic and tectonic activity to a surface shaped only by occasional impact and eolian processes. It is now feasible to send a mission to Venus that could provide SAR imaging at 1-5-m resolution; topography with tens-of-meters spatial resolution by utilizing interferometric SAR (InSAR) and stereo radargrammetry; and surface deformation at centimeter-scale vertical resolution through InSAR. Such a mission would substantially further our understanding of Venus by means of: (1) assessing the fundamental framework of the planet's geologic history (e.g., catastrophic change, slow evolution, uniformitarian) by imaging key stratigraphic contacts; (2) expanding the global framework of geomorphic unit types and relative stratigraphy with reconnaissance surveys of large geographic provinces; (3) directly detecting volcanic and tectonic activity through imaging of flows and fault-related activities (e.g., landslides) that occur between imaging passes; (4) monitoring present-day volcanic and tectonic activity with repeat-pass InSAR deformation studies; (5) constraining the nature of Venusian geologic volcanic and tectonic processes, and their relationship to mantle convective processes; (6) understanding the role of eolian processes in modifying the surface and the use of eolian features as stratigraphic markers (e.g., parabolic features) through detailed examination; (7) constraining Venusian impact processes, particularly the role of the atmosphere in the ejecta emplacement process; (8) constraining the processes responsible for the abrupt decrease in emissivity at high altitudes; (9) selecting landing sites for future missions; and (10) identifying past landers/probes to place them in geologic context. Our state of knowledge about Venus is currently analogous to our knowledge of Mars in the post-Viking era, and a high-resolution imaging radar mission to Venus could revolutionize our understanding of Venus in the way that the Mars Global Surveyor mission did for Mars.

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

    NASA Astrophysics Data System (ADS)

    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

    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.

  2. In-Situ Exploration of Venus: Major Science Objectives, Investigations, and Mission Platform Options

    NASA Astrophysics Data System (ADS)

    Baines, K. H.; Limaye, S. S.; Hall, J. L.; Atreya, S. K.; Bullock, M. A.; Crisp, D.; Grinspoon, D. H.; Mahaffy, P. R.; Russell, C. T.; Webster, C. R.; Zahnle, K. J.

    2013-12-01

    In-situ missions to Venus have been recommended by both the 2011 and 2003 Decadal Studies of the NRC and have been proposed numerous times to NASA's Discovery and New Frontiers programs as well as to ESA's Cosmic Vision program. Such missions would revolutionize our understanding of Venus, as they address key questions of Venus's origin, evolution, and current state via high precision measurements of (1) noble gases and their isotopes, and (2) reactive trace gases and aerosol associated with Venus's active photo- and thermo-chemistry and sulfur cycle, including components potentially responsible for the poorly-understood uv-absorbing haze layer. Fundamental questions, as promoted in recent VEXAG documents, include: (1) Did Venus, Mars, and Earth have a common origin? (2) What roles did comets from the outer Solar System play in delivering volatiles to Venus? (3) Did Venus once have and lose a global ocean? (4) How much has Venus outgassed, and what is the current rate of outgassing, particularly of sulfur, the major driver of Venus clouds? and (5) Through the deposition of energy within them, what role do these clouds play in (a) driving the cloud-level thermal structure and (b) generating and maintaining the super-rotating zonal windfield that covers the globe? Fundamental answers could be uniquely provided through in-situ sampling via mass spectrometry of the noble gases and their isotopes - in particular of the 8 stable Xe isotopes, the bulk abundances of Kr, and the 3 isotopes of Ne. Measurements of the relative abundances of the light isotopes of N, O, H, S and O, by, for example, tunable laser spectrometry, would provide additional insights into Venus's origin, surface outgassing and planetary escape. Such measurements could be performed by probes, landers, or balloons. On descent through the uv-absorbing layer and the surrounding H2SO4 cloud, each of these platforms could explore both the absorber and sulfur-cycle-associated reactive species and aerosols, thus addressing VEXAG desires for enhanced understanding of Venus' chemical cycles, aerosol properties, and radiative transfer. On descent to the surface, probes and landers can provide vertical profiles of temperatures and species abundances, as well as provide near-surface measurements of sulfur isotopes and trace sulfuric gases indicative of outgassing. Additional major in-situ goals dealing with Venus's global circulation and local dynamics can be addressed by a balloon platform floating within the convective middle cloud near ~55-km altitude. Drifting over a wide range of latitudes and all times-of-day and longitudes, such a floating platform could accurately measure (1) motions in all three dimensions - zonal, meridional, and vertical, including motions associated with convection and gravity waves, (2) simultaneous measurements of cloud particle size, their parent molecules, the local temperature, and vertical velocity, to study cloud formation/dissipation processes, and (3) the power and frequency of local lightning. Altogether, such in-situ measurements would potentially revolutionize our understanding of (1) Venus's circulation, including the role of waves and solar cloud heating in powering the planet's poorly-understood super-rotation, (2) Venus's sulfur cycle, key to Venus's current climate, and (3) how Earth's neighbor formed and evolved over the aeons.

  3. Venus

    NASA Astrophysics Data System (ADS)

    Fegley, B., Jr.

    2003-12-01

    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).

  4. The Surface of Venus and Implications for its Geological and Geodynamical Evolution: The View Before Venus Express and Outstanding Questions for the Future

    NASA Astrophysics Data System (ADS)

    Head, J. W.; Ivanov, M. A.; Basilevsky, A. T.

    2008-12-01

    Prior to the Venera 15/16 and the Magellan missions to Venus, a wide range of ideas existed concerning the nature of the surface of Venus, the geological processes currently operating there, their link to interior processes, the implied geological and geodynamical history of the planet, and how all this compared with the nature and history of other terrestrial planetary bodies. The history of exploration of the surface of Venus represents the acquisition of data with increasing spatial and areal coverage, culminating in the near-global high-resolution image, altimetry, physical property and gravity data obtained by the Magellan mission. Among the most fundamental findings of the global Magellan image data are: 1) that volcanism and tectonism represent the most abundant geological processes operating on the observed surface, 2) that the styles and abundance of volcanism and tectonism combine attributes of both the Earth (e.g., very heavily tectonically deformed regions such as tessera) and the smaller terrestrial planetary bodies (e.g., vast volcanic plains deformed by wrinkle ridges), 3) that the distribution and nature of impact craters precludes active plate tectonics despite many Earth-like tectonic features (e.g., folded mountain belts), 4) that some features (e.g., coronae) are somewhat unique to Venus and may provide important information on mantle convection and lithospheric evolution processes, 5) that the number of impact craters is very small, indicating that the surface geological record is very young, less than 20% of the history of the planet itself, 6) that 80% of the geological record of Venus is no longer obviously preserved in the surface morphology, but may be preserved in the surface rocks, 7) that the distribution and state of preservation of existing impact craters may be consistent with a range of catastrophic resurfacing models, and 8) that the geological record and sequence of events can be correlated with geophysical data to assess crustal thickness variations and mantle convection patterns. The relationships of major elements of global topography and the sequence of events in the observed geological history (as recorded by major geologic units and structures) suggest that much of the current long-wavelength topography of Venus (tessera highlands and lowlands with regional plains) may have formed prior to emplacement of regional plains and been preserved since that time. These observations may favor evolutionary geodynamic models that are characterized by changes in geological style and rates, and may involve non-linear heat loss mechanisms that could have profound influence on the atmosphere. Although the observed surface of Venus dates from relatively recent planetary history, comparative planetology permits inferences to be made about the major stages in the earlier history of Venus. The evolution of the understanding of the surface from early speculations to present observations and interpretations provides an important context for: 1) establishing the relationships of the surface of Venus to the nature of the atmosphere and its evolution as assessed by Venus Express, 2) the comparison of the geological features and history of Venus relative to the Moon, Mars, Mercury and the Earth, and 3) defining the major outstanding problems and questions to be addressed by future experiments and missions to Venus.

  5. High temperature, high intensity solar array. [for Venus Radar Mapper mission

    NASA Technical Reports Server (NTRS)

    Smith, B. S.; Brooks, G. R.; Pinkerton, R.

    1985-01-01

    The solar array for the Venus Radar Mapper mission will operate in the high temperature, high intensity conditions of a low Venus orbit environment. To fulfill the performance requirements in this environment at minimum cost and mass while maximizing power density and packing factor on the panel surface, several features were introduced into the design. These features included the use of optical surface reflectors (OSR's) to reduce the operating temperature; new adhesives for conductive bonding of OSR's to avoid electrostatic discharges; custom-designed large area cells and novel shunt diode circuit and panel power harness configurations.

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  9. The Water Vapor Abundance Near the Surface of Venus from Venus Express / VIRTIS Observations

    NASA Astrophysics Data System (ADS)

    Bezard, Bruno; Tsang, C. C. C.; Carlson, R. W.; Piccioni, G.; Marcq, E.; Drossart, P.; VIRTIS/Venus Express Team

    2008-09-01

    We present an analysis of Venus Express/VIRTIS observations of the 1.18-?m window on Venus' night side. We used the infrared M-channel of the VIRTIS instrument, an imaging spectrometer for the range 1-5 ?m with a resolution of about 17 nm. The 1.18-?m window probes down to the surface and allows us to map and monitor the water abundance in the lowest scale height of the atmosphere. Besides CO2 and H2O molecular bands, an additional "continuum" source of absorption exists in the window, likely due to CO2 collision-induced bands and extreme far wings of strong CO2 bands. From the variation of the emission with surface elevation, we determined this absorption to be 1.1 0.2 10-9 cm-1 amagat-2. From the best fit of the 1.18-micron window in various areas of Venus' southern hemisphere, we derived a H2O mole fraction of 32 7 ppm in the altitude range 0-15 km. This result agrees with previous ground-based and Galileo/NIMS determinations (Taylor et al. 1997, in Venus II, pp. 325-351) but has significantly lower error bars. The derived mole fraction is similar to that inferred at higher altitudes from the 2.3- and 1.74-?m windows, suggesting a constant-with-height water profile from the surface up to 40 km. We also searched for spatial variations of the H2O near-surface abundance using various VIRTIS-M observational sequences and did not detect any latitudinal variations to within 1.5% (i.e. 0.5 ppm) in the range 60S - 20N.

  10. Magnetic states of the ionosphere of Venus observed by Venus Express

    NASA Astrophysics Data System (ADS)

    Angsmann, A.; Frnz, M.; Dubinin, E.; Woch, J.; Barabash, S.; Zhang, T. L.; Motschmann, U.

    2011-03-01

    Strong ultraviolet radiation from the Sun ionizes the upper atmosphere of Venus, creating a dense ionosphere on the dayside of the planet. In contrast to Earth, the ionosphere of Venus is not protected against the solar wind by a magnetic field. However, the interaction between charged ionospheric particles and the solar wind dynamic and magnetic pressure creates a pseudo-magnetosphere which deflects the solar wind flow around the planet ( Schunk and Nagy, 1980). The combination of changing solar radiation and solar wind intensities leads to a highly variable structure and plasma composition of the ionosphere. The instrumentation of the Venus Express spacecraft allows to measure the magnetic field (MAG experiment) as well as the electron energy spectrum and the ion composition (ASPERA-4 experiment) of the upper ionosphere and ionopause. In contrast to the earlier Pioneer Venus Orbiter (PVO) measurements which were conducted during solar maximum, the solar activity was very low in the period 2006-2009. A comparison with PVO allows for an investigation of ionospheric properties under different solar wind and EUV radiation conditions. Observations of MAG and ASPERA have been analyzed to determine the positions of the photoelectron boundary (PEB) and the "magnetopause" and their dependence on the solar zenith angle (SZA). The PEB was determined using the ELS observations of ionospheric photoelectrons, which can be identified by their specific energy range. It is of particular interest to explore the different magnetic states of the ionosphere, since these influence the local plasma conductivity, currents and probably the escape of electrons and ions. The penetration of magnetic fields into the ionosphere depends on the external conditions as well as on the ionospheric properties. By analyzing a large number of orbits, using a combination of two different methods, we define criteria to distinguish between the so-called magnetized and unmagnetized ionospheric states. Furthermore, we confirm that the average magnetic field inside the ionosphere shows a linear dependence on the magnetic field in the region directly above the PEB.

  11. Mars Express and Venus Express Data Retention In-Flight Performance

    NASA Astrophysics Data System (ADS)

    Lebrdonchel, J.; Rombeck, F.-J.

    2007-08-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

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

    PubMed

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

    2005-12-01

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

  14. Preliminary study of laser-induced breakdown spectroscopy (LIBS) for a Venus mission

    SciTech Connect

    Arp, Z. A.; Cremers, D. A.; Wiens, R. C.

    2004-01-01

    Laser-Induced Breakdown Spectroscopy (LIBS) has been proposed as a candidate analysis system for missions to Mars, asteroids, and recently Venus. This technique has several distinct advantages over other techniques which have been used on past missions (X-Ray fluorescence on Viking 1 and 2, 1976; APXS on Pathfiider, 1997; MER, 2004). Two of the more important advantages LIBS has over other techniques for a mission to Venus is rapid elemental analysis of both high and low Z value elements and stand-off analysis at distances of many meters. Rapid elemental analysis and stand-off analysis are very important to missions to Venus due to the harsh environment at the planet surface. From the Venera missions it is known that on the Venusian surface the pressures are approximately 9.1 MPa (90 atm) and the temperature is near 735 K. For these reasons, the Soviet Venera surface probes had operational lifetimes of less than 2 hours. Currently Venus is the target of one of four missions specifically mentioned for consideration for NASA's New Frontier Program with a launch date of 2010 or earlier. In light of this, it is beneficial to evaluate different analysis methods such as LIBS, which offer to greatly increase the scientific return from such a mission. Currently we have begun to evaluate LIBS detection in an environment with pressures and compositions which are similar to those found on Venus. Although the temperature of Venus ({approx} 735 K) has not been taken into account in these experiments, due to the high temperature of the plasma ({approx}8000 K) signifcant perturbations of excitation characteristics sufficient to affect LIBS analytical capability would not be expected. Previous work, however, has shown that the pressure of the surrounding atmosphere can have a strong effect on the detection of elements in soil. These studies have mainly concentrated on pressures at or below earth ambient pressure, but one study has shown successful results at elevated pressures (3.0 MPa). Here we show results from a LIBS study at 9.1 MPa (90 atm) which demonstrates the feasibility of using this technique for elemental analysis at high pressure.

  15. Venus' interior structure and dynamics

    NASA Astrophysics Data System (ADS)

    Sotin, C.; Davaille, A.; Lenardic, A.; Smrekar, S. E.

    2014-04-01

    The information that the mission Venus Express has collected for a better understanding of Venus' interior structure and dynamics is limited. However, during the lifetime of this mission, models of the interior dynamics of a terrestrial-type planet have progressed. This paper reviews the models that have been developed in order to understand why the two sister planets Earth and Venus are so dramatically different. The relationship between mantle convection and plate tectonics deserves particular attention. This question is triggered by the discovery of terrestrial exoplanets that raises the issue of whether they are Earth-like or Venus-like.

  16. Venus Exploration Analysis Group (VEXAG)

    NASA Astrophysics Data System (ADS)

    Limaye, Sanjay; Smrekar, Sue

    2010-05-01

    The Venus Exploration Analysis Group (VEXAG) was established by NASA in July 2005 to identify scientific priorities and strategy for exploration of Venus. This community-based forum is designed to provide scientific input and technology development plans for planning and prioritizing the exploration of Venus over the next several decades. VEXAG is currently composed of two co- chairs and several groups. The focus groups actively solicit input from the scientific community and meet during VEXAG meetings, held at least once a year. VEXAG reports its findings and provides input to NASA, but does not make recommendations. VEXAG holds meetings open to the global scientific community with interest in understanding Venus and receives input from the scientists and engineers around the world on the current open issues regarding understanding Venus as a planet. VEXAG regularly evaluates Venus exploration goals, scientific objectives, investigations and critical measurement requirements, including especially recommendations in the National Academy of Sciences Decadal Survey and the Solar System Exploration Strategic Roadmap. VEXAG is coordinating the preparation of several White papers on different topics, including science, technology, and the recent flagship study, relevant to Venus exploration for the current Decadal Survey can be found on the VEXAG website (http://www.lpi.usra.edu/vexag). VEXAG provides a forum for learning about international efforts in exploring Venus and facilitates collaboration in combined observation programs from space and earth based observatories. At present, Venus Express mission launched by European Space Agency in November 2005 is the only active mission collecting data from orbit around Venus since April 2006. It will soon be joined in December 2010 by Japan's Venus Climate Orbiter which is under development for a launch in May 2010. Other missions to Venus are being considered by NASA (Venus Flagship mission), Russia (Venera D) and in the European community (European Venus Explorer). In addition, it is anticipated that several mission concepts will be proposed to NASA's Discovery (Announcement of Opportunity anticipated winter 2010). The three New Frontiers proposals selected by NASA in December 2009 include a proposal for a mission to Venus - Surface and Atmosphere and Geochemical Explorer. The Venus community recognizes that science return can be maximized by coordinating observations as much as feasible. VEXAG is one forum where the discussions can take place and the community is invited to actively participate in the VEXAG meetings and activities. The next VEXAG meeting and a workshop on the Venus atmosphere and its interaction with the surface will be held in Madison, Wisconsin, during 30 August - 2 September 2010. VEXAG's past activities, current efforts and future plans will be presented. The scientific community interested in Venus is invited to participate in VEXAG and support the exploration of Venus by the interested space agencies.

  17. Cyclostrophic winds in Venus mesosphere from VIRTIS/Venus Express temperature retrievals

    NASA Astrophysics Data System (ADS)

    Piccialli, A.; Titov, D. V.; Migliorini, A.; Grassi, D.; Khatuntsev, I.; Drossart, P.; Piccioni, G.

    2008-09-01

    Venus mesosphere (60 - 100 km altitude) is a transition region between two dynamical regimes: a retrograde super-rotation dominates in the troposphere and mesosphere with wind speed of up to 120 m/s near the cloud top (~70 km), while solar-antisolar circulation dominates in the thermosphere. Earlier studies [1], [2], [3] have proved that the strong zonal winds near the cloud top are well described by the thermal wind equation, which directly relates the zonal winds to the mesospheric temperature field. The thermal wind equation is obtained assuming the cyclostrophic approximation, which consists in the balance between the equatorward component of the centrifugal force and the poleward component of the pressure gradient force. VIRTIS (Visible and Infrared Thermal Imaging Spectrometer) on board Venus Express is investigating the thermal structure of Venus mesosphere for more than 2 years with a very good spatial and temporal coverage of Venus' south hemisphere. Here we present the retrievals of cyclostrophic winds from VIRTIS - M temperature profiles. Our retrieved zonal winds show three important features: a midlatitude jet connected to the cold collar located at the cloud top around 50° latitude with a speed of 90 ± 10 m/s; a fast decrease of wind speed from 50° latitude towards the pole; and a gradual decrease of wind speed with height above the cloud tops [4]. Preliminary analysis shows only weak dependence of zonal winds on local time. Comparison of the thermal wind with cloud tracked winds measured by VMC (Venus Monitoring Camera) show general good agreement at middle and high latitudes and disagreement at low latitudes [5]. References [1] Newman, M. et al. (1984) J. of Atm. Sciences, 41, 1901-1913. [2] Roos-Serote, M. et al. (1994) Icarus, 114(2), 300- 309. [3] Zasova, L. V. and I. V. Khatuntsev (1997) Adv. Space Res., 19(8), 1181-1190. [4] Piccialli, A. et al. (2008) J. Geophys. Res., (submitted). [5] Moissl, R. R. et al. (2008) J. Geophys. Res., (submitted).

  18. Integration of Radioisotope Heat Source with Stirling Engine and Cooler for Venus Internal-Structure Mission

    SciTech Connect

    Schock, Alfred

    1993-10-01

    The primary mission goal is to perform long-term seismic measurements on Venus, to study its largely unknown internal structure. The principal problem is that most payload components cannot long survive Venus's harsh environment, 90 bars at 500 degrees C. To meet the mission life goal, such components must be protected by a refrigerated payload bay. JPL Investigators have proposed a mission concept employing a lander with a spherical payload bay cooled to 25 degrees C by a Stirling cooler powered by a radioisotope-heated Sitrling engine. To support JPL's mission study, NASA/Lewis and MTI have proposed a conceptual design for a hydraulically coupled Stirling engine and cooler, and Fairchild Space - with support of the Department of Energy - has proposed a design and integration scheme for a suitable radioisotope heat source. The key integration problem is to devise a simple, light-weight, and reliable scheme for forcing the radioisotope decay heat to flow through the Stirling engine during operation on Venus, but to reject that heat to the external environment when the Stirling engine and cooler are not operating (e.g., during the cruise phase, when the landers are surrounded by heat shields needed for protection during subsequent entry into the Venusian atmosphere.) A design and integration scheme for achieving these goals, together with results of detailed thermal analyses, are described in this paper. There are 7 copies in the file.

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

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

  20. A study of an orbital radar mapping mission to Venus. Volume 2: Configuration comparisons and systems evaluation

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Configuration comparisons and systems evaluation for the orbital radar mapping mission of the planet Venus are discussed. Designs are recommended which best satisfy the science objectives of the Venus radar mapping concept. Attention is given to the interaction and integration of those specific mission-systems recommendations with one another, and the final proposed designs are presented. The feasibility, cost, and scheduling of these configurations are evaluated against assumptions of reasonable state-of-the-art growth and space funding expectations.

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

    NASA Astrophysics Data System (ADS)

    Barstow, J. K.; Tsang, C. C. C.; Wilson, C. F.; Irwin, P. G. J.; Taylor, F. W.; McGouldrick, K.; Drossart, P.; Piccioni, G.; Tellmann, S.

    2012-02-01

    Spatially-resolved near-infrared spectra from the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) on Venus Express have been used to derive improved models of the vertical structure and global distribution of cloud properties in the southern hemisphere of Venus. VIRTIS achieved the first systematic, global mapping of Venus at wavelengths within transparency windows in the 1.6-2.6 μm range, which are sensitive on the nightside to absorption by the lower and middle cloud layers of thermally-emitted radiation from the hot lower atmosphere ( Taylor, F.W., Crisp, D., Bézard, B. [1997]. Venus II: Geology, Geophysics, Atmosphere, and Solar Wind Environment, pp. 325-351). The cloud model used to interpret the spectra is based on previous work by Pollack et al. (Pollack, J., Dalton, J., Grinspoon, D., Wattson, R., Freedman, R., Crisp, D., Allen, D., Bézard, B., de Bergh, C., Giver, L. [1993]. Icarus 103, 1-42), Grinspoon et al. (Grinspoon, D.H., Pollack, J.B., Sitton, B.R., Carlson, R.W., Kamp, L.W., Baines, K.H., Encrenaz, T., Taylor, F.W. [1993]. Planet. Space Sci. 41, 515-542) and Crisp (Crisp, D. [1986]. Icarus 67, 484-514), and assumes a composition for the cloud particles of sulfuric acid and water, with acid concentration as a free parameter to be determined. Other retrieved parameters are the average size of the particles and the altitude of the cloud base in the model. Latitudinal variation in the atmospheric temperature structure was incorporated using data from the Venus Radio Science experiment (VeRa). Values are estimated initially using wavelength pairs selected for their unique sensitivity to each parameter, and then validated by comparing measured to calculated spectra over the entire wavelength range, the latter generated using the NEMESIS radiative transfer and retrieval code (Irwin, P.G.J., Teanby, N.A., de Kok, R., Fletcher, L.N., Howett, C.J.A., Tsang, C.C.C., Wilson, C.F., Calcutt, S.B., Nixon, C.A., Parrish, P.D. [2008]. J. Quant. Spectrosc. Radiat. Trans. 109, 1136-1150). The sulfuric acid concentration in the cloud particles is found to be higher in regions of optically thick cloud. The cloud base altitude shows a dependence on latitude, reaching a maximum height near -50°. The increased average particle size near the pole found by Wilson et al. (Wilson, C.F., Guerlet, S., Irwin, P.G.J., Tsang, C.C.C., Taylor, F.W., Carlson, R.W., Drossart, P., Piccioni, G. [2008]. J. Geophys. Res. (Planets) 113, E12) and the finding of spatially variable water vapor abundance at35-40 km altitude first reported by Tsang et al. (Tsang, C.C.C., Wilson, C.F., Barstow, J.K., Irwin, P.G.J., Taylor, F.W., McGouldrick, K., Piccioni, G., Drossart, P., Svedhem, H. [2010]. Geophys. Res. Lett. 37, L02202) are both confirmed. The implications of these improved descriptions of cloud structure and variability for the chemistry, meteorology, and radiative energy balance on Venus are briefly discussed.

  2. Analysis of Venus Express optical extinction due to aerosols in the upper haze of Venus

    NASA Astrophysics Data System (ADS)

    Parkinson, Christopher; Bougher, Stephen; Mahieux, Arnaud; Tellmann, Silvia; Ptzold, Martin; Vandaele, Ann C.; Wilquet, Valrie; Schulte, Rick; Yung, Yuk; Gao, Peter; Bardeen, Charles

    Observations by the SPICAV/SOIR instruments aboard Venus Express (VEx) have revealed that the Upper Haze of Venus is populated by two particle modes, as reported by Wilquet et al. (J. Geophys. Res., 114, E00B42, 2009; Icarus 217, 2012). Gao et al. (In press, Icarus, 2013) posit that the large mode is made up of cloud particles that have diffused upwards from the cloud deck below, while the smaller mode is generated by the in situ nucleation of meteoric dust. They tested this hypothesis by using version 3.0 of the Community Aerosol and Radiation Model for Atmospheres, first developed by Turco et al. (J. Atmos. Sci., 36, 699-717, 1979) and upgraded to version 3.0 by Bardeen et al. (The CARMA 3.0 microphysics package in CESM, Whole Atmosphere Working Group Meeting, 2011). Using the meteoric dust production profile of Kalashnikova et al. (Geophys. Res. Lett., 27, 3293-3296, 2000), the sulfur/sulfate condensation nuclei production profile of Imamura and Hashimoto (J. Atmos. Sci., 58, 3597-3612, 2001), and sulfuric acid vapor production profile of Zhang et al. (Icarus, 217, 714-739, 2012), they numerically simulate a column of the Venus atmosphere from 40 to 100 km above the surface. Their aerosol number density results agree well with Pioneer Venus Orbiter (PVO) data from Knollenberg and Hunten (J. Geophys. Res., 85, 8039-8058, 1980), while their gas distribution results match that of Kolodner and Steffes below 55 km (Icarus, 132, 151-169, 1998). The resulting size distribution of cloud particles shows two distinct modes, qualitatively matching the observations of PVO. They also observe a third mode in their results with a size of a few microns at 48 km altitude, which appears to support the existence of the controversial third mode in the PVO data. This mode disappears if coagulation is not included in the simulation. The Upper Haze size distribution shows two lognormal-like distributions overlapping each other, possibly indicating the presence of the two distinct modes. In this work, we significantly extend the analysis to include new SOIR (PSS, 2014 Submitted) and VeRa VEx temperature profiles (which are quite different from the PVO profiles) and discuss our new results in context of the recent VEx observations (Wilquet et al., Icarus 217, 2012) with an inter comparison with the PVO data. We will also discuss similarities and differences arising from the PVO and VEx epochs where they exist.

  3. Mariner-Venus-Mercury optical navigation demonstration - Results and implications for future missions

    NASA Technical Reports Server (NTRS)

    Acton, C. H., Jr.; Ohtakay, H.

    1975-01-01

    Optical navigation uses spacecraft television pictures of a target body against a known star background in a process which relates the spacecraft trajectory to the target body. This technology was used in the Mariner-Venus-Mercury mission, with the optical data processed in near-real-time, simulating a mission critical environment. Optical data error sources were identified, and a star location error analysis was carried out. Several methods for selecting limb crossing coordinates were used, and a limb smear compensation was introduced. Omission of planetary aberration corrections was the source of large optical residuals.

  4. Using SFOC to fly the Magellan Venus mapping mission

    NASA Technical Reports Server (NTRS)

    Bucher, Allen W.; Leonard, Robert E., Jr.; Short, Owen G.

    1993-01-01

    Traditionally, spacecraft flight operations at the Jet Propulsion Laboratory (JPL) have been performed by teams of spacecraft experts utilizing ground software designed specifically for the current mission. The Jet Propulsion Laboratory set out to reduce the cost of spacecraft mission operations by designing ground data processing software that could be used by multiple spacecraft missions, either sequentially or concurrently. The Space Flight Operations Center (SFOC) System was developed to provide the ground data system capabilities needed to monitor several spacecraft simultaneously and provide enough flexibility to meet the specific needs of individual projects. The Magellan Spacecraft Team utilizes the SFOC hardware and software designed for engineering telemetry analysis, both real-time and non-real-time. The flexibility of the SFOC System has allowed the spacecraft team to integrate their own tools with SFOC tools to perform the tasks required to operate a spacecraft mission. This paper describes how the Magellan Spacecraft Team is utilizing the SFOC System in conjunction with their own software tools to perform the required tasks of spacecraft event monitoring as well as engineering data analysis and trending.

  5. Interplanetary Coronal Mass Ejections Observed by MESSENGER and Venus Express

    NASA Astrophysics Data System (ADS)

    Good, S. W.; Forsyth, R. J.

    2016-01-01

    Interplanetary coronal mass ejections (ICMEs) observed by the MESSENGER and Venus Express spacecraft have been catalogued and analysed. The ICMEs were identified by a relatively smooth rotation of the magnetic field direction consistent with a flux rope structure, coinciding with a relatively enhanced magnetic field strength. A total of 35 ICMEs were found in the surveyed MESSENGER data (primarily from March 2007 to April 2012), and 84 ICMEs in the surveyed Venus Express data (from May 2006 to December 2013). The ICME flux rope configurations have been determined. Ropes with northward leading edges were about four times more common than ropes with southward leading edges, in agreement with a previously established solar cycle dependence. Ropes with low inclinations to the solar equatorial plane were about four times more common than ropes with high inclinations, possibly an observational effect. Left- and right-handed ropes were observed in almost equal numbers. In addition, data from MESSENGER, Venus Express, STEREO-A, STEREO-B and ACE were examined for multipoint signatures of the catalogued ICMEs. For spacecraft separations below 15° in heliocentric longitude, the second spacecraft observed the ICME flux rope in 82 % of cases; this percentage dropped to 49 % for separations between 15 and 30°, to 18 % for separations between 30 and 45°, and to 12 % for separations between 45 and 60°. As the spacecraft separation increased, it became increasingly likely that only the sheath and not the flux rope of the ICME was observed, in agreement with the notion that ICME flux ropes are smaller in longitudinal extent than the shocks or discontinuities that they often drive. Furthermore, this study has identified 23 ICMEs observed by pairs of spacecraft close to radial alignment. A detailed analysis of these events could lead to a better understanding of how ICMEs evolve during propagation.

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

    NASA Astrophysics Data System (ADS)

    Good, S. W.; Forsyth, R. J.

    2015-12-01

    Interplanetary coronal mass ejections (ICMEs) observed by the MESSENGER and Venus Express spacecraft have been catalogued and analysed. The ICMEs were identified by a relatively smooth rotation of the magnetic field direction consistent with a flux rope structure, coinciding with a relatively enhanced magnetic field strength. A total of 35 ICMEs were found in the surveyed MESSENGER data (primarily from March 2007 to April 2012), and 84 ICMEs in the surveyed Venus Express data (from May 2006 to December 2013). The ICME flux rope configurations have been determined. Ropes with northward leading edges were about four times more common than ropes with southward leading edges, in agreement with a previously established solar cycle dependence. Ropes with low inclinations to the solar equatorial plane were about four times more common than ropes with high inclinations, possibly an observational effect. Left- and right-handed ropes were observed in almost equal numbers. In addition, data from MESSENGER, Venus Express, STEREO-A, STEREO-B and ACE were examined for multipoint signatures of the catalogued ICMEs. For spacecraft separations below 15 in heliocentric longitude, the second spacecraft observed the ICME flux rope in 82 % of cases; this percentage dropped to 49 % for separations between 15 and 30, to 18 % for separations between 30 and 45, and to 12 % for separations between 45 and 60. As the spacecraft separation increased, it became increasingly likely that only the sheath and not the flux rope of the ICME was observed, in agreement with the notion that ICME flux ropes are smaller in longitudinal extent than the shocks or discontinuities that they often drive. Furthermore, this study has identified 23 ICMEs observed by pairs of spacecraft close to radial alignment. A detailed analysis of these events could lead to a better understanding of how ICMEs evolve during propagation.

  7. Long-term orbit prediction for the Venus Radar Mapper Mission using an averaging method

    NASA Technical Reports Server (NTRS)

    Kwok, J. H.

    1984-01-01

    A set of singly averaged equations of motion are presented and applied to long-term orbit prediction of an orbiting spacecraft around a slowly rotating planet, using the Venus Radar Mapper Mission as an example. The equations of motion used are valid for all eccentricities less than one. The disturbing potentials used include nonsphericity of the Venus gravity field and third-body effects due to the sun. Recursive relationships are used in the expansion and evaluation of these potentials and their respective partial derivatives. Special care is taken to optimize computational efficiency. The averaging method is compared with high precision Cowell's method using a desktop microcomputer and shows computational saving of about two orders of magnitude.

  8. Reassessing the possibility of life on venus: proposal for an astrobiology mission.

    PubMed

    Schulze-Makuch, Dirk; Irwin, Louis N

    2002-01-01

    With their similar size, chemical composition, and distance from the Sun, Venus and Earth may have shared a similar early history. Though surface conditions on Venus are now too extreme for life as we know it, it likely had abundant water and favorable conditions for life when the Sun was fainter early in the Solar System. Given the persistence of life under stabilizing selection in static environments, it is possible that life could exist in restricted environmental niches, where it may have retreated after conditions on the surface became untenable. High-pressure subsurface habitats with water in the supercritical liquid state could be a potential refugium, as could be the zone of dense cloud cover where thermoacidophilic life might have retreated. Technology based on the Stardust Mission to collect comet particles could readily be adapted for a pass through the appropriate cloud layer for sample collection and return to Earth. PMID:12469368

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

    NASA Astrophysics Data System (ADS)

    2006-04-01

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

  10. Analysis of Trajectory Parameters for Probe and Round-Trip Missions to Venus

    NASA Technical Reports Server (NTRS)

    Dugan, James F., Jr.; Simsic, Carl R.

    1960-01-01

    For one-way transfers between Earth and Venus, charts are obtained that show velocity, time, and angle parameters as functions of the eccentricity and semilatus rectum of the Sun-focused vehicle conic. From these curves, others are obtained that are useful in planning one-way and round-trip missions to Venus. The analysis is characterized by circular coplanar planetary orbits, successive two-body approximations, impulsive velocity changes, and circular parking orbits at 1.1 planet radii. For round trips the mission time considered ranges from 65 to 788 days, while wait time spent in the parking orbit at Venus ranges from 0 to 467 days. Individual velocity increments, one-way travel times, and departure dates are presented for round trips requiring the minimum total velocity increment. For both single-pass and orbiting Venusian probes, the time span available for launch becomes appreciable with only a small increase in velocity-increment capability above the minimum requirement. Velocity-increment increases are much more effective in reducing travel time for single-pass probes than they are for orbiting probes. Round trips composed of a direct route along an ellipse tangent to Earth's orbit and an aphelion route result in the minimum total velocity increment for wait times less than 100 days and mission times ranging from 145 to 612 days. Minimum-total-velocity-increment trips may be taken along perihelion-perihelion routes for wait times ranging from 300 to 467 days. These wait times occur during missions lasting from 640 to 759 days.

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

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

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

  12. PC-402 Pioneer Venus orbiter spacecraft mission operational characteristics document

    NASA Technical Reports Server (NTRS)

    Barker, F. C.; Butterworth, L. W.; Daniel, R. E.; Drean, R. J.; Filetti, K. A.; Fisher, J. N.; Nowak, L. A.; Porzucki, J.; Salvatore, J. O.; Tadler, G. A.

    1978-01-01

    The operational characteristics of the Orbiter spacecraft and its subsystems are described. In extensive detail. Description of the nominal phases, system interfaces, and the capabilities and limitations of system level performance are included along with functional and operational descriptions at the subsystem and unit level the subtleties of nominal operation as well as detailed capabilities and limitations beyond nominal performance are discussed. A command and telemetry logic flow diagram for each subsystem is included. Each diagram encountered along each command signal path into, and each telemetry signal path out of the subsystem. Normal operating modes that correspond to the performance of specific functions at the time of specific events in the mission are also discussed. Principal backup means of performing the normal Orbiter operating modes are included.

  13. Nuclear Polar VALOR: An ASRG-Enabled Venus Balloon Mission Concept

    NASA Astrophysics Data System (ADS)

    Balint, T. S.; Baines, K. H.

    2008-12-01

    In situ exploration of Venus is expected to answer high priority science questions about the planet's origin, evolution, chemistry, and dynamics as identified in the NRC Decadal Survey and in the VEXAG White Paper. Furthermore, exploration of the polar regions of Venus is key to understanding its climate and global circulation, as well as providing insight into the circulation, chemistry, and climatological processes on Earth. In this paper we discuss our proposed Nuclear Polar VALOR mission, which would target one of the polar regions of Venus, while building on design heritage from the Discovery class VALOR concept, proposed in 2004 and 2006. Riding the strong zonal winds at 55 km altitude and drifting poleward from mid-latitude this balloon-borne aerial science station (aerostat) would circumnavigate the planet multiple times over its one- month operation, extensively investigating polar dynamics, meteorology, and chemistry. Rising and descending over 1 km altitude in planetary waves - similar to the two VEGA balloons in 1985 - onboard instrumentation would accurately and constantly sample and measure other meteorological and chemical parameters, such as atmospheric temperature and pressure, cloud particle sizes and their local column abundances, the vertical wind component, and the chemical composition of cloud-forming trace gases. As well, when viewed with terrestrial radio telescopes on the Earth-facing side of Venus, both zonal and meridional winds would be measured to high accuracy (better than 10 cm/sec averaged over an hour). Due to three factors: the lack of sunlight near the poles; severe limitations on the floating mass-fraction available for a power source; and the science requirements for intensive and continuous measurements of the balloon's environment and movement, a long-duration polar balloon mission would require a long-lived internal power source in a relatively lightweight package. For our concept we assumed an Advanced Stirling Radioisotope Generator (ASRG). In return, this mission would provide two orders of magnitude more science data than expected from the original battery-powered VALOR concept, and could reduce measurement uncertainties by a factor of five. In addition to the science return, the secondary objective of this proposed mission would be to space qualify ASRGs through all mission phases and in various operating environments. Lifetime testing would be demonstrated using a second ASRG on the carrier that would keep operating after the in-situ element is delivered. Based on the results of this and another eight ongoing NASA funded studies, NASA will make a decision about the inclusion of ASRGs in the next Discovery AO, due in the summer of 2009.

  14. Thermal zonal winds in the Venus mesosphere from the Venus Express temperature soundings

    NASA Astrophysics Data System (ADS)

    Piccialli, Arianna; Titov, Dmitri; Tellmann, Silvia; Migliorini, Alessandra; Read, Peter; Grassi, Davide; Paetzold, Martin; Haeusler, Bernd; Piccioni, Giuseppe; Drossart, Pierre

    The Venus mesosphere (60-100 km altitude) is a transition region characterized by extremely complex dynamics: strong retrograde zonal winds dominate in the troposphere and lower meso-sphere while a solar-antisolar circulation can be observed in the upper mesosphere. The super-rotation extends from the surface up to the cloud top (65 km altitude) with wind speeds of only a few meters per second near the surface and reaching a maximum value of 100 m s-1 at cloud top, corresponding to a rotation period of 4 Earth days (60 times faster than Venus itself). The solar-antisolar circulation is driven by the day-night contrast in solar heating, and occurs above 110 km altitude with speeds of 120 m s-1 . The processes responsible for maintain-ing the zonal super-rotation in the lower atmosphere and its transition to the solar-antisolar circulation in the upper atmosphere are still poorly understood (Schubert et al.,2007). Different techniques have been used to obtain direct observations of wind at various altitudes: tracking of clouds in ultraviolet (UV) and near infrared (NIR) images give information on wind speeds at the cloud top (Moissl et al., 2009; Sanchez-Lavega et al., 2008) and within the clouds (47 km, 61 km) (Sanchez-Lavega et al., 2008) while ground-based measurements of Doppler shifts in the CO2 band at 10 m (Sornig et al., 2008) and in several CO millimiter lines (Rengel et al., 2008) provide wind speeds above the clouds up to 110 km altitude. The deep atmosphere from the surface up to the cloud top has been investigated through the Doppler tracking of descent probes and balloons (Counselman et al., 1980; Kerzhanovich and Limaye, 1985). In the mesosphere, between 45-85 km of altitude, where direct observations of wind are not possible, the zonal wind field can be derived from the vertical temperature structure using a special approximation of the thermal wind equation: based on cyclostrophic balance. Previous studies (Leovy, 1973; Newman et al., 1984) showed that on a slowly rotating planet, like Venus, strong zonal winds at the cloud top can be described by a cyclostrophic balance in which the equatorward component of centrifugal force is balanced by the meridional pressure gradient. This equation gives a possibility to reconstruct the zonal wind if the temperature field is known, together with a suitable boundary condition on u. Two experiments onboard Venus Express are sounding the temperature structure of the Venus mesosphere: VIRTIS sounds the Venus Southern hemisphere in the altitude range 65-90 km with a very good spatial and temporal coverage (Grassi et al., 2008) and the Northern hemi-sphere but with more limited coverage; VeRa observes both northern and southern hemispheres between 40-90 km altitude with a vertical resolution of 500 m (Tellmann et al., 2008). Here we present zonal thermal winds derived applying cyclostrophic balance from VIRTIS and VeRa temperature retrievals. The main features of the retrieved winds are: (1) a midlatitude jet with a maximum speed up to 140 15 m s-1 which occurs around 50 S latitude at 70 km altitude; (2) the fast decrease of the wind speed from 60 S toward the pole; (3) the decrease of the wind speed with increasing height above the jet (Piccialli et al., 2008). Cyclostrophic winds show satisfactory agreement with the cloud-tracked winds derived from the Venus Monitoring Camera (VMC/VEx) UV images, although a disagreement is observed at the equator and near the pole due to the breakdown of the cyclostrophic approximation. From zonal thermal winds the Richardson number has been evaluated. In good agreement with previous studies (Allison et al., 1994), we have found that the atmosphere is dominated by convection from 45 km altitude up to the cloud top. A high value of Richardson number has been determined, cor-responding to the midlatitude jet and indicating a highly stable atmosphere. Verification of the necessary condition for barotropic instability implies that barotropic instability may occur on the poleward side of the midlatitude jet where pl

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

    NASA Astrophysics Data System (ADS)

    Tsang, Constantine; McGouldrick, Kevin

    2015-11-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  17. Venus cloud bobber mission: A long term survey of the Venusian surface

    NASA Technical Reports Server (NTRS)

    Wai, James; Derengowski, Cheryl; Lautzenhiser, Russ; Emerson, Matt; Choi, Yongho

    1994-01-01

    We have examined the Venus Balloon concept in order to further develop the ideas and concepts behind it, and to creatively apply them to the design of the major Venus Balloon components. This report presents our models of the vertical path taken by the Venus Balloon and the entry into Venusian atmosphere. It also details our designs of the balloon, gondola, heat exchanger, power generator, and entry module. A vehicle is designed for a ballistic entry into the Venusian atmosphere, and an atmospheric model is created. The model is then used to set conditions. The shape and material of the vehicle are optimized, and the dimensions of the vehicle are then determined. Equipment is chosen and detailed that will be needed to collect and transmit information and control the mission. A gondola is designed that will enable this sensitive electronic equipment to survive in an atmosphere of very high temperature and pressure. This shape and the material of the shell are optimized, and the size is minimized. Insulation and supporting structures are designed to protect the payload equipment and to minimize mass. A method of cooling the gondola at upper altitudes was established. Power needs of the gondola equipment are determined. Power generation options are discussed and two separate thermoelectric generation models are outlined.

  18. Exploring Venus

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.

    2008-01-01

    With a temperature higher than the inside of your oven and atmospheric pressure equal to that a kilometer under the ocean, the surface of Venus is one of the most hostile environments in the solar system, and Venus exploration presents a challenge to technology. This lecture presents mission trade-offs and discusses a proposed mission concept for rover and aircraft based exploration of the surface and atmosphere of Venus. Several approaches to the technology, electronics, mechanical parts, and power systems, are discussed.

  19. A recommended entry reconstruction process for the Pioneer Venus multi-probe mission

    NASA Technical Reports Server (NTRS)

    Findlay, J. T.; Kelly, G. M.

    1978-01-01

    A method for determining the entry trajectories for the Pioneer Venus multi-probe mission is presented that utilizes earth based Doppler and onboard accelerometry as observables to provide updates for the spacecraft state and atmospheric parameters. The evolution of this method, based on error analyses and actual simulation results, is discussed. A derivative of the Viking radio science orbit determination software is recommended for the reconstruction. Telemetry data pre-processing requirements were defined. A cubic spline derivative routine is recommended to extract accelerations from the accumulated velocity decrements.

  20. Future of Venus Research and Exploration

    NASA Astrophysics Data System (ADS)

    Glaze, L.; Limaye, S.; Nakamura, M.; Wilson, C.; Zasova, L.

    2014-04-01

    A great deal is known about Venus from the Venera, Pioneer-Venus, Magellan, and Venus Express missions. However, many significant questions remain regarding the origin, evolution and current geologic and atmospheric processes. Much can be learned from theoretical modeling of the planetary interior and atmospheric circulation, as well as from laboratory spectroscopic studies. However, to answer many of the outstanding questions, new space flight missions are needed. Multiple international space agencies are considering Venus as a possible destination for future exploration. Collaborative international participation provides a viable path to further understanding of Earth's sister planet and her role in the formation of our solar system.

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

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

    NASA Astrophysics Data System (ADS)

    Tsang, Constantine C. C.; Irwin, Patrick G. J.; Wilson, Colin F.; Taylor, Fredric W.; Lee, Chris; de Kok, Remco; Drossart, Pierre; Piccioni, Giuseppe; Bezard, Bruno; Calcutt, Simon

    2008-10-01

    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 required for complete spatial coverage. We calculate the mean abundance for carbon monoxide at the equator to be 23 +/- 2 ppm. The CO concentration increases toward the poles, peaking at a latitude of approximately 60S, with a mean value of 32 +/- 2 ppm. This 40% equator-to-pole increase is consistent with the values found by Collard et al. (1993) from Galileo/NIMS observations. Observations suggest an overturning in this CO gradient past 60S, declining to abundances seen in the midlatitudes. Zonal variability in this peak value has also been measured, varying on the order of 10% (~3 ppm) at different longitudes on a latitude circle. The zonal variability of the CO abundance has possible implications for the lifetime of CO and its dynamics in the troposphere. This work has definitively established a distribution of tropospheric CO, which is consistent with a Hadley cell circulation, and placed limits on the latitudinal extent of the cell.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

  5. Retrieval of the cyclostrophic wind in the Venus mesosphere from the VIRTIS/Venus Express temperature sounding.

    NASA Astrophysics Data System (ADS)

    Piccialli, Arianna; Titov, Dmitri; Grassi, Davide; Khatuntsev, Igor; Drossart, Pierre; Piccioni, Giuseppe; Migliorini, Alessandra

    Venus mesosphere is characterized by an extremely complex dynamics: a retrograde super rotation flow near the cloud top completes a full rotation of the planets in only four earth days and in the upper thermosphere a solar - antisolar circulation reaches speeds of 100 m/s. Earlier studies have shown that the strong zonal winds at cloud top are the result of local balance of pressure gradient and centripetal force which is called cyclostrophic balance. The thermal wind equation that describes this balance relates the vertical wind gradient to the latitudinal temperature gradient on isobaric levels. The temperature structure of Venus mesosphere has been observed with a good spatial and temporal coverage in the last two years from VIRTIS (Visual and Infrared Thermal Imaging Spectrometer) on board the Venus Express spacecraft. Here we present preliminary retrievals of the cyclostrophic wind derived from VIRTIS temperature sounding. The main features of the wind are 1) the midlatitude jet with a maximum speed of 80 - 90 10 m/s which occurs around 50 S latitude at 70 km altitude; 2) the fast decrease of the wind speed from 60 S toward the pole; 3) the decrease of the wind speed with increasing height above the jet. The dependence of zonal wind on local time has been analysed, our preliminary results show that parameters of the mid-latitude jet only weekly depend on local solar time. Comparison with cloud - tracked wind derived from the Venus Monitoring Camera (VMC) show a general good agreement.

  6. The electrical performance of Ag Zn batteries for the Venus multi-probe mission

    NASA Technical Reports Server (NTRS)

    Palandati, C.

    1975-01-01

    An evaluation of 5 Ah and 21 Ah Silver-Zinc batteries was made to determine their suitability to meet the energy storage requirements of the bus vehicle, 3 small probes and large probe for the Venus multi-probe mission. The evaluation included a 4 Ah battery for the small probe, a 21 Ah battery for the large probe, one battery of each size for the bus vehicle power, a periodic cycling test on each size battery and a wet stand test of charged and discharged cells of both cell designs. The study on the probe batteries and bus vehicle batteries included both electrical and thermal simulation for the entire mission. The effects on silver migration and zinc penetration of the cellophane separators caused by the various test parameters were determined by visual and X-ray fluorescence analysis. The 5 Ah batteries supported the power requirements for the bus vehicle and small probe. The 21 Ah large probe battery supplied the required mission power. Both probe batteries delivered in excess of 132 percent of rated capacity at the completion of the mission simulation.

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  8. Sulfuric acid vapor in the atmosphere of Venus as observed by the Venus Express Radio Science experiment VeRa

    NASA Astrophysics Data System (ADS)

    Oschlisniok, Janusz; Ptzold, Martin; Husler, Bernd; Tellmann, Silvia; Bird, Mike; Andert, Thomas; Remus, Stefan

    2015-04-01

    The cloud deck within Venus' atmosphere, which covers the entire planet between approx. 50 and 70 km altitude, consists mostly of liquid and gaseous sulfuric acid. The gaseous part increases strongly just below the main clouds and builds an approx. 15 km thick haze layer of H2SO4. This region is responsible for a strong absorption of radio waves as seen in VeRa radio science observations. The absorption of the radio signals during occultations is used to derive the abundance of gaseous sulfuric acid. VeRa probes the atmosphere of Venus since 2006 with radio signals at 13 cm (s-band) and 3.6 cm (x-band) wavelengths. The collection of nine years of radio science data provides a picture of the global distribution of the sulfuric acid vapor distribution within Venus' atmosphere. We present H2SO4 profiles retrieved with VeRa and compare those with H2SO4 profiles observed by previous missions.

  9. Future dedicated Venus-SGG flight mission: Accuracy assessment and performance analysis

    NASA Astrophysics Data System (ADS)

    Zheng, Wei; Hsu, Houtse; Zhong, Min; Yun, Meijuan

    2016-01-01

    This study concentrates principally on the systematic requirements analysis for the future dedicated Venus-SGG (spacecraft gravity gradiometry) flight mission in China in respect of the matching measurement accuracies of the spacecraft-based scientific instruments and the orbital parameters of the spacecraft. Firstly, we created and proved the single and combined analytical error models of the cumulative Venusian geoid height influenced by the gravity gradient error of the spacecraft-borne atom-interferometer gravity gradiometer (AIGG) and the orbital position error and orbital velocity error tracked by the deep space network (DSN) on the Earth station. Secondly, the ultra-high-precision spacecraft-borne AIGG is propitious to making a significant contribution to globally mapping the Venusian gravitational field and modeling the geoid with unprecedented accuracy and spatial resolution through weighing the advantages and disadvantages among the electrostatically suspended gravity gradiometer, the superconducting gravity gradiometer and the AIGG. Finally, the future dedicated Venus-SGG spacecraft had better adopt the optimal matching accuracy indices consisting of 3 × 10-13/s2 in gravity gradient, 10 m in orbital position and 8 × 10-4 m/s in orbital velocity and the preferred orbital parameters comprising an orbital altitude of 300 ± 50 km, an observation time of 60 months and a sampling interval of 1 s.

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

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

  11. Exploring Venus: the Venus Exploration Analysis Group (VEXAG)

    NASA Astrophysics Data System (ADS)

    Ocampo, A.; Atreya, S.; Thompson, T.; Luhmann, J.; Mackwell, S.; Baines, K.; Cutts, J.; Robinson, J.; Saunders, S.

    In July 2005 NASA s Planetary Division established the Venus Exploration Analysis Group VEXAG http www lpi usra edu vexag in order to engage the scientific community at large in identifying scientific priorities and strategies for the exploration of Venus VEXAG is a community-based forum open to all interested in the exploration of Venus VEXAG was designed to provide scientific input and technology development plans for planning and prioritizing the study of Venus over the next several decades including a Venus surface sample return VEXAG regularly evaluates NASA s Venus exploration goals scientific objectives investigations and critical measurement requirements including the recommendations in the National Research Council Decadal Survey and NASA s Solar System Exploration Strategic Roadmap VEXAG will take into consideration the latest scientific results from ESA s Venus Express mission and the MESSENGER flybys as well as the results anticipated from JAXA s Venus Climate Orbiter together with science community inputs from venues such as the February 13-16 2006 AGU Chapman Conference to identify the scientific priorities and strategies for future NASA Venus exploration VEXAG is composed of two co-chairs Sushil Atreya University of Michigan Ann Arbor and Janet Luhmann University of California Berkeley VEXAG has formed three focus groups in the areas of 1 Planetary Formation and Evolution Surface and Interior Volcanism Geodynamics etc Focus Group Lead Steve Mackwell LPI 2 Atmospheric Evolution Dynamics Meteorology

  12. A preliminary analysis of a radar-mapping mission to Venus

    NASA Technical Reports Server (NTRS)

    Mackay, J. S.; Edsinger, L. E.; Evans, L. C.; Manning, L. A.; Sinclair, K. F.; Swenson, B. L.

    1973-01-01

    A rather broad survey is reported of the Venus radar orbiter possibilities within the period 1983-1990. Minimum mission imaging requirements have been set by comparison with the improving capabilities of earth based radar systems and an examination of earth airborne radar imaging. This has led to a requirement for 80 percent coverage at a resolution of 100 m. A first main conclusion is that only the Shuttle-Centaur launch system would be capable of establishing a circular orbit under all possible launch conditions. Thus, orbit eccentricity has been introduced as a parameter throughout this presentation. An examination of typical radar designs has led to upper and lower limits on swath width of 100 and 50 km. A lower eccentricity of 0.2 was set by considering the current Viking propulsion system. An examination of solar perturbations indicates that orbit maintenance problems increase rapidly above an eccentricity of 0.5.

  13. Preliminary observations by Venus Express/VIRTIS of the distribution of carbon monoxide in the lower atmosphere of Venus

    NASA Astrophysics Data System (ADS)

    Tsang, C. C. C.; Taylor, F. W.; Irwin, P. G. J.; Drossart, P.; Piccioni, G.; Wilson, C. F.; Virtis/Venus Express

    The minor constituent carbon monoxide (CO) is an important tracer of the dynamics and chemistry of the Venusian atmosphere. Galileo/NIMS observations in 1990 found a poleward increase of CO in the height range around 40 km in the northern hemisphere (Collard et. al., PSS, 1993), which was confirmed by subsequent high-resolution ground-based spectral observations (Marq et al., Icarus, 2005). Taylor (Adv. Space Res., 1995) presented an interpretation of the NIMS observations of CO in terms of an atmospheric circulation containing hemispherical Hadley cells that extend from the surface up to the mesosphere. Here we present some new observations by the VIRTIS instrument on Venus Express of the variability of CO below the clouds on Venus. They show that the equator-to-pole gradient is also present in the southern hemisphere, and that it peaks near 60 degrees. A search for longitudinal variations of CO will be shown.

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

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

  16. Future Exploration of Venus: Opportunities and Challenges

    NASA Astrophysics Data System (ADS)

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

    2012-07-01

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

  17. High energy particles at Mars and Venus: Phobos-2, Mars Express and Venus Express observations and their interpretation by hybrid model simulations

    NASA Astrophysics Data System (ADS)

    McKenna-Lawlor, Susan; Kallio, Esa; Fram, Rudy A.; Alho, Markku; Jarvinen, Riku; Dyadechkin, Sergey; Wedlund, Cyril Simon; Zhang, Tielong; Collinson, Glyn A.; Futaana, Yoshifumi

    2013-04-01

    Mars and Venus can both be reached by Solar Energetic Particles (SEPs). Such high energy particles (protons, multiply charged heavy ions, electrons) penetrate the upper atmospheres of Mars and Venus because, in contrast to Earth, these bodies do not have a significant, global, intrinsic magnetic field to exclude them. One especially well documented, complex and prolonged SEP took in place in early 1989 (Solar Cycle 23) when the Phobos-2 spacecraft was orbiting Mars. This spacecraft had a dedicated high energy particle instrument onboard (SLED), which measured particles with energies in the keV range up to a few tens of MeV. There was in addition a magnetometer as well as solar wind plasma detectors onboard which together provided complementary data to support contemporaneous studies of the background SEP environment. Currently, while the Sun is displaying maximum activity (Solar Cycle 24), Mars and Venus are being individually monitored by instrumentation flown onboard the Mars Express (MEX) and Venus Express (VEX) spacecraft. Neither of these spacecraft carry a high energy particle instrument but their Analyzer of Space Plasmas and Energetic Atoms (ASPERA) experiments (ASPERA-3 on MEX and ASPERA-4 on VEX), can be used to study SEPs integrated over E ≥ ~30 MeV which penetrate the instrument hardware and form background counts in the plasma data. In the present work we present SEP events measured at Mars and Venus based on Phobos-2, 1989 data and on, more recent, MEX and VEX (identified from particle background) observations. We further introduce numerical global SEP simulations of the measured events based on 3-D self-consistent hybrid models (HYB-Mars and HYB-Venus). Through comparing the in situ SEP observations with these simulations, new insights are provided into the properties of the measured SEPs as well as into how their individual planetary bow shocks and magnetospheres affect the characteristics of their ambient Martian and Venusian SEP environments.

  18. Horizontal Distribution of CO, OCS and H2O Below the Clouds of Venus From Venus Express/VIRTIS Observations

    NASA Astrophysics Data System (ADS)

    Bezard, Bruno; Marcq, E.; Tsang, C. C.; Taylor, F. W.; Drossart, P.; Piccioni, G.; Encrenaz, T.; Vex/VIRTIS Team

    2006-09-01

    Nightside spectroscopy in the 2.3-?m window allows us to probe the composition of the lower atmosphere of Venus in the altitude range 28-42 km. Besides CO2, signatures from CO, OCS, H2O, HDO, HF and SO2 can be detected (e.g. Bzard et al. 1990, Nature 345, 508-511; Taylor et al. 1997, in Venus II, pp. 325-351, Univ. Arizona Press, Tucson). We report here on the first observations of this window on Venus' night side obtained with the VIRTIS instrument aboard Venus Express. It was observed at a resolving power (R) of about 2000 with the H-channel, a high-resolution spectrometer covering the range 1.9-5 ?m, and at R 250 with the infrared M-channel, an imaging spectrometer for the range 1-5 ?m. We present maps of CO in the southern hemisphere obtained with the M-channel and latitudinal variations of CO, OCS and H2O derived from a set of VIRTIS-H scans. CO clearly increases from equator to 60S with a slight decrease polewards. Longitudinal structure is also present. The inferred gradient is consistent with the ground-based observations of Marcq et al. (2005, Icarus 179, 375-386; 2006, Planet. Space Sci., in press) below 40 latitude and mirrors the enhancement seen at high northern latitudes in the Galileo data (Collard et al. 1993, Planet. Space Sci. 41, 487-494). CO appears as a tracer of the atmospheric dynamics, giving evidence for upwelling in the equatorial region and subsidence at high latitudes.

  19. Geologic interpretation of the near-infrared images of the surface taken by the Venus Monitoring Camera, Venus Express

    NASA Astrophysics Data System (ADS)

    Basilevsky, A. T.; Shalygin, E. V.; Titov, D. V.; Markiewicz, W. J.; Scholten, F.; Roatsch, Th.; Kreslavsky, M. A.; Moroz, L. V.; Ignatiev, N. I.; Fiethe, B.; Osterloh, B.; Michalik, H.

    2012-02-01

    We analyze night-time near-infrared (NIR) thermal emission images of the Venus surface obtained with the 1-μm channel of the Venus Monitoring Camera onboard Venus Express. Comparison with the results of the Magellan radar survey and the model NIR images of the Beta-Phoebe region show that the night-time VMC images provide reliable information on spatial variations of the NIR surface emission. In this paper we consider if tessera terrain has the different NIR emissivity (and thus mineralogic composition) in comparison to the surrounding basaltic plains. This is done through the study of an area SW of Beta Regio where there is a massif of tessera terrain, Chimon-mana Tessera, surrounded by supposedly basaltic plains. Our analysis showed that 1-μm emissivity of tessera surface material is by 15-35% lower than that of relatively fresh supposedly basaltic lavas of plains and volcanic edifices. This is consistent with hypothesis that the tessera material is not basaltic, maybe felsic, that is in agreement with the results of analyses of VEX VIRTIS and Galileo NIMS data. If the felsic nature of venusian tesserae will be confirmed in further studies this may have important implications on geochemical environments in early history of Venus. We have found that the surface materials of plains in the study area are very variegated in their 1-μm emissivity, which probably reflects variability of degree of their chemical weathering. We have also found a possible decrease of the calculated emissivity at the top of Tuulikki Mons volcano which, if real, may be due to different (more felsic?) composition of volcanic products on the volcano summit.

  20. Tracking of Mars Express and Venus Express spacecraft with VLBI radio telescopes

    NASA Astrophysics Data System (ADS)

    Molera Calvés, G.; Pogrebenko, S. V.; Wagner, J.; Cimò, G.; Gurvits, L.; Duev, D.

    2010-12-01

    The ESA Mars Express and Venus Express spacecraft (S/C) have been observed for the last two years with the European VLBI radio telescopes of Metsähovi (FI), Wettzell (GE), Yebes (SP), Medicina, Matera, Noto (IT), Puschino (RU) and Onsala (SW). The campaign is in the framework of the assessment study and preparation of the European VLBI Network to the upcoming ESA and other deep space missions. It also offers new opportunities for applications of radio astronomy techniques to planetary science, geophysics and geodesy. Observations are carried out either in single- or multi-dish modes when S/C is locked to the ESA’s ESTRACK ground stations (Cebreros or New Nortia) observing the two way link. Data are recorded locally at the stations using standard VLBI equipment and transferred to the Metsähovi for processing. Further on, the data are transferred from Metsähovi to Joint Institute for VLBI in Europe for further post-analysis. High dynamic range of the S/C signal detections allowed us to determine the apparent topocentric frequency of the S/C carrier line and accompanying ranging tones down to milli-Hz spectral accuracy and to extract the phase of the S/C signal carrier line. With multi-station observations, the respective phases can be calibrated on the per-baseline basis using VLBI phase referencing technique and observations of background quasars close to S/C in their celestial position using far-field VLBI delay model for quasars and near-field model for S/C. The post-analysis of the S/C tracking data enables us to study several parameters of the S/C signals. Of these, the phase fluctuations of the signal can be used for characterization of the interplanetary plasma density fluctuations along the signal propagation line at different spatial and temporal scales and different solar elongations. These fluctuations are well represented by a near-Kolmogorov spectrum. Multi-station observations can distinguish the contributions of propagation effects in the plasma along the up- and down-link paths as seen from different VLBI stations through different Fresnel channels. We also demonstrated high accuracy S/C Doppler tracking with 3 EVN stations (Metsähovi, Wettzell and Yebes) during the MEX-Phobos flyby, which occurred on 2010 march 03. These multi-station observing sessions could help to better determine the Phobos gravity field and together with phase referencing provide additional geometrical constrains on the orbiter/Phobos trajectories. VEX S/C signal detection with four VLBI antennae (23/08/2010).

  1. A study of an orbital radar mapping mission to Venus. Volume 3: Parametric studies and subsystem comparisons

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Parametric studies and subsystem comparisons for the orbital radar mapping mission to planet Venus are presented. Launch vehicle requirements and primary orbiter propulsion system requirements are evaluated. The systems parametric analysis indicated that orbit size and orientation interrelated with almost all of the principal spacecraft systems and influenced significantly the definition of orbit insertion propulsion requirements, weight in orbit capability, radar system design, and mapping strategy.

  2. Venusian bow shock as seen by the ASPERA-4 ion instrument on Venus Express

    NASA Astrophysics Data System (ADS)

    Whittaker, I.; Guymer, G.; Grande, M.; Pintér, B.; Barabash, S.; Federov, A.; Mazelle, C.; Sauvaud, J. A.; Lundin, R.; Russell, C. T.; Futaana, Y.; Fränz, M.; Zhang, T. L.; Andersson, H.; 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.; Koskinen, H. E. J.; Kallio, E.; Riihelä, P.; Schmidt, W.; Kozyra, J.; McKenna-Lawlor, S.; Thocaven, J. J.; Orsini, S.; Cerulli-Irelli, R.; Mura, A.; Milillo, M.; Maggi, M.; Roelof, E.; Brandt, P.; Frahm, R. A.; Sharber, J. R.; Wurz, P.; Bochsler, P.

    2010-09-01

    The Analyzer of Space Plasmas and Energetic Atoms (ASPERA-4) instrument on Venus Express is used to determine bow shock position at Venus using ion data alone, using data recorded during a solar minimum from the Ion Mass Analyzer (IMA) which is part of the ASPERA-4 package. Previous models constructed from solar minimum data using Venus Express, Pioneer Venus Orbiter (PVO) and Venera 9 and 10 are also compared to the current fit. An important feature of this new fit is a statistical accuracy introduced in the form of a probability weighting function for the data points, based on the time spent in particular locations. The bow shock curve is then compared to two-dimensional ion maps. These verify the accuracy of this and previous solar minimum fit curves based on PVO and Venus Express magnetic data. Comparing all bow shock models to the 2D ion maps shows that a combination of models produces the best fit. Since all the fitted curves show differences in position they are investigated relative to the solar conditions pertaining at the times when the individual data sets were measured. The sub solar point and terminator distance were thus found to vary linearly with sunspot number and hence with solar activity. This relationship, which was already known to exist between solar maximum and solar minimum, is now shown to exist between different solar minima and even within the same minimum. This indicates a need for the mechanisms for bow shock maintenance and variance to be more closely modeled.

  3. Pluto Express: Mission to Pluto

    NASA Technical Reports Server (NTRS)

    Giuliano, J. A.

    1996-01-01

    Pluto is the smallest, outermost and last-discovered planet in the Solar System and the only one that has never been visited by a spacecraft from Earth. Pluto and its relatively large satellite Charon are the destinations of a proposed spacecraft mission for the next decade, being developed for NASA by scientists and engineers at NASA's Jet Propulsion Laboratory.

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  5. Waves in the Mesosphere of Venus as seen by the Venus Express Radio Science Experiment VeRa

    NASA Astrophysics Data System (ADS)

    Tellmann, Silvia; Häusler, B.; Hinson, D. P.; Tyler, G.; Andert, T. P.; Bird, M. K.; Imamura, T.; Pätzold, M.; Remus, S.

    2013-10-01

    The Venus Express Radio Science Experiment (VeRa) has retrieved more than 700 profiles of the mesosphere and troposphere of Venus. These profiles cover a wide range of latitudes and local times, enabling study of atmospheric wave phenomena over a range spatial scales at altitudes of 40-90 km. In addition to quasi-horizontal waves and eddies on near planetary scales, diurnally forced eddies and thermal tides, small-scale gravity waves, and turbulence play a significant role in the development and maintenance of atmospheric super-rotation. Small-scale temperature variations with vertical wavelengths of 4 km or less have wave amplitudes reaching TBD km in the stable atmosphere above the tropopause, in contrast with much weaker temperature perturbations observed in the middle cloud layer below. The strength of gravity waves increases with latitude in both hemispheres. The results suggest that convection at low latitudes and topographical forcing at high northern latitudes—possibly in combination with convection and/or Kelvin-Helmholtz instabilities—play key roles in the genesis of gravity waves. Further, thermal tides also play an important role in the mesosphere. Diurnal and semi-diurnal wave modes are observed at different latitudes and altitudes. The latitudinal and height dependence of the thermal tide modes will be investigated.

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

    NASA Astrophysics Data System (ADS)

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

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

  7. Analysis of Solar Cell Efficiency for Venus Atmosphere and Surface Missions

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.; Haag, Emily

    2013-01-01

    A simplified model of solar power in the Venus environment is developed, in which the solar intensity, solar spectrum, and temperature as a function of altitude is applied to a model of photovoltaic performance, incorporating the temperature and intensity dependence of the open-circuit voltage and the temperature dependence of the bandgap and spectral response of the cell. We use this model to estimate the performance of solar cells for both the surface of Venus and for atmospheric probes at altitudes from the surface up to 60 km. The model shows that photovoltaic cells will produce power even at the surface of Venus.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

  10. Sulfur Dioxide variability in the Venus Atmosphere

    NASA Astrophysics Data System (ADS)

    Vandaele, Ann C.; Esposito, Larry W.; Lefevre, Franck; Mills, Franklin; Limaye, Sanjay; Mahieux, Arnaud; Belyaev, Denis; Encrenaz, Therese; Marcq, Emmanuel; Korablev, Oleg; Parkinson, Christopher; Wilson, Colin; Wilquet, Valrie; Chamberlain, Sarah; Jessup, Kandis Lea; Stolzenbach, Aurelien

    The recent observations of SO _{2} by SOIR and SPICAV-UV on board Venus Express and ground-based observations of SO _{2} and SO have provoked much reaction in the scientific community. SO _{2} is strongly related to the formation of the clouds and haze on Venus, which are composed of sulfuric acid combined to water complexes. Presence and variations of SO _{2} could be the proof of a possible volcanism on Venus. The most intriguing are discrepancies among different observations, and the suspected long-term variations of the SO _{2} abundance observed on the scales of several years, in particular during Pioneer Venus Orbiter and Venus Express missions. Similar trends are also observed in the super-rotation period and circulation patterns, which suggest that these aspects may be more strongly coupled than expected. An ISSI international team has been built in view of considering different aspects of sulfur chemistry on Venus. This includes comparison and validation of observations, from past missions, from Venus Express, from the Earth, and from Hubble Space Telescope, modeling of photochemistry and of other processes in which the sulfur family is involved. We will consider not only SO _{2}, but also SO and other constituents involved in its cycle. Reference density and vmr fields will be constructed from the detailed analysis and comparison of data. These will be included into the next generation of the VIRA references atmosphere.

  11. Venus geology

    NASA Technical Reports Server (NTRS)

    Mclaughlin, W. I.

    1991-01-01

    The Magellan mission to Venus is reviewed. The scientific investigations conducted by 243-day cycles encompass mapping with a constant incidence angle for the radar, observing surface changes from one cycle to the next, and targeting young-looking volcanos. The topography of Venus is defined by the upper boundary of the crust and upwelling from lower domains. Tectonic features such as rift zones, linear mountain belts, ridge belts, and tesserae are described. The zones of tesserae are unique to the planet. Volcanism accounts for about 80 percent of the observed surface, the remainder being volcanic deposits which have been reworked by tectonism or impacts. Magellan data reveal about 900 impact craters with flow-like ejecta resulting from the fall of meteoroids. It is concluded that the age of the Venusian surface varies between 0 and 800 million years. Tectonic and volcanic activities dominate the formation of the Venus topography; such processes as weathering and erosion are relatively unimportant on Venus.

  12. Aeronomy of the Venus upper atmosphere

    NASA Astrophysics Data System (ADS)

    Grard, J.-C.; Bougher, S. W.; Drossart, P.; Lopez-Valverde, M.; Ptzold, M.; Piccioni, G.

    2014-04-01

    The structure and content of the 'aeronomy' chapter of the Venus III book will be discussed. This chapter will review all recent results obtained from remote sensing of the upper atmosphere with emphasis on non-thermal emissions, global transport, wind, chemistry and composition related to airglow observations and modeling. Measurements of the ionospheric structure and its variability will be described. Data collected with instruments on board the Venus Express missions will be complemented with ground-based observations and results collected during the Cassini Venus flyby. Recent developments in global modeling coupling photochemistry, transport and gravity waves will also be compared with this set of new observations.

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

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

  15. A suggested trajectory for a Venus-sun, earth-sun Lagrange points mission, Vela

    NASA Technical Reports Server (NTRS)

    Bender, D. F.

    1979-01-01

    The possibility is suggested of investigating the existence of small, as-yet undiscovered, asteroids orbiting in the solar system near the earth-sun or Venus-sun stable Lagrange points by means of a spacecraft which traverses these regions. The type of trajectory suggested lies in the ecliptic plane and has a period of 5/6 years and a perihelion at the Venus orbital distance. The regions in which stable orbits associated with the earth and with Venus may lie are estimated to be a thin and tadpole-shaped area extending from 35 deg to 100 deg from the planet. Crossings of the regions by the trajectory are described, and the requirements for detecting the presence of 1 km sized asteroids are presented and shown to be attainable.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    Based on the analysis of UV images (at 365 nm) of Venus cloud top collected with VMC camera on board Venus Express[4,5], it is found that the zonal wind speed south of the equator (from 5°S to 15°s) shows a conspicuous variation with geographic longitude of Venus, correlated with underlying relief of Aphrodite Terra. We interpret this pattern as the result of stationary gravity waves produced at ground level by the up lift of air when the horizontal wind encounters a mountain slope. The cloud albedo map at 365 nm varies also in longitude and latitude, perhaps the result of increased vertical mixing associated to wave breaking, and decreased abundance of the UV absorber which makes the contrast in images.

  17. Constraints on Magmatic Diversity on Venus from Terrestrial Analog Crystallization Experiments with Data Implications for Future Missions

    NASA Astrophysics Data System (ADS)

    Filiberto, J.

    2013-12-01

    Igneous diversity,common on the Earth, is possible on Venus based on: the Venera and Vega analyses of rocks on the surface of Venus [1,2], orbital analyses of surface features [3], and thermochemical modeling of Venera and Vega basalts [4]. From these results, Venus and Earth have similar bulk chemistry and diversity of igneous rocks. However, the data from the Venera and Vega landers have large error bars compared with terrestrial geochemical analyses and do not provide mineralogy of the target rock, thereby making direct conclusions from this data challenging [e.g., 1, 2]. In order to make predictions about the types of magmas that could be on Venus, I will rely on crystallization experiments on terrestrial tholeiitic compositions. By comparing experimental results on terrestrial mafic basalts and natural terrestrial suites with the data from Venera and Vega, I constrain the types of igneous rocks that could be present on Venus, as well as the quality of data needed from future missions to distinguish the different suites. Extensive crystallization experiments have been conducted on terrestrial olivine tholeiites at varying pressures, temperatures, and water contents in order to understand the residual liquids produced by igneous differentiation [e.g., 5-10]. If similar processes of magma ponding and differentiation have occurred on Venus, then compositions similar to terrestrial igneous suites would be expected. The potential residual liquids produced by differentiation of a Venus tholeiite, based on experiments on analog compositions, range from rhyolites to phonolites, depending on pressure of crystallization and bulk water content. These experimental results are consistent with the interpretation of the Venera 13 analysis as a silica-undersaturated alkali basalt which suggests deep partial melting of a carbonated source region [11], while the identification of Venera 14 and Vega 2 as tholeiites suggests relatively shallow melting of a lherzolitic or peridotite source region. References: [1]. Kargel, J.S. et al. (1993) Icarus. 103(2): p. 253-275. [2] Treiman, A.H. (2007) in Exploring Venus as a Terrestrial Planet, Geophysical Monograph Series. p. 250. [3] Hashimoto, G.L., et al. (2008) JGR Planets. 113(E00B24): p. doi:10.1029/2008JE003134. [4] Shellnutt, J.G. (2013) JGR Planets. 118: p. 1350-1364, doi:10.1002/jgre.20094. [5] Spulber, S.D. and M.J. Rutherford (1983) Journal of Petrology. 24(1): p. 1-25. [6] Whitaker, M., et al. (2008) Bulletin of Volcanology. 70(3): p. 417-434. [7] Whitaker, M.L., et al. (2007) Journal of Petrology. 48(2): p. 365-393. [8] Nekvasil, H., et al. (2004) Journal of Petrology. 45(4): p. 693-721. [9] Green, D.H. (1970) Physics of the Earth and Planetary Interiors. 3: p. 221-235. [10] Filiberto, J. and Nekvasil H. (2003) GSA Abstracts with Programs. 35(6): p. 632. [11] Dasgupta, R., Hirschmann, M., and Smith, N. (2007) Journal of Petrology 48, 2093-2124.

  18. Venus Express observations of atmospheric oxygen escape during the passage of several coronal mass ejections

    NASA Astrophysics Data System (ADS)

    Luhmann, J. G.; Fedorov, A.; Barabash, S.; Carlsson, E.; Futaana, Y.; Zhang, T. L.; Russell, C. T.; Lyon, J. G.; Ledvina, S. A.; Brain, D. A.

    2008-08-01

    The solar wind interaction contributes to the loss of Venus atmospheric constituents, especially oxygen, by direct antisunward acceleration of planetary ions and possibly by related sputtering of neutrals. Both comet-like ``ion pickup'' and related sputtering processes may have played a key role in Venus' atmosphere evolution, but the significance of their effects, as well as other proposed escape mechanisms, is still uncertain. In particular, recent reports of only modest ion escape rates measured on Venus Express (VEX) during the current low-activity phase of the solar cycle make it important to reconsider the evidence seen in both Pioneer Venus Orbiter and VEX observations suggesting significantly enhanced escaping O+ ion fluxes during periods of disturbed interplanetary conditions. At present, the most extreme interplanetary conditions result from the effects of coronal mass ejections (CME), which may have been more prevalent in the first 1-2 billion years of the Sun's history. The Analyser of Space Plasmas and Energetic Atoms 4 (ASPERA-4) Ion Mass Analyzer and Magnetometer on Venus Express have now made detailed measurements during several periods when CME disturbances encountered Venus. The observations and models described in this report provide further insights into the possible response of oxygen ion escape to solar activity. In particular, they illustrate nuances of in situ sampling of large-gyroradius pickup ions, related to the atmospheric source properties, spacecraft orbit geometry, and the prevailing interplanetary conditions, that make the estimation of the variable global escape fluxes due to that process particularly challenging. In three of the four cases examined in some detail, ionospheric oxygen ions were either unobservable or below the limit of detectability for passes well within interplanetary coronal mass ejection (ICME) intervals. In the fourth example, where ionospheric ions were observed as expected from the model, O+ pickup ions were observed in greater abundance than is typical in undisturbed solar wind. Other escape processes are not considered here, although it is assumed the source population for the modeled pickup ions is a preaccelerated upper atmosphere component. Analysis of many more ICME events, expected to be obtained as the Sun becomes more active in future years, are necessary to resolve the question of the importance of ICME to Venus oxygen escape.

  19. Pioneer Venus

    NASA Astrophysics Data System (ADS)

    Luhmann, Janet

    In the tradition of the NASA special publications on planetary missions, the book, Pioneer Venus, offers a piece of history for a small investment. After a brief historical introduction, this book provides an informal but thorough documentation of a successful planetary mission with the human element very much at the forefront. Even the politics of funding are given acknowledgment. The amount of thought and planning that went into the design of the Pioneer Venus mission, from the feasibility studies and the announcement of opportunity in 1971 to the arrival of the orbiter and multiprobe spacecraft at Venus in late 1978, is given testimonial by the first half of the book, which is replete with tables and figures. It is evident from the vitality with which the two chapters on such mundane but crucial matters as mission operations, parachute development, tracking, data systems, and spacecraft engineering are written that the authors were intensely and actively involved in all aspects of the project. A separate chapter on scientific investigations gives brief descriptions of the experiments, highlighted with photographs of the instruments and principal investigators. The selection of experiments is especially noteworthy because the Pioneer Venus spacecraft was carefully outfitted to return complementary measurements, a trend that today's mission planners also adhere to.

  20. PC-403: Pioneer Venus multiprobe spacecraft mission operational characteristics document, volume 3

    NASA Technical Reports Server (NTRS)

    Barker, F. C.

    1978-01-01

    The Pioneer Venus spacecraft primary and backup operational modes and operational limitations for maneuvers, roll references transfer, attitude determination, spacecraft power discipline and spacecraft thermal discipline, are described. The functions and operations of the large and small probes, as well detailed performance in the normal operating modes and backup modes are presented.

  1. Preparation of In-Situ Data from the VEGA Balloon Mission at Venus for Archival on the PDS

    NASA Astrophysics Data System (ADS)

    Lorenz, Ralph; Crisp, David

    In 1985, the pioneering Soviet VEGA mission deployed two helium balloons into the atmosphere of Venus - the first, and so far only, planetary balloon mission. The balloons were tracked by an international network of radio telescopes, with a slow trickle of in-situ pressure, temperature, optical and wind measurements transmitted directly to Earth over 46 hours until battery depletion. While the key results of the mission were published at the time, the data have not been generally available in numerical form. Here we report an effort to archive the data on the NASA Planetary Data System (PDS). In fact the very low telemetry rate dictated by the direct-to-Earth communication and minimal energy budget on-board demanded heavy data compression/selection, and the reconstruction of the history of altitude and meteorological measurements had to address ambiguities in the lossy compression scheme. These challenges entailed a significant effort as part of the postdoctoral work of D. Crisp, and have not been documented fully in the literature. Here we summarize the mission and the telemetry data, together with the approach used to reconstruct/interpolate the archival dataset. This documentation and numerical files are being prepared for submission to the PDS Atmospheres Node, where it will be available to all.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  3. Sprites and lightning in Venus: constraints for observations by the Planet-C mission

    NASA Astrophysics Data System (ADS)

    Takahashi, Y.; Yair, Y.; Goto, Y.; Sentman, D.; Yoshida, J.; Sato, M.; Hoshino, N.

    2007-12-01

    Lightning activity in Venus has been mystery for long period, although many studies based on observations both by spacecrafts and by ground-based telescope have been carried out. This situation may be attributed to the ambiguity of these evidential measurements. In order to conclude this controversial subject, we are developing a new type of lightning detector, LAC (Lightning and Airglow Camera), which will be onboard Planet-C (Venus Climate Orbiter: VCO). PLanet-C will be launched in 2010 by JAXA. To distinguish optical lightning flash from other pulsing noises, high-speed sampling at 50kHz for each pixel, that enables us to investigate the time variation of each lightning flash phenomenon, is adopted. On the other hand, spatial resolution is not first priority. For this purpose we developed new type of APD (avalanche photo diode) array with a format of 8 x 8. Narrow band interference filter at wavelength of 777.4 nm (OI), which is expected lightning color based on laboratory discharge experiment, is chosen for lightning measurement. LAC detects lightning flash with an optical intensity of average of Earth's lightning or less at a distance of 3 Rv. We also present results of theoretical calculations of the expected occurrance heights and emissions of sprites above thunderstorms in the CO2 atmosphere of Venus and the Hydrogen-Helium atmospheres of Jupiter and Saturn. General detection methodology of sprites/lightning in planetary atmospheres by orbiting spacecraft will be discussed.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  5. Dayside temperatures in the Venus upper atmosphere from Venus Express/VIRTIS nadir measurements at 4.3 μm

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  6. Venus geology and tectonics - Hotspot and crustal spreading models and questions for the Magellan mission

    NASA Technical Reports Server (NTRS)

    Head, James W.; Crumpler, L. S.

    1990-01-01

    Spacecraft and ground-based observations of Venus have revealed a geologically young and active surface - with volcanoes, rift zones, orogenic belts and evidence for hotspots and crustal spreading - yet the processes responsible for these features cannot be identified from the available data. The Magellan spacecraft will acquire an unprecedented global data set which will provide a comprehensive and well resolved view of the planet. This will permit global geological mapping, an assessment of the style and relative importance of geological processes, and will help in the understanding of links between the surface geology and mantle dynamics of this earth-like planet.

  7. Venus volcanism

    SciTech Connect

    Head, J.W.

    1985-01-01

    Eruption styles and processes on the planets are known to be strongly influenced by such factors as gravity, temperature, and atmospheric characteristics. The ascent and eruption of magma on Venus in the current Venus environment must take into account the influence of the extreme surface temperatures (650-750 K) and pressures (40-100 bars) on these processes. Conditions on Venus will reduce the subsurface exsolution of volatiles and lead to a reduction of the possible range of explosive interactions with the atmosphere. Pyroclastic eruptions will be severely inhibited and continuous magma disruption by gas bubble growth may not occur at all unless the exsolved magma volatile content exceeds several weight percent. Recent US and USSR spacecraft missions and Earth-based radar observations are beginning to provide a view of the range of Venus volcanic features, including domes, cones, calderas, shields, and flows. The nature of many lava flows suggests that numerous eruptions have effusion rates exceeding common terrestrial rates and lying more in the range inferred for lunar basaltic flood eruptions (10/sup 4/-10/sup 5/m/sup 3//s). Shield volcanoes are often wide but are low (<2 km elevation) relative to those on Mars and the Earth. Volcano height depends in part on the depth of origin of the magma and the density contrast between the lava and the rocks between the source and the surface, both of which may be different on Venus. Correlations between volcanic style and tectonic structure are emerging.

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

    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 460C. 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.

  9. International Collaboration for Venus Exploration

    NASA Astrophysics Data System (ADS)

    Cutts, James; Limaye, Sanjay; Zasova, Ludmila; Wilson, Colin; Ocampo, Adriana; Glaze, Lori; Svedhem, H.; Nakamura, Masato; Widemann, Thomas

    The Venus Exploration Analysis Group (VEXAG) was established by NASA in July 2005 to identify scientific priorities and strategy for exploration of Venus. From the outset, VEXAG has been open to the international community participation and has followed the progress of the ESA Venus Express Mission and the JAXA Akasuki mission as well exploring potential broad international partnerships for Venus exploration through coordinated science and missions. This paper discussed three mechanisms through which these collaborations are being explored in which VEXAG members participate One pathway for international collaboration has been through COSPAR. The International Venus Exploration Working Group (IVEWG) was formed during the 2012 COSPAR general assembly in Mysore, India. Another potentially significant outcome has been the IVEWGs efforts to foster a formal dialog between IKI and NASA/PSD on the proposed Venera D mission resulting in a meeting in June 2013 to be followed by a discussion at the 4MS3 conference in October 2013. This has now resulted in an agreement between NASA/PSD and IKI to form a joint Science Definition Team for Venera D. A second pathway has been through an international focus on comparative climatology. Scientists from the established space faring nations participated in a first international conference on Comparative Climatology for Terrestrial Planet (CCTP) in Boulder Colorado in June 2012 sponsored by several international scientific organizations. A second conference is planned for 2015. The Planetary Robotics Exploration Coordinating Group (PRECG) of International Academy of Astronautics (IAA) the IAA has been focusing on exploring affordable contributions to the robotic exploration by non-space-faring nations wishing to get involved in planetary exploration. PRECG has sponsored a two year study of Comparative Climatology for which Venus is the focal point and focused on engaging nations without deep space exploration capabilities. A third area of interchange has been the International Planetary Probe Workshop (IPPW) , now in its eleventh year, which brings together scientists, technologists and mission designers interested in the exploration of planets with atmospheres and particularly in the challenges of entry, descent and landing and sustained flight on other planets. IPPW has been an opportunity for developing the collaborations at a grass roots level. With both NASA and ESA favoring competitive rather than strategic approaches for selecting planetary missions (except for Moon and Mars), future collaboration on Venus exploration will involve flexible partnerships. However, international standards for proximity communication frequencies and protocols will be vital to international collaboration.

  10. Solar wind interaction with Venus and impact on its atmosphere

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    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.

  11. Mars Express: Mission and Science Goals (Invited)

    NASA Astrophysics Data System (ADS)

    Chicarro, A. F.

    1999-09-01

    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.

  12. Return to Venus of AKATSUKI, the Japanese Venus Orbiter

    NASA Astrophysics Data System (ADS)

    Nakamura, M.; Iwagami, N.; Satoh, T.; Taguchi, M.; Watanabe, S.; Takahashi, Y.; Imamura, T.; Suzuki, M.; Ueno, M.; Yamazaki, A.; Fukuhara, T.; Yamada, M.; Ishii, N.; Ogohara, K.

    2011-12-01

    Japanese Venus Climate Orbiter 'AKATSUKI' (PLANET-C) was proposed in 2001 with strong support by international Venus science community and approved as an ISAS mission soon after the proposal. AKATSUKI and ESA's Venus Express complement each other in Venus climate study. Various coordinated observations using the two spacecraft have been planned. Also participating scientists from US have been selected. Its science target is to understand the climate of Venus. The mission life we expected was more than 2 Earth years in Venus orbit. AKATSUKI was successfully launched at 06:58:22JST on May 21, by H-IIA F17. After the separation from H-IIA, the telemetry from AKATSUKI was normally detected by DSN Goldstone station (10:00JST) and the solar cell paddles' expansion was confirmed. AKATSUKI was put into the 3-axis stabilized mode in the initial operation from Uchinoura station and the critical operation was finished at 20:00JST on the same day. The malfunction, which happened during the Venus Orbit Insertion (VOI) on7 Dec, 2010 is as follows. We set all commands on Dec. 5. Attitude control for Venus orbit insertion (VOI) was automatically done on Dec. 6. Orbital maneuver engine (OME) was fired 08:49 JST on Dec. 7. 1min. after firing the spacecraft went into the occultation region and we had no telemetry, but we expected to continuous firing for 12min. Recording on the spacecraft told us later that, unfortunately the firing continued just 152sec. and stopped. The reason of the malfunction of the OME was the blocking of check valve of the gas pressure line to push the fuel to the engine. We failed to make the spacecraft the Venus orbiter, and it is rotating the sun with the orbital period of 203 days. As the Venus orbit the sun with the period of 225 days, AKATSUKI has a chance to meet Venus again in 5 or 6 years depending on the orbit correction plan. Let us summarize the present situation of AKATSUKI. Most of the fuel still remains. But the condition of the propulsion system is unclear. ISAS is examining various scenarios of second Venus orbit insertion depending on the conditions of the check valve and the OME. Thermal condition during the extended cruise phase is severe. The solar flux (W/m2) to which the spacecraft is exposed from May 21, 2010 (Launch date) to the end of 2016. We expected about 2600W/m2 in the Venus orbit, but it is exposed to more than 3600W/m2 at perihelion (0.6AU from the sun). The temperatures of the instruments exposed to space gradually increased as the spacecraft approaching the perihelion. We tried to minimize the number of instruments whose temperatures exceed the allowed upper limits by letting a certain side of the spacecraft face to the sun. After passing the perihelion every instruments have been working normally. The degradation of the reflectivity of the outer film (MLI) during the extended cruise may influence the temperature tendency. Laboratory tests to evaluate the degradation are ongoing. We operate the test maneuver of the OME in September and hopefully the orbit maneuver in November, which leads the spacecraft close to Venus in 2015. We will report the result in the presentation.

  13. Requirements on Atmospheric Entry of Small Probes for Several Planets: Venus, Saturn, Neptune and Uranus in Preparation for the Future ESA Cosmic Vision Missions

    NASA Astrophysics Data System (ADS)

    Tomuta, D.; Rebuffat, D.; Larranaga, J.; Erd, C.; Bavdaz, M.; Falkner, P.

    2011-02-01

    In preparation for the ESA Cosmic Vision new call for medium class missions, a set of entry probes for inner and outer planets have been preliminary investigated by ESA using its Concurrent Design Facility. These Entry Probe missions are hypothetically assumed for launching time 2020-2035. A preliminary design of the probes arrived at a mass of about 300kg. In the following, the study is focused on the entry conditions for each of the planets Venus, Saturn, Neptune and Uranus with the aim to define the conditions for the Entry and Descent System (EDS) and its required technologies. For Venus case, two scenarios where considered: one where the entry probe is released during a typical gravity assist by a large interplanetary mission and another scenario featuring a stand alone mission targeted to Venus. During the entry in Venus atmosphere (mainly composed of CO2 (96.5%) and N2 (3.5%)), the probes are subjected to maximum heat fluxes of 60MW/m2, which is highly demanding in both scenarios. For the outer planet missions, only flyby scenarios with a targeted release of the probe were considered. The entry probes for the outer planets are subjected to heat fluxes above 100MW/m2, which is even more challenging the Thermal Protection Systems (TPS) and therefore requiring the use of special high temperature protection technology to prevent the destruction during the entry. ESA efforts for future missions are directed towards the development of an European Light Ablative Material (ELAM), though used in PEP study only for the Back Cover of the Entry Module. The TPS as well as both radiative and convective heat fluxes need simulations and verification by means of ground facility experiments. Based on the lessons learned from previous mission studies (mission to a near-Earth objects c.f. Marco Polo, Deimos Sample return), an Atmospheric Mars Sample Return is now under study. For sample return missions on return to Earth, a passive re-entry capsule delivering the sample(s) would need to withstand heat fluxes of around 15MW/m2. A MSR mission is currently investigated in cooperation with NASA to be launched in the mid 2020's and could take advantage of the TPS technology developments, such as ELAM. We present an overview of the assumptions and results of the Entry Probe mission studies and related technology developments.

  14. Large scale atmospheric waves in the Venus mesosphere as seen by the VeRa Radio Science instrument on Venus Express

    NASA Astrophysics Data System (ADS)

    Tellmann, Silvia; Häusler, Bernd; Hinson, David P.; Tyler, G. Leonard; Andert, Thomas P.; Bird, Michael K.; Imamura, Takeshi; Pätzold, Martin; Remus, Stefan

    2015-04-01

    Atmospheric waves on all spatial scales play a crucial role in the redistribution of energy, momentum, and atmospheric constituent in planetary atmosphere and are thought to be involved in the development and maintenance of the atmospheric superrotation on Venus. The Venus Express Radio-Science Experiment VeRa sounded the Venus neutral atmosphere and ionosphere in Earth occultation geometry using the spacecraft radio subsystem at two coherent frequencies. Radial profiles of neutral number density, covering the altitude range 40-90 km, are then converted to vertical profiles of temperature and pressure, assuming hydrostatic equilibrium. The extensive VeRa data set enables us to study global scale atmospheric wave phenomena like thermal tides in the mesosphere and troposphere. A pronounced local time dependency of the temperature is found in the mesosphere at different altitude levels. Wave-2 structures dominate the low latitude range in the upper mesosphere while the higher latitudes show a strong wave-1 structure at the top of the cloud layer. The investigation of these wave structures provides valuable information about the energy transport in the atmosphere.

  15. Composition and Chemistry of the Neutral Atmosphere of Venus

    NASA Astrophysics Data System (ADS)

    Marcq, E.; Millis, F.; Sandor, B.; Vandaele, A. C.

    2014-04-01

    With the pending ending of the ESA Venus Express mission after 8 years of scientific success, a new page in the in situ exploration of the inner solar system is on the verge of being turned. Considering how much our vision of Venus has been updated and refined thanks to it, the scientific community has decided to summarize our new picture of Venus in a dedicated book. This talk aims at presenting the structure and some contents of the Composition and Chemistry of the Neutral Atmosphere chapter.

  16. Studying the surface composition of Venus from orbit

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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 500C 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  18. Habitats for life in the Venusian Environment? Can the VENUS EXPRESS payload answer?

    NASA Astrophysics Data System (ADS)

    Muller, C.

    2003-04-01

    The Venusian conditions are unique in the solar system. Venus abounds in molecules which could feed a life form except that the usual missing factor, energy, is present in excessive amounts from both active geothermic phenomena and from the nearby solar radiation trapped in a dense carbon dioxide atmosphere. Its surface conditions are hotter than the best practiced in hospital sterilisation; volcanism injects highly toxic gases which in the absence of water can accumulate in the atmosphere. Its upper atmosphere lays bare to solar radiation with only carbon dioxide to act as a confirmed EUV filter, so any consideration of life might seem excessive compared to what was known from life on earth before extremophile bacterias were discovered in dark undersea high temperature sulphur rich volcanic vents. However, some regions of the atmosphere might show conditions similar to the earth surface and could be a habitat of earth like microbial life. A synergy between the different atmospheric instruments of the VENUS-Express payload: SPICAM, VIRTIS and PFS can provide the way to probe the actual environmental conditions of this region and to check its capabilities of preserving an extant life or providing nutrients to a new one.

  19. Mariner-Venus 1967

    NASA Technical Reports Server (NTRS)

    1971-01-01

    Detailed information on the spacecraft performance, mission operations, and tracking and data acquisition is presented for the Mariner Venus 1967 and Mariner Venus 1967 extension projects. Scientific and engineering results and conclusions are discussed, and include the scientific mission, encounter with Venus, observations near Earth, and cruise phase of the mission. Flight path analysis, spacecraft subsystems, and mission-related hardware and computer program development are covered. The scientific experiments carried by Mariner 5 were ultraviolet photometer, solar plasma probe, helium magnetometer, trapped radiation detector, S-band radio occultation, dual-frequency radio propagation, and celestial mechanics. The engineering experience gained by converting a space Mariner Mars 1964 spacecraft into one flown to Venus is also described.

  20. Mars Express and Venus Express multi-point observations of geoeffective solar flare events in December 2006

    NASA Astrophysics Data System (ADS)

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

    2008-05-01

    In December 2006, a single active region produced a series of proton solar flares, with X-ray class up to the X9.0 level, starting on 5 December 2006 at 10:35 UT. A feature of this X9.0 flare is that associated MeV particles were observed at Venus and Mars by Venus Express (VEX) and Mars Express (MEX), which were ˜80° and ˜125° east of the flare site, respectively, in addition to the Earth, which was ˜79° west of the flare site. On December 5, 2006, the plasma instruments ASPERA-3 and ASPERA-4 on board MEX and VEX detected a large enhancement in their respective background count levels. This is a typical signature of solar energetic particle (SEP) events, i.e., intensive MeV particle fluxes. The timings of these enhancements were consistent with the estimated field-aligned travel time of particles associated with the X9.0 flare that followed the Parker spiral to reach Venus and Mars. Coronal mass ejection (CME) signatures that might be related to the proton flare were twice identified at Venus within <43 and <67 h after the flare. Although these CMEs did not necessarily originate from the X9.0 flare on December 5, 2006, they most likely originated from the same active region because these characteristics are very similar to flare-associated CMEs observed on the Earth. These observations indicate that CME and flare activities on the invisible side of the Sun may affect terrestrial space weather as a result of traveling more than 90° in both azimuthal directions in the heliosphere. We would also like to emphasize that during the SEP activity, MEX data indicate an approximately one-order of magnitude enhancement in the heavy ion outflow flux from the Martian atmosphere. This is the first observation of the increase of escaping ion flux from Martian atmosphere during an intensive SEP event. This suggests that the solar EUV flux levels significantly affect the atmospheric loss from unmagnetized planets.

  1. Basic facts about Venus

    NASA Technical Reports Server (NTRS)

    Colin, L.

    1983-01-01

    Because of the disturbing influence of the earth's atmosphere on terrestrial and airborne telescopy, radiometry, thermal mapping, spectroscopy, polarimetry and radar astronomy of Venus, major improvements in the body of theory concerning that planet, began with the Mariner 2 planetary exploration program in 1962. The effect of spacecraft exploration culminated with the influx of data yielded by the Pioneer Venus and Venera 11 and 12 missions of 1978. Attention is presently given to the quantitative enhancement of widely accepted, basic facts about Venus that has resulted from the analysis of space probe data, together with an overview of the major features of past and planned planetary missions.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  3. Synthesis of global thematic mapping, Venus: Geologic correlations/questions for the Magellan gravity mission

    NASA Technical Reports Server (NTRS)

    Crumpler, L. S.; Aubele, J. C.; Head, J. W.

    1993-01-01

    An important characteristic of the Magellan mission and the resulting data is that it is both global in coverage as well as extremely high in resolution. As a result, global questions may be addressed based on the constraints of extremely detailed geological evidence. An important first step in the task of interpreting the global geological record will be a synthesis of the primary geological characteristics and their relationship to significant questions. The following is a brief synthesis based on a comparison of mapped distributions, initial interpretations, and some questions that these results raise.

  4. Hybrid Simulations of Venus' Dynamic Plasma Environment

    NASA Astrophysics Data System (ADS)

    Wiehle, S.; Motschmann, U. M.; Fraenz, M.

    2013-12-01

    The interaction of a dynamic solar wind with the plasma environment of Venus is studied using a 3D hybrid simulation code. Due to the lack of a shielding magnetosphere, Venus' plasma environment is highly sensitive to fluctuations in the upstream solar wind, which are known to happen on short time scales (~1min) compared to the reaction time of the upper ionosphere (~30min). Events like a magnetic sector boundary crossing or the sudden increase or decrease of upstream velocity can cause significant changes to the plasma environment. In data of missions like the ongoing Venus Express mission, variations in the solar wind cannot be measured at the same time as the modifications to the close-by plasma environment they induce and vice versa. Simulations, on the other hand, provide the opportunity to obtain information from all places at the same time under controlled changes of the upstream conditions. In a series of self-consistent simulations using the A.I.K.E.F. (Adaptive Ion Kinetic Electron Fluid) 3D hybrid simulation code, we simulated Venus' plasma environment and analyzed the consequences of dynamic solar wind induced distortions like changes of the magnetic field direction and varying solar wind velocity. We use increasing levels of grid refinement in the vicinity of the planetary body to better resolve the processes in Venus' strong ionosphere, which allows the simulation of features like ionospheric magnetization states which are known to be strongly related to the solar wind upstream conditions.

  5. Revealing the face of Venus: Magellan

    NASA Technical Reports Server (NTRS)

    1993-01-01

    An overview of the Magellan spacecraft and mission is presented. Topics covered include: a description of the Magellan spacecraft; Venus geology; Venus gravity; synthetic aperture radar; and radar sensing.

  6. Progress towards a Venus reference cloud model

    NASA Astrophysics Data System (ADS)

    Wilson, Colin; Ignatiev, Nikolay; Marcq, Emmanuel

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

  7. Introduction to the special issue on Venus exploration

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

  8. Priorities for Venus Exploration

    NASA Astrophysics Data System (ADS)

    Glaze, L. S.; Beauchamp, P. M.; Chin, G.; Crisp, D.; Grimm, R. E.; Herrick, R. R.; Johnston, S.; Limaye, S. S.; Smrekar, S. E.; Ocampo, A.; Thompson, T. W.

    2013-12-01

    Venus remains one of the most enigmatic bodies in our Solar System. Important questions remain regarding the origin and evolution of the atmosphere, the history of the surface and interior, and how the surface and atmosphere interact. In a broader context, understanding Venus has implications for understanding the evolution of terrestrial planets in our Solar System as well as for interpreting the growing set of observations of extra-solar planets. The Venus Exploration Analysis Group (VEXAG), established in 2005, is chartered by NASA's Planetary Science Division and reports its findings to the NASA Advisory Council. Open to all interested scientists, VEXAG regularly evaluates Venus exploration goals, scientific objectives, investigations and critical measurement requirements, including especially recommendations in the NRC Decadal Survey and the Solar System Exploration Strategic Roadmap. At the last general meeting in November 2012, VEXAG resolved to update the scientific priorities and strategies for Venus exploration. To achieve this goal, three major tasks were defined for 2013, (1) update the document prioritizing Goals, Objectives and Investigations for Venus Exploration, (2) develop a Roadmap for Venus exploration that is consistent with VEXAG priorities as well as Planetary Decadal Survey priorities, and (3) develop a white paper on technologies for Venus missions. Proposed versions of all three documents were presented at the VEXAG general meeting in November 2013. Here, we present the findings and final versions of all three documents for community comment and feedback. A follow-on Workshop on Venus Exploration Targets is also being planned for the early summer of 2014. The workshop will provide a forum for the Venus science community to discuss approaches for addressing high priority investigations. Participants will be encouraged to present their ideas for specific targets on Venus (interior, surface and atmosphere) as well as to present specific data requirements (measurement type, resolution, precision, etc.) needed to answer key questions.

  9. The geophysics of Venus

    NASA Astrophysics Data System (ADS)

    Solomon, S. C.

    1993-07-01

    Data obtained from the Magellan mission to Venus are discussed with particular attention given to surface age, tectonics, gravity anomalies, catastrophic resurfacing and evolutionary hypotheses, and high-resolution gravity measurements. It is concluded that the inner workings of Venus manifest themselves at the surface in a fashion very different from that on earth. The surface of Venus is surprisingly unscarred by tectonic deformation and volcanic flows and it has been subjected to a unique resurfacing history that challenges the ability to interpret it.

  10. Detailed Expression Pattern of Aldolase C (Aldoc) in the Cerebellum, Retina and Other Areas of the CNS Studied in Aldoc-Venus Knock-In Mice

    PubMed Central

    Ajioka, Itsuki; Yamazaki, Maya; Abe, Manabu; Oh-Nishi, Arata; Sakimura, Kenji; Sugihara, Izumi

    2014-01-01

    Aldolase C (Aldoc, also known as zebrin II), a brain type isozyme of a glycolysis enzyme, is expressed heterogeneously in subpopulations of cerebellar Purkinje cells (PCs) that are arranged longitudinally in a complex striped pattern in the cerebellar cortex, a pattern which is closely related to the topography of input and output axonal projections. Here, we generated knock-in Aldoc-Venus mice in which Aldoc expression is visualized by expression of a fluorescent protein, Venus. Since there was no obvious phenotypes in general brain morphology and in the striped pattern of the cerebellum in mutants, we made detailed observation of Aldoc expression pattern in the nervous system by using Venus expression in Aldoc-Venus heterozygotes. High levels of Venus expression were observed in cerebellar PCs, cartwheel cells in the dorsal cochlear nucleus, sensory epithelium of the inner ear and in all major types of retinal cells, while moderate levels of Venus expression were observed in astrocytes and satellite cells in the dorsal root ganglion. The striped arrangement of PCs that express Venus to different degrees was carefully traced with serial section alignment analysis and mapped on the unfolded scheme of the entire cerebellar cortex to re-identify all individual Aldoc stripes. A longitudinally striped boundary of Aldoc expression was first identified in the mouse flocculus, and was correlated with the climbing fiber projection pattern and expression of another compartmental marker molecule, heat shock protein 25 (HSP25). As in the rat, the cerebellar nuclei were divided into the rostrodorsal negative and the caudoventral positive portions by distinct projections of Aldoc-positive and negative PC axons in the mouse. Identification of the cerebellar Aldoc stripes in this study, as indicated in sample coronal and horizontal sections as well as in sample surface photos of whole-mount preparations, can be referred to in future experiments. PMID:24475166

  11. Venus - Ushas Mons

    NASA Technical Reports Server (NTRS)

    1990-01-01

    This area of Venus northeast of Ushas Mons measures 40 by 112 kilometers (25 by 70 miles) and shows evidence of possible explosive volcanism. A surface deposit that shows brightly in radar extends and broadens away from the 1 kilometer diameter (0.6 mile diameter) crater in the middle of the image. The deposit is brighter near the crater, fades gradually into the plains and ends about 10 kilometers (6 miles) from the crater. The underlying crisscross pattern becomes more visible away from the crater as the covering deposit thins out. These characteristics are typical of deposits on Earth formed by fallout from volcanic explosion plumes. A similar but darker deposit extends to the right of the crater. The crater on the western edge of the image also shows similar deposits. North is at the top of the image. The Magellan Mission Magellan is a NASA spacecraft mission to map the surface of Venus with imaging radar. The basic scientific instrument is a synthetic aperture radar, or SAR, which can look through the thick clouds perpetually shielding the surface of Venus. Magellan is in orbit around Venus which completes one turn around its axis in 243 Earth days. That period of time, one Venus day, is the length of Magellan's primary mission. During that time Magellan will map about 80 percent of the Venus surface. Subsequent missions of equal duration will provide complete mapping of the planet. Magellan was launched May 4, 1989, aboard the space shuttle Atlantis and went into orbit around Venus August 10, 1990. The spacecraft completes one orbit every three hours and 15 minutes, passing as close to the planet as 294 kilometers (183 miles) and as far away from Venus as 8,472 kilometers (5,265 miles). The smallest objects seen in this image measure approximately 120 meters (400 feet).

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

    NASA Technical Reports Server (NTRS)

    Chin, Gordon

    2011-01-01

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

  13. Ionospheric photoelectrons at Venus: Initial observations by ASPERA-4 ELS

    NASA Astrophysics Data System (ADS)

    Coates, A. J.; Frahm, R. A.; Linder, D. R.; Kataria, D. O.; Soobiah, Y.; Collinson, G.; Sharber, J. R.; Winningham, J. D.; Jeffers, S. J.; Barabash, S.; Sauvaud, J.-A.; Lundin, R.; Holmström, M.; Futaana, Y.; Yamauchi, M.; Grigoriev, A.; Andersson, H.; Gunell, H.; Fedorov, A.; Thocaven, J.-J.; Zhang, T. L.; Baumjohann, W.; Kallio, E.; Koskinen, H.; Kozyra, J. U.; Liemohn, M. W.; Ma, Y.; Galli, A.; Wurz, P.; Bochsler, P.; Brain, D.; Roelof, E. C.; Brandt, P.; Krupp, N.; Woch, J.; Fraenz, M.; Dubinin, E.; McKenna-Lawlor, S.; Orsini, S.; Cerulli-Irelli, R.; Mura, A.; Milillo, A.; Maggi, M.; Curtis, C. C.; Sandel, B. R.; Hsieh, K. C.; Szego, K.; Asamura, A.; Grande, M.

    2008-05-01

    We report the detection of electrons due to photo-ionization of atomic oxygen and carbon dioxide in the Venus atmosphere by solar helium 30.4 nm photons. The detection was by the Analyzer of Space Plasma and Energetic Atoms (ASPERA-4) Electron Spectrometer (ELS) on the Venus Express (VEx) European Space Agency (ESA) mission. Characteristic peaks in energy for such photoelectrons have been predicted by Venus atmosphere/ionosphere models. The ELS energy resolution (Δ E/ E˜7%) means that these are the first detailed measurements of such electrons. Considerations of ion production and transport in the atmosphere of Venus suggest that the observed photoelectron peaks are due primarily to ionization of atomic oxygen.

  14. MESSENGER's Venus Flyby: Early Results

    NASA Astrophysics Data System (ADS)

    Solomon, Sean C.; MESSENGER Science Team

    2007-10-01

    The MESSENGER spacecraft flew by Venus on 5 June 2007 for a gravity assist to its subsequent encounters with Mercury. Closest approach was at 338 km altitude over 12S, 165E, near the boundary between the lowlands plains of Rusalka Planitia and the rifted uplands of Aphrodite Terra. All of the MESSENGER instruments operated during the flyby. The camera system imaged the night side in near-infrared bands and obtained color and higher-resolution monochrome mosaics of both the approaching and departing hemispheres. The ultraviolet and visible spectrometer obtained profiles of atmospheric species on the day and night sides as well as observations of the exospheric tail on departure. The visible and infrared spectrograph made observations of the planet near closest approach to gather compositional information on the upper atmosphere and clouds, and the laser altimeter carried out passive radiometry at 1064 nm and attempted to range to one or more cloud decks for several minutes near closest approach. That the European Space Agency's Venus Express mission was operating at the time of the flyby permitted the simultaneous observation of the planet from two independent spacecraft, a situation of particular value for characterization of the particle and field environment at Venus. MESSENGER's energetic particle and plasma spectrometer observed charged particle acceleration at the Venus bow shock and elsewhere, and the magnetometer provided measurements of the upstream interplanetary magnetic field (IMF), bow shock signatures, and pick-up ion waves as a reference for energetic particle and plasma observations by both spacecraft. The encounter also enabled two-point measurements of IMF penetration into the Venus ionosphere, primary plasma boundaries, and the near-tail region.

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

    PubMed

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

    2015-12-01

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

  16. Venusian ion populations and bow shock as seen by the ASPERA-4 ion instrument on Venus Express

    NASA Astrophysics Data System (ADS)

    Grande, M.; Whittaker, I.; Guymer, G.; Barabash, S.

    2008-09-01

    Introduction We examine ion populations at Venus. Previous models use magnetic crossing points to derive the bow shock position. The current work uses data from the ASPERA-4 (Analyser of Space Plasmas and Energetic Atoms) [1] instrument to measure ion populations and derive a bow shock position at Venus. Instrumentation The ASPERA-4 instrument flies onboard Venus Express (VEX) and is comprised of five different detectors (Barabash et al 2006 [1]). A neutral particle detector and analyser, an electron spectrometer and the Ion Mass Analyser (IMA) (ref). This paper uses the IMA instrument for all its data and an explanation of the specifications is required. The instrument is a top hat electrostatic analyser; it runs through voltages to scan look angles and also acceptance energies. In one look direction it scans through 96 different energy values before changing to the next. A full scan of all look directions and energies takes 192 seconds. Data Collection All data is weighed dependant upon its probability of the spacecraft measuring at a particular point and when fitted produces a value of 1.24 RV, somewhat closer distance for the sub solar point than previous authors - see figure 1. We separate the data according to slow or fast solar wind and not the similarities and differences in the results derived. The inbound and outbound bow shock crossings were taken by inspection of 106 orbits between November 2006 and February 2007. Any orbits where the crossing point was not clear or with data missing were ignored. The occupational probability is found from orbital mechanics. By setting up a grid and deriving the amount of time it takes to cross each square the probability as a whole can then be determined. Ion distribution plots Two dimensional maps of the ions are produced and the bow shock model overplotted to verify its accuracy, as shown in figure 3. The test of the bow shock is to place it upon real data and examine the fit. To do this ion distribution plots are created and have the bow shock model placed upon them. The maps are shown in fig 8 and comprise 6 months of data from VEX in 2007. The count rates of all spectra of every orbit were stored and binned into a grid system. Each box in the grid being averaged from all values placed into it. The results were then smoothed and the maps created for individual species and plot types. Fig 3 shows maps for hydrogen ions in the x-y plane and in cylindrical coordinates signed with y. This plot is the same as a standard cylindrical plot but the r value is positive if y is positive and negative if y is negative. Effect of Coronal mass Ejections The HI imager on STEREO is able to image Coronal mass Ejections (CME) in the inner Solar System. In a recent paper, Roullard et al 2008 [2] have considered a CME observed to impact Venus, and used in situ measurements to examine the response of the magnetosphere. The plots in figure4 show the measured ion response to this and an earlier CME. We will examine the ion signatures in detail. Acknowledgements We acknowledge the contributions of the entire Aspera 4 team: S. Barabash, R. Lundin, H. Andersson, K. Brinkfeld, A. Grigoriev, H. Gunell, M. Holmström, M. Yamauchi, K. Asamura, P. Bochsler, P. Wurz, R. Cerulli-Irelli, A. Mura, A. Milillo, M. Maggi, S. Orsini, A. J. Coates, D. R. Linder, D. O. Kataria, C. C. Curtis, K. C. Hsieh, B. R. Sandel, R. A. Frahm, J. R. Sharber, J. D. Winningham, M. Grande, E. Kallio, H. Koskinen, P. Riihelä, W. Schmidt, T. Säles, J. U. Kozyra,N. Krupp, J. Woch,.S. Livi, J. G., Luhmann, S. McKenna-Lawlor, E. C. Roelof, D. J. Williams, J.-A. Sauvaud, A. Fedorov, and J.-J. Thocaven. References [1] S. Barabash, R. Lundin, H. Andersson, K. Brinkfeld, A. Grigoriev, H. Gunell, M. Holmström, M. Yamauchi, K. Asamura, P. Bochsler, P. Wurz, R. Cerulli-Irelli, A. Mura, A. Milillo, M. Maggi, S. Orsini, A. J. Coates, D. R. Linder, D. O. Kataria, C. C. Curtis, K. C. Hsieh, B. R. Sandel, R. A. Frahm, J. R. Sharber, J. D. Winningham, M. Grande, E. Kallio, H. Koskinen, P. Riihelä, W. Schmidt, T. Säles, J. U. Kozyra,N. Krupp, J. Woch,.S. Livi, J. G., Luhmann, S. McKenna-Lawlor, E. C. Roelof, D. J. Williams, J.-A. Sauvaud, A. Fedorov, and J.-J. Thocaven The Analyser of Space Plasmas and Energetic Atoms (ASPERA-3) for the Mars Express Mission. SPACE SCIENCE REVIEWS, 126 (1-4): 113-164 OCT 2006 [2] P. Rouillard et al 2008 submitted Science.

  17. Venus Express: highlights of a four-year survey of our planet-neighbour

    NASA Astrophysics Data System (ADS)

    Titov, Dmitri; Svedhem, Hkan; Barabash, S.; Bertaux, J.-L.; Drossart, P.; Haeusler, B.; Korablev, O. I.; Markiewicz, W. J.; Paetzold, M.; Piccioni, G.; Taylor, F. W.; Vandaele, A.-C.; Zhang, T.

    Since April 2006 Venus Express has been performing a global survey of the remarkably dense, cloudy, and dynamic atmosphere of our near neighbour. A consistent picture of the climate on Venus is emerging on the basis of the new data, which enables us to provide an overview of the global temperature structure, the composition and its variations, the cloud morphology at various levels, the atmospheric dynamics and general circulation, and near-infrared emissions from trace species such as oxygen in the mesosphere. Vertical profiles of atmospheric tempera-ture in the mesosphere and upper troposphere show strong variability correlated with changes in the cloud top structure and many fine details indicating dynamical processes. Temperature sounding also shows that the cloud deck at 50-60 km is convectively unstable, in agreement with the analysis of UV images. Imaging also reveals strong latitudinal variations and significant temporal changes in the global cloud top morphology, which will inevitably 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, marking vast polar depressions that form as a result of the Hadley-type meridional circulation. Stellar and solar occultation measurements have revealed an extended upper haze of submicron particles and provided information on its optical properties. Solar occultation observations and deep atmosphere spectroscopy in several spectral transparency windows have quantified the distribution of the major trace gases H2O, SO2, CO, COS and their variations above and below the clouds, and so provided important input and validation for models of chemical cycles and dynamical transport. Cloud motion monitoring has characterised the mean state of the atmospheric circulation as well as its vari-ability. Low and middle latitudes show an almost constant zonal wind speed of 100+/-20 m/s at the cloud tops and vertical wind sheer of 2-3 m/s/km. Towards the pole, the wind speed drops quickly and the vertical shear vanishes. The meridional poleward wind ranges from 0 to about 15 m/s and there is some indication that it may change its direction at high latitudes. Comparison of the thermal wind field derived from temperature sounding to the cloud tracked winds confirms the approximate validity of cyclostrophic balance, at least in the latitude range from 30 S to 70S. Non-LTE infrared emissions in the lines of O2, NO, CO2, OH originating near the mesopause at 95-105 km altitude were detected and mapped. The data show that the peak intensity occurs close to the anti-solar point, which is consistent with current models of the thermospheric circulation.

  18. Venus Express observations of magnetic field fluctuations in the magnetosheath: A case study and a statistical study

    NASA Astrophysics Data System (ADS)

    Du, J.; Zhang, T. L.; Wang, C.; Volwerk, M.; Delva, M.; Baumjohann, W.

    2009-04-01

    Using magnetosheath crossings of Venus Express on two consecutive days, we investigate magnetic fluctuations in the same locations for two extreme interplanetary magnetic field orientations, i.e. nearly along and nearly perpendicular to the solar wind flow. The strength and properties of the fluctuations are strongly controlled by the types of the upstream bow shock. The magnetic fluctuations behind a quasi-parallel bow shock are quite strong and turbulent, having a strongly varying angle αeB between maximum variance direction of the fluctuations and the direction of the magnetic field, and may be convected from the upstream wave region in the foreshock. The magnetic fluctuations behind a quasi-perpendicular bow shock are less intensive and wave-like, showing a less perturbed angle αeB, and are probably generated locally by some instability. Based on the Venus Express observations in 2006 and 2007, we also investigate the spatial distributions of magnetic field fluctuations in the Venus magnetosheath statistically. Both the compressional and transverse components of the field fluctuations decrease as the θBn angle (the angle between the interplanetary magnetic field and the bow shock normal) increases.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  20. A Retrospective Look at the Collected Results on the Large Scale Ionospheric Magnetic Fields at Venus

    NASA Astrophysics Data System (ADS)

    Luhmann, J. G.; Ma, Y.-J.; Villarreal, M.; Russell, C. T.; Zhang, T.-L.; Alvarez, K.

    2015-10-01

    We revisit the collected large scale ionospheric magnetic field results obtained by the Pioneer Venus Orbiter (PVO) and Venus Express (VEX) missions to ask how much we really understand about that field's global structure. To assist in this assessment we make use of several previously described MHD simulations of the solar wind interaction that reproduce its other observed features. These comparisons help to support our conceptual pictures in some cases, and to raise questions in others.

  1. Power system comparison for the Pluto Express mission

    SciTech Connect

    Harty, R.B.

    1995-12-31

    This paper presents a comparison of three advanced radioisotope power systems, along with a down sized RTG for the Pluto Express mission. These three advanced radioisotope power systems were the Radioisotope Alkali Metal Thermal--to-Electric Converter (RAMTEC), Radioisotope Stirling, and Radioisotope Thermophotovoltaic (RTPV). For the Pluto Express mission, the power requirement at the end of the 10-y mission is 74 We. It was found that all three advanced power systems could meet the required end of mission power with two General Purpose Heat Source (GPHS) modules. The RTG required six modules to meet the power requirement. Only the RAMTEC and RTPV met the mass goal of 9.5 kg. The AMTEC has a radiator area more than a factor of 10 lower than the Stirling and RTPV power systems, which simplifies spacecraft integration.

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

    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 Earths 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.

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

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  4. 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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    One of the difficulties in modeling Venus' nightside atmospheric windows is the need to apply CO2 continuum opacity due to collision-induced CO2 bands and/or extreme far wings of strong allowed CO2 bands. Characterizing the CO2 continuum absorption at near-IR wavelengths as well as searching for a possible vertical gradient of minor species near the surface require observations over different surface elevations. The largest change in altitude occurs during a passage above Maxwell Montes at high northern latitudes. In 2011, 2012 and 2013 the SPICAV instrument aboard the Venus Express satellite performed three sets of observations over Maxwell Montes with variation of surface altitude from -2 to 9 km in the 1.10, 1.18 and 1.28-?m windows. The retrieved CO2 continuum absorption for the 1.10- and 1.18-?m windows varies from 0.29 to 0.6610-9 cm-1 amagat-2 and from 0.30 to 0.7810-9 cm-1 amagat-2, respectively, depending on the assumed input parameters. The retrieval is sensitive to possible variations of the surface emissivity. Our values fall between the results of Bzard et al., (2009, 2011) based on VIRTIS-M observations and laboratory measurements by Snels et al. (2014). We can also conclude that the continuum absorption at 1.28 ?m can be constrained below 2.010-9 cm-1 amagat-2. Based on the 1.18 ?m window the constant H2O mixing ratio varying from 25.7+1.4-1.2 ppm to 29.4+1.6-1.4 ppm has been retrieved assuming the surface emissivity of 0.95 and 0.6, respectively. No firm conclusion from SPICAV data about the vertical gradient of water vapor content at 10-20 km altitude could be drawn because of low signal-to-noise ratio and uncertainties in the surface emissivity.

  5. Venus cartography

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

  6. Pioneer Venus orbiter

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The orbiter mission of the Pioneer Venus probe is discussed. In accordance with the low-cost Pioneer Venus concept, NASA intends to use the same basic spacecraft, known as the bus, for the execution of the two missions. The bus will be equipped with all of the subsystems common to the probe and orbiter missions (for example, thermal control, solar cells and power supply, attitude measurement and control, telemetry and communication electronics, and auxiliary propulsion unit). For the 1977 mission, the bus will be equipped with the large and small probes and a special antenna system. For the orbiter mission, the bus will be equipped with a retro-propulsion motor and a high-gain antenna. A diagram of the system envisaged is shown.

  7. Magellan: The unveiling of Venus

    NASA Technical Reports Server (NTRS)

    1989-01-01

    In the late 1970s and early 1980s, the United States and the Soviet Union sent the Pioneer Venus and Venera spacecraft, respectively, to study Venus more closely and to image its surface with radar. These missions have answered many questions about Venus, but many more questions remain unanswered about the extent to which Venus' surface was shaped by volcanoes, plate tectonics, impact craters, and water and wind erosion. To help answer these remaining questions a new radar imaging spacecraft Magellan will be launched from the Space Shuttle. Magellan will spend eight months mapping most of the planet at a resolution nearly ten times better than any previous views of the surface. The mission of Magellan, the radar equipment, orbiting of Venus, planetary imaging, and surface exploration are discussed.

  8. Geologic Analysis of the Surface Thermal Emission Images Taken by the VMC Camera, Venus Express

    NASA Astrophysics Data System (ADS)

    Basilevsky, A. T.; Shalygin, E. V.; Titov, D. V.; Markiewicz, W. J.; Scholten, F.; Roatsch, Th.; Fiethe, B.; Osterloh, B.; Michalik, H.; Kreslavsky, M. A.; Moroz, L. V.

    2010-03-01

    Analysis of Venus Monitoring Camera 1-µm images and surface emission modeling showed apparent emissivity at Chimon-mana tessera and shows that Tuulikki volcano is higher than that of the adjacent plains; Maat Mons did not show any signature of ongoing volcanism.

  9. Chemical Weathering Kinetics of Basalt on Venus

    NASA Technical Reports Server (NTRS)

    Fegley, Bruce, Jr.

    1997-01-01

    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.

  10. The role of magnetospheric energy sources on Titan and Venus: A comparative evaluation

    NASA Astrophysics Data System (ADS)

    Mueller-Wodarg, I.; Yelle, R.; Cui, J.; Galand, M.

    2010-05-01

    The atmospheres of Venus and Titan on one level share many similarities, but at the same time host interesting differences which motivate a more comprehensive comparison. As a result of highly successful missions like Pioneer Venus and Venus Express, the atmosphere of Venus is the most extensively observed planetary atmosphere apart from the Earth's. The ongoing tour of Cassini-Huygens has led to a vast increase in our knowledge and understanding of Titan's atmosphere, but important information gaps remain. How much can we learn from Venus when attempting to understand the upper atmosphere of Titan? One fundamental question to address is that of the global energy balance in the atmosphere of Titan, and in particular in the upper atmosphere (thermosphere/ionosphere region), which in turns drives the global dynamics and affects the neutral and ion species distribution. One potentially important energy source on Titan derives from magnetosphere-atmosphere coupling by a combination of energetic particle precipitation and the closing of magnetospheric currents in the ionosphere. As a result of weaker solar forcing at Titan, these magnetospheric energy sources may play a comparatively stronger factor in driving the global energy balance and thereby dynamics on Titan than they do on Venus. This paper will evaluate the energy balance on Venus and Titan by assessing the ease at which numerical models driven by solar heating reproduce observed thermosphere densities. We will discuss the relative roles of solar and magnetospheric energy sources on Venus and Titan and outline the wider consequences of their differences.

  11. Orbital Express mission operations planning and resource management using ASPEN

    NASA Astrophysics Data System (ADS)

    Chouinard, Caroline; Knight, Russell; Jones, Grailing; Tran, Daniel

    2008-04-01

    As satellite equipment and mission operations become more costly, the drive to keep working equipment running with less labor-power rises. Demonstrating the feasibility of autonomous satellite servicing was the main goal behind the Orbital Express (OE) mission. Like a tow-truck delivering gas to a car on the road, the "servicing" satellite of OE had to find the "client" from several kilometers away, connect directly to the client, and transfer fluid (or a battery) autonomously, while on earth-orbit. The mission met 100% of its success criteria, and proved that autonomous satellite servicing is now a reality for space operations. Planning the satellite mission operations for OE required the ability to create a plan which could be executed autonomously over variable conditions. As the constraints for execution could change weekly, daily, and even hourly, the tools used create the mission execution plans needed to be flexible and adaptable to many different kinds of changes. At the same time, the hard constraints of the plans needed to be maintained and satisfied. The Automated Scheduling and Planning Environment (ASPEN) tool, developed at the Jet Propulsion Laboratory, was used to create the schedule of events in each daily plan for the two satellites of the OE mission. This paper presents an introduction to the ASPEN tool, an overview of the constraints of the OE domain, the variable conditions that were presented within the mission, and the solution to operations that ASPEN provided. ASPEN has been used in several other domains, including research rovers, Deep Space Network scheduling research, and in flight operations for the NASA's Earth Observing One mission's EO1 satellite. Related work is discussed, as are the future of ASPEN and the future of autonomous satellite servicing.

  12. Some questions about the Venus atmosphere from past measurements

    NASA Astrophysics Data System (ADS)

    Limaye, Sanjay

    2015-11-01

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

  13. Ion Escape From Mars and Venus (Invited)

    NASA Astrophysics Data System (ADS)

    Barabash, S. V.

    2013-12-01

    Ions in the upper atmospheres / exospheres of planets can be accelerated by electric fields resulting from the planet - solar wind interaction (external forcing). Also, the acceleration (energy gain) may also result from the redistribution of the inner energy of the atmosphere. If an ion gains an energy exceeding the planet's escape energy, it escapes the atmosphere. Therefore, all planetary atmospheres lose their matter through the ion escape channel. For planets with high gravity such as Venus the escape energy is high (the oxygen escape energy is about 10 eV) and the ion escape due to external forcing dominates. The electric fields acting on ions include convective field of the solar wind (pick-up process), fields resulting from pressure gradients ('polar' wind), induced electric field (JxB-force), and fields of electromagnetic waves (wave-plasma interaction). We review the most recent measurements of the ion escape from the atmospheres of Mars and Venus conducted by the Mars Express and Venus Express missions. In the light of the coming MAVEN mission the focus will be given to the review of the measured escape rates, explanation of the differences between various published numbers, and discussion on experimental difficulties in calculating the global escape rates from in-situ measurements. We will also discuss how the escape rates depend on the upstream and solar conditions.

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

    Electron density profiles of Venus' ionosphere are inverted from the Venus Express (VEX) one-way open-loop radio occultation experiments carried out by the Shanghai 25 m antenna from November 2011 to January 2012 at solar maximum conditions and by the New Norcia 35 m antenna from August 2006 to June 2008 at solar intermediate conditions. The electron density profile (from 110 km to 400 km), retrieved from the X-band egress observation at the Shanghai station, shows a single peak near 147 km with a peak density of about 2 104 cm-3 at a solar zenith angle of 94. As a comparison, the VEX radio science (VeRa) observations at the New Norcia station were also examined, including S- and X-band and dual-frequency data in the ingress mode. The results show that the electron density profiles retrieved from the S-band data are more analogous to the dual-frequency data in terms of the profile shape, compared with the X-band data. Generally, the S-band results slightly underestimate the magnitude of the peak density, while the X-band results overestimate it. The discrepancy in the X-band profile is probably due to the relatively larger unmodeled orbital errors. It is also expected that the ionopause height is sensitive to the solar wind dynamical pressure in high and intermediate solar activities, usually in the range of 200-1000 km on the dayside and much higher on the nightside. Structural variations (bulges and fluctuations) can be found in the electron density profiles during intermediate solar activity, which may be caused by the interaction of the solar wind with the ionosphere. Considerable ionizations can be observed in Venus' nightside ionosphere, which are unexpected for the Martian nightside ionosphere in most cases.

  15. Hesperos: A Post-Alpbach Mission Result

    NASA Astrophysics Data System (ADS)

    Koopmans, R.-J.; Bia?ek, A.; Donohoe, A.; Fernndez Jimnez, M.; Frasl, B.; Gurciullo, A.; Kleinschneider, A.; ?osiak, A.; Mannel, T.; Muoz Elorza, I.; Nilsson, D.; Oliveira, M.; Srensen-Clark, P. M.; Timoney, R.; van Zelst, I.

    2015-10-01

    Despite similarities between Venus and Earth relatively little is known about its internal structure and processes. For this reason a geophysical mission to Venus is proposed. Its aim is to investigate the existence of tectonic activity, Venus internal structure and composition. The mission consists of an orbiter and balloon that will investigate Venus for a total of five years.

  16. Automated and Adaptive Mission Planning for Orbital Express

    NASA Technical Reports Server (NTRS)

    Chouinard, Caroline; Knight, Russell; Jones, Grailing; Tran, Daniel; Koblick, Darin

    2008-01-01

    The Orbital Express space mission was a Defense Advanced Research Projects Agency (DARPA) lead demonstration of on-orbit satellite servicing scenarios, autonomous rendezvous, fluid transfers of hydrazine propellant, and robotic arm transfers of Orbital Replacement Unit (ORU) components. Boeing's Autonomous Space Transport Robotic Operations (ASTRO) vehicle provided the servicing to the Ball Aerospace's Next Generation Serviceable Satellite (NextSat) client. For communication opportunities, operations used the high-bandwidth ground-based Air Force Satellite Control Network (AFSCN) along with the relatively low-bandwidth GEO-Synchronous space-borne Tracking and Data Relay Satellite System (TDRSS) network. Mission operations were conducted out of the RDT&E Support Complex (RSC) at the Kirtland Air Force Base in New Mexico. All mission objectives were met successfully: The first of several autonomous rendezvous was demonstrated on May 5, 2007; autonomous free-flyer capture was demonstrated on June 22, 2007; the fluid and ORU transfers throughout the mission were successful. Planning operations for the mission were conducted by a team of personnel including Flight Directors, who were responsible for verifying the steps and contacts within the procedures, the Rendezvous Planners who would compute the locations and visibilities of the spacecraft, the Scenario Resource Planners (SRPs), who were concerned with assignment of communications windows, monitoring of resources, and sending commands to the ASTRO spacecraft, and the Mission planners who would interface with the real-time operations environment, process planning products and coordinate activities with the SRP. The SRP position was staffed by JPL personnel who used the Automated Scheduling and Planning ENvironment (ASPEN) to model and enforce mission and satellite constraints. The lifecycle of a plan began three weeks outside its execution on-board. During the planning timeframe, many aspects could change the plan, causing the need for re-planning. These variable factors, ranging from shifting contact times to ground-station closures and required maintenance times, are discussed along with the flexibility of the ASPEN tool to accommodate changes to procedures and the daily or long-range plan, which contributed to the success of the mission. This paper will present an introduction to ASPEN, a more in-depth discussion on its use on the Orbital Express mission, and other relative work. A description of ground operations after the SRP deliveries were made is included, and we briefly discuss lessons learned from the planning perspective and future work.

  17. Recent discoveries of the thermospheres and ionospheres of Venus and Mars (Invited)

    NASA Astrophysics Data System (ADS)

    Witasse, O. G.

    2013-12-01

    Of all the non-terrestrial ionospheres and thermospheres, those of Venus and Mars have been explored and studied the most, thanks to the Pioneer Venus Orbiter and the Mars Global Surveyor from NASA, and the Venus Express and the Mars Express from ESA. We know that the thermosphere and ionosphere are atmospheric layers strongly influenced by solar wind and solar extreme ultra-violet and soft X-ray flux. This talk will outline the most significant discoveries made recently, which have strong implications on how atmospheres evolve and interact with the Sun. For Venus, there is the sporadic behaviour of the atomic oxygen green line emission, and there is the strong variability of the polar upper atmospheric density. For Mars, there are the responses of the upper atmosphere to solar energetic particle events, the effect of the crustal magnetic field, and the ionospheric vertical structure and boundaries. Finally, this talk will address questions that need to be answered by future missions.

  18. Orbital Express Mission Operations Planning and Resource Management using ASPEN

    NASA Technical Reports Server (NTRS)

    Chouinard, Caroline; Knight, Russell; Jones, Grailing; Tran, Daniel

    2008-01-01

    As satellite equipment and mission operations become more costly, the drive to keep working equipment running with less man-power rises.Demonstrating the feasibility of autonomous satellite servicing was the main goal behind the Orbital Express (OE) mission. Planning the satellite mission operations for OE required the ability to create a plan which could be executed autonomously over variable conditions. The Automated-Scheduling and Planning Environment (ASPEN)tool, developed at the Jet Propulsion Laboratory, was used to create the schedule of events in each daily plan for the two satellites of the OE mission. This paper presents an introduction to the ASPEN tool, the constraints of the OE domain, the variable conditions that were presented within the mission, and the solution to operations that ASPEN provided. ASPEN has been used in several other domains, including research rovers, Deep Space Network scheduling research, and in flight operations for the ASE project's EO1 satellite. Related work is discussed, as are the future of ASPEN and the future of autonomous satellite servicing.

  19. Venus within ESA probe reach

    NASA Astrophysics Data System (ADS)

    2006-03-01

    Venus Express mission controllers at the ESA Space Operations Centre (ESOC) in Darmstadt, Germany are making intensive preparations for orbit insertion. This comprises a series of telecommands, engine burns and manoeuvres designed to slow the spacecraft down from a velocity of 29000 km per hour relative to Venus, just before the first burn, to an entry velocity some 15% slower, allowing the probe to be captured into orbit around the planet. The spacecraft will have to ignite its main engine for 50 minutes in order to achieve deceleration and place itself into a highly elliptical orbit around the planet. Most of its 570 kg of onboard propellant will be used for this manoeuvre. The spacecraft’s solar arrays will be positioned so as to reduce the possibility of excessive mechanical load during engine ignition. Over the subsequent days, a series of additional burns will be done to lower the orbit apocentre and to control the pericentre. The aim is to end up in a 24-hour orbit around Venus early in May. The Venus orbit injection operations can be followed live at ESA establishments, with ESOC acting as focal point of interest (see attached programme). In all establishments, ESA specialists will be on hand for interviews. ESA TV will cover this event live from ESOC in Darmstadt. The live transmission will be carried free-to-air. For broadcasters, complete details of the various satellite feeds are listed at http://television.esa.int. The event will be covered on the web at venus.esa.int. The website will feature regular updates, including video coverage of the press conference and podcast from the control room at ESA’s Operations Centre. Media representatives wishing to follow the event at one of the ESA establishments listed below are requested to fill in the attached registration form and fax it back to the place of their choice. For further information, please contact: ESA Media Relations Division Tel : +33(0)1.53.69.7155 Fax: +33(0)1.53.69.7690 Venus Express Orbit Insertion - Tuesday 11 April 2006 ESA/ESOC, Robert Bosch Strasse, 5 - Darmstadt (Germany) PROGRAMME 07:30 - Doors open 08:45 - Start of local event, welcome addresses 09:10 - ESA TV live from Mission Control Room (MCR) starts 09:17 - Engine burn sequence starts 09:45 - Occultation of spacecraft by Venus starts 09:55 - Occultation ends 10:07 - Main engine burn ends 10:20 - Address by Jean-Jacques Dordain, ESA’s Director General, and other officials Break and buffet Interview opportunities 11:30-12:15 - Press Conference Jean-Jacques Dordain, Director General, ESA Prof. David Southwood, Director of Science, ESA Gaele Winters, Director of Operations and Infrastructure, ESA Manfred Warhaut, Flight Operations Director, ESA Håkan Svedhem, Venus Express Project Scientist, ESA Don McCoy, Venus Express Project Manager, ESA 13:15 - End of event at ESOC ACCREDITATION REQUEST FORM Venus Express Orbit Insertion - ESA/ESOC Darmstadt - 11 April 2006 First name:___________________ Surname:_____________________ Media:______________________________________________________ Address: ___________________________________________________ ____________________________________________________________ Tel:_______________________ Fax: ___________________________ Mobile :___________________ E-mail: ________________________ I will be attending the Venus Express Orbit Insertion event at the following site: [ ] Germany Location: ESA/ESOC Address: Robert Bosch Strasse 5, Darmstadt, Germany Opening hours: 07:30 - 13:00 Contact: Jocelyne Landeau-Constantin, Tel: +49.6151.902.696 - Fax: +49.6151.902.961 [ ] France Location: ESA HQ Address: 8/10, rue Mario Nikis - Paris 15, France Opening hours: 08:00 - 13:00 Contact: Anne-Marie Remondin - Tel: +33(0)1.53.69.7155 - fax: +33(0)1.53.69.7690 [ ] The Netherlands Location: Newton Room, ESA/ESTEC Address: Keplerlaan 1, Noordwijk, The Netherlands Opening hours: 08:30 - 12:30 Contact: Michel van Baal, tel. + 31 71 565 3006, fax + 31 71 565 5728 [ ] Italy Location: ESA/ESRIN Address: Via Galileo Galilei, Frascati (Rome), Italy Opening hours: 07:00 - 14:00 Contact: Franca Morgia - Tel: +39.06.9418.0951 - Fax: +39.06.9418.0952 [ ] Spain Location: ESA/ESAC Address: Urbanización Villafranca del Castillo, Villanueva de la Cañada, Madrid, Spain Opening hours: 8:30 - 13:30 Contact: Monica Oerke, Tel + 34 91 813 13 27/59 - Fax: + 34 91 813 12 19

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

    NASA Astrophysics Data System (ADS)

    Blumberg, D. G.

    2012-04-01

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

  1. AMTEC radioisotope power system for the Pluto Express mission

    SciTech Connect

    Ivanenok, J.F. III; Sievers, R.K.

    1995-12-31

    The Alkali Metal Thermal to Electric Converter (AMTEC) technology has made substantial advances in the last 3 years through design improvements and technical innovations. In 1993 programs began to produce an AMTEC cell specifically for the NASA Pluto Express Mission. A set of efficiency goals was established for this series of cells to be developed. According to this plan, cell {number_sign}8 would be 17% efficient but was actually 18% efficient. Achieving this goal, as well as design advances that allow the cell to be compact, has resulted in pushing the cell from an unexciting 2 W/kg and 2% efficiency to very attractive 40 W/kg and 18% measured efficiency. This paper will describe the design and predict the performance of a radioisotope powered AMTEC system for the Pluto Express mission.

  2. Abundance of unusual objects on the planet venus according to the data of missions of 1975-1982

    NASA Astrophysics Data System (ADS)

    Ksanfomality, L. V.

    2014-11-01

    The results of processing the archival data of the television experiment performed on the surface of the planet by the VENERA spacecraft in 1975 and 1982 are presented. In previously published papers, the author tried to show all diverse objects found by that time and their properties. In 2012-2014, new groups of objects have been found. This paper focuses on only one type of new finding (the conventional name is "hesperos") and their morphological features. It is shown that similar objects with dimensions from 13 to 25 cm, having the forms of a large fallen leaf or a spindle, are met in the regions of the planet Venus separated by distances of 900 and 4400 km.

  3. The structure of Venus' middle atmosphere and ionosphere.

    PubMed

    Ptzold, M; Husler, B; Bird, M K; Tellmann, S; Mattei, R; Asmar, S W; Dehant, V; Eidel, W; Imamura, T; Simpson, R A; Tyler, G L

    2007-11-29

    The atmosphere and ionosphere of Venus have been studied in the past by spacecraft with remote sensing or in situ techniques. These early missions, however, have left us with questions about, for example, the atmospheric structure in the transition region from the upper troposphere to the lower mesosphere (50-90 km) and the remarkably variable structure of the ionosphere. Observations become increasingly difficult within and below the global cloud deck (<50 km altitude), where strong absorption greatly limits the available investigative spectrum to a few infrared windows and the radio range. Here we report radio-sounding results from the first Venus Express Radio Science (VeRa) occultation season. We determine the fine structure in temperatures at upper cloud-deck altitudes, detect a distinct day-night temperature difference in the southern middle atmosphere, and track day-to-day changes in Venus' ionosphere. PMID:18046400

  4. On the Ionospheric Holes of Venus

    NASA Astrophysics Data System (ADS)

    Collinson, G.; Fedorov, A.; Futaana, Y.; Masunaga, K.; Hartle, R. E.; Stenberg, G.; Budnik, E.; Grebowsky, J. M.; Holmstrom, M.; andre, N.; Barabash, S. V.; Zhang, T.

    2013-12-01

    One of the most intriguing unsolved mysteries that endures from the Pioneer Venus Orbiter is that of ~1000km wide ``Holes" in the nightside Ionosphere. The phenomena remains unexplained, despite their frequent observation during the first three years of the mission, and more than thirty years having elapsed since their first description in the literature. We present new observations by the ESA Venus Express of Ionospheric Holes at very high altitudes, providing us with the opportunity to study this fascinating phenomena with modern instrumentation. We discuss the insight that these new data give us into the effect of Ionospheric Holes on atmospheric escape, and the evidence that suggests that Ionospheric Holes are due to an internal planetary magnetic field.

  5. The surface of Venus

    NASA Technical Reports Server (NTRS)

    Saunders, R. Stephen

    1990-01-01

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

  6. Venus Atmosphere and Surface Explorer

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  8. Moon Express: Lander Capabilities and Initial Payload and Mission

    NASA Astrophysics Data System (ADS)

    Spudis, P.; Richards, R.; Burns, J. O.

    2013-12-01

    Moon Express Inc. is developing a common lander design to support the commercial delivery of a wide variety of possible payloads to the lunar surface. Significant recent progress has been made on lander design and configuration and a straw man mission concept has been designed to return significant new scientific and resource utilization data from the first mission. The Moon Express lander is derived from designs tested at NASA Ames Research Center over the past decade. The MX-1 version is designed to deliver 26 kg of payload to the lunar surface, with no global restrictions on landing site. The MX-2 lander can carry a payload of 400 kg and can deliver an upper stage (designed for missions that require Earth-return, such as sample retrieval) or a robotic rover. The Moon Express lander is powered by a specially designed engine capable of being operated in either monoprop or biprop mode. The concept for the first mission is a visit to a regional pyroclastic deposit on the lunar near side. We have focused on the Rima Bode dark mantle deposits (east of crater Copernicus, around 13 N, 4 W). These deposits are mature, having been exposed to solar wind for at least 3 Ga, and have high Ti content, suggesting high concentrations of implanted hydrogen. Smooth areas near the vent suggest that the ash beds are several tens of meters thick. The projected payload includes an imaging system to document the geological setting of the landing area, an APX instrument to provide major element composition of the regolith and a neutron spectrometer to measure the bulk hydrogen composition of the regolith at the landing site. Additionally, inclusion of a next generation laser retroreflector would markedly improve measurements of lunar librations and thus, constrain the dimensions of both the liquid and solid inner cores of the Moon, as well as provide tests of General Relativity. Conops are simple, with measurements of the surface composition commencing immediately upon landing. APX chemical analysis and neutron measurements would be completed within an hour or so. If any propellant remains after landing and a 'hop' to another site was undertaken, we can repeat these analyses at the second site, adding confidence that we have obtained representative measurements. Thus, the scientific goals of the first Moon Express mission are satisfied early and easily in the mission profile. This mission scenario provides significant scientific accomplishment for very little investment in payload and operations. Although minimally configured, the payload has been chosen to provide the most critical ground truth parameters for mapping hydrogen concentrations across the entire lunar surface. As hydrogen is a key element to the development of the Moon, understanding its occurrences in both non-polar and polar environments is critical. This mission achieves significant new scientific accomplishment as well as taking the first steps towards lunar presence and permanence.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  11. MESSENGER's Venus Flyby: An Overview of Early Results

    NASA Astrophysics Data System (ADS)

    Solomon, S. C.; Ho, G. C.; Izenberg, N. R.; Lawrence, D. J.; McClintock, W. E.; Neumann, G. A.; Prockter, L. M.; Raines, J. M.; Rhodes, E. A.; Robinson, M. S.; Slavin, J. A.; Smith, D. E.; Starr, R. D.; Zuber, M. T.; MESSENGER Science Team

    2007-12-01

    The MESSENGER spacecraft flew by Venus on 5 June 2007 for a gravity assist to its subsequent encounters with Mercury. Closest approach was at 338 km altitude over 12S, 165E, near the boundary between the lowland plains of Rusalka Planitia and the rifted uplands of Aphrodite Terra. All of the MESSENGER instruments operated during the flyby. The camera system imaged the night side in near-infrared bands and obtained color and higher-resolution monochrome mosaics of both the approaching and departing hemispheres. The ultraviolet and visible spectrometer obtained profiles of atmospheric species on the day and night sides as well as observations of the exospheric tail on departure. The visible and infrared spectrograph made observations of the Venus dayside near closest approach to gather compositional information on the upper atmosphere and clouds, and the laser altimeter carried out passive radiometry at 1064 nm and attempted to range to one or more cloud decks for several minutes near closest approach. The gamma-ray and neutron spectrometers observed gamma-rays and neutrons from the Venus atmosphere, providing information for planning the upcoming Mercury flybys and for calibration from a source of known composition. That the European Space Agency's Venus Express mission was operating at the time of the flyby permitted the simultaneous observation of the planet from two independent spacecraft, a situation of particular value for characterization of the particle and field environment at Venus. MESSENGER's energetic particle and plasma spectrometer observed charged particle acceleration at the Venus bow shock and elsewhere, and the magnetometer provided measurements of the upstream interplanetary magnetic field (IMF), bow shock signatures, and pick-up ion waves as a reference for energetic particle and plasma observations by both spacecraft. The encounter also enabled two-point measurements of IMF penetration into the Venus ionosphere, primary plasma boundaries, and the near-tail region.

  12. Extreme Environments Technologies for Probes to Venus and Jupiter

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

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

  13. Understanding divergent evolution of Earth-like planets: The case for a Venus exploration program

    NASA Astrophysics Data System (ADS)

    Crisp, D.

    The planet Venus is our most Earth-like neighbor in size, mass, and solar distance. In spite of these similarities, the Venus surface and atmosphere are characterized by some of the most enigmatic features seen anywhere in the solar system. Here, we propose a Venus exploration program designed to explain the origin and divergent evolution of the interiors, surfaces, and atmospheres of the terrestrial planets in our solar system, and provide greater insight into the conditions that may affect the habitability of terrestrial planets in other solar systems. This program includes: - The Noble Gas and Trace Gas Explorer is the highest priority mission because itsdata are vital to our understanding of the origin of Venus. This Discovery classmission requires a single entry probe that will carry the state-of-the-art instrumentsneeded to complete the noble gas and trace gas inventories between the cloud topsand the surface. - The Global Geological Process Mapping Orbiter is a Discovery class mission. Itwill carry a C- and/or X-band radar designed for stereo or interferometric imaging,to provide global maps of the surface at horizontal resolutions of 25 to 50 metersto identify and characterize the geologic processes that have shaped the Venussurface. - The Atmospheric Composition Orbiter is a Discovery class mission that will carryremote sensing instruments for characterizing clouds and trace gas variationsthroughout the atmosphere. This mission will collect the data needed tocharacterize the radiative, chemical, and dynamical processes that are maintainingthe thermal structure and composition of the present atmosphere. - The Atmospheric Dynamics Explorer is a New Frontiers class mission that willdeploy 12 to 24 long-lived balloons over a range of latitudes and altitudes toidentify the mechanisms responsible for maintaining the atmosphericsuperrotation. - The Surface and Interior Explorer is a New Frontiers class mission that will deploythree or more long-lived landers on the Venus surface. Each lander will carry aseismometer for studies of the interior structure, as well as in situ instruments forcharacterizing the surface mineralogy and elemental composition. This missionrequires significant technology development. - A Sample Return mission will eventually be needed to conduct investigations ofthe Venus surface and atmosphere that cannot be conducted by instruments onremote sensing platforms or on entry probes. This will probably require a largemission and significant technology development. This series of missions will complement and expand on the science objectives of the proposed ESA Venus Express Mission and the ISAS Venus Climate Orbiter.

  14. Venus Transit 2004

    NASA Astrophysics Data System (ADS)

    Mayo, L. A.; Odenwald, S. F.

    2002-09-01

    December 6th, 1882 was the last transit of the planet Venus across the disk of the sun. It was heralded as an event of immense interest and importance to the astronomical community as well as the public at large. There have been only six such occurrences since Galileo first trained his telescope on the heavens in 1609 and on Venus in 1610 where he concluded that Venus had phases like the moon and appeared to get larger and smaller over time. Many historians consider this the final nail in the coffin of the Ptolemaic, Earth centered solar system. In addition, each transit has provided unique opportunities for discovery such as measurement and refinement of the astronomical unit, calculation of longitudes on the earth, and detection of Venus' atmosphere. The NASA Sun Earth Connection Education Forum in partnership with the Solar System Exploration Forum, DPS, and a number of NASA space missions is developing plans for an international education program centered around the June 8, 2004 Venus transit. The transit will be visible in its entirety from Europe and partially from the East Coast of the United States. We will use a series of robotic observatories including the Telescopes In Education network distributed in latitude to provide observations of the transit that will allow middle and high school students to calculate the A.U. through application of parallax. We will also use Venus transit as a probe of episodes in American history (e.g. 1769: revolutionary era, 1882: post civil war era, and 2004: modern era). Museums and planetariums in the US and Europe will offer real time viewing of the transit and conduct educational programs through professional development seminars, public lectures, and planetarium shows. We are interested in soliciting advice from the research community to coordinate professional research interests with this program.

  15. Aeolian processes on Venus

    NASA Technical Reports Server (NTRS)

    Greeley, Ronald

    1989-01-01

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

  16. Robotic Technology for Exploration of Venus

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.

    2003-01-01

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

  17. Ion signatures of magnetic flux ropes in the Venusian ionosphere as observed by APSERA-4 and MAG onboard Venus Express

    NASA Astrophysics Data System (ADS)

    Guymer, G.; Grande, M.; Whittaker, I.

    2008-09-01

    Abstract Venus has a negligible intrinsic magnetic moment with an upper limit a factor 10-5 of earth's [1]. This entails that the ionosphere is vulnerable to scavenging by the solar wind. However, magnetic fields may be induced in the ionosphere by interaction with the interplanetary magnetic field frozen-in to the solar wind. The presence of small scale magnetic structures in the dayside ionosphere of the planet Venus has been long established and were first observed in Pioneer Venus Orbiter (PVO) data in 1979 [2] during the run up to solar maximum. These ionospheric `flux ropes' were observed in over 70% of passes in which the orbit of PVO intersected the dayside ionosphere [3]. Magnetic flux ropes are identified as brief, discrete disturbances from any background magnetic field, lasting a few seconds with a magnitude of up to many 10's of nano-Teslas in strength [3, 4]. Flux ropes have a strong central, axial field, that is wrapped with field lines of weakening strength and increased helical angle with distance from the central field lines [4]. Due to this particular structure, flux ropes present a specific signature in the three variance projections (also known as a hodogram) when minimum variance analysis is applied to the magnetic data set [2]. With Venus Express now in operational orbit around the planet, flux ropes are being observed in the data retrieved by the magnetometers (MAG [5]) onboard. The magnetic data used in this analysis is the 1Hz data set provided by H. Wei (of UCLA). Variance projections have been produced for several structures in 2006, revealing them to be flux ropes (see figure 1). Using the Ion Mass Analyser (IMA; part of the ASPERA-4 package [6]) and MAG, the ion composition within the ropes and the effect of such magnetic structures upon ionospheric erosion is being studied. Where flux ropes have been evident in the magnetic data, ion spectra have been produced in an attempt to deduce any compositional differences between a flux rope free ionosphere and one in which flux ropes have been detected. The spectra have been constructed to show protons, alpha particles, singly ionised helium and singly ionised oxygen, displaying a mix of solar wind and atmospheric particles. ELS (electron spectrometer [6]) data sets have been inspected to ascertain if the ropes occur deep in the ionosphere or at its fringes. The case that is primarily being studied occurs on 2006-07-11, DOY 192. The spacecraft travels along a near-terminator orbit from midnight to midday. H+ and He++ spectra show double energy populations in the region of the flux rope. These double populations show strongly in the count rate. A double population can also be weakly observed in the O+ spectra. The energies of these populations are approximately 1KeV and 20eV, indicating a mix of solar wind and planetary ions. The electron data does not appear to show any signature of the ionosphere, but is suspected to be in a position at the fringe of the night-side ionopause (see figure 2). In order to determine the pressure balance across the ropes the average plasma and magnetic pressures both across the ropes and during a three minute period either side of the ropes has been calculated. Flux ropes with a force-free nature have increased magnetic pressure but do not have a decreased thermal pressure. Indicating that particle density within the flux rope will not be reduced [7]. For ions to be eroded from the atmosphere by flux ropes, the ropes would need to be force-free, i.e., non-density depleted.

  18. Thermal Structure and Radiative Balance of the Venus Atmosphere

    NASA Astrophysics Data System (ADS)

    Limaye, S. S.

    2014-04-01

    Venus Express, observing since April 2006 has returned a wealth of useful information about the atmospheric temperature and density structure of the planet. New and refined instruments have advanced not only the accuracy but also the altitude range of the inferred structure. With multiple experiments on Venus Express contributing to the inferred vertical structure, there is overlap in some altitude regions, allowing and requiring conciliation of the inferred values in terms of spatial and temporal coverage as well as errors and biases. In addition, there are older spacecraft results as well as recent ground based observations that contribute to the new information about the thermal structure of the atmosphere. Regarding the radiative balance, we have new information about changes in the absorbed solar radiation over the duration of the Venus Express mission, but little new information in terms of the emitted radiation from the planet. A coordinated effort was initiated in late 2013 to assess these new data through an international team hosted by the International Space Studies Institute [1]. This solicited chapter for the Venus III book being developed at present [2] is based on the efforts of this group.

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

    NASA Astrophysics Data System (ADS)

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

    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 ESAs 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.

  20. Venus Syndrome

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

    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.

  1. Venus Phasing.

    ERIC Educational Resources Information Center

    Riddle, Bob

    1997-01-01

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

  2. Exploring Venus.

    ERIC Educational Resources Information Center

    The Universe in the Classroom, 1985

    1985-01-01

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

  3. Orbital Express Mission Operations Planning and Resource Management using ASPEN

    NASA Technical Reports Server (NTRS)

    Chouinard, Caroline; Knight, Russell; Jones, Grailing; Tran, Danny

    2008-01-01

    The Orbital Express satellite servicing demonstrator program is a DARPA program aimed at developing "a safe and cost-effective approach to autonomously service satellites in orbit". The system consists of: a) the Autonomous Space Transport Robotic Operations (ASTRO) vehicle, under development by Boeing Integrated Defense Systems, and b) a prototype modular next-generation serviceable satellite, NEXTSat, being developed by Ball Aerospace. Flexibility of ASPEN: a) Accommodate changes to procedures; b) Accommodate changes to daily losses and gains; c) Responsive re-planning; and d) Critical to success of mission planning Auto-Generation of activity models: a) Created plans quickly; b) Repetition/Re-use of models each day; and c) Guarantees the AML syntax. One SRP per day vs. Tactical team

  4. Future exploration of Venus (post-Pioneer Venus 1978)

    NASA Technical Reports Server (NTRS)

    Colin, L.; Evans, L. C.; Greeley, R.; Quaide, W. L.; Schaupp, R. W.; Seiff, A.; Young, R. E.

    1976-01-01

    A comprehensive study was performed to determine the major scientific unknowns about the planet Venus to be expected in the post-Pioneer Venus 1978 time frame. Based on those results the desirability of future orbiters, atmospheric entry probes, balloons, and landers as vehicles to address the remaining scientific questions were studied. The recommended mission scenario includes a high resolution surface mapping radar orbiter mission for the 1981 launch opportunity, a multiple-lander mission for 1985 and either an atmospheric entry probe or balloon mission in 1988. All the proposed missions can be performed using proposed space shuttle upper stage boosters. Significant amounts of long-lead time supporting research and technology developments are required to be initiated in the near future to permit the recommended launch dates.

  5. Venus Atmospheric Maneuverable Platform (VAMP)

    NASA Astrophysics Data System (ADS)

    Shapiro Griffin, Kristen L.; Sokol, D.; Dailey, D.; Lee, G.; Polidan, R.

    2013-10-01

    We have explored a possible new approach to Venus upper atmosphere exploration by applying Northrop Grumman (non-NASA) development programs to the challenges associated with Venus upper atmosphere science missions. Our concept is a low ballistic coefficient (<50 Pa), semi-buoyant aircraft that deploys prior to entering the Venus atmosphere, enters the atmosphere without an aeroshell, and provides a long-lived (months to years), maneuverable vehicle capable of carrying science payloads to explore the Venus upper atmosphere. In this presentation we report results from our ongoing study and plans for future analyses and prototyping. We discuss the overall mission architecture and concept of operations from launch through Venus arrival, orbit, entry, and atmospheric science operations. We 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 specifically focus upon four key factors impacting the design and performance of VAMP: 1. Feasibility of and options for the deployment of the vehicle in space 2. Entry into the Venus atmosphere, including descent profile, heat rate, total heat load, stagnation temperature, control, and entry into level flight 3. Characteristics of flight operations and performance in the Venus atmosphere: altitude range, latitude and longitude access, day/night performance, aircraft performance (aerodynamics, power required vs. power available, propulsion, speed, percent buoyancy), performance sensitivity to payload weight 4. Science payload accommodation, constraints, and opportunities We discuss interdependencies of the above factors and the manner in which the VAMP strawmans characteristics affect the CONOPs and the science objectives. We show how these factors provide constraints as well as enable opportunities for novel long duration scientific studies of the Venus upper atmosphere that support VEXAG goals 2 and 3.

  6. A balloon-borne stratospheric telescope for Venus observations

    NASA Astrophysics Data System (ADS)

    Young, Eliot F.; Bullock, Mark A.; Kraut, Alan; Orr, Graham; Swartzlander, Kevin; Wimer, Tony; Wong, Elton; Little, Patrick; Nakaya, Yusuke; Mellon, Russell; Germann, Lawrence

    2008-07-01

    A terrestrial stratospheric telescope is ideally suited for making infrared observations of Venus' night hemisphere during inferior conjunctions. The near-space environment at 35 km altitude has low daytime sky backgrounds and lack of atmospheric turbulence, both of which are necessary for observing Venus' night side at the diffraction limit when Venus is close to the Sun. In addition, the duration of the observing campaign will be around 3 weeks, a time period that is achievable by current long duration flights. The most important advantage, however, will be the ability of a balloonborne telescope to clearly image Venus' night side continuously throughout a 12-hr period (more for certain launch site latitudes), a capability that cannot be matched from the ground or from the Venus Express spacecraft currently in orbit around Venus. Future missions, such as the Japanese Venus Climate Orbiter will also not be able to achieve this level of synoptic coverage. This capability will provide a detailed, continuous look at evolving cloud distributions in Venus' middle and lower cloud decks through atmospheric windows at 1.74 and 2.3 ?m, which in turn will provide observational constraints on models of Venus' circulation. The science requirements propagate to several aspects of the telescope: a 1.4-m aperture to provide a diffraction limit of 0.3" at 1.74 ?m (to improve upon non-AO ground-based resolution by a factor of 2); a plate scale of 0.1" per pixel, which in turn requires an f/15 telescope for 13 ?m pixels; pointing and stability at the 0.05" level; stray light baffling; a field of view of 2 arc minutes; ability to acquire images at 1.26, 1.74 and 2.3 ?m and ability to operate aloft for three weeks at a time. The specific implementations of these requirements are outlined in this paper. Briefly, a 1.4-m Gregorian telescope is proposed, with stray light baffling at the intermediate focus. A three-stage pointing system is described, consisting of a coarse azimuthal rotator, a moderate pointing system based on a star tracker and ALT/AZ gimbals, and a fine pointing system based on analog photodiodes and a fine steering mirror. The science detectors are not discussed here, except to specify the requirement for moderate resolution (R > 1000) spectroscopy.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

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

  9. Meeting Venus

    NASA Astrophysics Data System (ADS)

    Sterken, Christiaan; Aspaas, Per Pippin

    2013-06-01

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

  10. The Magellan Venus explorer's guide

    NASA Technical Reports Server (NTRS)

    Young, Carolynn (Editor)

    1990-01-01

    The Magellan radar-mapping mission to the planet Venus is described. Scientific highlights include the history of U.S. and Soviet missions, as well as ground-based radar observations, that have provided the current knowledge about the surface of Venus. Descriptions of the major Venusian surface features include controversial theories about the origin of some of the features. The organization of the Magellan science investigators into discipline-related task groups for data-analysis purposes is presented. The design of the Magellan spacecraft and the ability of its radar sensor to conduct radar imaging, altimetry, and radiometry measurements are discussed. Other topics report on the May 1989 launch, the interplanetary cruise, the Venus orbit-insertion maneuver, and the in-orbit mapping strategy. The objectives of a possible extended mission emphasize the gravity experiment and explain why high-resolution gravity data cannot be acquired during the primary mission. A focus on the people of Magellan reveals how they fly the spacecraft and prepare for major mission events. Special items of interest associated with the Magellan mission are contained in windows interspersed throughout the text. Finally, short summaries describe the major objectives and schedules for several exciting space missions planned to take us into the 21st century.

  11. Venus lightning

    NASA Technical Reports Server (NTRS)

    Russell, C. T.

    1991-01-01

    Although it is not unanimously accepted, many independent observations lead to the conclusion that lightning is prevalent on Venus. The EM signals detected by all four Venera landers are most readily explained as generation by lightning. The Venera 9 spectrometer appears to have observed a lightning storm on one occasion. The Pioneer Venus plasma-wave instrument detects waves both below the electron gyrofrequency (that may be due to lightning) and signals above the electron gyrofrequency but at very low altitudes (that may be due to the near field of the lightning). The VLF observations suggest that Venus lightning must be an intracloud phenomenon which is most frequent in the afternoon and evening sector. The occurrence rate is likely to be greater than on earth.

  12. Venus gravity

    NASA Technical Reports Server (NTRS)

    Reasenberg, Robert D.

    1993-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  14. Venus Atmospheric Maneuverable Platform (VAMP)

    NASA Astrophysics Data System (ADS)

    Griffin, K.; Sokol, D.; Lee, G.; Dailey, D.; Polidan, R.

    2013-12-01

    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 (<50 Pa), semi-buoyant aircraft that deploys prior to entering the Venus atmosphere, enters the Venus atmosphere without an aeroshell, and provides a long-lived (months to years), maneuverable vehicle capable of carrying science payloads to explore the Venus upper atmosphere. In 2012 we initiated a feasibility study for a semi-buoyant maneuverable vehicle that could operate in the upper atmosphere of Venus. In this presentation we report results from the ongoing study and plans for future analyses and prototyping to advance and refine the concept. 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. Feasibility of and options for the deployment of the vehicle in space 2. Entry into the Venus atmosphere, including descent profile, heat rate, total heat load, stagnation temperature, control, and entry into level flight 3. Characteristics of flight operations and performance in the Venus atmosphere: altitude range, latitude and longitude access, day/night performance, aircraft performance (aerodynamics, power required vs. power available, propulsion, speed, percent buoyancy), performance sensitivity to payload weight 4. Science payload accommodation, constraints, and opportunities 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 2 and 3. We will also discuss how the VAMP platform itself can facilitate some of these science measurements.

  15. Venus Atmospheric Maneuverable Platform (VAMP)

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    Over the past years we have explored a possible new approach to Venus upper atmosphere exploration by applying recent Northrop Grumman (non-NASA) development programs to the challenges associated with Venus upper atmosphere science missions. Our concept is a low ballistic coefficient (<50 Pa), semibuoyant aircraft that deploys prior to entering the Venus atmosphere, enters the Venus atmosphere without an aeroshell, and provides a long-lived (months to years), maneuverable vehicle capable of carrying science payloads to 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.

  16. The VEGA Venus Balloon Experiment.

    PubMed

    Sagdeev, R Z; Linkin, V M; Blamont, J E; Preston, R A

    1986-03-21

    In June 1985, two instrumented balloons were placed in the atmosphere of Venus as part of the VEGA mission. Each balloon traveled about 30 percent of the way around the planet at a float altitude near 54 kilometers. In situ sensors measured pressure, temperature, vertical wind velocity, cloud particle backscatter, ambient light level, and frequency of lightning. A ground-based network of 20 radio antennas tracked the balloons by very long baseline interferometry (VLBI) techniques to monitor the Venus winds. The history, organization, and principal characteristics of this international balloon experiment are described. PMID:17748079

  17. The Venus environment

    SciTech Connect

    Not Available

    1982-08-01

    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.

  18. Venus, Earth, Xenon

    NASA Astrophysics Data System (ADS)

    Zahnle, K. J.

    2013-12-01

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

  19. Reference atmospheres: VIRA II -Venus International Reference Atmosphere update.

    NASA Astrophysics Data System (ADS)

    Zasova, Ludmila

    2012-07-01

    VIRA I was started in 1982 (30 years ago) and published in1985 (ASR,v5,n11, 1985) by G. Keating, A. Kliore, and V. Moroz. The purpose was to produce a concise, descriptive model summarizing the physical properties of the atmosphere of Venus, which by then had been extensively observed by instruments on board the Venera and Pioneer space probes. VIRA was used by many scientists and engineers in their studies as referent standard of atmospheric data. Afterwards several missions have obtained new data. In particular the experiments on late Veneras and Venus Express. Experiments on board of VEX, working on the orbit for 6 years, provide new high quality data on atmospheric structure, clouds properties, dynamics, composition of the atmosphere, thermal balance, ionosphere. These new data will be used for VIRA update. Original data consists of 7 Chapters.(1 ) Models of the structure of the atmosphere of Venus from the surface to 100 km altitude, (2) Circulation of the atmosphere from surface to 100 km, (3) Particulate matter in the Venus atmosphere, (4) Models of Venus neutral upper atmosphere: structure and composition, (5) Composition of the atmosphere below 100 km altitude, (6) Solar and thermal radiation in the Venus atmosphere, (7) The Venus ionosphere. By 2002 Gerry Keating collected materials to update VIRA. But only two chapter were published: (1 ) Models of the structure of the atmosphere of Venus from the surface to 100 km altitude (Zasova et al, 2006, Cosmic Research, 44, N4), (5) Composition of the atmosphere below 100 km altitude (De Bergh et al. 2006, PSS). Both these chapters were based on the data, obtained before VEX. At the moment the structure of the original VIRA looks acceptable for VIRA II also, however, new Chapters may be added. At COSPAR 2014 in Moscow the session on Reference atmospheres (RAPS), may be proposed to continue discussion on VIRA, and start working on MIRA, and complete VIRA and publish (including CD) after COSPAR 2016 (or may be even after COPAR 2014). MIRA was published in 1982 (Kliore A., The Mars reference atmosphere, ASR, vol. 2, no. 2, 1982). The amount data on Martian atmosphere and variability of the conditions at different regions, seasonal, local time variations, etc., requires more complex, interactive model. CIRA experience may be very useful in the case of MIRA.

  20. Weak, Quiet Magnetic Fields Seen in the Venus Atmosphere

    PubMed Central

    Zhang, T. L.; Baumjohann, W.; Russell, C. T.; Luhmann, J. G.; Xiao, S. D.

    2016-01-01

    The existence of a strong internal magnetic field allows probing of the interior through both long term changes of and short period fluctuations in that magnetic field. Venus, while Earth’s twin in many ways, lacks such a strong intrinsic magnetic field, but perhaps short period fluctuations can still be used to probe the electrical conductivity of the interior. Toward the end of the Venus Express mission, an aerobraking campaign took the spacecraft below the ionosphere into the very weakly electrically conducting atmosphere. As the spacecraft descended from 150 to 140 km altitude, the magnetic field became weaker on average and less noisy. Below 140 km, the median field strength became steady but the short period fluctuations continued to weaken. The weakness of the fluctuations indicates they might not be useful for electromagnetic sounding of the atmosphere from a high altitude platform such as a plane or balloon, but possibly could be attempted on a lander. PMID:27009234

  1. Weak, Quiet Magnetic Fields Seen in the Venus Atmosphere.

    PubMed

    Zhang, T L; Baumjohann, W; Russell, C T; Luhmann, J G; Xiao, S D

    2016-01-01

    The existence of a strong internal magnetic field allows probing of the interior through both long term changes of and short period fluctuations in that magnetic field. Venus, while Earth's twin in many ways, lacks such a strong intrinsic magnetic field, but perhaps short period fluctuations can still be used to probe the electrical conductivity of the interior. Toward the end of the Venus Express mission, an aerobraking campaign took the spacecraft below the ionosphere into the very weakly electrically conducting atmosphere. As the spacecraft descended from 150 to 140 km altitude, the magnetic field became weaker on average and less noisy. Below 140 km, the median field strength became steady but the short period fluctuations continued to weaken. The weakness of the fluctuations indicates they might not be useful for electromagnetic sounding of the atmosphere from a high altitude platform such as a plane or balloon, but possibly could be attempted on a lander. PMID:27009234

  2. Search for ongoing volcanic activity on Venus

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  3. Spaceborne radar studies of Venus

    SciTech Connect

    Nozette, S.

    1980-01-01

    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.

  4. Mariner Venus-Mercury 1973 Project. Volume 1: Venus and Mercury 1 Encounters

    NASA Technical Reports Server (NTRS)

    1976-01-01

    The primary mission report includes the Venus encounter and the first Mercury encounter. Plans and activities undertaken to successfully achieve the mission objectives are described. Operational activities are identified by mission operation system functions, providing a brief summary of each discipline. Spacecraft performance is summarized by subsystems.

  5. Comparative analysis of Venus and Mars magnetotails

    NASA Astrophysics Data System (ADS)

    Fedorov, A.; Ferrier, C.; Sauvaud, J. A.; Barabash, S.; Zhang, T. L.; Mazelle, C.; Lundin, R.; Gunell, H.; Andersson, H.; Brinkfeldt, K.; Futaana, Y.; 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.; Thocaven, J.-J.; Grande, M.; Koskinen, H.; Kallio, E.; Sales, T.; Schmidt, W.; Riihela, P.; Kozyra, J.; Krupp, N.; Woch, J.; Luhmann, J.; McKenna-Lawlor, S.; Orsini, S.; Cerulli-Irelli, R.; Mura, A.; Milillo, A.; Maggi, M.; Roelof, E.; Brandt, P.; Russell, C. T.; Szego, K.; Winningham, J. D.; Frahm, R. A.; Scherrer, J.; Sharber, J. R.; Wurz, P.; Bochsler, P.

    2008-05-01

    We have an unique opportunity to compare the magnetospheres of two non-magnetic planets as Mars and Venus with identical instrument sets Aspera-3 and Aspera-4 on board of the Mars Express and Venus Express missions. We have performed both statistical and case studies of properties of the magnetosheath ion flows and the flows of planetary ions behind both planets. We have shown that the general morphology of both magnetotails is generally identical. In both cases the energy of the light ( H+) and the heavy ( O+, etc.) ions decreases from the tail periphery (several keV) down to few eV in the tail center. At the same time the wake center of both planets is occupied by plasma sheet coincident with the current sheet of the tail. Both plasma sheets are filled by accelerated (500-1000 eV) heavy planetary ions. We report also the discovery of a new feature never observed before in the tails of non-magnetic planets: the plasma sheet is enveloped by consecutive layers of He+ and H+ with decreasing energies.

  6. Pioneer Mars surface penetrator mission. Mission analysis and orbiter design

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The Mars Surface Penetrator mission was designed to provide a capability for multiple and diverse subsurface science measurements at a low cost. Equipment required to adapt the Pioneer Venus spacecraft for the Mars mission is described showing minor modifications to hardware. Analysis and design topics which are similar and/or identical to the Pioneer Venus program are briefly discussed.

  7. Pioneer Venus orbiter electron temperature probe

    NASA Technical Reports Server (NTRS)

    Brace, Larry H.

    1994-01-01

    This document lists the scientific accomplishments of the Orbiter Electron Temperature Probe (OETP) group. The OETP instrument was fabricated in 1976, integrated into the PVO spacecraft in 1977, and placed in orbit about Venus in December 1978. The instrument operated flawlessly for nearly 14 years until PVO was lost as it entered the Venusian atmosphere in October 1992. The OETP group worked closely with other PVO investigators to examine the Venus ionosphere and its interactions with the solar wind. After the mission was completed we continued to work with the scientist selected for the Venus Data Analysis Program (VDAP), and this is currently leading to additional publications.

  8. Venus reconsidered.

    PubMed

    Kaula, W M

    1995-12-01

    The Magellan imagery shows that Venus has a crater abundance equivalent to a surface age of 300 million to 500 million years and a crater distribution close to random. Hence, the tectonics of Venus must be quiescent compared to those of Earth in the last few 100 million years. The main debate is whether the decline in tectonic activity on Venus is closer to monotonic or episodic, with enhanced tectonism and volcanism yet to come. The former hypothesis implies that most radioactive heat sources have been differentiated upward; the latter, that they have remained at depth. The low level of activity in the last few 100 million years inferred from imagery favors the monotonic hypothesis; some chemical evidence, particularly the low abundance of radiogenic argon, favors the episodic. A problem for both hypotheses is the rapid decline of thermal and tectonic activity some 300 million to 500 million years ago. The nature of the convective instabilities that caused the decline, and their propagation, are unclear. PMID:7491490

  9. Venus mapping

    NASA Technical Reports Server (NTRS)

    Batson, R. M.; Morgan, H. F.; Sucharski, Robert

    1991-01-01

    Semicontrolled image mosaics of Venus, based on Magellan data, are being compiled at 1:50,000,000, 1:10,000,000, 1:5,000,000, and 1:1,000,000 scales to support the Magellan Radar Investigator (RADIG) team. The mosaics are semicontrolled in the sense that data gaps were not filled and significant cosmetic inconsistencies exist. Contours are based on preliminary radar altimetry data that is subjected to revision and improvement. Final maps to support geologic mapping and other scientific investigations, to be compiled as the dataset becomes complete, will be sponsored by the Planetary Geology and Geophysics Program and/or the Venus Data Analysis Program. All maps, both semicontrolled and final, will be published as I-maps by the United States Geological Survey. All of the mapping is based on existing knowledge of the spacecraft orbit; photogrammetric triangulation, a traditional basis for geodetic control on planets where framing cameras were used, is not feasible with the radar images of Venus, although an eventual shift of coordinate system to a revised spin-axis location is anticipated. This is expected to be small enough that it will affect only large-scale maps.

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

    NASA Astrophysics Data System (ADS)

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

    2010-10-01

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

  11. First laboratory high-temperature emissivity measurements of Venus analog measurements in the near-infrared atmospheric windows

    NASA Astrophysics Data System (ADS)

    Helbert, J.; Maturilli, A.; Ferrari, S.; Dyar, M. D.; Smrekar, S. E.

    2014-12-01

    The permanent cloud cover of Venus prohibits observation of the surface with traditional imaging techniques over most of the visible spectral range. Venus' CO2 atmosphere is transparent exclusively in small spectral windows near 1 μm. The Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) team on the European Space Agency Venus-Express mission have recently used these windows successfully to map the southern hemisphere from orbit. VIRTIS is showing variations in surface brightness, which can be interpreted as variations in surface emissivity. Deriving surface composition from these variations is a challenging task. Comparison with laboratory analogue spectra are complicated by the fact that Venus has an average surface temperature of 730K. Mineral crystal structures and their resultant spectral signatures are notably affected by temperature, therefore any interpretations based on room temperature laboratory spectra database can be misleading. In order to support the interpretation of near-infrared data from Venus we have started an extensive measurement campaign at the Planetary Emissivity Laboratory (PEL, Institute of Planetary Research of the German Aerospace Center, Berlin). The PEL facility, which is unique in the world, allows emission measurements covering the 1 to 2 μm wavelength range at sample temperatures of up to 770K. Conciliating the expected emissivity variation between felsic and mafic minerals with Venera and VEGA geochemical data we have started with a set of five analog samples. This set includes basalt, gneiss, granodiorite, anorthosite and hematite, thus covering the range of mineralogies. Preliminary results show significant spectral contrast, thus allowing different samples to be distinguished with only 5 spectral points and validating the use of thermal emissivity for investigating composition. This unique new dataset from PEL not only allows interpretation of the Venus Express VIRTIS data but also provide a baseline for considering new instrument designs for future Venus missions.

  12. Hot Flow Anomalies at Venus

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  13. Hypothetical flora and fauna of Venus

    NASA Astrophysics Data System (ADS)

    Ksanfomality, L. V.

    2014-12-01

    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.

  14. The exploration of Venus - A Magellan progress report

    NASA Technical Reports Server (NTRS)

    Saunders, Steve

    1991-01-01

    The salient features of the Magellan mission to Venus are described together with the radar system used for mapping the Venusian features. Three types of Venusian terrain observed on Magellan images are described in detail: impact craters and two highland regions. These are Ishtar Terra (which includes Maxwell Montes) and Aphrodite Terra. The manner in which Venus's high surface temperature and its thick atmosphere have affected the processes that shaped the Venus's surface is discussed.

  15. Interplanetary mission planning

    NASA Technical Reports Server (NTRS)

    1971-01-01

    A long range plan for solar system exploration is presented. The subjects discussed are: (1) science payload for first Jupiter orbiters, (2) Mercury orbiter mission study, (3) preliminary analysis of Uranus/Neptune entry probes for Grand Tour Missions, (4) comet rendezvous mission study, (5) a survey of interstellar missions, (6) a survey of candidate missions to explore rings of Saturn, and (7) preliminary analysis of Venus orbit radar missions.

  16. The impact of a slow interplanetary coronal mass ejection on Venus

    NASA Astrophysics Data System (ADS)

    Collinson, Glyn A.; Grebowsky, Joseph; Sibeck, David G.; Jian, Lan K.; Boardsen, Scott; Espley, Jared; Hartle, Dick; Zhang, Tielong L.; Barabash, Stas; Futaana, Yoshifumi; Kollmann, Peter

    2015-05-01

    We present Venus Express observations of the impact of a slow interplanetary coronal mass ejection (ICME), which struck Venus on 23 December 2006, creating unusual quasi steady state upstream conditions for the 2 h close to periapsis: an enhanced ( nT) interplanetary magnetic field (IMF), radially aligned with the Sun-Venus line; and a dense ( cm-3) solar wind. Contrary to our current understanding and expectations, the ionosphere became partially demagnetized. We also find evidence for shocked sheathlike solar wind protons and electrons in the wake of Venus, and powerful (? nT2/Hz) foreshock whistler mode waves radiating from the bow shock at an unexpectedly low frequency (0.6 Hz). Given the abnormally high density of escaping heavy ions at the magnetopause boundary (295 cm-3, one of the highest of the whole mission) and the enhanced density of escaping heavy ions in the wake, we find that even weak ICMEs with no driving shocks can increase atmospheric loss rates at Venus and suggests that the Bx component of the IMF may be a factor in atmospheric escape rates.

  17. Scientific Balloons for Venus Exploration

    NASA Astrophysics Data System (ADS)

    Cutts, James; Yavrouian, Andre; Nott, Julian; Baines, Kevin; Limaye, Sanjay; Wilson, Colin; Kerzhanovich, Viktor; Voss, Paul; Hall, Jeffery

    Almost 30 years ago, two balloons were successfully deployed into the atmosphere of Venus as an element of the VeGa - Venus Halley mission conducted by the Soviet Union. As interest in further Venus exploration grows among the established planetary exploration agencies - in Europe, Japan, Russia and the United States, use of balloons is emerging as an essential part of that investigative program. Venus balloons have been proposed in NASAs Discovery program and ESAs cosmic vision program and are a key element in NASAs strategic plan for Venus exploration. At JPL, the focus for the last decade has been on the development of a 7m diameter superpressure pressure(twice that of VeGa) capable of carrying a 100 kg payload (14 times that of VeGA balloons), operating for more than 30 days (15 times the 2 day flight duration of the VeGa balloons) and transmitting up to 20 Mbit of data (300 times that of VeGa balloons). This new generation of balloons must tolerate day night transitions on Venus as well as extended exposure to the sulfuric acid environment. These constant altitude balloons operating at an altitude of about 55 km on Venus where temperatures are benign can also deploy sondes to sound the atmosphere beneath the probe and deliver deep sondes equipped to survive and operate down to the surface. The technology for these balloons is now maturing rapidly and we are now looking forward to the prospects for altitude control balloons that can cycle repeatedly through the Venus cloud region. One concept, which has been used for tropospheric profiling in Antarctica, is the pumped-helium balloon, with heritage to the anchor balloon, and would be best adapted for flight above the 55 km level. Phase change balloons, which use the atmosphere as a heat engine, can be used to investigate the lower cloud region down to 30 km. Progress in components for high temperature operation may also enable investigation of the deep atmosphere of Venus with metal-based balloons.

  18. Results on atmospheric dynamics at the Venus cloud tops from wind tracking in VMC images

    NASA Astrophysics Data System (ADS)

    Moissl, R.; Khatuntsev, I.; Limaye, S. S.; Titov, D. T.; Markiewicz, W. J.

    2008-09-01

    The upper clouds of Venus have been studied extensively from ground and space borne observations in the past, especially in the ultraviolet part of the spectrum. To date we know that the atmosphere of Venus is in a constant state of super-rotation, reaching speeds around 100 ms-1 at the cloud tops and that the cloud markings in the UV are caused by SO2 and another, yet unknown, UV absorber. This presentation deals with the results on the atmospheric dynamics at the cloud top region (? 65-70 km above the surface) of Venus, derived from manual and automated cloud tracking in the UV channel (lambda= 365 +- 10 nm) of the Venus Monitoring Camera Experiment (VMC) on board the Venus Express mission. With the VMC it became possible to investigate the global dynamics with a relatively high resolution in space and time on a long term basis. In addition to the confirmation of results from previous studies on the atmospheric dynamics, the observations of the southern hemisphere by the VMC allowed for detailed studies of the strong cloud-level super-rotation phenomenon on Venus and its variability on different timescales ranging from hours to several months. Information on the latitudinal wind speed profiles could be obtained for latitudes up to ?85 degree S, extending the results from previous studies by almost 20 degree. Global wave modes which are believed to play a key role for understanding energy transport phenomena in the venusian atmosphere, such as a 4-day Kelvin wave mode in low latitudes and diurnal and semidiurnal solar thermal tides have been detected in the analysis cloud tracked wind fields of the southern hemisphere of Venus.

  19. Spatial and Temporal distribution of CO_{2} 4.3-mu m NLTE Emission from nadir VIRTIS-H/Venus Express observations

    NASA Astrophysics Data System (ADS)

    Peralta, Javier; ngel Lpez-Valverde, Miguel; Gilli, Gabriella; Drossart, Pierre; Piccioni, Giuseppe

    2010-05-01

    Non-Local Thermodynamic Equilibrium (non-LTE) emissions are known to play a key role in the radiative heating and cooling of the Venus mesosphere and lower thermosphere (Dickinson, JAS, 1973; Roldan et al., Icarus, 2000). In the case of the Venusian atmosphere, CO2 vibrational-rotational emissions at 4.3 ?m and 2.7 ?m were predicted to give intense emissions, and since they are originated between 80 and 150 km, their observation might give information on the atmospheric parameters at those altitudes, depending on sensitivity and spectral resolution. The VIRTIS spectrometer on board Venus Express allows for the first time the systematic sounding of these bands in the Venus atmosphere, both in nadir and limb observing geometries. The limb data by VIRTIS has been recently studied by our team (Gilli et al., JGR, 2009; Lpez-Valverde et al., 2010 submitted; Gilli et al., 2010 submitted), focusing on its vertical distribution and the validation of non-LTE models, but an exhaustive study of nadir observations has not been presented so far, except for the detection of gravity waves by Garca et al. (2008; 2009). In this work, we have used the nadir observations to study the horizontal distribution of the CO2 non-LTE emissions at 4.3 ?m, mainly originated at altitudes about ~110 km. The analyzed dataset comprises the whole nadir measurements with VIRTIS-H (the highest spectral resolution channel) obtained up to September 2009, covering nearly 900 days of observations and more than 140,000 spectra. Similarly to the case of limb data, it was found that the nadir radiance depends not only on the Solar Zenith Angle, but also on the Emission Angle, as predicted by our non-LTE model. After careful radiance averages, the small dispersion found in the mean emission of this band suggests that the Venus lower thermosphere is more stable than expected, with scarce episodes of significant variation during the studied period. Since the spectral resolution of VIRTIS-H allows separating different CO2 isotopic and hot bands, this dataset implies a valuable test for non-LTE models. Therefore, a revision of some key rate coefficients for collisional relaxation of CO2 vibrational energy levels is also carried out, by means of a systematic comparison between radiance ratios measured by VIRTIS-H and the ones obtained with our non-LTE radiative transfer model. Conclusions will be briefly discussed at the meeting.

  20. Measurements Needed to Understand Superrotation and Circulation in the Venus Atmosphere

    NASA Astrophysics Data System (ADS)

    Parish, H. F.; Schubert, G.; Covey, C. C.

    2013-12-01

    An understanding of the dynamics of Venus' atmosphere is a high priority in future Venus research (VEXAG and the Planetary Science Decadal Survey). Venus' atmosphere is characterized by strong superrotation, in which the winds at cloud heights reach velocities over 100 m/s, around 60 times faster than the surface rotation rate. When realistic background conditions are applied, numerical models simulate cloud level superrotation with wind magnitudes smaller than the largest winds observed. In addition, no model to date has been able to generate superrotating winds in the dense atmosphere between the surface and the clouds with magnitudes comparable to those measured in situ; hence the vertically integrated atmospheric angular momentum in models is far less than observed. One obstacle to realistically modeling the atmosphere below the cloud level and understanding how angular momentum is transported from the surface to the cloud level is the scarcity of observations in Venus' lower atmosphere. The only wind profiles in the 0 to 40 km altitude range come from a few entry probes on the Pioneer Venus and Venera missions. Interplanetary trajectories under minimum-energy constraints largely confined these probes to low latitudes between midnight and early afternoon and measurements only covered the limited time intervals for each probe to fall to the surface. Simulated lower atmosphere winds may be sensitive to the parameterization of surface-atmosphere interactions, but the values of relevant parameters cannot currently be measured. In spite of the apparent symmetry of Venus' orbit and the lack of significant seasons, variability in space and time is also found to be an important feature of Venus' atmosphere. Periodicities with timescales of several years are found in observations of zonal winds, temperatures and composition, for example, in Pioneer Venus measurements of cloud top winds, ground based observations of CO and temperature, and measurements of SO2 taken by many satellite and ground based instruments. Recent measurements from Venus Express also indicate that the average cloud top wind speeds have steadily and significantly increased over the last six years. Variability on multi-year and shorter timescales occurs in at least one Venus general circulation model (Parish et al., 2011) for a variety of choices of input assumptions (Lebonnois et al., 2012). The same model also indicates significant hemispheric asymmetries in the zonal winds and angular momentum, related to hemispheric asymmetries in the surface topography. Accordingly, future observations must include multi-year observations and in situ measurements of the lower atmosphere that cover a full range of both latitudes and local solar times.

  1. Solar Wind Interaction with Venus

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    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.

  2. The Plains of Venus

    NASA Astrophysics Data System (ADS)

    Sharpton, V. L.

    2013-12-01

    Volcanic plains units of various types comprise at least 80% of the surface of Venus. Though devoid of topographic splendor and, therefore often overlooked, these plains units house a spectacular array of volcanic, tectonic, and impact features. Here I propose that the plains hold the keys to understanding the resurfacing history of Venus and resolving the global stratigraphy debate. The quasi-random distribution of impact craters and the small number that have been conspicuously modified from the outside by plains-forming volcanism have led some to propose that Venus was catastrophically resurfaced around 725375 Ma with little volcanism since. Challenges, however, hinge on interpretations of certain morphological characteristics of impact craters: For instance, Venusian impact craters exhibit either radar dark (smooth) floor deposits or bright, blocky floors. Bright floor craters (BFC) are typically 100-400 m deeper than dark floor craters (DFC). Furthermore, all 58 impact craters with ephemeral bright ejecta rays and/or distal parabolic ejecta patterns have bright floor deposits. This suggests that BFCs are younger, on average, than DFCs. These observations suggest that DFCs could be partially filled with lava during plains emplacement and, therefore, are not strictly younger than the plains units as widely held. Because the DFC group comprises ~80% of the total crater population on Venus the recalculated emplacement age of the plains would be ~145 Ma if DFCs are indeed volcanically modified during plains formation. Improved image and topographic data are required to measure stratigraphic and morphometric relationships and resolve this issue. Plains units are also home to an abundant and diverse set of volcanic features including steep-sided domes, shield fields, isolated volcanoes, collapse features and lava channels, some of which extend for 1000s of kilometers. The inferred viscosity range of plains-forming lavas, therefore, is immense, ranging from the extremely fluid flows (i.e., channel formers), to viscous, possibly felsic lavas of steep-sided domes. Wrinkle ridges deform many plains units and this has been taken to indicate that these ridges essentially form an early stratigraphic marker that limits subsequent volcanism to a minimum. However, subtle backscatter variations within many ridged plains units suggest (but do not prove) that some plains volcanism continued well after local ridge deformation ended. Furthermore, many of volcanic sources show little, if any, indications of tectonic modification and detailed analyses have concluded that resurfacing rates could be similar to those on Earth. Improving constraints on the rates and styles of volcanism within the plains could lend valuable insights into the evolution of Venus's internal heat budget and the transition from thin-lid to thick-lid tectonic regimes. Improved spatial and radiometric resolution of radar images would greatly improve abilities to construct the complex local stratigraphy of ridged plains. Constraining the resurfacing history of Venus is central to understanding how Earth-sized planets evolve and whether or not their evolutionary pathways lead to habitability. This goal can only be adequately addressed if broad coverage is added to the implementation strategies of any future mapping missions to Venus.

  3. LUGH, the Proposed Mercury Express Mission, as an Ideal, Current, Low-Cost, Low-Risk Option for Mercury Exploration

    NASA Technical Reports Server (NTRS)

    Clark, P. E.; Lawlor, S. McKenna; Curtis, S.; Marr, G.; Giles, B.

    2000-01-01

    We propose an ESA Flexi Mission, LUGH, Mercury Express Mission, an extremely fast, low cost, low risk, high return, three-platform, multiple flyby mission which would provide data which are unique and complimentary to recently selected long lead time Mercury missions.

  4. Solar Powered Flight on Venus

    NASA Technical Reports Server (NTRS)

    Colozza, Anthony; Landis, Geoff (Technical Monitor)

    2004-01-01

    Solar powered flight within the Venus environment from the surface to the upper atmosphere was evaluated. The objective was to see if a station-keeping mission was possible within this environment based on a solar power generating system. Due to the slow rotation rate of Venus it would be possible to remain within the day light side of the planet for extended periods of time. However the high wind speeds and thick cloud cover make a station-keeping solar powered mission challenging. The environment of Venus was modeled as a function of altitude from the surface. This modeling included density, temperature, solar attenuation and wind speed. Using this environmental model flight with both airships and aircraft was considered to evaluate whether a station-keeping mission is feasible. The solar power system and flight characteristics of both types of vehicles was modeled and power balance was set up to determine if the power available from the solar array was sufficient to provide enough thrust to maintain station over a fixed ground location.

  5. A radar tour of Venus

    NASA Astrophysics Data System (ADS)

    Beatty, J. K.

    1985-06-01

    The surface of Venus is briefly characterized in a summary of results obtained by the Soviet Venera 15 and 16 8-cm synthetic-aperture radars, IR radiometers, and radar altimeters. A series of radar images, mainly from Kotelnikov et al. (1984), are presented and discussed, and the descent vehicles to be released by the two Vega spacecraft as they pass Venus in June 1985 on their way to an encounter with Halley's comet are described. Plans for the missions Phobos (two spacecraft to orbit Mars, rendezvous with Phobos and Deimos, release small instrumented landers, and perform mass spectrometry of vapors released by laser pulses directed at the satellite surfaces, beginning in 1988), a lunar-orbiter mission for 1989-1990, and Vesta (a not-yet-approved 1991 mission comprising a French probe to the asteroid 4 Vesta and perhaps 53 Kalypso and 453 Tea and a Soviet spacecraft to release a kite-supported Venus-atmosphere probe before flying on to an unknown destination) are considered.

  6. Exploration at the Edge of the Solar System: The Pluto-Kuiper Express Mission (Invited)

    NASA Astrophysics Data System (ADS)

    Terrile, R. J.

    1999-09-01

    The Pluto-Kuiper Express mission is one component of the Outer Planets/Solar Probe Project which is part of the exploration strategy laid out in the Solar System Exploration Roadmap. The first three missions of this project are the Europa Orbiter, Pluto-Kuiper Express and the Solar Probe. All require challenging new technologies and the ability to operate in deep space and at Jupiter. Use of common management and design approaches, avionics, and mission software is planned to reduce the costs of the three missions. The Pluto-Kuiper Express mission is planned to launch in 2004 and is designed to provide the first reconnaissance of the Solar System's most distant planet, Pluto, and it, moon Charon. A gravity assist from Jupiter will allow an 8-year flight time to Pluto and the possibility of encountering one or more Edgeworth-Kuiper Belt objects after the Pluto encounter. The primary science objectives for the mission include characterizing the global geology and geomorphology of Pluto and Charon, mapping their surface composition and characterizing Pluto's neutral atmosphere and its escape rate. This mission is currently soliciting scientific investigations through a NASA Announcement of Opportunity.

  7. Pioneer Venus small probes net flux radiometer experiment

    NASA Technical Reports Server (NTRS)

    Sromovsky, L. A.; Revercomb, H. E.; Suomi, V. E.

    1980-01-01

    The University of Wisconsin net flux experiment on the Pioneer Venus mission investigated the distribution of radiative energy deposition and loss which drives atmospheric circulation on Venus. The instrument used an external sensor and a novel method of chopping to measure the net flux of solar and planetary radiation during descent through the thick Venus atmosphere. The sensor, consisting of a high temperature flux plate detector and protective diamond windows, was designed to make accurate flux measurements while exposed to the severe Venus environment.

  8. Atmospheric tides on Venus. III - The planetary boundary layer

    NASA Technical Reports Server (NTRS)

    Dobrovolskis, A. R.

    1983-01-01

    Diurnal solar heating of Venus' surface produces variable temperatures, winds, and pressure gradients within a shallow layer at the bottom of the atmosphere. The corresponding asymmetric mass distribution experiences a tidal torque tending to maintain Venus' slow retrograde rotation. It is shown that including viscosity in the boundary layer does not materially affect the balance of torques. On the other hand, friction between the air and ground can reduce the predicted wind speeds from about 5 to about 1 m/sec in the lower atmosphere, more consistent with the observations from Venus landers and descent probes. Implications for aeolian activity on Venus' surface and for future missions are discussed.

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

    NASA Astrophysics Data System (ADS)

    McGouldrick, Kevin; Tsang, Constantine C. C.

    2015-11-01

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

  10. New measurements of Venus winds with ground-based Doppler velocimetry at CFHT

    NASA Astrophysics Data System (ADS)

    Machado, P.; Widemann, T.; Luz, D.; Peralta, J.; Berry, D. L.

    2012-04-01

    Since Venus Express spacecraft operations started in 2006, an ongoing effort has been made to coordinate its operations with observations from the ground using various techniques and spectral domains (Lellouch and Witasse, 2008). We present an analysis of Venus Doppler winds at cloud tops based on observations made at the Canada France Hawaii 3.6-m telescope (CFHT) with the ESPaDOnS visible spectrograph. These observations consisted of high-resolution spectra of Fraunhofer lines in the visible range (0.37-1.05 ?m) to measure the winds at cloud tops using the Doppler shift of solar radiation scattered by cloud top particles in the observer's direction (Widemann et al., 2007, 2008). The observations were made during 19-20 February 2011 and were coordinated with Visual Monitoring Camera (VMC) observations by Venus Express. The complete optical spectrum was collected over 40 spectral orders at each point with 2-5 seconds exposures, at a resolution of about 80000. The observations included various points of the dayside hemisphere at a phase angle of 67, between +10 and -60 latitude, in steps of 10 , and from +70 to -12 longitude relative to sub-Earth meridian in steps of 12. The Doppler shift measured in scattered solar light on Venus dayside results from two instantaneous motions: (1) a motion between the Sun and Venus upper cloud particles; (2) a motion between the observer and Venus clouds. The measured Doppler shift, which results from these two terms combined, varies with the planetocentric longitude and latitude and is minimum at meridian ?N = ?Sun - ?Earth where the two components subtract to each other for a pure zonal regime. Due to the need for maintaining a stable velocity reference during the course of acquisition using high resolution spectroscopy, we measure relative Doppler shifts to ?N. The main purpose of our work is to provide variable wind measurements with respect to the background atmosphere, complementary to simultaneous measurements made with the VMC camera onboard the Venus Express. We will present first results from this work, comparing with previous results by the CFHT/ESPaDOnS and VLT-UVES spectrographs (Machado et al., 2012), with Galileo fly-by measurements and with VEx nominal mission observations (Peralta et al., 2007, Luz et al., 2011). Acknowledgements: The authors acknowledge support from FCT through projects PTDC/CTE-AST/110702/2009 and PEst-OE/FIS/UI2751/2011. PM and TW also acknowledge support from the Observatoire de Paris. Lellouch, E., and Witasse, O., A coordinated campaign of Venus ground-based observations and Venus Express measurements, Planetary and Space Science 56 (2008) 1317-1319. Luz, D., et al., Venus's polar vortex reveals precessing circulation, Science 332 (2011) 577-580. Machado, P., Luz, D. Widemann, T., Lellouch, E., Witasse, O, Characterizing the atmospheric dynamics of Venus from ground-based Doppler velocimetry, Icarus, submitted. Peralta J., R. Hueso, A. Snchez-Lavega, A reanalysis of Venus winds at two cloud levels from Galileo SSI images, Icarus 190 (2007) 469-477. Widemann, T., Lellouch, E., Donati, J.-F., 2008, Venus Doppler winds at Cloud Tops Observed with ESPaDOnS at CFHT, Planetary and Space Science, 56, 1320-1334.

  11. High Temperature, Wireless Seismometer Sensor for Venus

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Cardesn Moinelo, Alejandro

    2010-04-01

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

  13. Zephyr: A Landsailing Rover for Venus

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

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

  14. Hinode Views the 2012 Venus Transit - Duration: 8 seconds.

    NASA Video Gallery

    On June 5, 2012, Hinode captured these stunning views of the transit of Venus -- the last instance of this rare phenomenon until 2117. Hinode is a joint JAXA/NASA mission to study the connections o...

  15. Hinode Views the 2012 Venus Transit - Duration: 4 seconds.

    NASA Video Gallery

    On June 5, 2012, Hinode captured these stunning views of the transit of Venus -- the last instance of this rare phenomenon until 2117. Hinode is a joint JAXA/NASA mission to study the connections o...

  16. Hinode Views the Transit of Venus - Duration: 48 seconds.

    NASA Video Gallery

    On June 5, 2012, Hinode captured this stunning view of the transit of Venus -- the last instance of this rare phenomenon until 2117. Hinode is a joint JAXA/NASA mission to study the connections of ...

  17. Planetary geometry handbook: Venus positional data, 1988 - 2020, volume 2

    NASA Technical Reports Server (NTRS)

    Sergeyevsky, A. B.; Snyder, G. C.; Paulson, B. L.; Cunniff, R. A.

    1983-01-01

    Graphical data necessary for the analysis of planetary exploration missions to Venus are presented. Positional and geometric information spanning the time period from 1988 through 2020 is provided. The data and the usage are explained.

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

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

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

  19. High Temperature Mechanisms for Venus Exploration

    NASA Astrophysics Data System (ADS)

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

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

  20. Venus Aerobot Surface Science Imaging System (VASSIS)

    NASA Technical Reports Server (NTRS)

    Greeley, Ronald

    1999-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Frampton, Robert; Peltz, Leora; Rubin, Seymour

    2008-09-01

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

  2. AKATSUKI status after the Venus orbit insertion

    NASA Astrophysics Data System (ADS)

    Nakamura, M.; Ishii, N.; Imamura, T.; Ueno, M.; Yamazaki, A.; Satoh, T.; Suzuki, M.; Iwagami, N.; Taguchi, M.; Watanabe, S.; Takahashi, Y.; Fukuhara, T.; Ohtsuki, S.; PLANET-C Project Team

    2010-12-01

    Japanese Venus Climate Orbiter 'AKATSUKI' (PLANET-C) was successfully launched at 06:58:22JST on May 21, by H-IIA F17. After the separation from H-IIA, the telemetry from AKATSUKI was normally detected by DSN Goldstone station (10:00JST) and the solar cell paddles' expansion was confirmed. AKATSUKI was put into the 3-axis stabilized mode in the initial operation from Uchinoura station and the critical operation was finished at 20:00JST on the same day. AKATSUKI will arrive at Venus on Dec 7, 2010. From the orbit around Venus, it will take pictures of the distribution of clouds and minor gas components at different wavelength by 4 cameras. These data will be analyzed to study the meteorology on Venus, especially the mechanism of the super-rotation of Venusian atmosphere which is still the top mystery of the Venus science. Simultaneous observation with ESA's Venus Express is highly expected to study the Venusian atmosphere. We will present the present status of AKATSUKI after the Venus orbit insertion with the latest results from the cameras.

  3. Results On Atmospheric Dynamics At The Venus Cloud Tops From Digital And Manual Wind Tracking In Vmc Images

    NASA Astrophysics Data System (ADS)

    Moissl, Richard; Limaye, S. S.; Khatuntsev, I.; Markiewicz, W. J.; Titov, D. V.

    2008-09-01

    The upper clouds of Venus have been studied extensively from ground and space borne observations in the past, especially in the ultraviolet part of the spectrum. To date we know that the atmosphere of Venus is in a constant state of super-rotation, reaching speeds around 100 m/s at the cloud tops and that the cloud markings in the UV are caused by SO2 and another, yet unknown, UV absorber. This presentation deals with the results on the atmospheric dynamics at the cloud top region ( 65-70 km above the surface) of Venus, derived from manual and automated cloud tracking in the UV channel (wavelength= 365 +/- 10 nm) of the Venus Monitoring Camera Experiment (VMC) on board the Venus Express mission. With the VMC it became possible to investigate the global dynamics with a relatively high resolution in space and time on a long term basis. In addition to the confirmation of results from previous studies on the atmospheric dynamics, the observations of the southern hemisphere by the VMC allowed for detailed studies of the strong cloud-level super-rotation phenomenon on Venus and its variability on different timescales ranging from hours to several months. Information on the latitudinal wind speed profiles could be obtained for latitudes up to 85 degrees south, extending the results from previous studies by almost 20 degrees. Global wave modes which are believed to play a key role for understanding energy transport phenomena in the venusian atmosphere, such as a 4-day Kelvin wave mode in low latitudes and diurnal and semidiurnal solar thermal tides have been detected in the analysis cloud tracked wind fields of the southern hemisphere of Venus.

  4. Systems design study of the Pioneer Venus spacecraft. Volume 3. Specifications

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Pioneer Venus spacecraft performance requirements are presented. The specifications include: (1) Design criteria and performance requirements for the Pioneer Venus spacecraft systems and subsystems for a 1978 multiprobe mission and a 1978 orbiter mission, spacecraft system interface, and scientific instrument integration.

  5. The Atmosphere and Climate of Venus

    NASA Astrophysics Data System (ADS)

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

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

  6. Planetary atmospheres. [Venus, Mars, Jupiter, Titan

    NASA Technical Reports Server (NTRS)

    Gierasch, P. J.

    1975-01-01

    A few of the advances and theoretical issues gained or raised by recent missions of unmanned spacecraft, notably Mariner 9, Pioneer 10, and Mariner 10, are discussed. Emphasis is on dynamics. Workers reviewed include Murray et al, Young, Marov et al, Hansen (Venus), Leovy, Sagan, Masursky, Leighton and Murray, Hartmann, Goody, Conrath (Mars), Gehrels et al, Williams and Robinson, Westphal, Kliore et al (Jupiter), Trafton, Hunten, Gillette et al, Pollack, Danielson et al (Titan). Planned future spacecraft missions are mentioned.

  7. Long-term Behaviour Of Venus Winds At Cloud Level From Virtis/vex Observations

    NASA Astrophysics Data System (ADS)

    Hueso, Ricardo; Peralta, J.; Snchez-Lavega, A.; Prez-Hoyos, S.; Piccioni, G.; Drossart, P.

    2009-09-01

    The Venus Express (VEX) mission has been in orbit to Venus for more than three years now. The VIRTIS instrument onboard VEX observes Venus in two channels (visible and infrared) obtaining spectra and multi-wavelength images of the planet. Images in the ultraviolet range are used to study the upper cloud at 66 km while images in the infrared (1.74 ?m) map the opacity of the lower cloud deck at 48 km. Here we present an analysis of the overall dynamics of Venus atmosphere at both levels using observations that cover a large fraction of the VIRTIS dataset. We will present our latest results concerning the zonal winds, the overall stability in the lower cloud deck motions and the variability in the upper cloud. Meridional winds are also observed in the upper and lower cloud in the UV and IR images obtained with VIRTIS. While the upper clouds present a net meridional motion consistent with the upper branch of a Hadley cell the lower cloud present more irregular, variable and less intense motions in the meridional direction. Acknowledgements This work has been funded by Spanish MEC AYA2006-07735 with FEDER support and Grupos Gobierno Vasco IT-464-07. RH acknowledges a "Ramn y Cajal contract from MEC.

  8. Venus - Mead Crater

    NASA Technical Reports Server (NTRS)

    1991-01-01

    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.

  9. First observation of energetic neutral atoms in the Venus environment

    NASA Astrophysics Data System (ADS)

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

    2008-05-01

    The ASPERA-4 instrument on board the Venus Express spacecraft offers for the first time the possibility to directly measure the emission of energetic neutral atoms (ENAs) in the vicinity of Venus. When the spacecraft is inside the Venus shadow a distinct signal of hydrogen ENAs usually is detected. It is observed as a narrow tailward stream, coming from the dayside exosphere around the Sun direction. The intensity of the signal reaches several 105cm-2sr-1s-1, which is consistent with present theories of the plasma and neutral particle distributions around Venus.

  10. Near infrared imaging of the surface of Venus and implications for crustal composition

    NASA Astrophysics Data System (ADS)

    Mller, N.; Helbert, J.

    2009-04-01

    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 at the wavelengths of the atmospheric window at 1.02 m shows evidence for variation of surface emissivity on the southern hemisphere [Mueller et al. 2008]. Inferred surface emissivity is correlated to some extend with morphological units identified from radar images of the NASA/JPL Magellan mission [Tanaka et al. 1997]. Alpha and Phoebe Regios are highlands mostly composed of tessera terrain, which is defined as a region strongly deformed by compressive and extensional tectonism in at least two directions. In comparison to lowland plains and other less tectonized highlands, these regions generally emit less thermal radiation, which implies lower emissivity. A recent analysis of NIR data from the Galileo fly-by in 1990 finds, that highland regions on Venus on average have a lower emissivity than lowlands [Hashimoto et al. 2008]. As a significant part of Venus highlands in the area observed by Galileo is composed of tessera, this observation is consistent with the observation of Mueller et al. [2008]. In situ measurements by the Venera and Vega landers are at most places consistent with basaltic surface composition. The hypsometry of Venus is unimodal. Inferred lava viscosity of most volcanic features is low, consistent with basaltic composition. All these observations hint towards a crust mostly composed of basalt [Basilevsky et al 1997]. However, no landing site was on tessera terrain, tessera are hypsometrically elevated and the morphology is dominated by tectonic deformation. Among other arguments this leads to the hypothesis that tessera highlands crust is more abundant in feldspar and silica, comparable to lunar highlands or continents on Earth [Nikolaeva et al., 1992]. NIR mapping supports this hypothesis, although other interpretations of the NIR data can not be ruled out. Generation of felsic crust is unlikely under the current climatic and tectonic regime on Venus. The lunar highland crust is believed to be a remnant of an magma ocean [Taylor 1974]. Enrichment in silica as in the continental crust of Earth requires recycling of water into the mantle [Campbell and Taylor 1984]. The surface of Venus is extremely dry and Venus and crustal recycling by plate tectonics does not operate at present. Any crust with felsic bulk composition had to be created during the early history of the planet. In a stratigraphic analysis tessera terrain predates all units it is in contact with [Ivanov and Head 1996]. Tessera terrain is defined by an extensive history of tectonic deformation. Assuming that tessera highlands indeed represent less dense crustal blocks created early in the history of Venus, implications arise from their persistence on the surface of Venus regarding resurfacing mechanism, crustal recycling and thermal evolution. If tessera highlands are enriched in silica relative to basalt this implies existence of a primordial ocean on Venus [Hashimoto et al. 2008]. In either case Venus would even more closely resemble the Earth-Moon system than previously assumed, making Venus an excellent subject for general studies of earth-like planets. Basilevsky, A. T.,et al. (1997), The Resurfacing History of Venus, in Venus II, pp. 1047-1084. Hashimoto, et al. (2008), Galileo Near Infrared Mapping Spectrometer (NIMS) Data Suggests Felsic Highland Crust on Venus, JGR, in press. Ivanov, M. A., et al. (1996), Tessera terrain on Venus: A survey of the global distribution, characteristics, and relation to surrounding units from Magellan data, JGR, 101, 14,861-14,908. Mueller, N., et al. (2008), Venus surface thermal emission at one micrometer in VIRTIS imaging observations - evidence for variation of crust and mantle differentiation conditions, JGR , in press. Nikolaeva, O. V., et al. (1992), Evidence on the crustal dichotomy, pp. 129-139, Venus Geology, Geochemistry, and Geophysics - Research results from the USSR. Tanaka, K. L., et al. (1997), Physiography, Geomorphic/geologic Mapping and Stratigraphy of Venus, in Venus II, pp. 667-694. Taylor, S. R. (1974), Geochemical Evolution of the Moon, LPI Contributions, 195, 7-9. Taylor, S. R., and I. H. Campbell (1983), No water, no granites - No oceans, no continents, GRL, 10, 1061-1064.

  11. Venusian upper haze properties from UV to IR wavelengths: results from SPICAV/SOIR on Venus Express

    NASA Astrophysics Data System (ADS)

    Montmessin, Franck; Fedorova, Anna; Wilquet, Valerie; Mahieux, Arnaud; Korablev, Oleg; Bertaux, Jean-Loup; Vandaele, Ann-Carine

    The SPICAV suite of instruments is composed of three separate channels: UV (110 to 320 nm), near-IR (0.7 to 1.7 µm) and the SOIR channel (2.3 to 4.4 µm). On specific opportunities, all three channels have operated simultaneously during solar occultations and have provided almost contiguous spectral information from 0.11 to 4.4 µm. Occultation observations provide several advantages, in particular it does not require cross-calibrating the channels together as scientific analysis is based on relative measurements; i.e. atmospheric transmissions which are the ratio of spectra obtained at a given altitude where the atmosphere produces some attenuation onto that collected outside the atmosphere where the sun can be observed free of any absorption. Haze opacities are readily retrieved using Beer-Lambert's law and vertical distribution from 65 to 120 km is inferred using regular onion peeling technique. Over the interval covered by SPICAV/SOIR, the spectral behavior of haze particles can be fully and robustly evaluated since the size parameter varies by more than one order of magnitude. Extraction of extinction coefficients have been performed for all three channels, allowing derivation of size distribution parameters. Details on the observations made for each channel will be presented. Profiles exhibit peculiar wavy structures that suggest gravity wave vertical propagations or localized destruction processes. Size distribution results will be discussed, in particular the possibility for a multi-modal distribution potentially implying different processes of formation and destruction at work in the mesosphere of Venus.

  12. System design of the Pioneer Venus spacecraft. Volume 1: Executive summary

    NASA Technical Reports Server (NTRS)

    Dorfman, S. D.

    1973-01-01

    The NASA Ames Research Center Pioneer Venus Project objective is to conduct scientific investigations of the planet Venus using spin stabilized spacecraft. The defined approach to accomplish this goal is to implement a multiprobe spacecraft mission and an orbiter spacecraft mission. Candidate launch vehicles for the Pioneer Venus missions were the Thor/Delta and Atlas/Centaur. The multiprobe spacecraft consists of a probe bus, one large probe, and three small probes. The probes are designed to survive to the surface of Venus, and to make in situ measurements of the Venusian atmosphere; the probe bus enters the atmosphere and makes scientific measurements until it burns out. The orbiter mission uses a spacecraft designed to orbit Venus for 225 days with an orbit period of about 24 hours (h). The probe bus and orbiter designs are to use a common spacecraft bus.

  13. Colonization of Venus

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.

    2003-01-01

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

  14. Venus in Violet and Near Infrared Light

    NASA Technical Reports Server (NTRS)

    1990-01-01

    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.

  15. Venus: Geochemical conclusions from the Magellan data

    NASA Technical Reports Server (NTRS)

    Wood, J. A.

    1992-01-01

    Though the Magellan mission was not designed to collect geochemical or petrological information, it has done so nonetheless. Since the time of the Pioneer Venus mission it has been known that high-altitude (greater than 2.5-5 km) mountainous areas on Venus exhibit anomalously low radiothermal emissivity (e less than 0.6). Magellan has greatly refined and extended these observations. The low emissivity requires surface material in the uplands to have a mineralogical composition that gives it a high bulk dielectric constant, greater than 20. The dielectric constant of dry terrestrial volcanic rocks seldom exceeds 7. The high-dielectric character of high-altitude surface material cannot be a primary property of the local volcanic rock, because there is no reason why rock having the required special mineralogy would erupt only at high altitudes. Therefore it is a secondary property; the primary Venus rock has reacted with the atmosphere to form a mineralogically different surface layer, and the secondary minerals formed are controlled by the ambient temperature, which decreases with altitude on Venus. A further investigation of venusian mineralogy is presented.

  16. GSFC Venus atmosphere simulator

    NASA Technical Reports Server (NTRS)

    Cridlin, M. S.; Munford, J. A.

    1974-01-01

    The design and preliminary testing of a Venus Atmosphere Simulation System are described. The system was designed for testing a quadrupole mass spectrometer proposed for the Pioneer-Venus Experiment. The system is capable of providing programmed temperature cycles up to 550 C, and manually controlled pressure up to 100 atmospheres.

  17. Hybrid modelling studies of solar wind interactions at Venus and Mars

    NASA Astrophysics Data System (ADS)

    Jarvinen, R.; Kallio, E.; Dyadechkin, S.; Wedlund, C. Simon; Alho, M.

    2013-09-01

    We present hybrid modelling of solar wind interactions of unmagnetized Solar System bodies and, more specifically, we discuss the solar wind induced ion escape and the structure of induced magnetospheres at Venus and at Mars. The modelling work is based on the HYB hybrid simulation model family, which has been developed for over a decade at the Finnish Meteorological Institute (FMI) and has been used to study plasma environments of unmagnetized and weakly magnetized celestial objects. In the hybrid approach ions are treated as particles moving under the Lorentz force and self-consistently coupled to the electric and magnetic field via Maxwell's equations while electrons form a massless, charge-neutralizing fluid. Especially, the global HYB hybrid simulations have been used to interpret in situ observations made by the ASPERA plasma instruments on the Mars Express and the Venus Express missions. We discuss the recent results of our hybrid simulation studies of the solar wind interaction with Venus and Mars as well as the newest developments of our hybrid simulation model.

  18. Atmosphere/mantle coupling and feedbacks on Venus

    NASA Astrophysics Data System (ADS)

    Gillmann, Cedric; Tackley, Paul

    2014-06-01

    We investigate the coupled evolution of the atmosphere and mantle on Venus. Here we focus on mechanisms that deplete or replenish the atmosphere: atmospheric escape to space and volcanic degassing of the mantle. These processes are linked to obtain a coupled model of mantle convection and atmospheric evolution, including feedback of the atmosphere on the mantle via the surface temperature. During early atmospheric evolution, hydrodynamic escape is dominant, while for later evolution we focus on nonthermal escape, as observed by the Analyzer of Space Plasma and Energetic Atoms instrument on the Venus Express Mission. The atmosphere is replenished by volcanic degassing from the mantle, using mantle convection simulations based on those of Armann and Tackley [2012], and include episodic lithospheric overturn. The evolving surface temperature is calculated from the amount of CO2 and water in the atmosphere using a gray radiative-convective atmosphere model. This surface temperature in turn acts as a boundary condition for the mantle convection model. We obtain a Venus-like behavior (episodic lid) for the solid planet and an atmospheric evolution leading to the present conditions. CO2 pressure is unlikely to vary much over the history of the planet, with only a 0.25-20% postmagma-ocean buildup. In contrast, atmospheric water vapor pressure is strongly sensitive to volcanic activity, leading to variations in surface temperatures of up to 200 K, which have an effect on volcanic activity and mantle convection. Low surface temperatures trigger a mobile lid regime that stops once surface temperatures rise again, making way to stagnant lid convection that insulates the mantle.

  19. Ion flows in Venus' magnetotail

    NASA Astrophysics Data System (ADS)

    Kollmann, P.; Brandt, P. C.; Futaana, Y.; Fedorov, A.

    2014-12-01

    The plasma environment of Venus, including its magnetotail up to 3 Venus radii distance has been studied by the Venus Express spacecraft since 2006. We use the ASPERA/IMA instrument that measures protons and oxygen ions in the eV to keV range. Oxygen ions deriving from Venus' atmosphere and flowing down the magnetotail have been reported and contribute to atmospheric escape (Barabash et al. 2007). There have also been ions observed that flow Venusward in the tail (Dubinin et al. 2014). Signatures of magnetic reconnection have been found (Zhang et al. 2012), which might contribute to these flows. We have numerically calculated flow velocities and densities of protons and oxygen ions in the tail. Since the IMA instrument cannot cover all directions during one scan, we manually identified hundreds of cases of clear and mostly unbiased plasma flows. This approach avoids cases that lead to incorrect results. We find that the Venusward fluxes of both protons and oxygen ions are on average smaller but on the same order of magnitude as the tailward escape fluxes. Venusward fluxes are commonly quasi-steady i.e. observed throughout most of a tail passage, which takes several ten minutes. The instantaneous flow directions can differ by more than 100 degrees in the tail. Their net tailward or Venusward direction is opposite in about half of the cases. Comparison with magnetic field data shows that tailward and Venusward bulk flows are roughly field-aligned. The calculation of plasma moments does not imply that the underlying distributions are thermal and described well with a Maxwellian distribution. About a third of the proton spectra show a suprathermal component. Such cases are more common for Venusward fluxes and can be observed over longer periods. In some cases the additional component is a clearly separated second peak but most of the time it fits well with a flat power law (exponents 0 to 3).

  20. Radar characteristics of small craters - Implications for Venus

    NASA Technical Reports Server (NTRS)

    Greeley, Ronald; Christensen, Philip R.; Mchone, John F.

    1987-01-01

    Shuttle radar images (SIR-A) of volcanic and impact craters were examined to assess their appearance on radar images. Radar characteristics were determined for (1) nine maarlikie craters in the Pinacate volcanic field, Sonora, Mexico; (2) the caldera of Cerro Volcan Quemado, in the Bolivian Andes; (3) Talemzane impact crater, Algeria; and (4) Al Umchaimin, a possible impact structure in Iraq. SIR-A images were compared with conventional photographs and with results from field studies. Consideration was then given to radar images available for Venus, or anticipated from the Magellan mission. Of the criteria ordinarily used to identify impact craters, some can be assessed with radar images and others cannot be used; planimetric form, expressed as circularity, and ejecta-block distribution can be assessed on radar images, but rim and floor elevations relative to the surrounding plain and disposition of rim strata are difficult or impossible to determine. It is concluded that it will be difficult to separate small impact craters from small volcanic craters on Venus using radar images and is suggested that it will be necessary to understand the geological setting of the areas containing the craters in order to determine their origin.

  1. A comparative analysis of Simplified General Circulation Models of Venus atmosphere

    NASA Astrophysics Data System (ADS)

    Lebonnois, Sebastien; Covey, Curt; Lee, Christopher; Lewis, Stephen R.; Parish, Helen; Read, Peter L.; Schubert, Gerald; Yamamoto, Masaru

    2010-05-01

    With the successful Venus Express mission and future missions planned for Venus exploration in the near future, study of the Venus atmosphere has been rapidly expending in the last few years. The development of General Circulation Models (GCMs) has focused on helping researchers to understand the details of the superrotation mechanism and other interactions within this complex atmospheric system. Several groups that have been developing such tools have joined together within the framework of a working group supported by the International Space Science Institute (ISSI, Berne, Switzerland), and have started to compare how the different models behave under the same forcing conditions. The goal of this intercomparison project is to test how robust the response of the different numerical models is to identical constraints. Such a project has already been conducted recently at CalTech (Lee and Richardson, JGR in press, 2009) using three different dynamical cores within a common model frame, and we wanted to build upon this first study. We developed a common protocol and conducted many simulations of Venus atmospheric circulation with five additional GCMs, using different types of dynamical cores (spectral, finite differences or finite volumes). The baseline common parameters include resolution, initial conditions, planetary and atmospheric parameters as well as several physical parameterizations: thermal forcing, upper and lower boundary conditions. In this work, thermal forcing is reduced to a simple newtonian cooling parameterization with diurnally averaged conditions and no orbital variation of solar forcing. Comparison among the models shows how the different models spin up, yielding different final states. Though all models do reach states with significantly positive superrotation, the amplitude and shape of the zonal wind fields is highly variable between different GCMs. We discuss the angular momentum transport mechanism, as well as the response of the different models to variations in key parameters (resolution, boundary conditions, the form of the temperature forcing function, ...). Though this work is done using a simplified thermal forcing and therefore may not be fully representative of the real Venus atmosphere, it brings some guiding elements to the community on the degree of complexity and sensitivity of the GCMs currently developed for the Venus atmosphere. It also illustrates interesting differences between dynamical model cores of the type in common use in terrestrial GCMs under conditions which lead to small residual differences becoming highly significant.

  2. Vénus version Express

    NASA Astrophysics Data System (ADS)

    Nazé, Yaël

    2010-04-01

    En avril 2006, Vénus a "capturé" un objet d'un genre particulier: une sonde robotique européenne, baptisée Venus Express et destinée à scruter cette planète sous tous les angles. Bilan de cette mission 5 ans après le lancement de la sonde, dont 4 d'observations vénusiennes.

  3. Venus Ionosphere and Solar Wind Interaction

    NASA Astrophysics Data System (ADS)

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

    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.

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

    SciTech Connect

    Pasachoff, Jay M.; Schneider, Glenn; Widemann, Thomas

    2011-04-15

    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.

  5. Explosive propulsion applications. [to future unmanned missions

    NASA Technical Reports Server (NTRS)

    Nakamura, Y.; Varsi, G.; Back, L. H.

    1974-01-01

    The feasibility and application of an explosive propulsion concept capable of supporting future unmanned missions in the post-1980 era were examined and recommendations made for advanced technology development tasks. The Venus large lander mission was selected as the first in which the explosive propulsion concept can find application. A conceptual design was generated and its performance, weight, costs, and interaction effects determined. Comparisons were made with conventional propulsion alternatives. The feasibility of the explosive propulsion system was verified for planetology experiments within the dense atmosphere of Venus as well as the outer planets. Additionally, it was determined that the Venus large lander mission could be augmented ballistically with a significant delivery margin.

  6. Pioneer Venus Data Analysis

    NASA Technical Reports Server (NTRS)

    Jones, Douglas E.

    1996-01-01

    Analysis and interpretation of data from the Orbiter Retarding Potential Analyzer (ORPA) onboard the Pioneer Venus Orbiter is reported. By comparing ORPA data to proton data from the Orbiter Plasma Analyzer (OPA), it was found that the ORPA suprathermal electron densities taken outside the Venusian ionopause represent solar wind electron densities, thus allowing the high resolution study of Venus bow shocks using both magnetic field and solar wind electron data. A preliminary analysis of 366 bow shock penetrations was completed using the solar wind electron data as determined from ORPA suprathermal electron densities and temperatures, resulting in an estimate of the extent to which mass loading pickup of O+ (UV ionized O atoms flowing out of the Venus atmosphere) upstream of the Venus obstacle occurred. The pickup of O+ averaged 9.95%, ranging from 0.78% to 23.63%. Detailed results are reported in two attached theses: (1) Comparison of ORPA Suprathermal Electron and OPA Solar Wind Proton Data from the Pioneer Venus Orbiter and (2) Pioneer Venus Orbiter Retarding Potential Analyzer Observations of the Electron Component of the Solar Wind, and of the Venus Bow Shock and Magnetosheath.

  7. Salt tectonics on Venus

    SciTech Connect

    Wood, C.A.; Amsbury, D.

    1986-05-01

    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 (470/sup 0/C) 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.

  8. Venus Gravity Handbook

    NASA Technical Reports Server (NTRS)

    Konopliv, Alexander S.; Sjogren, William L.

    1996-01-01

    This report documents the Venus gravity methods and results to date (model MGNP90LSAAP). It is called a handbook in that it contains many useful plots (such as geometry and orbit behavior) that are useful in evaluating the tracking data. We discuss the models that are used in processing the Doppler data and the estimation method for determining the gravity field. With Pioneer Venus Orbiter and Magellan tracking data, the Venus gravity field was determined complete to degree and order 90 with the use of the JPL Cray T3D Supercomputer. The gravity field shows unprecedented high correlation with topography and resolution of features to the 2OOkm resolution. In the procedure for solving the gravity field, other information is gained as well, and, for example, we discuss results for the Venus ephemeris, Love number, pole orientation of Venus, and atmospheric densities. Of significance is the Love number solution which indicates a liquid core for Venus. The ephemeris of Venus is determined to an accuracy of 0.02 mm/s (tens of meters in position), and the rotation period to 243.0194 +/- 0.0002 days.

  9. Active volcanism on Venus in the Ganiki Chasma rift zone

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    Venus is known to have been volcanically resurfaced in the last third of solar system history and to have undergone a significant decrease in volcanic activity a few hundred million years ago. However, fundamental questions remain: Is Venus still volcanically active today, and if so, where and in what geological and geodynamic environment? Here we show evidence from the Venus Express Venus Monitoring Camera for transient bright spots that are consistent with the extrusion of lava flows that locally cause significantly elevated surface temperatures. The very strong spatial correlation of the transient bright spots with the extremely young Ganiki Chasma, their similarity to locations of rift-associated volcanism on Earth, provide strong evidence for their volcanic origin and suggests that Venus is currently geodynamically active.

  10. Photoelectrons at Venus in the Ionosphere and the Tail

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

    Pioneer Venus Orbiter has shown that there is no intrinsic magnetic field at Venus. Instead, there is an induced magnetosphere caused by the solar wind interaction with the upper atmosphere of the planet. This interaction causes the solar wind's magnetic field lines to drape around the planet, dragging through the ionosphere where they continue on to form a magnetotail. Ionisation of the ionosphere by the solar HeII 30.4nm line leads to the production of ionospheric photoelectrons, recognisable by their characteristic spectral shape in the electron energy spectrum. These photoelectrons have been seen at Venus by the electron spectrometer, part of the ASPERA instrument, onboard the Venus Express spacecraft due to its energy resolution of ~7%. In addition, these ionospheric photoelectrons have now been seen in the induced magnetotail for the first time at Venus. Tailward photoelectrons have previously been seen at Earth, Mars and Titan. At Titan, they have been linked to ambipolar diffusion.

  11. Mesospheric circulation at the cloud top level of Venus according to Venus Monitoring Camera images

    NASA Astrophysics Data System (ADS)

    Khatuntsev, Igor; Patsaeva, Marina; Ignatiev, Nikolay; Titov, Dmitri; Markiewicz, Wojciech; Turin, Alexander

    We present results of wind speed measurements at the cloud top level of Venus derived from manual cloud tracking in the UV (365 nm) and IR (965 nm) channels of the Venus Monitoring Camera Experiment (VMC) [1] on board the Venus Express mission. Cloud details have a maximal contrast in the UV range. More then 90 orbits have been processed. 30000 manual vectors were obtained. The period of the observations covers more than 4 venusian year. Zonal wind speed demonstrates the local solar time dependence. Possible diurnal and semidiurnal components are observed [2]. According to averaged latitude profile of winds at level of the upper clouds: -The zonal speed is slightly increasing by absolute values from 90 on the equator to 105 m/s at latitudes 47 degrees; -The period of zonal rotation has the maximum at the equator (5 earth days). It has the minimum (3 days) at altitudes 50 degrees. After minimum periods are slightly increasing toward the South pole; -The meridional speed has a value 0 on the equator, and then it is linear increasing up to 10 m/s (by absolute value) at 50 degrees latitude. "-" denotes movement from the equator to the pole. -From 50 to 80 degrees the meridional speed is again decreasing by absolute value up to 0. IR (965+10 nm) day side images can be used for wind tracking. The obtained speed of the zonal wind in the low and middle latitudes are systematically less than the wind speed derived from the UV images. The average zonal speed obtained from IR day side images in the low and average latitudes is about 65-70 m/s. The given fact can be interpreted as observation of deeper layers of mesosphere in the IR range in comparison with UV. References [1] Markiewicz W. J. et al. (2007) Planet. Space Set V55(12). P.1701-1711. [2] Moissl R., et al. (2008) J. Geophys. Res. 2008. doi:10.1029/2008JE003117. V.113.

  12. Plasma waves at Venus

    NASA Technical Reports Server (NTRS)

    Strangeway, R. J.

    1991-01-01

    Many significant wave phenomena have been discovered at Venus with the plasma wave instrument on the Pioneer Venus Orbiter. It has been shown that whistler-mode waves in the magnetosheath of the planet may be an important source of energy for the topside ionosphere. Plasma waves are also associated with thickening of the ionopause current layer. Current-generated waves in plasma clouds may also provide anomalous resistance resulting in electron acceleration, possibly producing aurora. Ion-acoustic waves are observed in the bow shock, and appear to be a feature of the magnetotail boundary. Lastly, plasma waves have been cited as evidence for lightning on Venus.

  13. Sensor Amplifier for the Venus Ground Ambient

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

  14. Improved Knowlegde of Venus Atmospheric Structure

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  15. Temporal and Spatial Variations of Venus Cloud Properties

    NASA Astrophysics Data System (ADS)

    Hovenier, J. W.; Braak, C. J.; Knibbe, W. J. J.; de Haan, J. F.; Travis, L. D.

    1997-07-01

    Polarization observations made by the Pioneer Venus Orbiter early in its mission could not be explained solely by the micron sized particles deduced by Hansen and Hovenier [1974] from groundbased polarimetry. In addition to these particles, Kawabata et al. [1980] needed to assume the presence of smaller particles. These submicron sized particles are located above and within the main cloud deck. Using Pioneer Venus polarimetry data covering the entire mission, we analyzed the disk-averaged polarization to study temporal variations of the amount of submicron sized particles. We show that this amount decreased during the 1980's, while anomalous behavior occurred in 1983. The method used for this analysis is based on Newton-Raphson iteration and multiple scattering calculations. These calculations were performed using the adding/doubling method. We also present a method to conduct a similar analysis on a pixel-wise basis, in order to explore spatial variations of Venus' cloud properties. In this analysis, we pay attention to the relation between Venus' ultraviolet brightness variations and the amount og submicron sized particles. Preliminary results of this analysis are shown. References: Hansen, J. E., and J. W. Hovenier, "Interpretation of the polarization of Venus", J. Atmos. Sci. 31, 1137-1160, 1974 Kawabata, K., D. L. Coffeen, J. E. Hansen, W. A. Lane, M. Sato, and L. D. Travis, "Cloud and haze properties from Pioneer Venus polarimetry", J. Geophys. Res. 85, 8129-8140, 1980

  16. System design of the Pioneer Venus spacecraft. Volume 2: Science

    NASA Technical Reports Server (NTRS)

    Acheson, L. K.

    1973-01-01

    The objectives of the low-cost Pioneer Venus space probe program are discussed. The space mission and science requirements are analyzed. The subjects considered are as follows: (1) the multiprobe mission, (2) the orbiter mission, (3) science payload accomodations, and (4) orbiter spacecraft experimental interface specifications. Tables of data are provided to show the science allocations for large and small probes. Illustrations of the systems and components of various probe configurations are included.

  17. Transits of Venus and Mercury as muses

    NASA Astrophysics Data System (ADS)

    Tobin, William

    2013-11-01

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

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

    USGS Publications Warehouse

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

    2008-01-01

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

  19. Pioneer Venus Orbiter Ultraviolet Spectrometer: Operations and Data Analysis

    NASA Technical Reports Server (NTRS)

    Stewart, A. I. F.

    1997-01-01

    The Ultraviolet Spectrometer investigation on the Pioneer Venus Orbiter mission was extremely successful. The instrument was designed, built and tested at CU/LASP and delivered on time and within budget. The spacecraft and its instruments were required to operate for 243 days in Venus orbit. OUVS operated successfully for a further 13 years with only minor problems. The major scientific results listed above that deal with Venus were all unexpected and significant discoveries. The Comet Halley observations came about because of a favorable alignment of Halley, the Sun, and Venus, and were an important contribution to the international study of this comet. The scientific results of the OUVS investigation are to be found in the 41 papers listed in section 4 below. OUVS data provided material for 6 PhD and one MS dissertations, listed in section 5 below.

  20. Solar Flight on Mars and Venus

    NASA Astrophysics Data System (ADS)

    Landis, Geoffrey A.; LaMarre, Christopher; Colozza, Anthony

    2002-10-01

    Solar powered aircraft are of interest for exploring both Mars and Venus. The thin atmosphere of Mars presents a difficult environment for flying. It is clear that a new approach is needed. By making a totally solar airplane, we can eliminate many of the heavy components, and make an airplane that can fly without fuel. Using high efficiency solar cells, we can succeed with an airplane design that can fly for up to 6 hours in near-equatorial regions of Mars (4 hours of level flight, plus two hours of slow descent), and potentially fly for many days in the polar regions. By designing an airplane for a single day flight. In particular, this change means that we no longer have to cope with the weight of the energy storage system that made previous solar powered airplanes for Mars impractical). The new airplane concept is designed to fly only under the optimal conditions: near equatorial flight, at the subsolar point, near noon. We baseline an 8 kg airplane, with 2 kg margin. Science instruments will be selected with the primary criterion of low mass. Solar-powered aircraft are also quite interesting for the exploration of Venus. Venus provides several advantages for flying a solar-powered aircraft. At the top of the cloud level, the solar intensity is comparable to or greater than terrestrial solar intensities. The atmospheric pressure makes flight much easier than on planets such as Mars. The atmospheric pressure on Venus is presented. From an altitude of approximately 45 km (pressure = 2 bar), to approximately 60 km (pressure = 0.2 bar), terrestrial airplane experience can be easily applied to a Venus airplane design. At these flight altitudes, the temperature varies from 80 C at 45 km, decreasing to -35 C at 60 km. Also, the slow rotation of Venus allows an airplane to be designed for flight within continuous sunlight, eliminating the need for energy storage for nighttime flight. These factors make Venus a prime choice for a long-duration solar-powered aircraft. Fleets of solar-powered aircraft could provide an architecture for efficient and low-cost comprehensive coverage for a variety of scientific missions. Exploratory planetary mapping and atmospheric sampling can lead to a greater understanding of the greenhouse effect not only on Venus but on Earth as well.

  1. Solar Flight on Mars and Venus

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.; LaMarre, Christopher; Colozza, Anthony

    2002-01-01

    Solar powered aircraft are of interest for exploring both Mars and Venus. The thin atmosphere of Mars presents a difficult environment for flying. It is clear that a new approach is needed. By making a totally solar airplane, we can eliminate many of the heavy components, and make an airplane that can fly without fuel. Using high efficiency solar cells, we can succeed with an airplane design that can fly for up to 6 hours in near-equatorial regions of Mars (4 hours of level flight, plus two hours of slow descent), and potentially fly for many days in the polar regions. By designing an airplane for a single day flight. In particular, this change means that we no longer have to cope with the weight of the energy storage system that made previous solar powered airplanes for Mars impractical). The new airplane concept is designed to fly only under the optimal conditions: near equatorial flight, at the subsolar point, near noon. We baseline an 8 kg airplane, with 2 kg margin. Science instruments will be selected with the primary criterion of low mass. Solar-powered aircraft are also quite interesting for the exploration of Venus. Venus provides several advantages for flying a solar-powered aircraft. At the top of the cloud level, the solar intensity is comparable to or greater than terrestrial solar intensities. The atmospheric pressure makes flight much easier than on planets such as Mars. The atmospheric pressure on Venus is presented. From an altitude of approximately 45 km (pressure = 2 bar), to approximately 60 km (pressure = 0.2 bar), terrestrial airplane experience can be easily applied to a Venus airplane design. At these flight altitudes, the temperature varies from 80 C at 45 km, decreasing to -35 C at 60 km. Also, the slow rotation of Venus allows an airplane to be designed for flight within continuous sunlight, eliminating the need for energy storage for nighttime flight. These factors make Venus a prime choice for a long-duration solar-powered aircraft. Fleets of solar-powered aircraft could provide an architecture for efficient and low-cost comprehensive coverage for a variety of scientific missions. Exploratory planetary mapping and atmospheric sampling can lead to a greater understanding of the greenhouse effect not only on Venus but on Earth as well.

  2. The Atmosphere of Venus

    NASA Technical Reports Server (NTRS)

    Hansen, J. E. (Editor)

    1975-01-01

    Topics considered at the conference included the dynamics, structure, chemistry, and evolution of the Venus atmosphere, as well as cloud physics and motion. Infrared, ultraviolet, and radio occultation methods of analysis are discussed, and atmospheric models are described.

  3. Astrobiology and Venus exploration

    NASA Astrophysics Data System (ADS)

    Grinspoon, David H.; Bullock, Mark A.

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

  4. Solar Airplane Concept Developed for Venus Exploration

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.

    2004-01-01

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

  5. 10. The surface and interior of venus

    USGS Publications Warehouse

    Masursky, H.; Kaula, W.M.; McGill, G.E.; Pettengill, G.H.; Phillips, R.J.; Russell, C.T.; Schubert, G.; Shapiro, I.I.

    1977-01-01

    Present ideas about the surface and interior of Venus are based on data obtained from (1) Earth-based radio and radar: temperature, rotation, shape, and topography; (2) fly-by and orbiting spacecraft: gravity and magnetic fields; and (3) landers: winds, local structure, gamma radiation. Surface features, including large basins, crater-like depressions, and a linear valley, have been recognized from recent ground-based radar images. Pictures of the surface acquired by the USSR's Venera 9 and 10 show abundant boulders and apparent wind erosion. On the Pioneer Venus 1978 Orbiter mission, the radar mapper experiment will determine surface heights, dielectric constant values and small-scale slope values along the sub-orbital track between 50??S and 75??N. This experiment will also estimate the global shape and provide coarse radar images (40-80 km identification resolution) of part of the surface. Gravity data will be obtained by radio tracking. Maps combining radar altimetry with spacecraft and ground-based images will be made. A fluxgate magnetometer will measure the magnetic fields around Venus. The radar and gravity data will provide clues to the level of crustal differentiation and tectonic activity. The magnetometer will determine the field variations accurately. Data from the combined experiments may constrain the dynamo mechanism; if so, a deeper understanding of both Venus and Earth will be gained. ?? 1977 D. Reidel Publishing Company.

  6. Plate tectonics on Venus

    NASA Technical Reports Server (NTRS)

    Anderson, D. L.

    1981-01-01

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

  7. 3. ALTOVITI VENUS STATUE IN THE TEMPLE OF VENUS AS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. ALTOVITI VENUS STATUE IN THE TEMPLE OF VENUS AS SEEN FROM LIVING ROOM DOORS, SOUTHEAST FACADE OF KYKUIT HOUSE, ON AXIS WITH LINDEN ALLEE - Kykuit, 200 Lake Road, Pocantico Hills, Westchester County, NY

  8. Impeller Flow Characterisation for a High Temperature Venus Drill and Sample Delivery System

    NASA Astrophysics Data System (ADS)

    Pandey, S.; Zacny, K.

    2015-04-01

    Venus Drill and Sample Delivery System is being designed to conduct surface operations during future missions. The impact of ambient atmosphere on the performance of pneumatically driven components is investigated using finite volume model approach.

  9. Pioneer Venus data analysis for the retarding potential analyzer

    NASA Technical Reports Server (NTRS)

    Knudsen, William C.

    1993-01-01

    This report describes the data analysis and archiving activities, analysis results, and instrument performance of the orbiter retarding potential analyzer (ORPA) flown on the Pioneer Venus Orbiter spacecraft during the period, Aug. 1, 1988 to Sept. 30, 1993. During this period, the periapsis altitude of the Orbiter spacecraft descended slowly from 1900 km altitude, at which altitude the spacecraft was outside the Venus ionosphere, to approximately 130 km altitude in Oct. 1992 at which time communication with the spacecraft ceased as a result of entry of the spacecraft into the Venus atmosphere. The quantity of ORPA data returned during this reporting period was greatly reduced over that recovered in the previous years of the mission because of the reduced power capability of the spacecraft, loss of half of the onboard data storage, and partial failure of the ORPA. Despite the reduction in available data, especially ionospheric data, important scientific discoveries resulted from this extended period of the Pioneer Venus mission. The most significant discovery was that of a strong solar cycle change in the size of the dayside ionosphere and the resulting shutoff of flow of dayside ions into the nightside hemisphere. The large, topside O+ F2 ionospheric layer observed during the first three years of the Pioneer Venus mission, a period of solar cycle maximum activity, is absent during the solar cycle minimum activity period.

  10. Solar Energetic Particles Events and Models for Mars on the Eve of the MAVEN Mission Arrival

    NASA Astrophysics Data System (ADS)

    Luhmann, J. G.; Mays, M. L.; Odstrcil, D.; Baker, D. N.; Brain, D. A.; Larson, D.

    2014-04-01

    Planetary space weather has attracted much interest as missions including Mars Express and Venus Express observe the responses of the solar wind interactions and atmospheres at those planets to solar activity-related events. In addition, models of space weather phenomena are increasingly realistic and available. In this presentation we describe a particular advancement in the area of solar energetic particle event modeling with potential applications to the terrestrial planets. In particular, this tool can be used to relate particle events observed at several sites in the inner heliosphere, including Mars where the new MAVEN mission will be providing local measurements.

  11. Ionospheric dynamics at Mars and Venus

    NASA Astrophysics Data System (ADS)

    Frnz, M.; Dubinin, E.; Nielsen, E.; Angsmann, A.; Woch, J.; Barabash, S.; Lundin, R.; Fedorov, A.

    2011-10-01

    The upper ionospheres of Mars and Venus are permeated by the magnetic fields induced by the solar wind. It is a long-standing question whether these fields can put the dense ionospheric plasma into motion. If so, the transterminator flow of the upper ionosphere could explain a significant part of the ion escape from the planets atmospheres. But it has been technically very challenging to measure the ion flow at energies below 20eV. The only such measurements have been made by the ORPA instrument of the Pioneer Venus Orbiter reporting speeds of 1-5km/s for O+ ions at Venus above 300km altitude at the terminator (Knudsen et al. 1982). At Venus the transterminator flow is sufficient to sustain a permanent nightside ionosphere, at Mars a nightside ionosphere is observed only sporadically. We here report on new measurements of the ionospheric ion flows at Mars and Venus by the ASPERA-3 and -4 experiments on board Mars and Venus Express. For Mars we use support from the MARSIS radar experiment for some orbits with fortunate observation geometry. Here we have observed a transterminator flow of O+ and O+ 2 ions with a super-sonic velocity of around 5km/s and fluxes of 0.8 109/cm2s. If we assume a symmetric flux around the terminator this corresponds to an ion flow of 3.1 0.5 1025/s half of which is expected to escape from Mars (Fraenz et al, 2010). This escape flux is significantly higher than previously observed on the tailside of Mars, we discuss possible reasons for the difference. Possible mechanism to generate this flux can be the ionospheric pressure gradient between dayside and nightside or momentum transfer from the solar wind via the induced magnetic field since the flow velocity is in the Alfvnic regime. For Venus there is no independent observation of the cold plasma density by Venus Express and we can infer properties of the plasma distribution only using stronger assumption than for Mars. But measurements of the chemical plasma composition at low energies can help to get consistent flow parameters. We discuss the implication of these new observations for ion escape and possible extensions of the analysis to dayside observations which might allow us to infer the flow structure imposed by the induced magnetic field.

  12. Status of development of lightning detector for PLANET-C mission

    NASA Astrophysics Data System (ADS)

    Takahashi, Y.; Hoshino, N.; Sato, M.; Teraguchi, T.

    2008-12-01

    Magnetometer onboard Venus Express detected whistler mode waves whose source can be considered to be lightning discharge occurring well below the spacecraft orbit. However, there still remain some uncertainties to conclude finally such waves are originated by lightning discharge in the atmosphere. In order to identify the discharge phenomena in the atmosphere of Venus without any doubt, we plan to observe the lightning activity with high-speed optical detector onboard Planet-C, the Japanese Venus Climate Orbiter mission which will be launched in 2010 by JAXA. We are developing a new type of lightning detector, LAC (Lightning and Airglow Camera). Main difference from other equipments which have provided evidences of lightning existence in Venus is the high-speed sampling rate at 50kHz for each pixel, enabling us to distinguish the optical lightning flash from other pulsing noises. On the other hand, spatial resolution is not first priority as the first detector of Venus lightning. New type of APD (avalanche photo diode) array with a format of 8 x 8 is used and a narrow band interference filter at wavelength of 777.4 nm (OI) is selected for lightning measurement. The development is now at the stage for designing and manufacturing the flight model, based on the performance and environmental tolerance of the proto model. Especially, the algorithm for self- triggering is carefully improved in order to exclude false-trigger by other pulse-like noise.

  13. Venus Mobile Explorer with RPS for Active Cooling: A Feasibility Study

    NASA Technical Reports Server (NTRS)

    Leifer, Stephanie D.; Green, Jacklyn R.; Balint, Tibor S.; Manvi, Ram

    2009-01-01

    We present our findings from a study to evaluate the feasibility of a radioisotope power system (RPS) combined with active cooling to enable a long-duration Venus surface mission. On-board power with active cooling technology featured prominently in both the National Research Council's Decadal Survey and in the 2006 NASA Solar System Exploration Roadmap as mission-enabling for the exploration of Venus. Power and cooling system options were reviewed and the most promising concepts modeled to develop an assessment tool for Venus mission planners considering a variety of future potential missions to Venus, including a Venus Mobile Explorer (either a balloon or rover concept), a long-lived Venus static lander, or a Venus Geophysical Network. The concepts modeled were based on the integration of General Purpose Heat Source (GPHS) modules with different types of Stirling cycle heat engines for power and cooling. Unlike prior investigations which reported on single point design concepts, this assessment tool allows the user to generate either a point design or parametric curves of approximate power and cooling system mass, power level, and number of GPHS modules needed for a "black box" payload housed in a spherical pressure vessel.

  14. Characterizing the Venus atmospheric dynamics from ground-based Doppler velocimetry

    NASA Astrophysics Data System (ADS)

    Machado, Pedro; Luz, David; Widemann, Thomas; Lellouch, Emmanuel; Witasse, Olivier; Bertaux, Jean-Loup

    2010-05-01

    We present an analysis of observations of Venus made with the UVES instrument (Ultraviolet and Visual Echelle Spectrograph) at ESO's Very Large Telescope (VLT). The observations were carried out in May and June 2007 with the aim of characterizing the zonal wind flow in the atmosphere of Venus during the nominal mission phase of Venus Express. Doppler velocimetry measurements are based on solar Fraunhofer lines in the visible, probing the cloud tops velocity close to 65 km altitude. The narrow slit width of the UVES instrument, combined with the large apparent angular size of the planet, allows to simultaneously achieve high spectral resolving power and high spatial resolution. The observations were made at a central wavelength of 580 nm with the UVES red arm and at 437 and 860 nm in dichroic mode, using both the blue and red arms. In one observation block the field has been derotated in order to align the 0.3-arcsec aperture perpendicularly to Venus's rotation axis, while in other observations it was aligned parallel to it. In each case, spatial information, respectively in the East-West and in the North-South direction, is preserved in the spectra in the direction perpendicular to dispersion, allowing to spatially resolve relative variations in atmospheric rotation. We estimate both the relative variations of the atmospheric rotation with latitude and the hemispheric asymmetry of the zonal wind between 35S and 35N. The absolute magnitude of the zonal winds at latitudes of 23S, 13S and 2S has also been determined. [P. Machado acknowledges support from Fundao para a Cincia e a Tecnologia, grant SFRH-BD-66473-2009.

  15. O+ ion flow below the magnetic barrier at Venus post terminator

    NASA Astrophysics Data System (ADS)

    Szego, K.; Bebesi, Z.; Dobe, Z.; Frnz, M.; Fedorov, A.; Barabash, S.; Coates, A. J.; Zhang, T. L.

    2009-01-01

    Venus forms an obstacle in the streaming solar wind; inside the obstacle boundary (that is below the magnetic barrier) the ions of planetary origin dominate the plasma. The objective of this study is to investigate the properties of the O+ ions inside the obstacle boundary of Venus in the wake; we are especially interested in the characterization of the different plasma regions the O+ ions occupy. The study is based on the data collected by the ASPERA 4 plasma analyzer flying onboard of the Venus Express mission in a region never explored before experimentally. The obstacle boundary was approximately identified from the dropout of magnetospheric electrons and the sharp decrease of the proton speed; the entry point correlated well with the location of the magnetic barrier derived by eyes from magnetometer data. The most characteristic structures seen during the various flybys were (1) the tailward continuation of the mantle was evident; (2) in the mantle near Venus the O+ ion flow was significantly intense in low-energy counts; (3) the inbound and outbound crossings of the tailward boundary were sharp, characterized by less intense but higher-energy O+ beams; (4) the crossing of the central tail region (current sheet) was marked by the change of the sign of Bx and by an intense low-energy O+ ion flux; (5) it is remarkable that the O+ ion outflow was not confined to the central tail region; the intensity elsewhere was highly variable, resulting in a ray-like outflow pattern in most of the cases.

  16. Astrobiology and Venus Exploration

    NASA Astrophysics Data System (ADS)

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

    2005-12-01

    Venus has not traditionally been considered a promising target for Astrobiological exploration. We propose that Venus should be central to such an exploration program for several reasons. 1) Putting Earth life in context: Venus is the only other Earth-sized terrestrial planet that we know of, and certainly the only one we will have the opportunity to explore in the foreseeable future. Many geological and meteorological processes otherwise active only on Earth at present are currently active on Venus. For example, active volcanism is most likely responsible for maintaining the global cloud cover (Bullock and Grinspoon, 2001). Understanding the divergence of Earth and Venus is central to understanding the limits of habitability in the inner regions of habitable zones around solar-type stars. Thus Venus presents us with a unique opportunity for putting the bulk properties, evolution and ongoing geochemical processes of Earth in a wider context. 2) The possibility of extant life: Venus almost surely once had warm oceans. The evaporation of these oceans, and subsequent escape of hydrogen, most likely resulted in an oxygenated atmosphere. The duration of this phase is poorly understood, but during this time the terrestrial planets were not isolated. Rather, due to frequent impact transport, they represented a continuous environment for early microbial life. Life, once established in the early oceans of Venus, may have migrated to the clouds which, on present day Venus, may represent a habitable niche. Though highly acidic, this aqueous environment enjoys moderate temperatures, surroundings far from chemical equilibrium, and potentially useful radiation fluxes. Observations of unusual chemistry in the clouds, and particle populations that are not well characterized, suggest that this environment must be explored much more fully before biology can be ruled out. A sulfur-based metabolism for cloud-based life on Venus has recently been proposed (Schulze-Makuch et al., 2004). While speculative, these arguments, along with the discovery of terrestrial extremophile organisms that might survive in the Venusian clouds, establish the credibility of astrobiological exploration of Venus. Arguments for the possible existence of life on Mars or Europa are, by convention and repetition, seen as more mainstream than arguments for life elsewhere, but their logical status is no different from the plausibility arguments for life on Venus. 3) Rare planetary properties of astrobiological interest: All of our ideas about extraterrestrial biochemistry are, of necessity, extrapolations from the single example of life which we have been able to study. Our planetary exploration, with an increasing focus on Astrobiology, is designed to 'follow the water'. This is a reasonable strategy but it is based, at best, on an educated guess about life's universals. If we think beyond the specifics of a particular chemical system required to build complexity and heredity, we can ask what general properties a planet must possess in order to be considered a possible candidate for life. The answers might include an atmosphere with signs of flagrant chemical disequilibrium and active, internally driven cycling of volatile elements between the surface, atmosphere and interior. At present, the two planets we know of which possess these characteristics are Earth and Venus. Bullock, M.A. and D.H. Grinspoon (2001) Icarus, 150, 19-37 Schulze-Makuch, D.H. Grinspoon., O. Abbas, L.N. Irwin and M. Bullock. (2004) . Astrobiology, 4, 11-18.

  17. Aeolian processes on Venus

    NASA Technical Reports Server (NTRS)

    Greeley, R.

    1984-01-01

    Many of the questions regarding aeolian processes on Venus and the subsequent implications for surface history involve understanding the physics of particle motion in the venusian environment. The surface environment of Venus is simulated as closely as practicable using the Venus Wind Tunnel and to determine threshold wind speeds, particle flux, particle velocities, and the characteristics of various aeolian bedforms. Despite the relatively low wind speeds on Venus, the flux of windblown material on Venus is potentially high. A high fraction of material is transported as surface creep by rolling, estimates yield rates up to 100 kg per cm lane width per year depending upon the availability of material and wind frequency, suggesting that the formation of lowland plains by aeolian processes and the burial of various landforms such as impact craters could occur on short geological time-scales. Wind tunnel simulations demonstrate that aeolian processes may be very effective in modifying the surface through erosion and deposited and may have an important influence on the composition of the atmosphere.

  18. The Planet Venus

    NASA Astrophysics Data System (ADS)

    Luhmann, Janet

    This book is not so much for the space scientist looking for background material for research as it is for one interested in the history of planetary exploration. The first half (100 pps) is devoted to studies of Venus before the space age, starting at several hundred years BC. It is obvious from the multitude of detailed descriptions of observers' accounts that considerable library research went into this section. While sometimes tedious, this chronology of Venus research is punctuated with amusing facts. While many may know about the Velikovsky theory of the cometary origin of the planet, few may know that Lowell drew pictures of Cytherian canals similar to the canals of Mars or that Frederick the Great of Prussia proposed to name the (once suspected) satellite of Venus D'Alembert, after the mathematician. An equally amusing appendix shows the ups and downs of the rotation period of this planet with the invisible surface. Much attention is focused on early telescope observations, the ashen light, and transits of Venus. At the end of this half, one appreciates that Venus has played a fairly important role in history in the areas of religion, science, and technology.

  19. Mars and Venus ion cyclotron waves and their implications

    NASA Astrophysics Data System (ADS)

    Wei, H.; Russell, C.; Leisner, J.; Zhang, T.; Blanco-Cano, X.

    2009-05-01

    Mars and Venus do not have appreciable global magnetic fields to shield their neutral atmospheres from erosion by the solar wind. When their atmospheric hydrogen atoms are ionized and picked up by the solar wind, proton cyclotron waves are created from the free energy of the ring-beam distribution of the pick-up ions. At Mars, proton cyclotron waves observed by Mars Global Surveyor extend from the magnetosheath to over 12 Mars radii, with intermittent occurrence and amplitudes slowly varying with distance. The wave occurrence pattern indicates that the Martian hydrogen exosphere cannot be spherically symmetric but is rather disk- shaped with asymmetry in the direction of the interplanetary electric field. In order to travel across the magnetic field the picked up ions must be neutralized near where they are picked up and these fast neutrals are transported to distant regions where they get re-ionized and produce waves far downstream. Thus the top of Mars exosphere appears to extend in a disk to high altitude, with its orientation controlled by the interplanetary magnetic field. At Venus, proton cyclotron waves were first observed in the magnetosheath by Pioneer Venus Orbiter and later in the solar wind around Venus by Venus Express at a distance as far as 7 Venus radii. This paper compares the properties of the Mars and Venus waves and discusses the implication of these observations.

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

    USGS Publications Warehouse

    Campbell, Bruce A.; Clark, David A.

    2006-01-01

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

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

    SciTech Connect

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

    2014-10-10

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

  2. An analysis of AMTEC, multi-cell ground-demo for the Pluto/Express mission

    SciTech Connect

    Tournier, J.M.; El-Genk, M.S.

    1998-07-01

    Results of recent tests of an 8-cell, AMTEC ground-demo are analyzed and the performance of individual cells compared. The ground-demo produced a peak electric power of 27 W{sub e} at an output voltage of 16 V, when tested at hot and cold side temperatures of 1123 K and 553 K. The electric power output and terminal voltage of the individual cells, however, differed by as much as 25%, from 2.94 to 3.76 W{sub e}, and 1.73 to 2.21 V, respectively. These variations were attributed to differences in: (a) contact resistance between electrode / BASE / current collector; (b) current (or electrons) leakage between anode and cathode electrodes through the metal-ceramic braze joint between BASE tubes and support plate; and (c) the charge-exchange polarization losses. Model's predictions compared very well with measured voltage and electric power output of individual cells and of the ground-demo. At the operating conditions for the Pluto/Express spacecraft (T{sub hot} {approximately} 1200 K, T{sub cd} {approximately} 573 K), the best performing ground-demo cell would have delivered 5 W{sub e} at an output voltage of 3 V. These values, however, are still significantly lower than those needed to meet the Pluto/Express mission power requirements (8.2 W{sub e} at 3.5 V, per cell).

  3. Exploring Venus by Solar Airplane

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.

    2001-01-01

    A solar-powered airplane is proposed to explore the atmospheric environment of Venus. Venus has several advantages for a solar airplane. At the top of the cloud level, the solar intensity is comparable to or greater than terrestrial solar intensities. The Earthlike atmospheric pressure means that the power required for flight is lower for Venus than that of Mars, and the slow rotation of Venus allows an airplane to be designed for continuous sunlight, with no energy storage needed for night-time flight. These factors mean that Venus is perhaps the easiest planet in the solar system for flight of a long-duration solar airplane.

  4. Wireless Seismometer for Venus

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

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

  5. Geochemistry of Venus' Surface: Current limitations as future opportunities

    NASA Astrophysics Data System (ADS)

    Treiman, Allan H.

    Geochemical data about Venus' surface materials are quite limited and of poor precision. The Venera and VEGA lander missions (sources of the available data) were engineering and scientific triumphs, but their chemical analyses of the Venus surface do not permit detailed confident interpretation, such as are routine for terrestrial analyses and MER APXS rover analyses from Mars. In particular, the Venera and VEGA analyses of major elements (by XRF) did not return abundances of Na, and their data on Mg and Al are little more than detections at the 2? level. Their analyses for K, U, and Th (by gamma rays) are imprecise, except for one (Venera 8) with extremely high K contents (4% K2O) and one (Venera 9) with a non-chondritic U/Th abundance ratio. The landers did not return data on other critical trace and minor elements, like Cr and Ni. In addition, the Venera and VEGA landers sampled only materials from the Venus lowlandsthey did not target sites in any of the highland areas: shield volcanos, tesserae, nor the unique plateau costruct of Ishtar Terra. These limitations on current understanding of Venus' geochemistry emphasize the huge opportunities in additional chemical analyses of Venus' surface. Currently available instruments could provide much more precise analyses for major and minor elements, even within the engineering constraints of the Venera and VEGA lander systems. Such precise analyses would be welcome for basalts of Venus' lowland plains, but would be especially desirable for the highland tesserae and for Ishtar Terra. The tesserae may well represent ancient crust that predates the most recent volcanic resurfacing event and so provide a geochemical look into Venus' distant past. Ishtar Terra may be composed (at least in part) of granitic rocks like Earth's continental crust, which required abundant water to form. So, Ishtar Terra could possibly yield evidence on whether Venus once had an ocean, and thus the possibility of life.

  6. Venus - False Color Perspective of Sif and Gula Mons

    NASA Technical Reports Server (NTRS)

    1991-01-01

    A portion of western Eistla Regio is shown in this three dimensional, computer-generated view of the surface of Venus. The viewpoint is at an elevation of 1.2 kilometers (0.75 mile) at a location 700 kilometers (435 miles) southeast of Gula Mons, the volcano on the right horizon. Gula Mons reaches 3 kilometers (1.8 miles) high and is located around 22 degrees north latitude and 359 degrees east longitude. Sif Mons, the volcano on the left horizon, has a diameter of 300 kilometers (186 miles) and a height of 2 kilometers (1.2 miles). Magellan imaging and altimetry data are combined to develop a three-dimensional computer view of the planet's surface. Simulated color based on color images from the Soviet Venera 13 and 14 spacecraft is added to enhance small-scale structure. This image was produced at JPL's Multimission Image Processing Laboratory by Eric De Jong, Jeff Hall and Myche McAuley. Magellan is a NASA spacecraft mission to map the surface of Venus with imaging radar. The basic scientific instrument is a synthetic aperture radar, or SAR, which can look through the thick clouds perpetually shielding the surface of Venus. Magellan is in orbit around Venus which completes one turn around its axis in 243 Earth days. That period of time, one Venus day, is the length of a Magellan mapping cycle. The spacecraft completed its first mapping cycle and primary mission on May 15, 1991, and immediately began its second cycle. During the first cycle, Magellan mapped more than 80 percent of the planet's surface and the current and subsequent cycles of equal duration will provide complete mapping of Venus. Magellan was launched May 4, 1989, aboard the space shuttle Atlantis and went into orbit around Venus August 10, 1990.

  7. The galileo venus encounter.

    PubMed

    Johnson, T V; Yeates, C M; Young, R; Dunne, J

    1991-09-27

    The Galileo spacecraft passed Venus on its way to Jupiter on 10 February 1990, less than 4 months after launch from Earth aboard the shuttle Atlantis. Because Galileo's instruments were selected for broad-based planetary exploration, the spacecraft was able to obtain a wide range of measurements during the Venus encounter. Together with ground-based observations conducted during the encounter, these observations have yielded more accurate information about the planet's plasma environment, cloud patterns, and the possible existence of lightning. PMID:17784091

  8. Heavy metal frost on Venus

    NASA Astrophysics Data System (ADS)

    Schaefer, Laura; Fegley, Bruce

    2004-03-01

    Chemical equilibrium calculations of volatile metal geochemistry on Venus show that high dielectric constant compounds of lead and bismuth such as PbS (galena), Bi 2S 3 (bismuthite) or Pb-Bi sulfosalts condense in the venusian highlands and may be responsible for the low radar emissivities observed by Magellan and Pioneer Venus. Our calculations also show that elemental tellurium is unstable on Venus' surface and will not condense below 46.6 km. This is over 30 km higher than Maxwell Montes, the highest point on Venus' surface. Elemental analyses of Venus' highlands surface by laser induced breakdown spectroscopy (LIBS) and/or X-ray fluorescence (XRF) can verify the identity of the heavy metal frost on Venus. The Pb-Pb age of Venus could be determined by mass spectrometric measurements of the Pb 207/Pb 204 and Pb 206/Pb 204 isotopic ratios in Pb-bearing frosts. All of these measurements are technologically feasible now.

  9. Solar Wind Interaction with Venus and Mars: Comparison of Proton Pickup Rates

    NASA Astrophysics Data System (ADS)

    Wei, H.; Russell, C. T.; Blanco-Cano, X.

    2005-12-01

    Both Venus and Mars are unmagnetized planets whose ionospheres stand off the solar wind forming an ionopause, magnetosheath and standing bow shock. These planets can be compared using Pioneer Venus and Mars Global Surveyor data, and shortly with data from Venus Express. The principal difference in the solar wind from Venus to Mars is a decrease in the solar wind number density and the magnetic field strength. As a result, the dynamic pressure decreases, and the Mach number of the solar wind flow increases from Venus to Mars. The difference in the size of the planets may also be important. The radius of Mars and the escape velocity are close to half those of Venus. Pioneer Venus and Mars Global Surveyor data show that while the Mars solar wind interaction superficially resembles that of Venus, the occurrence of proton cyclotron waves in the solar wind near the two planets is very different. About 30 percent of the time proton cyclotron waves are found extending from the magnetosheath of Mars to over 12 RM with amplitudes that vary only slowly with distance. In contrast proton cyclotron waves at Venus appear to be confined to the magnetosheath. Since the electromagnetic energy flux of proton cyclotron waves is proportional to the rate of loss of the hydrogen exosphere from the planet, this simple observation indicates that Mars is losing hydrogen at a much more rapid rate than Venus at the present time.

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

    NASA Astrophysics Data System (ADS)

    Lorenz, Ralph D.

    2015-11-01

    We explore the quantitative limits that may be placed on Venus' present-day volcanic activity by radar imaging of surface landforms. The apparent nondetection of new lava flows in the areas observed twice by Magellan suggests that there is a ~60% chance that the eruption rate is ~1 km3/yr or less, using the eruption history and area/volume flow geometry of terrestrial volcanoes (Etna, Mauna Loa and Merapi) as a guide. However, if the detection probability of an individual flow is low (e.g. ~10%) due to poor resolution or quality and unmodeled viewing geometry effects, the constraint (<10 km3/yr) is not useful. Imaging at Magellan resolution or better of only ~10% of the surface area of Venus on a new mission (30 years after Magellan) would yield better than 99% chance of detecting a new lava flow, even if the volcanic activity is at the low end of predictions (~0.01 km3/yr) and is expressed through a single volcano with a stochastic eruption history. Closer re-examination of Magellan data may be worthwhile, both to search for new features, and to establish formal (location-dependent) limits on activity against which data from future missions can be tested. While Magellan-future and future-future comparisons should offer much lower detection thresholds for erupted volumes, a probabilistic approach will be required to properly understand the implications.

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

    NASA Astrophysics Data System (ADS)

    Majid, Walid

    2015-04-01

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

  12. Possible Signs of Fauna and Flora on Venus

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

  13. On the possibility of microbiota transfer from Venus to Earth

    NASA Astrophysics Data System (ADS)

    Wickramasinghe, N. C.; Wickramasinghe, J. T.

    2008-09-01

    The possibility of the clouds of Venus providing habitats for extremophilic microorganisms has been discussed for several decades. We show here that the action of the solar wind leads to erosion of parts of the atmosphere laden with aerosols and putative microorganisms, forming a comet-like tail in the antisolar direction. During inferior conjunctions that coincide with transits of the planet Venus this comet-like tail intersects the Earths magnetopause and injects aerosol particles. Data from ESAs Venus Express spacecraft and from SOHO are used to discuss the ingress of bacteria from Venus into the Earths atmosphere, which we estimate as 1011 1013 cells for each transit event.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  15. Storms On Venus: Lightning-induced Chemistry And Predicted Products

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

    Observations by many spacecraft that have visited Venus over the last 40 years appear to confirm the presence of lightning storms in the Venus atmosphere. Recent observations by Venus Express indicate that lightning frequency and power is similar to that on Earth. While storms are occurring, energy deposition by lightning into Venus atmospheric constituents will immediately dissociate molecules into atoms, ions and plasma from the high temperatures in the lightning column (>30,000 K) and the associated shock waves and heating, after which these atom and ion fragments will recombine during cooldown to form new sets of molecules. Lightning will re-sort the atoms of C,O,S,N,H to create highly energetic new products. Spark and discharge experiments in the literature suggest that lightning effects on the main atmospheric molecules CO2, N2, SO2, H2SO4 and H2O will yield new molecules such as mixed carbon oxides (CnOm), mixed sulfur oxides (SnOm), oxygen (O2), elemental sulfur (Sn), nitrogen oxides (NO, N2O, NO2, NO3), sulfuric acid clusters (HnSmOx-.aHnSmOx e.g. HSO4-.mH2SO4), polysulfur oxides, carbon soot, and also halogen oxides from HCl or HF and other exotic species. Many of these molecular species may be detectable by instruments onboard Venus Express. We explore the diversity of new products likely created in the storm clouds on Venus.

  16. Sampling the Cloudtop Region on Venus

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  17. Plains Tectonics on Venus

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

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

  18. Venus - Lessons for earth

    NASA Technical Reports Server (NTRS)

    Hunten, D. M.

    1992-01-01

    The old idea that Venus might possess surface conditions to those of an overcast earth has been thoroughly refuted by space-age measurements. Instead, the two planets may have started out similar, but diverged because of the greater solar flux at Venus. This cannot be proved, but is consistent with everything known. A runaway greenhouse effect could have evaporated an 'ocean'. The hydrogen would escape, and most of the oxygen would be incorporated into the crust. Without liquid water, CO2 would remain in the atmosphere. Chlorine atoms would catalyze the recombination of any free oxygen back to CO2. The same theories apply to the future of the earth, and to the explanation of the polar ozone holes; the analogies are striking. There is no likelihood that the earth will actually come to resemble Venus, but Venus serves both as a warning that major environmental effects can flow from seemingly small causes, and as a testbed for the predictive models of the earth.

  19. History of Venus Observations

    NASA Astrophysics Data System (ADS)

    Bonnet, Roger-Maurice; Grinspoon, David; Rossi, Angelo Pio

    Our image of Venus is that of a hellish, hot planet, permanently covered by fast-moving clouds, with its surface inaccessible to any Earth-based observer. But the perception and knowledge of our sister planet has been very different in the recent and more remote past.

  20. Second Venus spacecraft set for launch

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The launch phase of the Pioneer Venus Multiprobe spacecraft and cruise phases of both the Pioneer Venus Orbiter and the Multiprobe spacecraft are covered. Material pertinent to the Venus encounter is included.

  1. Venus tectonics: initial analysis from magellan.

    PubMed

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

    1991-04-12

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

  2. Signs of hypothetical fauna of Venus

    NASA Astrophysics Data System (ADS)

    Ksanfomality, Leonid V.

    2014-04-01

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

  3. Venus transit 2004: An international education program

    NASA Astrophysics Data System (ADS)

    Mayo, L.; Odenwald, S.

    2003-04-01

    December 6th, 1882 was the last transit of the planet Venus across the disk of the sun. It was heralded as an event of immense interest and importance to the astronomical community as well as the public at large. There have been only six such occurrences since Galileo first trained his telescope on the heavens in 1609 and on Venus in 1610 where he concluded that Venus had phases like the moon and appeared to get larger and smaller over time. Many historians consider this the final nail in the coffin of the Ptolemaic, Earth centered solar system. In addition, each transit has provided unique opportunities for discovery such as measurement and refinement of the detection of Venus' atmosphere, calculation of longitudes, and calculation of the astronomical unit (and therefore the scale of the solar system). The NASA Sun Earth Connection Education Forum (SECEF) in partnership with the Solar System Exploration (SSE) and Structure and Evolution of the Universe (SEU) Forums, AAS Division for Planetary Sciences (DPS), and a number of NASA space missions and science centers are developing plans for an international education program centered around the June 8, 2004 Venus transit. The transit will be visible in its entirety from Europe and partially from the East Coast of the United States. We will use a series of robotic observatories including the Telescopes In Education (TIE) network distributed in latitude to provide observations of the transit that will allow middle and high school students to calculate the A.U. through application of parallax. We will compare the terrestrial planets in terms of the evolutionary processes that define their magnetic fields, their widely differing interactions with the solar wind, and the implications this has for life on Earth and elsewhere in the universe. We will also use Venus transit as a probe of episodes in American history (e.g. 1769: revolutionary era, 1882: post civil war era, and 2004: modern era). Museums and planetariums in the US and Europe will offer real time viewing of the transit and conduct educational programs through professional development seminars, public lectures, and planetarium shows. We are interested in soliciting advice from the research community to coordinate professional research interests with this program.

  4. Pioneer Mars 1979 mission options

    NASA Technical Reports Server (NTRS)

    Friedlander, A. L.; Hartmann, W. K.; Niehoff, J. C.

    1974-01-01

    A preliminary investigation of lower cost Mars missions which perform useful exploration objectives after the Viking/75 mission was conducted. As a study guideline, it was assumed that significant cost savings would be realized by utilizing Pioneer hardware currently being developed for a pair of 1978 Venus missions. This in turn led to the additional constraint of a 1979 launch with the Atlas/Centaur launch vehicle which has been designated for the Pioneer Venus missions. Two concepts, using an orbiter bus platform, were identified which have both good science potential and mission simplicity indicative of lower cost. These are: (1) an aeronomy/geology orbiter, and (2) a remote sensing orbiter with a number of deployable surface penetrometers.

  5. Mars Express - ESA sets ambitious goals for the first European mission to Mars

    NASA Astrophysics Data System (ADS)

    2003-05-01

    Mars has always fascinated human beings. No other planet has been visited so many times by spacecraft. And still, it has not been easy to unveil its secrets. Martian mysteries seem to have increased in quantity and complexity with every mission. When the first spacecraft were sent - the Mariner series in 1960s - the public was expecting an Earth twin, a green, inhabited planet full of oceans. Mariner shattered this dream by showing a barren surface. This was followed by the Viking probes which searched for life unsuccessfully in 1976. Mars appeared dry, cold and uninhabited: the Earths opposite. Now, two decades later, modern spacecraft have changed that view, but they have also returned more questions. Current data show that Mars was probably much warmer in the past. Scientists now think that Mars had oceans, so it could have been a suitable place for life in the past. We do not know what happened to the planet in the past. Which process turned Mars into the dry, cold world we see today? says Agustin Chicarro, ESAs Mars Express project scientist. With Mars Express, we will find out. Above all, we aim to obtain a complete global view of the planet - its history, its geology, how it has evolved. Real planetology! Mars Express will reach the Red Planet by the end of December 2003, after a trip of just over six months. Six days before injection into its final orbit, Mars Express will eject the lander, Beagle 2, named after the ship on which Charles Darwin found inspiration to formulate his theory of evolution. The Mars Express orbiter will observe the planet and its atmosphere from a near-polar orbit, and will remain in operation for at least a whole Martian year (687 Earth days). Beagle 2 will land in an equatorial region that was probably flooded in the past, and where traces of life may have been preserved. The Mars Express orbiter carries seven advanced experiments, in addition to the Beagle 2 lander. The orbiters instruments have been built by group of scientific institutes from all over Europe, plus Russia, the United States, Japan and China. These instruments are a subsurface sounding radar; a high-resolution camera, several surface and atmospheric spectrometers, a plasma analyzer and a radio science experiment. The high-resolution camera will image the entire planet in full colour, in 3D, at a resolution of up to 2 metres in selected areas. One of the spectrometers will map the mineral composition of the surface with great accuracy. The missing water Data from some of the instruments will be key to finding out what happened with the water which was apparently so abundant in the past. For instance, the radar altimeter will search for subsurface water and ice, down to a depth of a few kilometres. Scientists expect to find a layer of ice or permafrost, and to measure its thickness. Other observations with the spectrometers will determine the amount of water remaining in the atmosphere. They will also tell whether there is a still a full water cycle on Mars, for example how water is deposited in the poles and how it evaporates, depending on the seasons. "These data will determine how much water there is left. We have clear evidence for the presence of water in the past, we have seen dry river beds and sedimentary layers, and there is also evidence for water on present-day Mars. But we do not know how much water there is. Mars Express will tell us, says Chicarro. The search for life The instruments on board Beagle 2 will investigate the geology and the climate of the landing site. But, above all, it will look for signs of life. Contrary to the Viking missions, Mars Express will search for evidence for both present and past life. Scientists are now more aware that a few biological experiments are not enough to search for life - they will combine many different types of tests to help discard contradictory results. To sniff out direct evidence of past or present biological activity, Beagle 2s nose is a gas analysis package. This will determine whether carbonate mineral

  6. Magellan - Initial analysis of Venus surface modification

    NASA Astrophysics Data System (ADS)

    Arvidson, R. E.; Baker, V. R.; Elachi, C.; Saunders, R. S.; Wood, J. A.

    1991-04-01

    Images of the Venus surface provided by the Magellan mission make it possible to see the fine-scale features diagnostic of weathering, erosion, and deposition. These include ejecta deposits extending up to 1000 km to the west of several impact craters, windblown deposits, features containing both obstacles and a source of particulate material, and evidence for degradation by atmosphere-surface interactions and mass movements. Initial Magellan observations pertaining to the nature, rate, and history of surficial processes are analyzed. Emphasis is placed on radar imaging, but results from radiometry and altimetry observations are also discussed.

  7. Tectonic connections to interior processes on Venus

    NASA Technical Reports Server (NTRS)

    Phillips, R. J.

    1992-01-01

    The ultimate goal of geophysical/geological exploration of Venus is to relate the present tectonic (and volcanic) state of the lithosphere to interior processes, particularly mantle convection, operating both now and in the past. The Magellan mission has provided a spectacular view of the surface, and upcoming gravity measurements, particularly if the Magellan orbit is circularized, will provide significant constraints on the state of the interior. This extended abstract focuses on several controversial issues regarding venusian tectonics and its relationship to geodynamic mechanisms in the planet's interior. The origin of highlands, coronae diapir structures, and trenches and subduction are discussed.

  8. Magellan - Initial analysis of Venus surface modification

    NASA Technical Reports Server (NTRS)

    Arvidson, R. E.; Baker, V. R.; Elachi, Charles; Saunders, R. S.; Wood, J. A.

    1991-01-01

    Images of the Venus surface provided by the Magellan mission make it possible to see the fine-scale features diagnostic of weathering, erosion, and deposition. These include ejecta deposits extending up to 1000 km to the west of several impact craters, windblown deposits, features containing both obstacles and a source of particulate material, and evidence for degradation by atmosphere-surface interactions and mass movements. Initial Magellan observations pertaining to the nature, rate, and history of surficial processes are analyzed. Emphasis is placed on radar imaging, but results from radiometry and altimetry observations are also discussed.

  9. The Stability of Climate on Venus

    NASA Astrophysics Data System (ADS)

    Bullock, Mark Alan

    The present climate of Venus is controlled by an efficient carbon dioxide-water greenhouse effect and by the radiative properties of its global cloud cover. Both the greenhouse effect and clouds are sensitive to perturbations in the abundance of atmospheric water vapor and sulfur gases. Planetary-scale processes involving the transport and sequestering of volatiles affect these abundances over time, driving changes in climate. I have developed a numerical model of the climate evolution of Venus. Atmospheric temperatures are calculated using a one-dimensional two-stream radiative-convective model that treats the transport of thermal infrared radiation in the atmosphere and clouds. These radiative transfer calculations are the first to utilize high temperature, high resolution spectral databases for the calculation of infrared absorption and scattering in Venus' atmosphere. I use a chemical/microphysical model of Venus' clouds to calculate changes in cloud structure that result from variations in atmospheric water and sulfur dioxide. Atmospheric abundances of water, sulfur dioxide, and carbon dioxide change under the influence of the exospheric escape of hydrogen, outgassing from the interior, and heterogeneous reactions with surface minerals. Radar images from the Magellan mission show that the surface of Venus has been geologically active on a global scale, yet its sparse impact cratering record is almost pristine. This geological record on Venus is consistent with an epoch of rapid plains emplacement 600-1100 million years ago. My models show that intense volcanic outgassing of sulfur dioxide and water during this time would have resulted in the formation of massive sulfuric acid/water clouds and the cooling of the surface for about 300 million years. The thick clouds would have subsequently given way to high, thin water clouds as atmospheric sulfur dioxide was lost to reactions with the surface. Surface temperatures approaching 900 K would have been reached about 500 million years after the onset of volcanic resurfacing. Evolution to current conditions would have proceeded due to loss of atmospheric water at the top of the atmosphere and the reappearance of sulfuric acid/water clouds. Current temperatures are maintained within a narrow range by the competing effects of cloud albedo and greenhouse warming. The present climate of Venus would be unstable if atmospheric carbon dioxide can react with surface minerals. Venus may be undergoing rapid climate change due to carbon dioxide reactions with the surface, but it is more likely stable because most of the surface is devoid of carbonate. Abundant atmospheric sulfur dioxide is maintained by the action of volcanic sources within the last 20 million years. Even if atmospheric carbon dioxide does not today react with the surface, volcanic outgassing sufficient to increase sulfur dioxide abundance 3-10 times the present value would cool the surface enough to engage carbon dioxide-mineral reactions. This would precipitate a climate runaway to a cooler, lower pressure state at 400 K and 43 bars within 60 million years. This may be the eventual fate of Venus anyway, as sulfur dioxide equilibrates with surface minerals in the absence of outgassing. The climate may oscillate between warm, cloudy conditions and a cooler, cloud-free regime before it runs away to the cooler stable state.

  10. The Venus nitric oxide night airglow: Model calculations based on the Venus thermospheric general circulation model

    SciTech Connect

    Bougher, S.W. ); Gerard, J.C. ); Stewart, A.I.F.; Fesen, C.G. )

    1990-05-01

    Pioneer Venus (PV) orbiter ultraviolet spectrometer (OUVS) images of the nightside airglow in the (0, 1) {delta} band of nitric oxide showed a maximum whose average location was at 0200 local solar time just south of the equator. The average airglow brightness calculated over a portion of the nightside for 35 early orbits during the Pioneer Venus mission was a factor of 4 lower than this maximum. Recent recalibration of the PV OUVS instrument and reanalysis of the data yield new values for this statistical maximum (1.9 {plus minus} 0.6 kR) and the nightside average (400-460 {plus minus} 120 R) nightglow. This emission is produced by radiative recombination of N and O atoms transported from their source on the dayside to the nightside by the Venus thermospheric circulation. The Venus Thermospheric General Circulation Model (VTGCM) has been extended to incorporate odd nitrogen chemistry in order to examine the dynamical and chemical processes required to give rise to this emission. Its predictions of dayside N atom densities are also compared with empirical models based on Pioneer Venus measurements. Calculations are presented corresponding to OUVS data taken during solar maximum. The average production of nitrogen atoms on the dayside is about 9.0 {times} 10{sup 9} atoms cm{sup {minus}2} s{sup {minus}1}. Approximately 30% of this dayside source is required for transport to the nightside to yield the observed dark-disk nightglow features. The statistical location and intensity of the bright spot are well reproduced, as well as the altitude of the airglow layer. The importance of the large-scale transport and eddy diffusion on the global N({sup 4}S) distribution is also evaluated.

  11. Mission and vehicle sizing sensitivities

    NASA Technical Reports Server (NTRS)

    Young, Archie C.

    1986-01-01

    Representative interplanetary space vehicle systems are sized to compare and show sensitivity of the initial mass required in low Earth orbit to one mission mode and mission opportunity. Data are presented to show the requirements for Earth-Mars opposition and conjunction class roundtrip flyby and stopover mission opportunities available during the time period from year 1997 to year 2045. The interplanetary space vehicle consists of a spacecraft and a space vehicle acceleration system. Propellant boil-off for the various mission phases is given for the Lox/LH (Liquid Oxygen/Liquid Hydrogen) propulsion systems. Mission abort information is presented for the 1999 Venus outbound swingby trajectory, transfer profile.

  12. Mariner Venus/Mercury 1973 solar radiation force and torques

    NASA Technical Reports Server (NTRS)

    Georgevic, R. M.

    1974-01-01

    The need for an improvement of the mathematical model of the solar radiation force and torques for the Mariner Venus/Mercury spacecraft arises from the fact that this spacecraft will be steering toward the inner planets (Venus and Mercury), where, due to the proximity of the Sun, the effect of the solar radiation pressure is much larger than it was on the antecedent Mariner spacecraft, steering in the opposite direction. Therefore, although the model yielded excellent results in the case of the Mariner 9 Mars Orbiter, additional effects of negligible magnitudes for the previous missions of the Mariner spacecraft should now be included in the model. This study examines all such effects and incorporates them into the already existing model, as well as using the improved model for calculation of the solar radiation force and torques acting on the Mariner Venus/Mercury spacecraft.

  13. Models of Venus atmosphere (1972)

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Criteria were developed in the following areas: environment, structures, guidance and control, and chemical propulsion. Quantitative data for the Venus atmosphere were obtained from earth-based observations and from spacecraft which have entered the Venus atmosphere or passed within several planetary radii of the planet. The models provide the temperature, pressure, and density profiles required to perform basic aerodynamic analyses. A set of engineering models are provided for the Venus atmosphere, based on theory and measured data available in January 1972.

  14. Tectonics and composition of Venus

    NASA Technical Reports Server (NTRS)

    Anderson, D. L.

    1980-01-01

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

  15. Tectonics and composition of Venus

    SciTech Connect

    Anderson, D.L.

    1980-01-01

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

  16. Venus Thermospheric Circulation.

    NASA Astrophysics Data System (ADS)

    Bougher, Stephen Wesley

    A variety of Pioneer Venus observations suggest a global scale, day-to-night Venus thermospheric circulation. The two-dimensional hydrodynamic model of Dickinson and Ridley (1977) correctly predicted the gross characteristics of this largely symmetric circulation. However, it failed to calculate the observed cold nightside temperatures, and the exact phases and densities of the neutral constituents. This thesis presents model studies of the dynamics and energetics of the Venus thermosphere, in order to address new driving, mixing and cooling mechanisms for an improved model simulation. The adopted approach has been to re-examine the circulation by first using the previous two-dimensional code to quantify those physical processes which can be inferred from the Pioneer Venus observations. Specifically, the model was used to perform sensitivity studies to determine the degree to which eddy cooling, eddy or wave drag, eddy diffusion and 15 (mu)m radiational cooling are necessary to bring the model temperature and composition fields into agreement with observations. Three EUV heating cases were isolated for study. Global temperature and composition fields in good agreement with Pioneer data were obtained. Large scale horizontal winds (LESSTHEQ)20 m/s were found to be consistent with the observed cold nightside temperatures and dayside bulges of O, CO and CO(,2). Fine tuning required that an eddy coefficient (LESSTHEQ)20% of previous one-dimensional models be used for nightside diffusion (K = 7.5 x 10('6) cm('2)/s). Very little eddy diffusion was required for the dayside (K (LESSTHEQ) 4 x 10('6) cm('2)/s). Observed dayside temperatures were obtained by using a 7-19% EUV heating efficiency profile. The enhanced 15(mu)m cooling needed for thermal balance is obtained using the best rate coefficient (K(,CO(,2)-0) = 5 x 10('-13) cm('3)/s) available for atomic O collisional excitation of CO(,2)(0,1,0). Eddy conduction was not found to be a viable cooling mechanism due to the weakened global circulation. The strong 15(mu)m damping and low EUV efficiency imply a very weak dependence of the general circulation to solar cycle variability. Finally, the NCAR terrestrial thermospheric general circulation model (TGCM) was adapted for Venus inputs using the above two-dimensional model parameters, to give a three-dimensional benchmark for future Venus modelling work.

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

    NASA Astrophysics Data System (ADS)

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

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

  18. Equatorial flattenings of planets - Venus

    NASA Astrophysics Data System (ADS)

    Bursa, M.; Sima, Z.

    1985-05-01

    The dimensions of Venus were found in order to calculate the degree of flattening due to gravity. The calculations were carried out within the framework of the general flattening theory of Bursa and Sima (1969). Data on the gravitational field of Venus, obtained during observations by Mottinger and Williams (1983) were incorporated in the equations. It is shown that the figure of Venus is different from all terrestrial bodies in the solar system: the surface in the equatorial zone is located above the best-fitting triaxial Venus ellipsoid. Deflections of the vertical at the planet surface are given.

  19. Aerobraking at Venus: A science and technology enabler

    NASA Astrophysics Data System (ADS)

    Hibbard, Kenneth; Glaze, Lori; Prince, Jill

    2012-04-01

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

  20. Growth of large volcanoes on Venus: Mechanical models and implications for structural evolution

    NASA Astrophysics Data System (ADS)

    McGovern, Patrick J.; Solomon, Sean C.

    1998-05-01

    The structure, tectonics, and evolution of large volcanoes on Venus, as revealed by data from the Magellan mission, appear to be distinct from those on Earth and Mars. To determine the conditions and processes that account for these differences, we model the evolution of stress and deformation in growing volcanic edifices on Venus using the finite element method. Large volcanoes on Venus are characterized by topographically prominent conical edifices surrounded by relatively flat flow aprons. The surfaces of both edifice and apron consist dominantly of radially oriented flows. Tectonic features, usually the surface expression of shallowly intruded dikes, also have predominantly radial orientations. Features similar to Hawaiian-style linear rift zones or large-scale flank failure, common on large volcanoes on Earth and Mars, are absent. By comparing predictions of faulting for models with detached and welded basal boundary conditions with the observed tectonic features, we determine that a welded condition is more likely. Horizontal compressive stresses transmitted into edifices across welded basal boundaries are inversely proportional to elastic lithosphere thickness Te. Contravening stress increments from magma chamber expansion, differential thermal contraction, or buoyant loading from beneath