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1

The Venus Express Mission  

NASA Astrophysics Data System (ADS)

The Venus Express Mission H. Svedhem (1), D. Titov (2), D. McCoy (1), J. Rodríguez-Canabal (3) and J. Fabrega (4) (1) ESA/ESTEC, Noordwijk, The Netherlands (Hakan.Svedhem@esa.int), (2) MPS, Katlenburg-Lindau, Germany, (3) ESA/ESOC, Darmstadt, Germany, (4) ASTRIUM-SAS, Toulouse, France The Venus Express mission was launched from Baikonur, Kazakhstan, on 9 November 2005. After a 5 months cruise phase, the spacecraft was inserted in a Venus orbit 11 April 2006. After another two months of testing and commissioning activities the nominal operational phase started 4 June. The mission main objective is to study the atmosphere and the plasma environment and some properties of the surface of Venus, both on a global level and on a detailed regional level. The nominal duration of the mission is two Venus sidereal days (486 earth days) and there is a possibility for extending the mission for a period of at least another two Venus days. The orbit is a highly elliptical polar orbit. It is optimised for remote observations at a global scale from high altitude, and for detailed studies of the northern hemisphere from low altitude, both at varying solar aspect angles. It will also allow for in-situ plasma measurements covering a large range of distances from the planet. The payload is selected for studies of the physics and chemistry of the atmosphere and the clouds and the related circulation at accuracy and a coverage presently not achieved. The interaction of the upper atmosphere with the solar wind will be investigated by dedicated instruments. With a time from the mission approval to the launch of just above three years this mission by far is the fastest scientific mission undertaken by ESA until now. This has been possible due to the re-build, with only minor modifications, of the Mars Express spacecraft, which in turn re-uses many of the Rosetta subsystems, and by using largely the same experienced teams from ESA and the industry. The scientific instruments are, in most cases, based on selected instruments from Mars Express and Rosetta. The spacecraft and the payload have demonstrated an excellent performance so far. This talk will focus on the mission design and the key features of the spacecraft and its payload.

Svedhem, H.; Titov, D.; McCoy, D.; Rodriguez-Canabal, J.; Fabrega, J.

2

Venus Express: a proposed ESA mission to Venus in 2005  

NASA Astrophysics Data System (ADS)

The Venus Express mission was proposed in response to the ESA Call for Ideas to reuse the Mars Express spacecraft and available instruments. The mission aims at a global investigation of Venus' atmosphere and plasma environment from polar orbit, and addresses several important aspects of the geology and surface physics. Reuse of the Mars Express bus offers an excellent and appropriate platform for Venus exploration. The instruments developed for the Mars Express and Rosetta missions are well suited for this task. A combination of spectroscopic and imaging instruments covering the UV to mid -IR range, along with low-frequency radar for subsurface sounding, and plasma instruments can provide global study of the Venus surface, atmosphere up to about 200 km, and solar wind interactions. Compared with earlier missions, a breakthrough will be accomp lished by fully exploiting the existence of spectral "windows" in the near-infrared spectrum of Venus' nightside in which radiation from the lower atmosphere and even the surface escapes to space and can be measured. A preliminary assessment of the mission profile indicates that the Mars Express spacecraft can accommodate eight instruments. The Soyuz-Fregat launcher can deliver this payload to a polar orbit around Venus with pericenter at ~250 km, apocenter at ~60,000 km, and period of ~24 hours. In comparison to the Pioneer Venus spinning spacecraft, Mars Express is an advanced 3 axis stabilised platform which provides significantly enhanced spectroscopic and imaging capabilities. The proposed duration of the nominal orbital mission is two Venus years (~ 450 Earth days). Venus Express will be a natural continuation of the first phase of Venus exploration by Soviet and American spacecraft. It will play the role of pathfinder for future, more complex missions to the planet, and the data obtained will help in planning and optimizing future investigations.

Titov, D.; Lebreton, J.; Lellouch, E.; Taylor, F.

3

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

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

4

Venus Express: scientific goals and payload of the mission  

NASA Astrophysics Data System (ADS)

The Venus Express mission aims at a global investigation of Venus' atmosphere and plasma environment from polar orbit, and addresses some aspects of the surface physics. More specifically the scientific goals of the mission are as follows. (1) Study of the atmospheric structure between 40 and 180 km by means of thermal IR sounding, and radio/solar/stellar occultation techniques. (2) Study of the atmospheric composition up to ˜180 km by high resolution spectroscopy in nadir and solar/stellar occultations geometry. Deep atmospheric sounding will fully exploit existence of the near IR transparency "windows" in the spectrum of Venus' nightside. (3) Study of the atmospheric dynamics between 50 and 120 km by tracking cloud features in the UV and IR images and retrieval of the thermal wind field in the mesosphere. (4) Investigation of the plasma environment, its interaction with the solar wind, and escape processes by in situ measurements of the energetic neutral atoms, ions and electrons, and in solar, stellar, and radio occultations. (5) Study of the physical properties of the surface by bi-static radar sounding and thermal mapping. The Venus Express payload consists of the instruments inherited from the Mars Express (ASPERA, PFS, SPICAM, VMC) and Rosetta (MAG, VeRa, VIRTIS) missions. These experiments are able to make a breakthrough in the Venus exploration and to shed a light on the mysteries of the planet. The mission will be a natural continuation of the first phase of Venus exploration by Soviet and American spacecraft. It will also play the role of pathfinder for future, more complex missions to the planet and will help in planning and optimizing future investigations.

Titov, D. V.; Lellouch, E.; Taylor, F. W.; Svedhem, H.

2003-04-01

5

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

NASA Astrophysics Data System (ADS)

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 55°S. Acknowledgements This work has been funded by the Spanish MICIIN AYA2009-10701 with FEDER support and Grupos Gobierno Vasco IT-464-07.

Hueso, Ricardo; Peralta, Javier; Sánchez-Lavega, Agustín.; Pérez-Hoyos, Santiago; Piccioni, Giuseppe; Drossart, Pierre

2010-05-01

6

Venus Express science planning  

Microsoft Academic Search

Venus Express is the first European mission to the planet Venus. Its payload consists of seven instruments and will investigate the atmosphere, the plasma environment, and the surface of Venus from orbit. Science planning is a complex process that takes into account requests from all experiments and the operational constraints. The planning of the science operations is based on synergetic

D. V. Titov; H. Svedhem; D. Koschny; R. Hoofs; S. Barabash; J.-L. Bertaux; P. Drossart; V. Formisano; B. Häusler; O. Korablev; W. J. Markiewicz; D. Nevejans; M. Pätzold; G. Piccioni; T. L. Zhang; D. Merritt; O. Witasse; J. Zender; A. Accomazzo; M. Sweeney; D. Trillard; M. Janvier; A. Clochet

2006-01-01

7

Venus Monitoring Camera for Venus Express  

Microsoft Academic Search

The Venus Express mission will focus on a global investigation of the Venus atmosphere and plasma environment, while additionally measuring some surface properties from orbit. The instruments PFS and SPICAV inherited from the Mars Express mission and VIRTIS from Rosetta form a powerful spectrometric and spectro-imaging payload suite. Venus Monitoring Camera (VMC)—a miniature wide-angle camera with 17.5° field of view—was

W. J. Markiewicz; D. V. Titov; N. Ignatiev; H. U. Keller; D. Crisp; S. S. Limaye; R. Jaumann; R. Moissl; N. Thomas; L. Esposito; S. Watanabe; B. Fiethe; T. Behnke; I. Szemerey; H. Michalik; H. Perplies; M. Wedemeier; I. Sebastian; W. Boogaerts; S. F. Hviid; C. Dierker; B. Osterloh; W. Böker; M. Koch; H. Michaelis; D. Belyaev; A. Dannenberg; M. Tschimmel; P. Russo; T. Roatsch; K. D. Matz

2007-01-01

8

Magellan Mission to Venus  

NSDL National Science Digital Library

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

9

The Pioneer Venus Missions.  

ERIC Educational Resources Information 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…

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

10

The planetary fourier spectrometer (PFS) onboard the European Venus Express mission  

Microsoft Academic Search

The planetary fourier spectrometer (PFS) for the Venus Express mission is an infrared spectrometer optimized for atmospheric studies. This instrument has a short wavelength (SW) channel that covers the spectral range from 1700 to 11400cm?1 (0.9–5.5?m) and a long wavelength (LW) channel that covers 250–1700cm?1 (5.5–45?m). Both channels have a uniform spectral resolution of 1.3cm?1. The instrument field of view

V. Formisano; F. Angrilli; G. Arnold; S. Atreya; K. H. Baines; G. Bellucci; B. Bezard; F. Billebaud; D. Biondi; M. I. Blecka; L. Colangeli; L. Comolli; D. Crisp; M. D’Amore; T. Encrenaz; A. Ekonomov; F. Esposito; C. Fiorenza; S. Fonti; M. Giuranna; D. Grassi; B. Grieger; A. Grigoriev; J. Helbert; H. Hirsch; N. Ignatiev; A. Jurewicz; I. Khatuntsev; S. Lebonnois; E. Lellouch; A. Mattana; A. Maturilli; E. Mencarelli; M. Michalska; J. Lopez Moreno; B. Moshkin; F. Nespoli; Yu. Nikolsky; F. Nuccilli; P. Orleanski; E. Palomba; G. Piccioni; M. Rataj; G. Rinaldi; M. Rossi; B. Saggin; D. Stam; D. Titov; G. Visconti; L. Zasova

2006-01-01

11

Results of Venus missions  

NASA Astrophysics Data System (ADS)

It is pointed out that Venus is the planet most similar to the earth in size, mass, mean density, and the amount of solar energy absorbed. Space missions conducted by the U.S. and the Soviet Union to explore Venus are related to Mariner flybys and an employment of Venera landers. Data concerning uranium, thorium, and potassium abundances and density measurements provide evidence that Venusian matter differentiated in the course of evolution during billions of years. Among the terrestrial planets Venus is distinguished mainly by the massive gaseous envelope that is responsible for its hot surface. Direct in situ measurements reliably established temperature and pressure at the Venus surface as high as 740 K and 90 kg/sq cm, respectively. Attention is given to planetary figure and surface, the structure and composition of the atmosphere, the problems of the light and heat budget, the clouds, dynamics, and upper atmosphere and near-space environment

Marov, M. Y.

12

Magnetic field investigation of the Venus plasma environment: Expected new results from Venus Express  

Microsoft Academic Search

The Venus Express mission is scheduled for launch in 2005. Among many other instruments, it carries a magnetometer to investigate the Venus plasma environment. Although Venus has no intrinsic magnetic moment, magnetic field measurements are essential in studying the solar wind interaction with Venus. Our current understanding of the solar wind interaction with Venus is mainly from the long lasting

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

2006-01-01

13

From Mars Express to Venus Express  

NASA Astrophysics Data System (ADS)

Venus Express, an Orbiter for the study of the atmosphere, the plasma environment, and the surface of Venus, is a mission which was proposed to ESA in response to the Call for ideas to re-use the Mars Express platform issued in March 2001. This mission was selected by ESA in June 2001 for an assessment study which was carried out over a 3-month period. The study, performed in the period July-October 2001, by ESA, Astrium and a team of scientific institutes has demonstrated that an orbiter mission to Venus could be carried out by adapting the Mars-Express satellite designed for a mission to Mars. The Mars Express spacecraft is under development for ESA by Astrium SAS of France. It is planned for launch in mid-2003, by a Soyuz-Fregat rocket. Its adaptation to a Venusian mission proved to be feasible with limited design modifications, essentially in the field of thermal control architecture and hardware. Taking thus advantage of the high level of recurrence and the optimum phasing between both projects, a launch during the Venus window of November 2005 appears to be feasible with an adequate schedule margin, and a moderate cost. The Venus Express mission and satellite are based on the following instruments set inherited from Mars Express and Rosetta programmes : Energetic Neutral Atoms Analyzer (ASPERA, from Mars Express), Atmospheric High Resolution Fourier Spectrometer (PFS, also from Mars Express), UV &IR Atmospheric Spectrometer (SPICAM, from Mars Express, complemented by SOIR), Radar Sounder VenSIS, adapted from the Mars Express MarSIS, Venus Monitoring Camera (new instrument, but with ROSETTA heritage), UV-Visible-near-IR imaging Spectrometer VIRTIS (from ROSETTA), Radio Science (VeRA, also on ROSETTA). The study demonstrated the feasibility of the proposed mission to Venus in 2005, based on the Mars Express spacecraft. The required adaptation of the spacecraft identified along the study is related to the thermal aspects during the orbital phase around Venus. This is due mainly to a solar flux four times stronger at Venus than at Mars, as well as a planet albedo which is much higher. In spite of this, the whole system approach (thermal control architecture and satellite pointing strategy for observation and for communication with the Earth) has been adapted from the Mars Express one, without introducing major modifications. The presentation will describe the Venus-Express mission and the spacecraft design. It will mainly focus on the technical feasibility of the adaptation of the Mars Express spacecraft to a Venus mission and discus the main programmatics constraints resulting from a short development imposed by the requirement to meet the 2005 launch opportunity.

Koeck, C.; Poinsignon, V.

2002-01-01

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)

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.

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

2004-08-01

15

Venus Express Italian Day on 4 October  

NASA Astrophysics Data System (ADS)

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

2004-09-01

16

Education and Public Outreach using Venus Express  

NASA Astrophysics Data System (ADS)

Nearly two decades after NASA’s Magellan radar mission to Venus, its atmosphere and surface is being investigated with new instruments by the Venus Express spacecraft from orbit. It was launched by the European Space Agency (ESA) on 11 November 2005, and has been orbiting Venus since April 2006. This mission provides an opportunity to focus on comparative planetary meteorology for education and public outreach efforts. We present an inquiry-based approach for informal and formal learning audiences by comparing atmospheric states of Venus and Earth using data available from Earth weather satellites and Venus Express. In the context of a middle or a high school curriculum, the science themes of Venus Express mission provide many connections to the themes of the National Science Education Standards. For the general audiences, Venus presents many of its mysteries such as its super rotation in the form of a giant hemispheric vortex akin to a hurricane, its deep atmosphere with sulfuric acid clouds, and the huge greenhouse effect concepts that are familiar to many. More than a dozen US scientists are participating in the Venus Express mission with support from NASA.

Pertzborn, Rosalyn A.; Limaye, S. S.; Pi, H. Y.

2006-12-01

17

The Venus Radar Mapper (VRM) mission  

NASA Astrophysics Data System (ADS)

The Venus Radar Mapper (VRM) mission is sponsored by NASA to put a single spacecraft in orbit around Venus to map the surface of Venus using a synthetic aperture mapping radar. The spacecraft is scheduled to be launched in April 1988 using a Shuttle-Centaur G combination. The spacecraft arrives at Venus in late July 1988 and begins its mapping mission which lasts for one Venus rotation or 243 days. This paper describes the VRM mission at its present state of design. The science objectives and project constraints are described. Key features of the spacecraft system and radar system are discussed. The interplanetary and mapping orbit design are covered. Navigation strategy is explained, including trajectory maneuvers and mapping phase orbit determination. Finally, the mapping sequences to optimize planet coverage are described.

Cutting, E.; Kwok, J. H.; Mohan, S. N.

1984-01-01

18

Compilation System for Venus Radar Mission (Magellan).  

National Technical Information Service (NTIS)

A synthetic aperture radar (SAR) compilation system was developed for extraction of topographic information of Venus from stereoradar imagery to be obtained from the Magellan mission. The system was developed for an AS-11AM analytical stereoplotter. Exten...

S. S. C. Wu F. J. Schafer A. Howington

1987-01-01

19

The Analyser of Space Plasmas and Energetic Atoms (ASPERA-4) for the Venus Express mission  

Microsoft Academic Search

The general scientific objective of the ASPERA-4 (Analyser of Space Plasmas and Energetic Atoms) experiment is to study the solar wind–atmosphere interaction and characterise the plasma and neutral gas environment in the near-Venus space through energetic neutral atom (ENA) imaging and local charged particle measurements. The studies to be performed address the fundamental question: How strongly do the interplanetary plasma

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

2007-01-01

20

PLANET-C: Venus Climate Orbiter Mission of Japan  

NASA Astrophysics Data System (ADS)

Venus is one of the most attractive targets in the solar system when we seek to understand the formation of the terrestrial environment. Venus is our nearest neighbor, and has a size very similar to the Earth's; however, previous spacecraft missions discovered an extremely dense (~90 bar) and dry CO[2] atmosphere with H[2]SO[4]-H[2]O clouds floating at high altitudes, and exotic volcanic features covering the whole planet. The abundant gaseous CO[2] brings about a high atmospheric temperature (~740 K) near the surface via greenhouse effect. The atmospheric circulation is also much different from the Earth's. The mechanisms which sustain such conditions are unclear and considered to be the keys to understand the origin of the terrestrial environment. In spite of the many previous missions that explored Venus, such as the Venera, Pioneer Venus, Vega and Magellan, most of the fundamental questions raised so far still remain unsolved. The Venus Climate Orbiter mission (PLANET-C), one of the future planetary missions of Japan, aims at understanding the atmospheric circulation of Venus. Meteorological data will be obtained by globally mapping clouds and minor constituents successively with 4 cameras at ultraviolet and infrared wavelengths, detecting lightning with a high-speed imager, and observing vertical structures of the atmosphere with radio science technique. The equatorial elongated orbit with westward revolution fits the observations of the movement and temporal variation of the Venusian atmosphere which rotates westward. The systematic, continuous imaging observations will provide us with an unprecedented large dataset of the Venusian meteorology. Additional targets of the mission are the exploration of the ground surface and the observation of zodiacal light. The mission will complement the ESA's Venus Express, which also explores the Venusian environment with different approaches. The spacecraft will be launched and arrive at Venus in 2010, and will perform 2 years of operation.

Ueno, M.; Nakamura, M.; Imamura, T.; Iwagami, N.; Satoh, T.; Watanabe, S.; Taguchi, M.; Takahashi, Y.; Suzuki, M.; Yamada, M.; Hashimoto, G.; Kasaba, Y.; Fukuhara, T.; Uemizu, K.; Abe, T.; Ishii, N.; Oyama, K.

2006-08-01

21

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)

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

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

2014-05-01

22

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

NASA Astrophysics Data System (ADS)

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.

Svedhem, H.; Titov, D.

2013-12-01

23

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

Microsoft Academic Search

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

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

2008-01-01

24

Future Venus Exploration: Mission Venera-D  

NASA Astrophysics Data System (ADS)

Venera-D is a strategic mission to explore Venus, included in the Russian Federal Space Program 2016-2025. Venera-D mission is in the phase A now. The Venera-D Roscosmos/IKI - NASA Joint Science Definition Team has been formed in February 2014.

Zasova, L. V.; Ignatiev, N. I.; Gerasimov, M. V.

2014-05-01

25

Magellan imaging radar mission to Venus  

Microsoft Academic Search

The Magellan imaging radar mapping mission has collected and processed data from the spacecraft in an elliptical orbit around Venus. A brief description is given of the mission and the spacecraft, followed by a more detailed description of the radar system design, which used Earth-orbiting synthetic aperture radar (SAR) experience and several innovations in its design to operate from an

WILLIAM T. K. JOHNSON

1991-01-01

26

Venus Express ready for lift-off  

NASA Astrophysics Data System (ADS)

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.

2005-10-01

27

Japanese Venus mission project ready to go  

NASA Astrophysics Data System (ADS)

A Japanese project to send a mission to Venus in 2009 is ready to start. The main scientific goal is to solve a long-standing mystery "The Super Rotation" by quantifying atmospheric circulation parameters from imaging/tracking cloud patterns.

Iwagami, N.; Nakamura, M.

2002-03-01

28

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

29

Systems Analysis for a Venus Aerocapture Mission  

NASA Technical Reports Server (NTRS)

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.

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

30

Venera-D -the future Russian mission to Venus  

NASA Astrophysics Data System (ADS)

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

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

31

Venus Geochemistry: Progress, Prospects, and New Missions - Program and Abstract Volume.  

National Technical Information Service (NTIS)

Topics covered include: In-Situ Aerial Exploration of Venus by Balloon - Science Objectives and Mission Architecture; Geochemical Aspects of the Geological History of Venus; The Role of Sulfur in Detecting Recent Climate Change on Venus; Venus Geochemical...

2009-01-01

32

Planet-C: Venus Climate Orbiter mission of Japan  

Microsoft Academic Search

The Venus Climate Orbiter mission (PLANET-C), one of the future planetary missions of Japan, aims at understanding the atmospheric circulation of Venus. Meteorological information will be obtained by globally mapping clouds and minor constituents successively with four cameras at ultraviolet and infrared wavelengths, detecting lightning with a high-speed imager, and observing the vertical structure of the atmosphere with radio science

Masato Nakamura; Takeshi Imamura; Munetaka Ueno; Naomoto Iwagami; Takehiko Satoh; Shigeto Watanabe; Makoto Taguchi; Yukihiro Takahashi; Makoto Suzuki; Takumi Abe; George L. Hashimoto; Takeshi Sakanoi; Shoichi Okano; Yasumasa Kasaba; Jun Yoshida; Manabu Yamada; Nobuaki Ishii; Takahiro Yamada; Kazunori Uemizu; Tetsuya Fukuhara; Koh-Ichiro Oyama

2007-01-01

33

Venus  

NASA Technical Reports Server (NTRS)

The present conference concerning the study of Venus discusses stellar magnitude and albedo data for the planet, radio astronomical studies, results of the Venera 13 and 14 missions, Venus optical properties, topography, surface properties and tectonic evolution, the tectonic implications of the interior of Venus, the thermal structure, photochemistry, composition, general circulation, and electrical activity of the Venus atmosphere, and the thermal balance of the lower, middle and upper atmoshere of Venus. Also discussed are the observation and interpretation of the Venus ionosphere, its model calculation, the interaction of the solar wind with the ionosphere of Venus in light of flow field models, the origin and evolution of the Venus atmosphere, and the problem posed by rare gases in the atmosphere of Venus.

Hunten, D. M. (editor); Colin, L. (editor); Donahue, T. M. (editor); Moroz, V. I.

1983-01-01

34

Observing the surface of Venus with VIRTIS on Venus Express  

NASA Astrophysics Data System (ADS)

The M channel of VIRTIS will allow the first systematic mapping of the surface and of the near-surface atmosphere of Venus in the near infrared wavelengths range This will be done using the atmospheric windows located at 1 10 1 18 mu m and if possible additionally using the window at 1 02 mu m Wattson and Rothman 1986 Kamp et al 1988 Moroz 2002 The latter is unfortunately right at the low end of the wavelength range of the IR channel and at the upper end of the VIS channel Therefore the usability of this window is unclear until first data from Venus are obtained The atmospheric windows will allow measuring the thermal emission of the surface as was demonstrated by Galileo NIMS Carlson et al 1991 and Cassini VIMS Baines et al 2000 While the atmospheric windows show no or little CO 2 absorption the radiance from the surface is still affected by scattering in the clouds This effect varies based on the optical thickness of the clouds We have developed a quicklook processing procedure which allows deriving surface emissivity variations from nighttime observations correcting for the atmospheric effects We will present the first version of this algorithm During the mission the algorithm will be refined based on the data returned from the different instruments on Venus Express The final goal is to derive maps of the absolute surface emissivity Based on these data two main science tasks for the surface analysis will be pursued Classification of the surface composition and study the interaction between low atmosphere and

Helbert, J.; Mariangeli, L.; Baines, K. H.; Garcia, R.; Erard, S.; Piccioni, G.; Drossart, P.; Müller, N.; Hashimoto, G.; Kostama, P.; Virtis Team

35

Enabling Venus In Situ Missions Using Mechanically Deployed Aerodynamic Decelerator  

NASA Astrophysics Data System (ADS)

Trade study and optimal solutions for guided entry and aerocapture for Venus in situ missions using Mechanically Deployed Aerodynamic Decelerator to reduce peak deceleration loads, as well as peak heat fluxes.

Saikia, S. J.; Saranathan, H.; Grant, M. J.; Longuski, J. M.

2014-06-01

36

Low-cost balloon missions to Mars and Venus  

NASA Technical Reports Server (NTRS)

The first successful flight demonstration of aerial deployment of Mars balloon prototypes in June 2002 and, earlier, of Venus balloon prototype deemed to be a turning point in the risk assessment of balloon missions.

Kerzhanovich, V.; Cutts, J.; Hall, J.

2003-01-01

37

A Venus Interior Structure Explorer Mission Using Balloons  

NASA Astrophysics Data System (ADS)

Although very similar to Earth, Venus remains a mystery. One key to the understanding this is the understanding of its interior structure. We propose a mission concept using balloons, based on solid/atmosphere coupling processes understanding.

Mimoun, D.; Garcia, R. F.

2014-06-01

38

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

39

Minor Species in the Deep Atmosphere of Venus: Dynamical Tracers seen by Venus Express  

NASA Astrophysics Data System (ADS)

Venus Express now approaches the end of its first extended mission, having been in Venus orbit since early 2006. The VIRTIS instrument, which covers a wavelength range between 0.25 to 5.1 ?m, has been continually measuring nightside thermal emissions from the deep atmosphere between 1.0 and 2.5 ?m. Absorption bands of CO, H2O and OCS in this region have been measured with unprecedented precision and resolution in space and time since Venus Express arrived. The results so far include the use of CO as a dynamical tracer for the large scale circulation in the lower atmosphere. We investigate the possible use of H2O as a tracer for mesoscale convection within and below the clouds, and discuss the role of OCS in understanding the chemistry in the lower atmosphere. This work was funded by STFC in the UK, as well as ASI and CNES from the PI institutes.

Tsang, Constantine; Wilson, C. F.; Barstow, J. K.; Bezard, B.; Irwin, P. G. J.; Taylor, F. W.; Piccioni, G.; Drossart, P.; McGouldrick, K.; Calcutt, S. B.

2009-09-01

40

ESA's Venus Express to reach final destination  

NASA Astrophysics Data System (ADS)

First step: catching Venus To begin to explore our Earth’s 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 planet’s 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 ESA’s 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 spacecraft’s 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 NASA’s Deep Space Network’s 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

2006-04-01

41

Mapping Venus: Modeling the Magellan Mission.  

ERIC Educational Resources Information Center

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)

Richardson, Doug

1997-01-01

42

The science return from Venus Express  

NASA Astrophysics Data System (ADS)

Since the beginning of the space era, Venus has been an attractive target for planetary scientists. Our nearest planetary neighbour and, in size at least, the Earth's twin sister, Venus was expected to be very similar to our planet. However, the first phase of Venus spacecraft exploration (1962-1985) discovered an entirely different, exotic world hidden behind a curtain of dense cloud. The earlier exploration of Venus included a set of Soviet orbiters and descent probes, the Veneras 4 to 14, the US Pioneer Venus mission, the Soviet Vega balloons and the Venera 15, 16 and Magellan radar-mapping orbiters, the Galileo and Cassini flybys, and a variety of ground-based observations. But despite all of this exploration by more than 20 spacecraft, the so-called "morning star" remains a mysterious world!

Svedhem, Håkan; Witasse, Olivier; Titov, Dmitri V.

2005-11-01

43

A conceptual venus rover mission using advanced radioisotope power system  

NASA Technical Reports Server (NTRS)

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

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

2006-01-01

44

Nuclear Electric Propulsion Application: RASC Mission Robotic Exploration of Venus  

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

45

Improved calibration of SOIR/Venus Express spectra.  

PubMed

The SOIR instrument on board the ESA Venus Express mission has been operational since the insertion of the satellite around Venus in April 2006. Since then, it has delivered high quality IR solar occultation spectra of the atmosphere of Venus. The different steps from raw spectra to archived data are described and explained in detail here. These consist of corrections for the dark current and for the non-linearity of the detector; removing bad pixels, as well as deriving noise. The spectral calibration procedure is described, along with all ancillary data necessary for the understanding and interpretation of the SOIR data. These include the full characterization of the AOTF filter, one of the major elements of the instrument. All these data can be found in the ESA PSA archive. PMID:24103989

Vandaele, Ann Carine; Mahieux, Arnaud; Robert, Séverine; Berkenbosch, Sophie; Clairquin, Roland; Drummond, Rachel; Letocart, Vincent; Neefs, Eddy; Ristic, Bojan; Wilquet, Valérie; Colomer, Frédéric; Belyaev, Denis; Bertaux, Jean-Loup

2013-09-01

46

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

NASA Astrophysics Data System (ADS)

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).

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

2006-11-01

47

Selection and Certification of TPS: Constraints and Considerations for Venus Missions  

Microsoft Academic Search

The science community is interested in planetary entry probe missions to improve our understanding of the atmospheres of Saturn, missions to Venus, and sample return missions from comets and asteroids. The In-Space Propulsion Program has completed aerocapture mission design studies that have defined requirements for the thermal protection system (TPS) to Venus, Mars, Titan and Neptune. There have been investments

E. Venkatapathy; B. Laub; G. J. Hartman; J. O. Arnold; M. J. Wright; G. A. Allen

48

Venus Express set for launch to the cryptic planet  

NASA Astrophysics Data System (ADS)

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

2005-10-01

49

A Conceptual Venus Rover Mission Using Advanced Radioisotope Power Systems  

NASA Astrophysics Data System (ADS)

This concept study demonstrates that a long lived Venus rover mission could be enabled by a novel application of advanced RPS technology. General Purpose Heat Source (GPHS) modules would be employed to drive an advanced thermoacoustic Stirling engine, pulse tube cooler and linear alternator that provides electric power and cooling for the rover. The Thermoacoustic Stirling Heat Engine (TASHE) is a system for converting high-temperature heat into acoustic power which then drives linear alternators and a pulse tube cooler to provide both electric power and coolin6g for the rover. A small design team examined this mission concept focusing on the feasibility of using the TASHE system in this hostile environment. A rover design is described that would provide a mobile platform for science measurements on the Venus surface for 60 days, with the potential of operating well beyond that. A suite of science instruments is described that collects data on atmospheric and surface composition, surface stratigraphy, and subsurface structure. An Earth-Venus-Venus trajectory would be used to deliver the rover to a low entry angle allowing an inflated ballute to provide a low deceleration and low heat descent to the surface. All rover systems would be housed in a pressure vessel in vacuum with the internal temperature maintained by the TASHE at under 50 °C.

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

2006-01-01

50

Aerocapture applied to Venus and Mars mission  

NASA Astrophysics Data System (ADS)

Engineering feasibility of exploring near earth planets such as Venus and Mars has been actively studied at ISAS (the Institute of Space and Astronautical Science), in association with development of ISAS's upgraded satellite launcher, M-V. When a spacecraft is inserted into an orbit around a planet with an atmosphere, aerodynamic force instead of propulsive deceleration enables it to increase a scientific payload. However, for the purpose of the successful achievement of the aero-assisted capture, several kinds of difficulties must be overcome. Technologies required to be established immediately are, for instance, (1) quite accurate determination and navigation of the approaching trajectory to the planet, (2) precise estimation of aero-thermodynamic behavior of the entry flight vehicle, and (3) detailed inspection of the planetary atmospheric characteristics such as composition, density, pressure and temperature. Development and verification of thermal protection materials, depending on the aerothermal environment of the aero-assisted flight, are also indispensable.

Ishii, Nobuaki; Kawaguchi, Jun'ichiro; Inatani, Yoshifumi; Abe, Takashi; Saito, Hirobumi; Nakatani, Ichiro

51

Rotation period of Venus estimated from Venus Express VIRTIS images and Magellan altimetry  

NASA Astrophysics Data System (ADS)

The 1.02 ?m wavelength thermal emission of the nightside of Venus is strongly anti-correlated to the elevation of the surface. The VIRTIS instrument on Venus Express has mapped this emission and therefore gives evidence for the orientation of Venus between 2006 and 2008. The Magellan mission provided a global altimetry data set recorded between 1990 and 1992. Comparison of these two data sets reveals a deviation in longitude indicating that the rotation of the planet is not fully described by the orientation model recommended by the IAU. This deviation is sufficiently large to affect estimates of surface emissivity from infrared imaging. A revised period of rotation of Venus of 243.023 ± 0.002 d aligns the two data sets. This period of rotation agrees with pre-Magellan estimates but is significantly different from the commonly accepted value of 243.0185 ± 0.0001 d estimated from Magellan radar images. It is possible that this discrepancy stems from a length of day variation with the value of 243.023 ± 0.002 d representing the average of the rotation period over 16 years.

Mueller, N. T.; Helbert, J.; Erard, S.; Piccioni, G.; Drossart, P.

2012-02-01

52

Altimetry of the Venus cloud tops from the Venus Express observations  

Microsoft Academic Search

Simultaneous observations of Venus by Visible and Infrared Thermal Imaging Spectrometer and Venus Monitoring Camera onboard the Venus Express spacecraft are used to map the cloud top altitude and to relate it to the ultraviolet (UV) markings. The cloud top altitude is retrieved from the depth of CO2 absorption band at 1.6 ?m. In low and middle latitudes the cloud

N. I. Ignatiev; D. V. Titov; G. Piccioni; P. Drossart; W. J. Markiewicz; V. Cottini; Th. Roatsch; M. Almeida; N. Manoel

2009-01-01

53

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

NASA Astrophysics Data System (ADS)

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

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

2009-07-01

54

ESA to present the latest Venus Express results to the media  

NASA Astrophysics Data System (ADS)

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

2007-11-01

55

An Atmospheric Variability Model for Venus Aerobraking Missions  

NASA Technical Reports Server (NTRS)

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.

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

2013-01-01

56

Image processing and products for the Magellan mission to Venus  

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

57

Toroidal and poloidal magnetic fields at Venus. Venus Express observations  

NASA Astrophysics Data System (ADS)

Magnetic field and plasma measurements carried out onboard Venus Express during solar minimum conditions suggest the existence of two kinds of magnetic field configuration in the Venusian ionosphere. We interpret these as the manifestation of two different types of generation mechanisms for the induced magnetosphere. A different magnetic field topology (toroidal and poloidal) arises if the induced currents are driven either by the solar wind motional electric field or by the Faraday electric field—a conducting ionosphere sees the magnetic field carried by solar wind as a time-varying field. At the dayside, both driving agents produce a similar draping pattern of the magnetic field. However, different magnetic field signatures inherent to both induction mechanisms appear at lower altitudes in the terminator region. The conditions at low solar EUV flux when the ionosphere of Venus becomes magnetized seem to be favorable to distinguish between two different types of the induced fields. We present cases of both types of the magnetic field topology. The cases when the effects of the Faraday induction become well noticeable are especially interesting since they provide us with an example of solar wind interaction with a tiny induced dipole field immersed into the ionosphere. Another interesting case when poloidal magnetic fields are evidently displayed is observed when the IMF vector is almost aligned with the solar wind velocity. In general case, both mechanisms of induction probably complement each other.

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

2013-10-01

58

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

NASA Technical Reports Server (NTRS)

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.

1988-01-01

59

Ballistic Mercury orbiter mission via Venus and Mercury gravity assists  

NASA Astrophysics Data System (ADS)

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.

Yen, Chen-Wan Liu

1989-09-01

60

Ballistic Mercury orbiter mission via Venus and Mercury gravity assists  

NASA Astrophysics Data System (ADS)

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.

Yen, C.-W. L.

1986-08-01

61

State of the Venus Atmosphere from Venus Express at the time of MESSENGER FLy- By  

NASA Astrophysics Data System (ADS)

The Venus Monitoring Camera (VMC) and the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) instruments on Venus Express spacecraft have been observing Venus since orbit insertion in April 2006. The state of the atmosphere in 2006 was in the form of a hemispheric vortex centered over the south pole, and presumably, another one in the northen hemisphere. The VMC and VIRTIS data have been used to determine cloud motions as well as the structure and organization of the atmospheric circulation from the the data collected since June 2006. In June 2007, the MESSENGER spacecraft flew-past Venus and also observed Venus on approach and departure from Venus. We report on the atmosphere of Venus as it appeared during this period.

Limaye, S. S.; Markiewicz, W. J.; Titov, D.; Piccione, G.; Baines, K. H.; Robinson, M.

2007-12-01

62

Venus Terminator Temperature Structure: Venus Express SOIR and VTGCM Comparisons  

NASA Astrophysics Data System (ADS)

Venus Express SOIR terminator profiles of CO2 densities and temperatures have been organized and presented for 100+ 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 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 global circulation models of the upper atmosphere. New Venus Thermospheric General Circulation Model (VTGCM) simulations are conducted for conditions appropriate to these SOIR measurements. In particular, solar minimum 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 presently used in the SOIR data analysis. Averaging of VTGCM temperature profiles in each of these bins (at each terminator) 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 level. 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 km. The SOIR terminator temperatures thusfar only reveal rather weak ET versus MT asymmetries above 140 km. Details of the underlying thermal balance processes are identified that give rise to these VTGCM simulated temperatures.

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

2013-10-01

63

Venus surface investigation based on VIRTIS measurements on Venus Express  

NASA Astrophysics Data System (ADS)

The dense atmosphere of Venus prevented systematic studies of its surface at optical wavelengths in the past. The discovery of near infrared nightside atmospheric windows has opened a new challenge for detailed surface studies. The Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) on Venus Express is the first experiment collecting continuously nightside surface emission data from the planet. The observed high variability of measured signatures is mainly due to spatial variations of cloud optical depth and surface elevation. The investigation of surface properties requires a convergent approach of radiative transfer simulations and VIR- TIS data analyses. Therefore, a selection of orbits with well calibrated data over the northern hemisphere was performed for footprints that cover a maximum range of surface elevation variations. Radiative transfer calculations demonstrate that the conservative character of cloud multiple scattering below 2 µm and a strong dependence of radiance ratios on surface elevation in this spectral region allow the mapping of surface topography and a retrieval of the surface temperature. To the first order, the surface temperature is a function of ground elevation. Small deviations from this first order dependence have been identified that are possibly due to different surface materials. 1 Institut f¨r Planetologie, Westf¨lische Wilhelms-Universit¨t M¨nster, Wilhelm-Klemm-Str.10, u a a u 48129 M¨nster, Germany u 2 German PlaceNameAerospace PlaceTypeCenter (DLR), Remote Sensing Technology Institute, Dpt. Marine Remote Sensing, Rutherfordstrasse 2, 12489 CityplaceBerlin, countryregionGermany 3 German PlaceNameAerospace PlaceTypeCenter (DLR), Institute for Planetary Research, Rutherfordstrasse 2, 12489 CityplaceBerlin, country-regionGermany 4 LESIA, Observatoire de Paris, CNRS, UPMC, Université Paris-Diderot, 5 place Jules Janssen, e 92195 Meudon, France 5 INAF-IASF (Instituto di Astrofisica Spaziale e Fisica Cosmica), via Statedel Fosso del Cavaliere, 100 00133 placeplaceCityRome, placeItaly

Arnold, Gabriele; Haus, Rainer; Döhler, Wolfgang; Kappel, David; Piccioni, Giuseppe; Drossart, Pierre

64

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

NASA Astrophysics Data System (ADS)

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.

Chassefiere, Eric

65

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

NASA Astrophysics Data System (ADS)

The European Venus Explorer (EVE) mission was proposed to the European Space Agency in 2007, as an M-class mission under the Cosmic Vision Programme. Although it has not been chosen in the 2007 selection round for programmatic reasons, the EVE mission may serve as a useful reference point for future missions, so it is described here. It consists of one balloon platform floating at an altitude of 50-60 km, one descent probe provided by Russia, and an orbiter with a polar orbit which will relay data from the balloon and descent probe, and perform science observations. The balloon type preferred for scientific goals is one which oscillates in altitude through the cloud deck. To achieve this flight profile, the balloon envelope contains a phase change fluid, which results in a flight profile which oscillates in height. The nominal balloon lifetime is 7 days—enough for one full circumnavigation of the planet. The descent probe’s fall through the atmosphere takes 60 min, followed by 30 min of operation on the surface. The key measurement objectives of EVE are: (1) in situ measurement from the balloon of noble gas abundances and stable isotope ratios, to study the record of the evolution of Venus; (2) in situ balloon-borne measurement of cloud particle and gas composition, and their spatial variation, to understand the complex cloud-level chemistry; (3) in situ measurements of environmental parameters and winds (from tracking of the balloon) for one rotation around the planet, to understand atmospheric dynamics and radiative balance in this crucial region. The portfolio of key measurements is complemented by the Russian descent probe, which enables the investigation of the deep atmosphere and surface.

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

2009-03-01

66

Aerocapture Performance Analysis of A Venus Exploration Mission  

NASA Technical Reports Server (NTRS)

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.

Starr, Brett R.; Westhelle, Carlos H.

2005-01-01

67

International Planetary Science Interoperability: The Venus Express Interface Prototype  

NASA Astrophysics Data System (ADS)

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.

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

68

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

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

69

Tracking Clouds on Venus using Venus Express Data  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

70

Foreshock ULF waves at Venus from Venus Express  

NASA Astrophysics Data System (ADS)

There exist large amplitude ultralow frequency (ULF) waves in the ion foreshock of the Venusian bow shock. With the magnetic field observations from Venus Express between 2006 and 2011, an abundance of quasi-monochromatic ULF waves (with frequency below and far enough from the local proton cyclotron frequency) have been identified by an automatic survey. One objective is to derive the relative occurrence of such foreshock waves and proton cyclotron waves associated to local pickup ions linked to exospheric hydrogen previously reported. The transverse part of the power spectrum dominates the parallel part for these foreshock ULF waves. The periods found are in the range from ~20 to ~40 seconds and most of the waves display left-hand polarization in the spacecraft frame. Taking into account the Doppler-shift by the high-speed solar wind, they may be right-hand polarized in the solar wind frame. These characteristics suggest that they are RH mode waves generated in the ion foreshock region by the field aligned beam protons reflected at the shock.

Shan, Lican; Mazelle, Christian; Lu, Quanming; Delva, Magda; Zhang, Tielong

2014-05-01

71

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

NASA Technical Reports Server (NTRS)

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.

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

1983-01-01

72

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

NASA Technical Reports Server (NTRS)

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

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

2009-01-01

73

Water vapor near the cloud tops of Venus from Venus Express/VIRTIS dayside data  

NASA Astrophysics Data System (ADS)

Observations of the dayside of Venus performed by the high spectral resolution channel (-H) of the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) on board the ESA Venus Express mission have been used to measure the altitude of the cloud tops and the water vapor abundance around this level with a spatial resolution ranging from 100 to 10 km. CO 2 and H 2O bands between 2.48 and 2.60 ?m are analyzed to determine the cloud top altitude and water vapor abundance near this level. At low latitudes (±40°) mean water vapor abundance is equal to 3 ± 1 ppm and the corresponding cloud top altitude at 2.5 ?m is equal to 69.5 ± 2 km. Poleward from middle latitudes the cloud top altitude gradually decreases down to 64 km, while the average H 2O abundance reaches its maximum of 5 ppm at 80° of latitude with a large scatter from 1 to 15 ppm. The calculated mass percentage of the sulfuric acid solution in cloud droplets of mode 2 (˜1 ?m) particles is in the range 75-83%, being in even more narrow interval of 80-83% in low latitudes. No systematic correlation of the dark UV markings with the cloud top altitude or water vapor has been observed.

Cottini, V.; Ignatiev, N. I.; Piccioni, G.; Drossart, P.; Grassi, D.; Markiewicz, W. J.

2012-02-01

74

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

NASA Astrophysics Data System (ADS)

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

2005-11-01

75

Cloud level winds from the Venus Express Monitoring Camera imaging  

NASA Astrophysics Data System (ADS)

Six years of continuous monitoring of Venus by European Space Agency's 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 40-50°S. Poleward of 50°S 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 50°S. The mean poleward meridional wind slowly increases from zero value at the equator to about 10 m/s at 50°S 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 35°S, 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 50°S 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.

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

76

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

NASA Astrophysics Data System (ADS)

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. Sánchez-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)

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

2011-12-01

77

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

NASA Technical Reports Server (NTRS)

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.

1973-01-01

78

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

NASA Technical Reports Server (NTRS)

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.

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

1974-01-01

79

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)

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.

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

2013-05-01

80

Venus  

Microsoft Academic Search

The characteristics of the planet Venus are discussed, including planetary dynamics, zonal circulation, atmosphere structure, planetary energy balance, and surface properties. Although measurements of Venus' rotational speed, based on radar observations, indicate that the phenomenon of resonance does not exist, an analysis of the relative movements of earth and Venus reveals the existence of a pseudo-synchronization between their rotations. The

G. Israel

1984-01-01

81

Venus NIR Surface Emissivity estimated from VIRTIS on Venus Express Observations  

NASA Astrophysics Data System (ADS)

Spectral window regions close to 1?m allow for the transfer of thermal radiation from the surface through the atmosphere of Venus. Results of radiative transfer modeling are used to invert VIRTIS images at 1.02, 1.10 and 1.18?m for thermal emission of the surface. Local atmospheric transmittance is derived from the VIRTIS band at 1.31?m. Several hundreds of VIRTIS images covering in total most of the southern hemisphere of Venus have thus been analyzed and stacked for improvement of signal to noise ratio. The results of this approach are to some extent ambiguous since neither surface emissivity nor surface temperature are well known. Furthermore aerosols or a gradient of absorbing gaseous constituents near the surface might affect the interpretation. But neglecting any effects of the near surface atmosphere and assuming parameters of the radiative transfer model within reasonable ranges it is possible to estimate either surface emissivity or surface temperature. Temperature of surface and atmosphere is mostly a function of altitude, no large diurnal, seasonal or latitudinal variations are expected in the lower atmosphere. The lapse rate is constrained by the adiabatic lapse rate. A hint for global average of surface emissivity is given by the dominance of probably basaltic volcanic plains on the southern hemisphere. It is however imaginable that temperature dependant weathering leads to a trend of emissivity with altitude similar to that seen in the Magellan radiothermal emissivity observations. Regardless of any global variations of lapse rate or emissivity with altitude, spatial variations of emissivity independent from topography can be examined by assuming constant emissivity and fitting surface temperature accordingly to the global relation of thermal emission to topography. This spatial variation of thermal emission is assumed to be due to variation of surface emissivity and shows correlation with some geological features known from Magellan radar images. In the Lada Terra region large lava streams, Cavillaca - and Juturna Fluctus, show increased emissivity with respect to neighboring regions of the same altitude. Other large lava streams in the region show a similar but less obvious relative emissivity. Large areas of tessera terrain on the contrary consistently show relative low emissivity. While this variation of emissivity might be related to content of mafic minerals it is also conceivable that weathering and thus age of the terrain in question is responsible. The accumulation of observations by VIRTIS during the Venus Express mission will allow us to study with a larger database these correlations and to further disentangle possible atmospheric from surface contributions and thus to increase understanding of surface composition as well as of composition and temperature of the atmosphere in contact with the surface.

Mueller, N.; Helbert, J.; Hashimoto, G.; Kostama, P.; Marinangeli, L.; Erard, S.; Piccioni, G.; Drossart, P.; Venus Express Team

2007-12-01

82

Exploration Targets for a Mission Concept with Multiple Venus Gliders  

NASA Astrophysics Data System (ADS)

Six targets have been identified for exploration with guided aerosondes that glide to their targets with high precision and conduct atmospheric and surface observations addressing all three of the major Venus scientific goals identified by VEXAG.

Cutts, J. A.; Nunes, D. C.; Mitchell, K. L.; Senske, D. A.; Pauken, M. T.; Matthies, L. H.; Tokamaru, P.

2014-05-01

83

Newest results from SPICAV on-board Venus Express  

NASA Astrophysics Data System (ADS)

Venus Express is now entering its eighth year of operation in Venusian orbit. Among the still working instruments, all three channels of the SPICAV [Bertaux et al., 2007] spectrometer are still fully working and routinely provide new insights on the Venusian atmosphere. We propose to review and highlight the results and the work in progress, among which (non-exhaustive list): a new mapping of the nightside airglow of nitric oxide (NO) using the nadir mode of SPICAV-UV ; the first detection of the dayglow due to CO and CO2+ using limb observations of SPICAV-UV [Chaufray et al., 2012] ; the secular evolution of SO2 column density above Venus' cloud top using SPICAV-UV in nadir mode [Marcq et al., 2013] ; polarimetric and phase function studies of the upper clouds of Venus using SPICAV-IR. Bibilography: Bertaux et al., SPICAV on Venus Express: Three spectrometers to study the global structure and composition of the Venus atmosphere, PSS (2007) Chaufray et al., First observation of the Venus UV dayglow at limb from SPICAV/VEX, Geophys. Res. Let. (2012) Marcq et al., Variations of sulphur dioxide at the cloud top of Venus's dynamic atmosphere, Nature Geoscience (2013)

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

2013-04-01

84

Lunar and Planetary Science XXXV: Venus  

NASA Technical Reports Server (NTRS)

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

2004-01-01

85

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)

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.

1974-01-01

86

Whistler mode bursts in the Venus ionosphere due to lightning: Statistical properties using Venus Express magnetometer observations  

NASA Astrophysics Data System (ADS)

The Venus Express mission has completed over four years in polar orbit about Venus with periapsis altitudes as low as 180 km. On each orbit around periapsis the fluxgate magnetometer samples the magnetic field at 128 Hz. The data reveal short-lived bursts with peak-to-peak amplitudes up to 1.5 nT in the frequency range 42 to 60 Hz. These signals are whistler mode waves with burst durations of about 100 ms and Poynting vectors similar to terrestrial whistler mode signals generated by atmospheric lightning when detected in the ionosphere. We have examined the occurrence of these bursts as a function of background magnetic field strength, altitude, latitude and local time. The burst rates are highest for magnetic fields of 15-30 nT, at altitudes near 215 km, and at local times near the terminators. The characteristics of these signals are consistent with generation in the dynamic Venus atmosphere, entry into the ionosphere, propagation along the ionospheric magnetic field, and ultimately damping in the ionospheric plasma.

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

2012-04-01

87

Venus  

ERIC Educational Resources Information Center

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

Martin, Paula; Stofan, Ellen

2004-01-01

88

Sulfur dioxide in the Venus atmosphere measured by SOIR on board Venus Express  

NASA Astrophysics Data System (ADS)

SO2 is a key constituent of the Venus mesosphere, playing an important role in the atmosphere chemistry, as it is a product of the photodisociation of the clouds constituent, H2SO4. New SO2 observations are important in the frame of constraining Global Computation Models (GCM), which simulate the circulation and the chemistry of the Venus atmosphere. The SOIR instrument flying on board the Venus Express spacecraft records infrared spectra of the Venus atmosphere, using the solar occultation technique. Amongst the species absorbing in the SOIR wavelength range, sulfur dioxide presents a weak band, from which regular observations are obtained in the 60 to 100 km altitude region. We derive number density and volume mixing ratio vertical profiles. Total density and temperature profiles are obtained from the carbon dioxide number density profiles. This study presents the latitude and temporal variations observed between 2006 and 2013. The results are compared to literature data and discussed. Future work will consist of including and comparing the data to Venus GCM.

Mahieux, Arnaud; Carine Vandaele, Ann; Drummond, Rachel; Robert, Séverine; Wilquet, Valérie; Belyaev, Denis; Bertaux, Jean-Loup

2014-05-01

89

Assessment of Guided Aerocapture and Entry for Venus In Situ Missions Using Mechanically Deployed Aerodynamic Decelerator  

NASA Astrophysics Data System (ADS)

The option of a a guided mechanically deployed aerodynamic decelerator (ADEPT) for in situ missions to Venus is evaluated to reduce both the peak deceleration loads to under 10g and and peak heat fluxes to less than 120 W/cm2.

Saikia, S. J.; Saranathan, H.; Longuski, J. M.; Grant, M. J.

2014-05-01

90

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

NASA Technical Reports Server (NTRS)

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.

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

2013-01-01

91

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

92

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

93

Magellan - Early results from the Venus mapping mission  

SciTech Connect

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.

Saunders, R.S.

1991-01-01

94

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

NASA Astrophysics Data System (ADS)

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.

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

95

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

NASA Astrophysics Data System (ADS)

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.

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

96

Venus  

NSDL National Science Digital Library

This lithograph shows a mosaic of Venus that was composed from Magellan images taken during radar investigations from 1990-1994. This is a false-color image that depicts topography. Images of the Venusian cloud tops and some surface features are also included. The images are accompanied by a brief description and history, some statistical facts, and a list of important dates in the exploration of Venus.

97

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

PubMed

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

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

2005-12-01

98

Mitigating Extreme Environments for In-Situ Jupiter and Venus Missions  

NASA Technical Reports Server (NTRS)

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

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

2006-01-01

99

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

NASA Astrophysics Data System (ADS)

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.

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

2012-09-01

100

Venus Exploration Analysis Group (VEXAG)  

NASA Astrophysics Data System (ADS)

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.

Limaye, Sanjay; Smrekar, Sue

2010-05-01

101

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

SciTech Connect

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.

Schock, Alfred

1993-10-01

102

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)

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.

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

2008-12-01

103

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

NASA Technical Reports Server (NTRS)

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.

1973-01-01

104

Venus Exploration opportunities within NASA's Solar System Exploration roadmap  

NASA Technical Reports Server (NTRS)

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

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

2006-01-01

105

The polar atmosphere of Venus: Radio occultation measurements with Venus Express and Magellan  

NASA Astrophysics Data System (ADS)

The ESA Venus Express (VEx) spacecraft has been conducting radio occultation experiments since 2006. The results reported to date are based on data recorded by 35-m antennas of the ESA Tracking Station Network (e.g., Tellmann et al., J. Geophys. Res., 114, E00B36, 2009). We have recently begun to derive complementary new results through analysis of high-quality "open-loop" data recorded by a 70-m antenna of the NASA Deep Space Network. This experiment sounded the polar atmosphere in both hemispheres at latitudes greater than 75 degrees. As in previous occultation measurements in this region, there is a deep convective layer at altitudes below about 60 km. The convective layer is capped by an abrupt transition to stable stratification, and the overlying free air is modulated by vertically propagating gravity waves. These new results will be compared with Magellan radio occultation measurements acquired at comparable latitudes in the early 1990s and with the VEx results reported by Tellmann et al. (2009). Our analysis also illustrates some of the challenges that can arise in radio occultation measurements at Venus. For example, the sharp temperature minimum at the tropopause creates a thin layer that eludes radio occultation sounding owing to its peculiar refractive properties. This research is funded in part by NASA Grant NNX10AE22G of the Venus Express Participating Scientist Program.

Hinson, D. P.; Tellmann, S.; Paetzold, M.; Haeusler, B.; Bird, M. K.; Tyler, G. L.

2012-12-01

106

Electronics and Sensor Cooling with a Stirling Cycle for Venus Surface Mission  

NASA Technical Reports Server (NTRS)

The inhospitable ambient surface conditions of Venus, with a 450 C temperature and 92 bar pressure, may likely require any extended-duration surface exploratory mission to incorporate some type of cooling for probe electronics and sensor devices. A multiple-region Venus mission study was completed at NASA GRC in December of 2003 that resulted in the preliminary design of a kinematically-driven, helium charged, Stirling cooling cycle with an estimated over-all COP of 0.376 to lift 100 watts of heat from a 200 C cold sink temperature and reject it at a hot sink temperature of 500 C. This paper briefly describes the design process and also describes and summarizes key features of the kinematic, Stirling cooler preliminary design concept.

Mellott, Ken

2004-01-01

107

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

NASA Technical Reports Server (NTRS)

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.

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

1975-01-01

108

Update of the Venus high and mid-altitude temperature profiles measured by SOIR on board Venus Express  

NASA Astrophysics Data System (ADS)

The SOIR instrument on board Venus Express regularly sounds the Venus atmosphere using the solar occultation technique. From the infrared measured spectra, number density and temperature profiles are inferred. In this work, we focus on the main Venus atmospheric species, carbon dioxide. This study is a continuation of the work published in [Mahieux et al., 2012], and is devoted to the update of the Venus Atmosphere from SOIR measurements at the Terminator (VAST) previously presented in the above cited work. The method has been improved and more data have been included into the VAST compilation. The new compilation is given on a finer latitudinal grid. The latitude and local solar time variations are discussed. VAST is finally compared to the literature. Reference Mahieux, A., A. C. Vandaele, S. Robert, V. Wilquet, R. Drummond, F. Montmessin and J. L. Bertaux (2012). 'Densities and temperatures in the Venus mesosphere and lower thermosphere retrieved from SOIR on board Venus Express: Carbon dioxide measurements at the Venus terminator.' J. Geophys. Res. 117(E07001): doi:10.1029/2012JE004058.

Mahieux, Arnaud; Carine Vandaele, Ann; Robert, Séverine; Drummond, Rachel; Wilquet, Valérie; Bertaux, Jean-Loup

2014-05-01

109

Mars Express and Venus Express Data Retention In-Flight Performance  

NASA Astrophysics Data System (ADS)

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

Lebrédonchel, J.; Rombeck, F.-J.

2007-08-01

110

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

Microsoft Academic Search

Images obtained by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS)-M channel instrument onboard Venus Express have been used to retrieve maps and apparent motions of the O2 (1?) infrared nightglow on Venus at 1.27 ?m. The nightglow distribution is highly inhomogeneous with the regions of brightest emission generally located at low latitudes near the midnight meridian. Unexpectedly some orbits

R. Hueso; A. Sánchez-Lavega; G. Piccioni; P. Drossart; J. C. Gérard; I. Khatuntsev; L. Zasova; A. Migliorini

2008-01-01

111

Vertical structure of the Venus cloud top from the VeRa and VIRTIS observations onboard Venus Express  

Microsoft Academic Search

We investigate the Venus cloud top structure by joint analysis of the data from Visual and Thermal Infrared Imaging Spectrometer (VIRTIS) and the atmospheric temperature sounding by the Radio Science experiment (VeRa) onboard Venus Express. The cloud top altitude and aerosol scale height are derived by fitting VIRTIS spectra at 4–5?m with temperature profiles taken from the VeRa radio occultation.

Y. J. Lee; Dmitriy Titov; Silvia Tellmann; A. Piccialli; N. Ignatiev; Martin Pätzold; B. Häusler; G. Piccioni; P. Drossart

2010-01-01

112

The Venus Monitoring Camera  

NASA Astrophysics Data System (ADS)

The Venus Monitoring Camera (VMC) is part of the Venus Express payload. One of the main goals of the Venus Express mission is to study the dynamics of the atmo- sphere. This objective requires global imaging of the planet. The VMC is designed to meet this goal with a wide field of view (FOV 30). The VMC will take images of Venus in six filters from UV to near-IR with spatial resolution from 0.25 km to 30 km depending on the distance from the planet. The full disc of Venus will be in the FOV near the apocentre of the orbit. The camera will complement other instru- ments of Venus Express 1.) by tracking cloud motions at 70 km (cloud tops) and at 50km (main cloud); 2.) by mapping O2 and NO night-glow and its variability that are optical tracers of the thermospheric dynamics (110-150 km); 3.) by mapping the night-side thermal emission from the surface and studying of the lapse rate and H2O content in the lower 6-10 km. In addition the camera will provide imaging context for the whole mission and its movies will be of significant interest for science but also for the public outreach programme. Moreover, the same instrument will be proposed for the Japanese Venus Orbiter.

Markiewicz, W. J.; Keller, H. U.; Kramm, R.; Titov, D.

113

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

114

PC-402 Pioneer Venus orbiter spacecraft mission operational characteristics document  

NASA Technical Reports Server (NTRS)

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.

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

115

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

NASA Astrophysics Data System (ADS)

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

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

116

Structure and variability of the Venus ionosphere inferred from photoelectron measurements by Venus Express  

NASA Astrophysics Data System (ADS)

The ionosphere of an unmagnetized planet lies at the boundary between the collisional atmosphere and the passing solar wind. Atmospheric particles escaping from the planet either originate in or pass through the ionosphere. The extent and variability of the ionosphere is of interest for both plasma escape, and the dynamics of the neutral upper atmosphere. Photoelectrons are excellent tracers of ionospheric plasma. Produced via photoionization of atmospheric neutral particles by solar EUV and X-ray radiation, photoelectrons remain tightly bound to magnetic field lines passing through their location of origin. Spacecraft measurements of ionospheric photoelectrons therefore allow us to infer which regions of space around a planet are magnetically connected to the ionosphere. At Venus, the dominant neutral species at high altitudes (i.e. above 300km) are atomic oxygen and carbon dioxide. Using the Electron Spectrometer (ELS) on the Analyser of Space Plasmas and Energetic Atoms (ASPERA-4) instrument package on Venus Express (VEX), previous case studies have reported the presence of ionospheric photoelectrons near Venus produced by solar HeII 30.4 nm photons. We aim to accomplish a comprehensive statistical survey of ionospheric photoelectrons, revealing the variability and extent of the ionosphere for different external conditions. We have developed and tested an automatic algorithm to detect the presence of photoelectrons in ASPERA-4 ELS measurements. The algorithm (filter) identifies ionospheric photoelectron distributions as a localized peak between 20 to 30 eV in electron energy spectrum. We have applied the filter to determine the distribution of photoelectron percentage of occurrence (photoelectron likelihood). The observations reveal increasing dayside ionospheric altitudes as solar zenith angle increases, followed by a sudden decrease at the terminator. Ionospheric photoelectrons are evident outside of the eclipse boundary on the night side tail of the planet to high altitudes. Increases in ionospheric altitude are correlated with increases in solar ionizing flux (i.e. EUV and soft x-ray). We present the characteristics of the measured photoelectron energy distributions, such as integrated flux, peak flux, width, and the measured energy of the peak, and we show how they vary temporally and spatially at Venus.

Molaverdikhani, K.; Brain, D. A.; Futaana, Y.

2012-12-01

117

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

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

118

Exploring Venus  

NASA Technical Reports Server (NTRS)

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.

Landis, Geoffrey A.

2008-01-01

119

Venus  

NSDL National Science Digital Library

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

120

VENUS EXPLORATION ANALYSIS GROUP (VEXAG)  

NASA Astrophysics Data System (ADS)

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 by end of 2009). 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 will be held following the second Inner Planets Panel Meeting, in Irvine, California, October 28-29, 2009 (see website for details). VEXAG’s past activities, current efforts and future plans will be presented. A workshop focused on Venus Atmosphere is being planned for summer 2010 in conjunction with a VEXAG meeting is being tentatively planned for summer 2010.

Limaye, S. S.; Smrekar, S. E.

2009-12-01

121

The OH Venus nightglow spectrum: Intensity and vibrational composition from VIRTIS—Venus Express observations  

NASA Astrophysics Data System (ADS)

Limb spectra of the OH nightglow emission corresponding to the ?v=1 and ?v=2 sequences have been collected with the VIRTIS infrared imaging spectrograph on board Venus Express between April 2006 and October 2008. A detailed statistical analysis shows that the peak intensity and altitude of the two vibrational sequences are significantly correlated, with a mean intensity ratio of the two sequences of 0.38±0.37. The altitude of the maximum of the ?v=2 emission is located ˜1 km lower than ?v=1. A spectral analysis shows that the ?v=1 sequence is composed at 44.6% by the (1-0) band, 9.3% by the (3-2) band and 7.1% by the (4-3) band. The ?v=2 emission is best fitted if solely including the (2-0) band. A non-LTE model of OH vibrational population by the O3+H reaction including radiative and collisional relaxation has been used to compare the expected spectral distribution, the altitude of the emission peak and the emission rate under different assumptions on the quenching processes to those observed with VIRTIS. The adopted carbon dioxide, atomic oxygen and ozone densities are based on recent Venus Express remote sensing measurements. We find that the "Sudden Death" quenching scheme by CO2 produces inadequate spectral distribution between the various bands and insufficient airglow brightness. Instead, the observed spectral distribution and the total emission intensity are reasonably well reproduced with the Single Quantum jump model, an O density profile peaking at 103.5 km with a maximum value of 1.9×1011 cm-3, a O3 density profile peaking at 5.8×106 cm-3 at 96.5 km and a H density profile close to 108 cm-3 between 90 and 120 km, in agreement with several photochemical models.

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

2012-12-01

122

Structure of the Venus neutral atmosphere as observed by the Radio Science experiment VeRa on Venus Express  

Microsoft Academic Search

The European Space Agency Venus Express Radio Science experiment (VeRa) obtained 118 radio occultation measurements of the Venusian atmosphere between July 2006 and June 2007. Southern latitudes are uniformly sampled; measurements in the northern hemisphere are concentrated near the pole. Radial profiles of neutral number density derived from the occultations cover the altitude range 40-90 km, which are converted to

Silvia Tellmann; Martin Pätzold; Bernd Häusler; Michael K. Bird; G. Leonard Tyler

2009-01-01

123

Water abundance and hydrogen isotopic ratio in the upper atmosphere of Venus from SOIR measurements on board Venus Express  

NASA Astrophysics Data System (ADS)

Water on Venus is much more scarce than on Earth, with volume mixing ratios lower than a part per million. The reason for this has always been of great interest, because it may give clues to the difference of evolution between the two planets. Studying water gives also access to another important planetary parameter, which is the deuterium to hydrogen isotopic ratio. H _{2}O and HDO are measured together with CO _{2} in the SOIR wavelength range, in the region 2.5 to 2.6 ?m (3800 to 4000 cm ^{-1}) for H _{2}O and 3.35 to 3.85 ?m (2600 to 3000 cm ^{-1}) for HDO, which allows the derivation of their vertical density profiles together with the temperature and total density profiles obtained from CO2 measurements [1], which can be used to calculate VMR profiles. The measurements all occur at the Venus terminator, both the morning and evening side, covering all latitudes from the North Pole to the South Pole. The vertical resolution is very good from the North Pole to 40° North (resolution of 500 m), and is poorer in the Southern hemisphere (resolution between 1000 m and 2500 m). The maximum extent of the H _{2}O and the HDO profiles is from 120 to 70 km, with variations from orbit to orbit. We will present results from the simultaneous measurements of H _{2}O and HDO that occur during the first 5 occultation seasons of Venus Express, i.e. from 04/09/2006 to 22/08/2007. 1. Mahieux, A., A.C. Vandaele, S. Robert, V. Wilquet, R. Drummond, F. Montmessin, and J.L. Bertaux, Densities and temperatures in the Venus mesosphere and lower thermosphere retrieved from SOIR on board Venus Express. Carbon dioxide measurements at the Venus terminator. J. Geophys. Res., (submitted) (2012)

Drummond, Rachel; Mahieux, Arnaud; Wilquet, Valerie; Bertaux, Jean-Loup; Robert, Severine; Vandaele, Ann C.; Matsui, Hiroki; Iwagami, Naomoto

2012-07-01

124

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

NASA Technical Reports Server (NTRS)

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.

Palandati, C.

1975-01-01

125

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

NASA Technical Reports Server (NTRS)

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.

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

2012-01-01

126

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

NASA Technical Reports Server (NTRS)

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.

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

2013-01-01

127

A preliminary analysis of a radar-mapping mission to Venus  

NASA Technical Reports Server (NTRS)

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.

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

1973-01-01

128

Dispersion Measurements of Whistler Mode Signals Observed in the Venus Ionosphere with the Venus Express Magnetometer  

NASA Astrophysics Data System (ADS)

Whistler mode signals produced by lightning have a distinct falling tone at the Earth. Venus whistler mode signals in the ionosphere has a similar "dispersion" consistent with their shorter travel path.

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

2012-03-01

129

SPICAV/SOIR on board Venus express: an overview of two years of observations.  

NASA Astrophysics Data System (ADS)

SPICAV (SPectroscopy for the Investigation of the Characteristics of the Atmosphere of Venus) is a suite of three spectrometers in the UV and IR range with a total mass of 12.3 kg flying on Venus Express orbiter, dedicated to the study of the atmosphere of Venus from ground level to the outermost hydrogen corona at more than 40,000 km. The UV spectrometer (118 - 320 nm, resolution 1.5 nm) has detected on the night side, the ? and ? bands of NO. In the stellar occultation mode the UV sensor is measuring the vertical profiles of CO2, temperature, SO2, clouds and aerosols. So far, star occultations on the night side indicates a higher temperature than predicted by the VIRA model and an aerosol horizontal opacity of 1 at 90 km altitude (variable), with a haze extending up to 104 km. SO2 is detected also in solar occultation. The SPICAV VIS-IR sensor (0.7-1.7 µm, resolution 0.5-1.2 nm) employs a pioneering technology: acousto-optical tunable filter (AOTF). In solar occultation this channel allows to measure the aerosols characteristics. On the day side, it measures water vapor at cloud top level (65 km), which seems latitude dependent. The SOIR spectrometer is a new Solar Occultation IR spectrometer in the range ?=2.2-4.3 µm, with a spectral resolution ˜20,000, the highest ever flown in a planetary mission. This new concept includes a combination of an echelle grating and an AOTF crystal to sort out one order at a time. Vertical profiles of CO, HDO, H2O, HCl, SO2 and CO2 isotopes have been retrieved, as well as aerosols. A new absorption signature near 2982 cm-1 was discovered, identified now with a previously unknown absorption band of CO2 isotope 12C16O18O. Details will not be discussed , since they are presented in various other contributed papers.

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

130

The dayside ionospheres of Mars and Venus: Comparing a one-dimensional photochemical model with MaRS (Mars Express) and VeRa (Venus Express) observations  

NASA Astrophysics Data System (ADS)

The electron density distributions of the lower ionospheres of Mars and Venus are mainly dependent on the solar X-ray and EUV flux and the solar zenith angle. The influence of an increasing solar flux is clearly seen in the increase of the observed peak electron density and total electron content (TEC) of the main ionospheric layers. The model “Ionization in Atmospheres” (IonA) was developed to compare ionospheric radio sounding observations, which were performed with the radio science experiments MaRS on Mars Express and VeRa on Venus Express, with simulated electron density profiles of the Mars and Venus ionospheres. This was done for actual observation conditions (solar flux, solar zenith angle, planetary coordinates) from the bases of the ionospheres to ?160 km altitude. IonA uses models of the neutral atmospheres at ionospheric altitudes (Mars Climate Database (MCD) v4.3 for Mars; VenusGRAM/VIRA for Venus) and solar flux information in the 0.5-95 nm wavelength range (X-ray to EUV) from the SOLAR2000 data base. The comparison between the observed electron density profiles and the IonA profiles for Mars, simulated for a selected MCD scenario (background atmosphere), shows that the general behavior of the Mars ionosphere is reproduced by all scenarios. The MCD “low solar flux/clear atmosphere” and “low solar flux/MY24” scenarios agree best (on average) with the MaRS set of observations, although the actual Mars atmosphere seemed to be still slightly colder at ionospheric altitudes. For Venus, the VenusGRAM model, based on VIRA, is too limited to be used for the IonA simulation of electron density profiles. The behavior of the V2 peak electron density and TEC as a function of solar zenith angle are in general reproduced, but the peak densities and the TEC are either over- or underestimated for low or high solar EUV fluxes, respectively. The simulated V2 peak altitudes are systematically underestimated by 5 km on average for solar zenith angles less than 45° and the peak altitudes rise for zenith angles larger than 60°. The latter is the opposite of the observed behavior. The explanation is that VIRA and VenusGRAM are valid only for high solar activity, although there is also very poor agreement with VeRa observations from the recent solar cycle, in which the solar activity increases to high values. The disagreement between the observation and simulation of the Venus electron density profiles proves, that the true encountered Venus atmosphere at ionospheric altitudes was denser but locally cooler than predicted by VIRA.

Peter, Kerstin; Pätzold, Martin; Molina-Cuberos, Gregorio; Witasse, Olivier; González-Galindo, F.; Withers, Paul; Bird, Michael K.; Häusler, Bernd; Hinson, David P.; Tellmann, Silvia; Tyler, G. Leonard

2014-05-01

131

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

NASA Technical Reports Server (NTRS)

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.

1973-01-01

132

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

NASA Astrophysics Data System (ADS)

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

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

133

Radio science investigations by VeRa onboard the Venus Express spacecraft  

Microsoft Academic Search

The Venus Express Radio Science Experiment (VeRa) uses radio signals at wavelengths of 3.6 and 13cm (“X”- and “S”-band, respectively) to investigate the Venus surface, neutral atmosphere, ionosphere, and gravity field, as well as the interplanetary medium. An ultrastable oscillator (USO) provides a high quality onboard reference frequency source; instrumentation on Earth is used to record amplitude, phase, propagation time,

B. Häusler; M. Pätzold; G. L. Tyler; R. A. Simpson; M. K. Bird; V. Dehant; J.-P. Barriot; W. Eidel; R. Mattei; S. Remus; J. Selle; S. Tellmann; T. Imamura

2006-01-01

134

The lower atmosphere of Venus after VEGA 1 and 2 missions  

NASA Astrophysics Data System (ADS)

The authors have computed the physical parameters for the Venus atmosphere between 0 - 64 km altitude by using Vega measurements. The proposed model can be used in order to study the structure of Venus atmosphere and its chemical composition between 60 - 64 km, where an inversion in temperature profiles has been measured by Vega.

Petropoulos, B.; Telonis, P.

1988-10-01

135

Venus atmospheric circulation: Known and unknown  

NASA Astrophysics Data System (ADS)

After a pause of more than two decades, Venus' atmosphere is being explored again. Since April 2006, European Space Agency's Venus Express has been acquiring data, exploiting the near-infrared windows that allow us to peer into the deep night-side atmosphere. In June 2007, NASA's MESSENGER mission will fly past Venus on its way to Mercury, collecting useful data for a few weeks. Instruments and experiments on Venus Express are expected to provide a more comprehensive set of atmospheric observations over three and perhaps more Venus days. Venus Express observations are already providing clues about the processes that maintain the rapid circulation of Venus' atmosphere. The early observations show not only that the global circulation is organized into two hemispheric vortices centered over respective poles, but also that the vortex organization extends deep into the atmosphere. The limited Galileo NIMS near-infrared observations in 1989 had revealed the deep circulation in the equatorial regions, but because of the spacecraft, flyby trajectory could not observe the high latitudes to elucidate the polar circulation and its organization. The long hiatus in systematic Venus observations has provided an opportunity to perform some new analysis of the previous Pioneer Venus observations. This paper presents a synopsis of the circulation measurements at high latitudes and an analysis of the solar thermal tides seen in the cloud motions and suggests some limitations of previous estimates of transport of angular momentum by eddies.

Limaye, Sanjay S.

2007-04-01

136

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

Microsoft Academic Search

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

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

2010-01-01

137

Composition of the upper Venus atmosphere using SPICAV-SOIR on board Venus Express  

NASA Astrophysics Data System (ADS)

The wavelength range probed by SOIR/VEX allows a detailed chemical inventory of the Venus atmosphere. Several trace gases, such as H2O/HDO, HF, HCl, CO, or SO2, are observed together with CO2, leading to the derivation of their vertical density profiles. Temperature and total density profiles are deduced from the CO2 density profiles and VMR are obtained for all trace gases. The measurements all occur at the Venus terminator, morning and evening sides, covering all latitudes from the North Pole to the South Pole. The vertical resolution is between 100 and 500 m in the Northern hemisphere, and is poorer at southern latitudes (between 1 and 2.5 km). The typical vertical extent of the profiles ranges from 70 to 120 km (for CO2: from 70 to 170 km), encompassing thus the mesosphere and the lower thermosphere of the planet. The Venus atmospheric region probed by SOIR is very special as it acts as a transition region between two distinct dynamic regimes characterized by different flow patterns: the zonal retrograde flow below 70 km and the subsolar to antisolar circulation above 100 km. Some of the detected trace gases play important roles in the chemistry of the atmosphere. The study of CO, which is mainly produced through photodissociation of CO2 at high altitudes by solar ultraviolet radiation, can lead to significant information on the dynamics in this region. Investigation of trace gases leads to a better understanding of the processes occurring in the upper atmosphere of Venus.

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

2013-09-01

138

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

Microsoft Academic Search

The upper atmosphere of a planet is a transition region in which energy is transferred between the deeper atmosphere and outer space. Molecular emissions from the upper atmosphere (90-120km altitude) of Venus can be used to investigate the energetics and to trace the circulation of this hitherto little-studied region. Previous spacecraft and ground-based observations of infrared emission from CO2, O2

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

2007-01-01

139

The evolution of co-orbiting material in the orbit of 2201 Oljato from 1980 to 2012 as deduced from Pioneer Venus Orbiter and Venus Express magnetic records  

NASA Astrophysics Data System (ADS)

Asteroid 2201 Oljato passed through perihelion inside the orbit of Venus near the time of its conjunction with Venus in 1980, 1983, and 1986. During those three years, many interplanetary field enhancements (IFEs) were observed by the Pioneer Venus Orbiter (PVO) in the longitude sector where the orbit of Oljato lies inside Venus' orbit. We attribute IFEs to clouds of fine-scale, possibly highly charged dust picked up by the solar wind after an interplanetary collision between objects in the diameter range of 10-1000 m. We interpret the increase rate in IFEs at PVO in these years as due to material in Oljato's orbit colliding with material in, or near to, Venus' orbital plane and producing a dust-anchored structure in the interplanetary magnetic field. In March 2012, almost 30 yr later, with Venus Express (VEX) now in orbit, the Oljato-Venus geometry is similar to the one in 1980. Here, we compare IFEs detected by VEX and PVO using the same IFE identification criteria. We find an evolution with time of the IFE rate. In contrast to the results in the 1980s, the recent VEX observations reveal that at solar longitudes in which the Oljato orbit is inside that of Venus, the IFE rate is reduced to the level even below the rate seen at solar longitudes where Oljato's orbit is outside that of Venus. This observation implies that Oljato not only lost its co-orbiting material but also disrupted the "target material," with which the co-orbiting material was colliding, near Venus.

Lai, Hairong; Russell, Christopher T.; Wei, Hanying; Zhang, Tielong

2014-01-01

140

The Transit of Venus of 1874: the Italian mission to Muddapur in the south-east of India  

NASA Astrophysics Data System (ADS)

The transit of Venus expected on December 8-9, 1874 gave to the Italian astronomers the opportunity of organizing an expedition to India. Pietro Tacchini of the Astronomical Observatory of Palermo was committed to organize the expedition and Giuseppe Lorenzoni of the Astronomical Observatory of Padua took care of getting the instruments ready for the observations. The observers were: Tacchini, A. Dorna of Turin Observatory , A. Abetti and the mechanic A. Cagnato of Padua Observatory. The main instruments were five refractors and two direct vision spectroscopes. In this mission the Italians obtained a very important result: they observed, for the first time, details of the spectrum of Venus which confirmed the existence of its atmosphere; the spectral range observed was that of the Fraunhofer lines C (H? at 6563 Å) and B (telluric line of O2 at 6867 Å). They demonstrated also the utility of the spectroscope to determine the exact instant of the contacts.

Pigatto, L.; Zanini, V.

141

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

NASA Astrophysics Data System (ADS)

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).

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

2010-12-01

142

Pc-403: Pioneer Venus Multiprobe Spacecraft Mission Operational Characteristics Document, Volume 3.  

National Technical Information Service (NTIS)

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 ...

F. C. Barker

1978-01-01

143

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

NASA Astrophysics Data System (ADS)

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

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

2007-11-01

144

Pluto Express: Mission to Pluto  

NASA Technical Reports Server (NTRS)

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.

Giuliano, J. A.

1996-01-01

145

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

NASA Astrophysics Data System (ADS)

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.

Filiberto, J.

2013-12-01

146

Interplanetary Scintillation, STEREO Heliospheric Imager and Venus Express ASPERA observations of solar wind structures in May 2007  

Microsoft Academic Search

We present results from a co-ordinated study of solar wind structure in the inner helisphere during May 2007, combining results from radio measurements of interplanetary scintillation (IPS), STEREO HI imaging of interplanetary structures and in-situ measurements from the ASPERA instrument on Venus Express. The ASPERA results revealed periodic disturbances in the solar wind at Venus, which we show correspond to

A. R. Breen; G. D. Dorrian; D. S. Brown; I. Whittaker; R. A. Fallows; J. A. Davies; A. Roulliard

2009-01-01

147

Venus geology  

NASA Astrophysics Data System (ADS)

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.

McLaughlin, W. I.

1991-05-01

148

Orbital Express program summary and mission overview  

NASA Astrophysics Data System (ADS)

The Orbital Express program was created to prove that the technical obstacles to satellite servicing were surmountable- to "take the technical excuse off the table" as it were. This mission demonstrated short range and long range autonomous rendezvous, capture and berthing, on-orbit electronics upgrades, on-orbit refueling, and autonomous fly-around visual inspection using a demonstration client satellite. The Orbital Express spacecraft were launched March 8, 2007 and completed their mission on July 22, 2007. 100% of mission success criteria and objectives were achieved. This paper describes, at a high level, the program goals and objectives, key milestones & events, accomplishments, and some of the obstacles that were overcome during the mission.

Friend, Robert B.

2008-05-01

149

O+ acceleration by the local convection electric field: Venus Express observations  

NASA Astrophysics Data System (ADS)

Using data from ASPERA-4 (Analyser of Space Plasma and Energetic Atoms) and MAG (magnetometer) experiments onboard Venus Express, we investigate spatial distributions of O+ fluxes (>100 eV) around Venus for two convection electric fields: solar wind electric field (SWEF; ESW = -VSW x BSW) and local convection electric field (LCEF; EL = -VL x BL). Comparison between these distributions under two different IMF configurations (namely IMF directs nearly perpendicular to the Venus-Sun line and nearly parallel to it), we find that the spatial distribution of the O+ fluxes depends on the LCEF's direction for both IMF configurations. We conclude that the O+ ions would be accelerated more effectively by LCEF rather than SWEF.

Masunaga, K.; Futaana, Y.; Yamauchi, M.; Barabash, S.; Zhang, T. L.; Fedorov, A. O.; Okano, S.; Terada, N.

2012-09-01

150

The Vega project: A space mission to Venus and Halley's comet  

NASA Astrophysics Data System (ADS)

The launch of the Soviet space probes Vega 1 and Vega 2 to explore Venus, including its atmosphere, and flyby Halley's comet, a rare guest in the inner Solar System, added a vivid page to the history of space exploration. This paper is dedicated to Designer General Vyacheslav M. Kovtunenko.

Dolgopolov, V. P.; Pichkhadze, K. M.; Sukhanov, K. G.

2012-12-01

151

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

NASA Technical Reports Server (NTRS)

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.

Barker, F. C.

1978-01-01

152

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

National Technical Information Service (NTIS)

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 ...

A. J. Colozza G. Benigno G. A. Landis K. Hoza S. Motiwala

2013-01-01

153

A updated view of the Venusian cloud system: synthesis of Venus Express results  

NASA Astrophysics Data System (ADS)

Physics and chemistry of planet-covering clouds of Venus are the major targets of ESA's Venus Express. The planet is entirely covered by layers of cloud and haze (amount to a total optical thickness of few tens) which are thought to control planet's heat balance, climate, and atmospheric dynamics. Until the time of Pioneer Venus, our knowledge was limited only to "remotely sensible" upper cloud/haze layer or to a few locations where descent probes made direct measurements in the atmosphere. The situation, however, has changed since discovery of so-called atmospheric "windows" (Allen and Crawford, 1984) in the infrared spectrum of Venus. The "windows" are wavelengths of relatively weak CO2 absorption (1.74 and 2.3 µm, for example) at which infrared radiation originating from deeper levels of Venus atmosphere can escape to the space through the dense clouds and atmosphere. Usefulness of observations in these windows to remotely sense the deeper atmosphere was demonstrated during Galileo's flyby (Carlson et al., 1991) although the data were not many. Venus Express is the first spacecraft to fully utilize these windows. VIRTIS utilizes near-infrared windows (distributed in 1 2.4-µm range) to sense clouds and gases in the middle to lower atmosphere. The VIRTIS data have revealed great variability of cloud opacity: particle size and number density of aerosols have been derived with higher accuracy and greater spatial coverage than previous studies. The vertical extent of lower cloud layer (the source of main opacity at 1.74 µm) is found to show discontinuous change at higher latitudes near so-called cold polar collar. SPICAV/SOIR, sensitive to upper haze and near cloud top as it utilizes a lay of light (from a star or the Sun) which grazes the atmosphere, also has found semi-periodic change in aerosol opacity with a large amplitude. Ultraviolet images acquired with VMC show fine structures of clouds (patches, cells, and waves) and their rapid changes. A remarkable brightening of the south polar haze (it also extended to equatorward) was witnessed by VMC. These findings, together with the vertical temperature profile obtained by radio occultation observations, ultimately allow us to study how enormous cloud of Venus is produced and maintained and how it is related to the atmospheric dynamics. The aim of this paper is to summarize Venus Express findings on clouds and haze and to draw a updated view.

Satoh, Takehiko

154

Updating the Venus International Reference Atmosphere (VIRA)  

NASA Astrophysics Data System (ADS)

The compilation of the Venus International Reference Atmosphere was completed in 1985 through the initiative of A.J. Kliore, V.I. Moroz, and G.M. Keating. Consisting of seven chapters, it presented a synthesis of the best available data at that time on the neutral atmosphere and ionosphere of Venus.This model consist of seven 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, and (7) The Venus ionosphere. VIRA provides tables and figures as well as description of how the models were synthesized from the available data and references. VIRA has helped many studies of Venus since its publication and in fact has proved invaluable in comparing and contrasting many studies by providing a common standard for atmospheric data.The organizers of VIRA had anticipated updating the model soon after publication as newer data were becoming available from Pioneer and Venera missions.Since then many other missions have yielded valuable data and newer findings. In particular the Venus Express mission is currently providing many new details of the atmospheric structure and radiation balance from its instruments, so an effort to update VIRA is timely. The Venus community continues to consider new missions to address the unanswered questions about Venus and hence updating the Reference Model in the near future will help both future studies and understanding the available observations through models that need the information. The Venus Exploration Analysis Group (VEXAG) sponsored by NASA provides an international forum to carry out the required effort and invites Venus scientists to propose models and participate in working group to update the model. The EGU meeting provides an opportunity to plan the update by considering gaps in the models, examine defects, review newer data and a proposed schedule for the final adoption. VEXAG meetings and other meetings of opportunity such as COSPAR, EPSC/DPS and others may be useful occasions for splinter meetings for the working groups.

Limaye, S.; Svedhem, H.; Titov, D.; Markiewicz, W.; Wilson, C.; Zasova, L.

2012-04-01

155

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)

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

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

2008-01-01

156

Stellar Occultation of the Ultraviolet Nitric Oxide Nightglow with SPICAV on Board Venus Express  

NASA Astrophysics Data System (ADS)

Ultraviolet nightglow have been detected on Venus for the first time by Barth and al., in 1968, from mariner 5, then identified like to be nitric oxide nightglow by Feldmann and al., and by Stewart and Barth, in 1979, with Pioneer. SPICAV (SPectroscopy for the Characteristics of the Atmosphere of Venus), currently in fly on board Venus Express, also see them. We descibe here a direct model allowed to reproduce this nitric oxide nightglows. It is a first approach in a better understanding of the dynamic phenomena of the venusian thermosphere. This nightglows are due to radiative recombinaison process. On the dayside of the planet, we have nitrogen and oxygen atoms created by UV disssociation of N2, CO2 and O2. This atoms are transported on the nightside, where they recombine themselves and emit an ultraviolet radiation. Thus NO nightglow are tracers of the descending branch of the solar, anti-solar circulation in the thermosphere of Venus. The model using geometric parameters who are fixed for each observation, simulate the travel of a ray of light inside the spectrometer and reproduce the spectra of nightglows. We model a nitric oxide layer, controled by his borderline altitudes and his brightness. Wa have to adjust the parameters of the layer to fit the data. The results, in the making, already are very supporting. Thus, fit the ultraviolet nitric oxide nightglows, as a tracer of the venusian thermospheric circulation, will lead to a better understanding of the dynamic phenomena in the same region of this atmosphere.

Royer, E.; Montmessin, F.; Bertaux, J.

2008-12-01

157

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

158

Preliminary results of the solar flux radiometer experiment aboard the pioneer venus multiprobe mission.  

PubMed

The solar flux radiometer aboard the Pioneer Venus large probe operated successfully during its descent through the atmosphere of Venus. Upward, downward, and net fluxes from 0.4 to 1.0 micrometers were obtained at more than 390 levels between 185 millibars (at an altitude of approximately 61 kilometers) and the surface. Fluxes from 0.4 to 1.8 micrometers were also obtained between 185 millibars and about the level at which the pressure was 2 atmospheres. Data from 80 to 185 millibars should be available after additional decoding by the Deep Space Network. Upward and downward intensities in a narrower band from 0.59 to 0.66 micrometers were also obtained throughout the descent in order to constrain cloud properties. The measurements indicate three cloud regions above the 1.3-atmosphere level (at an altitude of approximately 49 kilometers) and a clear atmosphere beneath that level. At the 67 degrees solar zenith of the probe entry site, some 15 watts per square meter are absorbed at the surface by a dark ground, which implies that about 2 percent of the solar energy incident on the planet is absorbed at the ground. PMID:17833001

Tomasko, M G; Doose, L R; Palmer, J; Holmes, A; Wolfe, W; Castillo, N D; Smith, P H

1979-02-23

159

Observations of Nonlinear Ionopause Waves in 32Hz Venus Express Magnetometer Data  

NASA Astrophysics Data System (ADS)

The solar wind interacts directly with the ionosphere of Venus. This is due to the lack of an intrinsic planetary magnetic field. This is significantly different to the terrestrial case where the ionosphere is protected by the Earth's magnetic field. The shear velocity profile at the boundary between the solar wind and Venusian ionosphere can lead to the formation of nonlinear waves along the boundary. High temporal resolution (32Hz) magnetic field data collected by Venus Express is used to analyse the structure, location and rate of occurrence of nonlinear waves on the ionopause. The implications of these observations, with respect to mass loading of the solar wind with ionospheric material and the redistribution of dayside ionospheric plasma to maintain the nightside ionosphere are discussed.

Pope, S. A.; Zhang, T. L.; Balikhin, M. A.; Dimmock, A.; Walker, S.

2008-12-01

160

Observations of nonlinear ionopause waves in 32Hz Venus Express Magnetometer data  

NASA Astrophysics Data System (ADS)

The solar wind interacts directly with the ionosphere of Venus. This is due to the lack of an intrinsic planetary magnetic field. This is significantly different to the terrestrial case where the ionosphere is protected by the Earth's magnetic field. The shear velocity profile at the boundary between the solar wind and Venusian ionosphere can lead to the formation of nonlinear waves along the boundary. High temporal resolution (32Hz) magnetic field data collected by Venus Express is used to analyse the structure, location and rate of occurrence of nonlinear waves on the ionopause. The implications of these observations, with respect to mass loading of the solar wind with ionospheric material and the redistribution of dayside ionospheric plasma to maintain the nightside ionosphere are discussed.

Pope, S. A.; Zhang, T. L.; Balikhin, M. A.; Walker, S.; Dimmock, A.

2009-04-01

161

Return to Venus of AKATSUKI, the Japanese Venus Orbiter  

NASA Astrophysics Data System (ADS)

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.

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

162

Venus Discovery-Class Balloon Missions: Science Objectives and Desired Latitudinal and Longitudinal Coverage  

NASA Astrophysics Data System (ADS)

Long-duration (several weeks) balloon missions sampling the Venusian cloud level can circle the globe several times, providing the longitudinal and latitudinal coverage to effectively address key science objectives of the Decadal Survey and VEXAG.

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

2014-05-01

163

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

Microsoft Academic Search

We report the detection of electrons due to photo-ionization of atomic oxygen and carbon dioxide in the Venus atmosphere by solar helium 30.4nm 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

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

2008-01-01

164

Radio science investigations by VeRa onboard the Venus Express spacecraft  

NASA Astrophysics Data System (ADS)

The Venus Express Radio Science Experiment (VeRa) uses radio signals at wavelengths of 3.6 and 13 cm ("X"- and "S"-band, respectively) to investigate the Venus surface, neutral atmosphere, ionosphere, and gravity field, as well as the interplanetary medium. An ultrastable oscillator (USO) provides a high quality onboard reference frequency source; instrumentation on Earth is used to record amplitude, phase, propagation time, and polarization of the received signals. Simultaneous, coherent measurements at the two wavelengths allow separation of dispersive media effects from classical Doppler shift. VeRa science objectives include the following: Determination of neutral atmospheric structure from the cloud deck (approximately 40 km altitude) to 100 km altitude from vertical profiles of neutral mass density, temperature, and pressure as a function of local time and season. Within the atmospheric structure, search for, and if detected, study of the vertical structure of localized buoyancy waves, and the presence and properties of planetary waves. Study of the H 2SO 4 vapor absorbing layer in the atmosphere by variations in signal intensity and application of this information to tracing atmospheric motions. Scintillation effects caused by radio wave diffraction within the atmosphere can also provide information on small-scale atmospheric turbulence. Investigation of ionospheric structure from approximately 80 km to the ionopause (<600 km), allowing study of the interaction between solar wind plasma and the Venus atmosphere. Observation of forward-scattered surface echoes obliquely reflected from selected high-elevation targets with anomalous radar properties (such as Maxwell Montes). More generally, such bistatic radar measurements provide information on the roughness and density of the surface material on scales of centimeters to meters. Detection of gravity anomalies, thereby providing insight into the properties of the Venus crust and lithosphere. Measurement of the Doppler shift, propagation time, and frequency fluctuations along the interplanetary ray path, especially during periods of superior conjunction, thus enabling investigation of dynamical processes in the solar corona.

Häusler, B.; Pätzold, M.; Tyler, G. L.; Simpson, R. A.; Bird, M. K.; Dehant, V.; Barriot, J.-P.; Eidel, W.; Mattei, R.; Remus, S.; Selle, J.; Tellmann, S.; Imamura, T.

2006-11-01

165

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

Microsoft Academic Search

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

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

2008-01-01

166

Mariner-Venus 1967  

NASA Technical Reports Server (NTRS)

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.

1971-01-01

167

The Highlands of Venus  

NASA Astrophysics Data System (ADS)

The Poisson-type hypsometry of Venus implies many independent events raise(d) highlands incrementally and their concentration into various forms make these interesting targets for an Interferometric SAR mission, for which key parameters are given.

Cochrane, C. G.; Ghail, R. C.

2014-05-01

168

Basic facts about Venus  

NASA Technical Reports Server (NTRS)

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.

Colin, L.

1983-01-01

169

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)

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.

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

170

Revealing the Face of Venus: Magellan.  

National Technical Information Service (NTIS)

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.

1993-01-01

171

Revealing the face of Venus: Magellan  

NASA Technical Reports Server (NTRS)

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.

1993-01-01

172

Hybrid Simulations of Venus' Dynamic Plasma Environment  

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

173

First ever in situ observations of Venus' polar upper atmosphere density using the tracking data of the Venus Express Atmospheric Drag Experiment (VExADE)  

NASA Astrophysics Data System (ADS)

On its highly elliptical 24 h orbit around Venus, the Venus Express (VEX) spacecraft briefly reaches a periapsis altitude of nominally 250 km. Recently, however, dedicated and intense radio tracking campaigns have taken place in August 2008, October 2009, February and April 2010, for which the periapsis altitude was lowered to the 186-176 km altitude range in order to be able to probe the upper atmosphere of Venus above the North Pole for the first time ever in situ. As the spacecraft experiences atmospheric drag, its trajectory is measurably perturbed during the periapsis pass, allowing us to infer total atmospheric mass density at the periapsis altitude. A Precise Orbit Determination (POD) of the VEX motion is performed through an iterative least-squares fitting process to the Doppler tracking data, acquired by the VEX radioscience experiment (VeRa). The drag acceleration is modelled using an initial atmospheric density model (VTS3 model, Hedin, A.E., Niemann, H.B., Kasprzak, W.T., Seiff, A. [1983]. J. Geophys. Res. 88, 73-83). A scale factor of the drag acceleration is estimated for each periapsis pass, which scales Hedin's density model in order to best fit the radio tracking data. Reliable density scale factors have been obtained for 10 passes mainly from the second (October 2009) and third (April 2010) VExADE campaigns, which indicate a lower density by a factor of about 1.8 than Hedin's model predicts. These first ever in situ polar density measurements at solar minimum have allowed us to construct a diffusive equilibrium density model for Venus' thermosphere, constrained in the lower thermosphere primarily by SPICAV-SOIR measurements and above 175 km by the VExADE drag measurements (Müller-Wodarg et al., in preparation). The preliminary results of the VExADE campaigns show that it is possible to obtain with the POD technique reliable estimates of Venus' upper atmosphere densities at an altitude of around 175 km. Future VExADE campaigns will benefit from the planned further lowering of VEX pericenter altitude to below 170 km.

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

2012-02-01

174

Deep Electromagnetic Sounding of Venus and Mars: The Concept  

NASA Astrophysics Data System (ADS)

The interaction of the solar wind with a planet with a weak magnetic field and a well-developed ionosphere can result in a transport of magnetic flux into the ionosphere and the build-up of a strong magnetic field layer at low altitudes. We can now illustrate the properties of this layer with the Pioneer Venus and Venus Express magnetometer data, but soon such measurements are expected to be returned by the MAVEN mission at Mars. In this paper we show how we could electromagnetically sound the interior of Mars, and especially to determine the size of the core using InSight and/or MAVEN measurements based on our understanding of the Pioneer Venus and Venus Express magnetic measurements. We await the MAVEN measurements in order to determine how much the crustal field affects the martian ionosphere.

Villarreal, Michaela; Russell, Christopher; Chi, Peter; Zhang, Tielong; Luhmann, Janet; Ma, Yingjuan

2014-05-01

175

Plasma boundaries around Venus  

NASA Astrophysics Data System (ADS)

We use data of the ASPERA-4 ion and electron spectrometers onboard Venus Express to define the location and shape of bow shock and magnetic barrier at Venus and their dependence on solar wind pressure and radiation. We compare our results with those of the Pioneer Venus Orbiter and discuss implications for atmospheric escape. We also discuss the differences to similar observations made by the ASPERA-3 instrument for the Martian plasma evironment.

Martinecz, C.; Fraenz, M.; Woch, J.; Krupp, N.; Dubinin, E.; Roussos, E.; Barabash, S.; Lundin, R.

176

Priorities for Venus Exploration  

NASA Astrophysics Data System (ADS)

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.

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

177

The geophysics of Venus  

NASA Astrophysics Data System (ADS)

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.

Solomon, S. C.

1993-07-01

178

Windows to the Universe: Venus  

NSDL National Science Digital Library

This site, a joint effort between the University of Michigan and the University Corporation for Atmospheric Research (UCAR), focuses on the planet Venus. Some of the topics discussed include: the atmosphere, interior, and surface of Venus, recent discoveries, missions to Venus, and myths. The activities are easily sorted in beginning, intermediate and advanced lessons. There are also many pictures and additional websites for more information. A Spanish translation is also available.

2009-05-20

179

Current View of the Venus-Solar Wind Interaction  

NASA Astrophysics Data System (ADS)

In this paper we endeavour to review the results on Venus-Solar Wind Interaction obtained in recent years and the current understanding of plasma processes at Venus. In the years after the Pioneer Venus Orbiter (PVO) the Cassini and Galileo spacecraft have flown by and made plasma measurements at Venus. Theoretical and numerical modelling have been used to study the interaction between Venus and the solar wind. The models that have been used include gas-dynamical, MHD, and quasi-neutral hybrid models. Several escape processes are at work at Venus: direct escape of pick-up ions, which yields escaper rates of 1×1025s-1 and 1.6×1025s-1 for H+and O+ respectively; sputtering of the atmosphere by incident pick-up ions is responsible for a oxygen atom loss rate of 6×1024s-1; detached plasma clouds, that were observed by PVO and may be the result of plasma instabilities have been estimate to contribute to a loss of 0.5-1×1025s-1; thermal escape and photo-chemical processes are expected to be negligible for oxygen, but for hydrogen the photo-chemical loss rate is 3.8×1025s-1. The numbers are quoted from Lammer et al. (Planetary and Space Science, in press, 2005). A wide variety of plasma waves are present at Venus. The waves can play an important role in the interaction between the solar wind and the ionosphere, and wave measurements can be used as a diagnostic tool for remote studies of plasma processes at the planet. Wave measurements at Venus have been interpreted as an indication of lightning, although this issue is still controversial. Energetic neutral atom (ENA) imaging is an emerging field that for Venus so far only has been studied through computer modelling. These numerical studies have predicted that the ENA flux at Venus is lower than that at Mars. Measurements by the Venus Express mission will shed more light on the physics behind the generation of ENAs. Venus has been observed in X-rays by the Chandra X-ray observatory. The observed X-rays can be explained by fluorescence of X-rays from the sun in Venus' atmosphere. X-rays from the solar wind charge exchange (SWCX) process have been found at Mars and are the dominating source of X-rays from comets. In agreement with the sensitivity of the observation no such X-rays were found at Venus, but SWCX X-rays may be revealed by future more sensitive observations.

Gunell, H.; Barabash, S.

2005-12-01

180

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

NASA Astrophysics Data System (ADS)

investigated the Venus O2 visible nightglow with imagery from the Venus Monitoring Camera on Venus Express. Drawing from data collected between April 2007 and January 2011, we study the global distribution of this emission, discovered in the late 1970s by the Venera 9 and 10 missions. The inferred limb-viewing intensities are on the order of 150 kR at the lower latitudes and seem to drop somewhat toward the poles. The emission is generally stable, although there are episodes when the intensities rise up to 500 kR. We compare a set of Venus Monitoring Camera observations with coincident measurements of the O2 nightglow at 1.27 µm made with the Visible and Infrared Thermal Imaging Spectrometer, also on Venus Express. From the evidence gathered in this and past works, we suggest a direct correlation between the instantaneous emissions from the two O2 nightglow systems. Possible implications regarding the uncertain origin of the atomic oxygen green line at 557.7 nm are noted.

GarcíA MuñOz, A.; Hueso, R.; SáNchez-Lavega, A.; Markiewicz, W. J.; Titov, D. V.; Witasse, O.; Opitz, A.

2013-06-01

181

Planetary missions  

NASA Technical Reports Server (NTRS)

The scientific and engineering aspects of near-term missions for planetary exploration are outlined. The missions include the Voyager Neptune flyby, the Magellan survey of Venus, the Ocean Topography Experiment, the Mars Observer mission, the Galileo Jupiter Orbiter and Probe, the Comet Rendezvous Asteroid Flyby mission, the Mars Rover Sample Return mission, the Cassini mission to Saturn and Titan, and the Daedalus probe to Barnard's star. The spacecraft, scientific goals, and instruments for these missions are noted.

Mclaughlin, William I.

1989-01-01

182

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

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

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

2014-01-01

183

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

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.

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

2014-01-01

184

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

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

185

Virtis: An Imaging Spectrometer for the Rosetta Mission  

Microsoft Academic Search

The VIRTIS (Visual IR Thermal Imaging Spectrometer) experiment has been one of the most successful experiments built in Europe\\u000a for Planetary Exploration. VIRTIS, developed in cooperation among Italy, France and Germany, has been already selected as\\u000a a key experiment for 3 planetary missions: the ESA-Rosetta and Venus Express and NASA-Dawn. VIRTIS on board Rosetta and Venus\\u000a Express are already producing

A. Coradini; F. Capaccioni; P. Drossart; G. Arnold; E. Ammannito; F. Angrilli; A. Barucci; G. Bellucci; J. Benkhoff; G. Bianchini; J. P. Bibring; M. Blecka; D. Bockelee-Morvan; M. T. Capria; R. Carlson; U. Carsenty; P. Cerroni; L. Colangeli; M. Combes; M. Combi; J. Crovisier; M. C. Desanctis; E. T. Encrenaz; S. Erard; C. Federico; G. Filacchione; U. Fink; S. Fonti; V. Formisano; W. H. Ip; R. Jaumann; E. Kuehrt; Y. Langevin; G. Magni; T. McCord; V. Mennella; S. Mottola; G. Neukum; P. Palumbo; G. Piccioni; H. Rauer; B. Saggin; B. Schmitt; D. Tiphene; G. Tozzi

2007-01-01

186

Magellan: The unveiling of Venus  

NASA Technical Reports Server (NTRS)

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.

1989-01-01

187

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

NASA Astrophysics Data System (ADS)

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.

Titov, Dmitri; Svedhem, Håkan; 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.

188

Atmospheric loss caused by Kelvin-Helmholtz instability: What can we expect from Mars- and Venus Express?  

NASA Astrophysics Data System (ADS)

Measurements of electron density by the Pioneer Venus Orbiter electron temperature probe showed extreme spatial irregularities in the form of detached plasma clouds on the night side of Venus. It is suggested that Kelvin Helmholtz (KH) instabilities may trigger such ionospheric bubbles on Mars too. The ASPERA instrument on board of the Russian Mars probe Phobos 2 has detected a large outflow of heavy ions containing a substantial mixture of molecular ions like O2+ and CO2+. Since heavy particles have scale heights much smaller than upper atmospheric constituents like O its concentration in the exosphere should be correspondingly low. Thus, there must be a mechanism to transport these heavy molecular ions into the solar wind interaction region. We investigate the KH-instability at the ionopause of Venus and Mars resulting from the flow of the solar wind for the case where the interplanetary magnetic field is oriented normal to the flow direction. Since the Larmor radius of the particles is comparable with the thickness of the boundary layer, an ideal magnetohydrodynamic formulation of the KH-instability is inapplicable to the stability problem at the interface of two interacting fluids with different shear velocities. Therefore, we apply simultaneously both effects to treat the general problem of the KH-instability. We estimate the escape rates of heavy atmospheric ions which are lost by ionospheric bubbles and compare these results with loss rates caused by other non-thermal atmospheric escape processes. Further, we discuss our results in view of the expected observations of heavy ion loss rates by ASPERA-3 on board of Mars Express and ASPERA-4 and the magnetormeter VEXMAG on board of Venus Express.

Penz, T.; Lammer, H.; Biernet, H. K.; Erkaev, N. V.; Gunell, H.; Kallio, E.; Holmström, M.; Barabash, S.; Lichtenegger, H. I. M.; Baumjohann, W.

2003-04-01

189

Venus cartography  

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

190

Observations Of The Ultraviolet Nitric Oxide (NO) Nightglow With SPICAV On Board Venus Express During Stellar Occultations  

NASA Astrophysics Data System (ADS)

Ultraviolet nightglow have been detected on Venus for the first time by Barth and al., in 1968, from Mariner 5, then identified like to be nitric oxide nightglow by Feldmann and al., and by Stewart and Barth, in 1979, with Pioneer. SPICAV (SPectroscopy for the Characteristics of the Atmosphere of Venus), on board Venus Express spacecraft, currently in orbit around Venus, also see them. We descibe here a forward model allowed to reproduce this nitric oxide nightglow. It is a first approach in a better understanding of the dynamic phenomena of the venusian thermosphere. When working in the spectrometric mode with the slit, SPICAV has shown that the Venus nightglow contains essentially Lyman-a and nitric oxide (NO) emission, well studied by Gerard et al. (2008b). What we show here is that, when SPICAV is used in the stellar occultation mode (without the slit), quite often an emission is present at the limb, in addition to the stellar spectrum. A forward model of the NO emission observed without the slit, when compared to the data, confirms that indeed this limb emission is due to NO nightglow. This observing mode without the slit is 50 times more sensitive than with the slit, owing to the larger subtended FOV. Terefore, its systematic extraction from stellar occultations will extend the data base of NO emission already collected in the limb spectroscopic mode (Gerard et al., 1981 and 2008b). This emission, due to recombinaison of N and O atoms produced on the dayside of Venus, and transported to the nightside, allows to study the Solar to Anti-solar thermospheric circulation (above 100 km). The comparaison with the forward model allows to derive the emission intensity, the altitude of the layer, and its scale height. Owing to the large number of star occultations recorded, and higher sensitivity, the systematic extraction of NO emission parameters from stellar occultations will add a large number of NO observations as tracers of the venusian thermospheric circulation, giving strong contraints on the thermospheric general circulation model (TGCM).

Royer, E.; Montmessin, F.; Bertaux, J.-L.

2009-04-01

191

Chasing Venus  

NSDL National Science Digital Library

This website tells the story of astronomers in pursuit of understanding and observing transits of Venus from 1631 to present day. Much of the content comes from rare books and articles on Venus transits written over the last four centuries.

Institution, Smithsonian

2004-07-14

192

Chemical Weathering Kinetics of Basalt on Venus  

NASA Technical Reports Server (NTRS)

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

Fegley, Bruce, Jr.

1997-01-01

193

Interplanetary Scintillation, STEREO Heliospheric Imager and Venus Express ASPERA observations of solar wind structures in May 2007  

NASA Astrophysics Data System (ADS)

We present results from a co-ordinated study of solar wind structure in the inner helisphere during May 2007, combining results from radio measurements of interplanetary scintillation (IPS), STEREO HI imaging of interplanetary structures and in-situ measurements from the ASPERA instrument on Venus Express. The ASPERA results revealed periodic disturbances in the solar wind at Venus, which we show correspond to solar wind structures seen in STEREO HI and IPS results. Most of the perturbations seen in ASPERA data correspond to the passage of co-rotating interaction regions over Venus, and we show that these can be identified with CIR signatures seen in IPS and by STEREO. One event is more complex, and we interpret this as the interaction between a coronal mass ejection and the compression region of a co-rotating interaction region. The combination of STEREO HI, IPS and VEX data has made it possible to investigate solar wind structures with a much higher degree of certainty, demonstrating the potential of such multi-technique programmes.

Breen, A. R.; Dorrian, G. D.; Brown, D. S.; Whittaker, I.; Fallows, R. A.; Davies, J. A.; Roulliard, A.

2009-04-01

194

Terraforming Venus  

Microsoft Academic Search

The methods and force magnitudes necessary for terraforming Venus into a habitable planet are calculated. The basic requirements are to bring the Venus daylength closer to an earth day and to reform the basically CO2 Venus atmosphere into an oxygen-inert gas mixture suitable for breathing without a spacesuit. The redirection of large, dense matter asteroids from the inner asteroid belt

S. J. Adelman

1982-01-01

195

Venus mapper resolution  

Microsoft Academic Search

NASA program managers for the Venus Radar Mapper (VRM) mission have decided to make improvements to the spacecraft's Synthetic Aperture Radar (SAR) system that will increase its mapping resolution by one and a half times over the original design. The changes, including a doubling of the system's range bandwidth, will add a total of about $5 million to a project

Tony Reichhardt

1984-01-01

196

Ion Escape From Mars and Venus (Invited)  

NASA Astrophysics Data System (ADS)

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.

Barabash, S. V.

2013-12-01

197

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

NASA Astrophysics Data System (ADS)

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.

Witasse, O. G.

2013-12-01

198

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

NASA Astrophysics Data System (ADS)

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.

Blumberg, D. G.

2012-04-01

199

Venus within ESA probe reach  

NASA Astrophysics Data System (ADS)

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:

2006-03-01

200

Orbital maneuvers: Magellan aerobrakes into Venus' atmosphere  

NASA Astrophysics Data System (ADS)

The aerobraking orbital activities of Magelland during the gravity mapping of Venus are discussed. The goal of aerobraking was to circularize Magellan's orbit. By aerobraking the spacecraft into a nearly circula orbit, the Magellan team was able to provide scientists with a different data set to deepen their understanding of what is going on beneath Venus' surface. Before undertaking its gravity-mapping mission, Magellan completed three cycles of radar mapping. This repeated coverage allowed the spacecraft to see some of Venus' geologic features from different viewing angles. Various aspects of the mission are discussed, and maps of Venus are presented.

Doody, D.

1994-04-01

201

Hybrid simulations of Venus' ionospheric magnetization states  

NASA Astrophysics Data System (ADS)

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

Wiehle, Stefan; Motschmann, Uwe; Fränz, Markus

2013-04-01

202

The structure of Venus' middle atmosphere and ionosphere.  

PubMed

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

Pätzold, M; Häusler, 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

203

The surface of Venus  

NASA Technical Reports Server (NTRS)

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.

Saunders, R. Stephen

1990-01-01

204

Orbital Express Mission Operations Planning and Resource Management using ASPEN  

NASA Technical Reports Server (NTRS)

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.

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

2008-01-01

205

To Venus with spare parts  

NASA Astrophysics Data System (ADS)

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

Bell, Peter M.

206

Writing the History of Space Missions: Rosetta and Mars Express  

NASA Astrophysics Data System (ADS)

Mars Express is the first planetary mission accomplished by the European Space Agency (ESA). Launched in early June 2003, the spacecraft entered Mars's orbit on Christmas day of that year, demonstrating the new European commitment to planetary exploration. Following a failed attempt in the mid-­-1980s, two valid proposals for a European mission to Mars were submitted to ESA's decision-­-making bodies in the early 1990s, in step with renewed international interest in Mars exploration. Both were rejected, however, in the competitive selection process for the agency's Science Programme. Eventually, the Mars Express proposal emerged during a severe budgetary crisis in the mid-­-1990s as an exemplar of a "flexible mission" that could reduce project costs and development time. Its successful maneuvering through financial difficulties and conflicting scientific interests was due to the new management approach as well as to the public appeal of Mars exploration. In addition to providing a case study in the functioning of the ESA's Science Programme, the story of Mars Express discussed in this paper provides a case study in the functioning of the European Space Agency's Science Programme and suggests some general considerations on the peculiar position of space research in the general field of the history of science and technology.

Coradini, M.; Russo, A.

2011-10-01

207

ULF and ELF Electromagnetic Waves over Venus Electrical Storms  

NASA Astrophysics Data System (ADS)

Venus Express (VEX) observations of electromagnetic signals from at both ULF and ELF frequencies have been enabled by new, improved cleaning algorithms using its dual fluxgate magnetometers. These data reveal two types of signals that are associated with electrical activity in Venus' atmosphere. The first signals occur only below about 20 Hz, at which frequencies signals can propagate perpendicular to the magnetic field. These signals consist of waves arriving from different directions across the field just as expected from discharges occurring in different places within the clouds beneath the spacecraft. Since these low frequency (ULF) signals can cross the magnetic field lines, they easily reach the spacecraft while horizontal ionospheric magnetic fields can prevent the entry of higher frequency (ELF) signals to the satellite. These signals allow us to map the occurrence rate of lightning on Venus much more directly and completely than we could previously with only the ELF portion of the spectrum. A second type of signal can occur at both low (<20 Hz) ULF and high (>20 Hz) ELF frequencies. This signal appears to represent connection via the ionospheric magnetic field to a more distant storm. The signals are right-hand circularly polarized and propagate parallel to the magnetic field. These were the signals used to perform our initial VEX studies of Venus lightning before the cleaning algorithm was perfected. They are the same type of signals detected "inside the resonance cone" on the Pioneer Venus mission using its electric field antenna and identified as propagating in the whistler mode.

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

2012-12-01

208

Extreme Environments Technologies for Probes to Venus and Jupiter  

NASA Technical Reports Server (NTRS)

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.

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

2007-01-01

209

Pioneer Venus Small Probes Net Flux Radiometer Experiment  

Microsoft Academic Search

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

L. A. Sromovsky; H. E. Revercomb; Verner E. Suomi

1980-01-01

210

Exploring Venus.  

National Technical Information Service (NTIS)

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 tech...

G. A. Landis

2008-01-01

211

Robotic Technology for Exploration of Venus  

NASA Technical Reports Server (NTRS)

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

Landis, Geoffrey A.

2003-01-01

212

Moon Express: Lander Capabilities and Initial Payload and Mission  

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

213

Analysis of MESSENGER/MASCS data during second Venus flyby  

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

214

Future exploration of Venus (post-Pioneer Venus 1978)  

NASA Technical Reports Server (NTRS)

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.

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

1976-01-01

215

Hinode Views the 2012 Venus Transit  

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...

216

Hinode Views the Transit of Venus  

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 ...

217

Venus Atmospheric Maneuverable Platform (VAMP)  

NASA Astrophysics Data System (ADS)

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 strawman’s 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.

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

2013-10-01

218

Venus Phasing.  

ERIC Educational Resources Information Center

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)

Riddle, Bob

1997-01-01

219

Exploring Venus.  

ERIC Educational Resources Information Center

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)

The Universe in the Classroom, 1985

1985-01-01

220

A balloon-borne stratospheric telescope for Venus observations  

NASA Astrophysics Data System (ADS)

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.

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

2008-08-01

221

Electromagnetic waves observed on a flight over a Venus electrical storm  

NASA Astrophysics Data System (ADS)

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.

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

2013-01-01

222

The Magellan Venus explorer's guide  

NASA Technical Reports Server (NTRS)

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.

Young, Carolynn (editor)

1990-01-01

223

Orbital Express Mission Operations Planning and Resource Management using ASPEN  

NASA Technical Reports Server (NTRS)

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

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

2008-01-01

224

Altitude-Controlled Balloons for Long-Duration Flights on Venus  

NASA Astrophysics Data System (ADS)

Balloons provide a relatively simple and well-proven platform for accessing the upper atmosphere of Venus. We analyze several types of altitude-controlled balloons and assess their suitability for an extended mission on Venus.

Voss, P. B.; Nott, J.; Cutts, J. A.; Hall, J. L.; Beauchamp, P. M.; Limaye, S. S.; Baynes, K. H.; Bennett, B.; Hole, L. R.

2014-06-01

225

Robotic Exploration of the Surface and Atmosphere of Venus  

NASA Technical Reports Server (NTRS)

Venus, the "greenhouse planet", is a scientifically fascinating place. In many ways it can be considered "Earth's evil twin." A huge number of important scientific questions remain to be answered: 1) Before the runaway greenhouse effect, was early Venus temperate? 2) Did Venus once have an ocean? 3) What causes the geological resurfacing of the planet? 4) Is Venus still geologically active? 5) What is the "snow" on Venus mountaintops? 6) Can we learn about Earth's climate from Venus? 7) Is the atmosphere of Venus suitable for life? To address these and other scientific questions, a robotic mission to study the surface and atmosphere of Venus has been designed. The mission includes both surface robots, designed with an operational lifetime of 90 days on the surface of Venus, and also solar-powered airplanes to probe the middle atmosphere. At 450 Celsius, and with 90 atmospheres of pressure of carbon-dioxide atmosphere, the surface of Venus is a hostile place for operation of a probe. This paper will present the mission design, discuss the technology options for materials, power systems, electronics, and instruments, and present a short summary of the mission.

Landis, Geoffrey A.

2004-01-01

226

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

NASA Astrophysics Data System (ADS)

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

Collinson, Glyn A.; Kataria, D. O.; Coates, Andrew J.; Tsang, Sharon M. E.; Arridge, Christopher S.; Lewis, Gethyn R.; Frahm, Rudy A.; Winningham, J. David; Barabash, Stas

2009-05-01

227

Venus gravity  

NASA Technical Reports Server (NTRS)

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.

Reasenberg, Robert D.

1993-01-01

228

Temporal variations of zonal wind speed at Venus cloud tops from Venus Monitoring Camera UV images  

NASA Astrophysics Data System (ADS)

Venus Monitoring Camera (VMC) [1] on board the Venus Express mission obtained great number of UV images of the upper cloud. The observations cover about 10 Venusian years. 600 orbits or about 25% of all available UV images were processed by the digital wind tracking routine resulting in ~400000 vectors for the whole period of observations. Mean profiles were calculated for individual orbits. Time series of zonal speed for 5 degrees latitude bins centered at 10, 15, 20, 25 and 30 South were created from the individual mean profiles. The time series were investigated for periodicities by using Deeming algorithm [2] for unequally-spaced data. Two groups of the periods were found. The first group is close to the period of superrotation at low latitudes (4.83±0.1 days) with the period 4.1-5.1 days and the amplitude ranging from ±4.26 to ±17.44 m/s. The amplitude and phase of oscillations demonstrates dependence from the latitude and also time variability with preserving stable parameters of oscillation during at least 70 days. The second one is a long term periods caused by orbital motion of Venus (116 days, 224 days) and is related to the periodicity in the VMC observations.

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

2012-09-01

229

Venus Transit  

NSDL National Science Digital Library

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

230

Pioneer Mars surface penetrator mission. Mission analysis and orbiter design  

NASA Technical Reports Server (NTRS)

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.

1974-01-01

231

Magellan mission summary  

Microsoft Academic Search

Magellan started mapping the planet Venus on September 15, 1990, and after one cycle (one Venus day or 243 earth days) had mapped 84 percent of the planet's surface. This returned an image data volume greater than all past planetary missions combined. Spacecraft problems were experienced in flight. Changes in operational procedures and reprogramming of onboard computers minimized the amount

R. S. Saunders; A. J. Spear; P. C. Allin; R. S. Austin; A. L. Berman; R. C. Chandlee; J. Clark; A. V. Decharon; E. M. de Jong; D. G. Griffith; J. M. Gunn; S. Hensley; W. T. K. Johnson; C. E. Kirby; K. S. Leung; D. T. Lyons; G. A. Michaels; J. Miller; R. B. Morris; A. D. Morrison; R. G. Piereson; J. F. Scott; S. J. Shaffer; J. P. Slonski; E. R. Stofan; T. W. Thompson; S. D. Wall

1992-01-01

232

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

NASA Astrophysics Data System (ADS)

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.

Zasova, Ludmila

2012-07-01

233

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

NASA Technical Reports Server (NTRS)

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.

1976-01-01

234

Venus, Earth, Xenon  

NASA Astrophysics Data System (ADS)

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

Zahnle, K. J.

2013-12-01

235

The Venus environment  

SciTech Connect

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.

Not Available

1982-08-01

236

Venus Atmospheric Dynamics  

NASA Astrophysics Data System (ADS)

Over the last four decades, we have learned much about the atmosphere of Venus and its circulation through earth-based, spacecraft orbiters and entry probes and even balloons. However, our understanding of the processes maintaining the atmospheric circulation of the atmosphere is poor. We have discovered every where we have measured, the atmosphere moves in the same direction as the underlying planet from east to west such that the rotational spin vector is pointing opposite to its orbit spin vector. At the cloud level, the magnitude of the mean zonal flow is as much as fifty times the tangential speed of the planet's surface and somewhat less fast all the way down to the surface. The mean flow exhibits a weak poleward flow at the levels where observations have been made. Much of what we have learnt has been measured from many different observational programs but all of these have suffered from limitations of spatial, temporal coverage and appropriate resolution. Much of what we know about the global structure of the circulation has been measured from spacecraft images of the day-side of Venus and much of the structure on the night side remains unmeasured extensively although limited Galileo and earth based observations provide important clues. What the observations confirm is that the Venus atmosphere and its thermal structure below the clouds is far from globally uniform and is quite dynamic, changing on a time scale of hours to days and weeks. The role of planetary scale waves and solar thermal tides in the Venus atmosphere is unknown due to lack of long term coverage, and the deep atmospheric circulation in the polar regions remains unmeasured. After more than two decades, Venus atmosphere is about to be explored again. These missions are likely to exploit the near infrared windows into its deep atmosphere to enable a determination of the circulation on the night side. Systematic, global observations of the atmospheric circulation are needed from these missions to gain further insight in the processes that maintain the super rotation of the atmosphere and an assessment of the role of solar thermal tides in sustaining the circulation. Other aspects that require systematic concurrent observations include the transport of heat, momentum and trace species in the atmosphere. Recently there have been some numerical modeling efforts that show promise of generating super rotation through momentum transport by waves, and the systematic observations will help evaluate their performance.

Limaye, S. S.

237

Detector of low energy neutral atoms onboard Mars Express mission  

NASA Astrophysics Data System (ADS)

Neutral Particle Detector (NPD) developed for the ESA Mars Express mission is a compact low weight (650g) high efficiency sensor to image low energy neutral atoms (ENA) resulted from the solar wind interaction with the Martian exosphere. NPD provides measurements of the ENA differential flux over the energy range 100 eV - 10 keV resolving H and O with a coarse 5^o yen 30o angular resolution and total efficiency 1 - 50%. The sensor consists of two identical detectors each with a 9^o yen 90^o intrinsic field of view placed on a scanning platform which performs 180^o scans to cover a hemisphere. The measurement principle is based on surface interaction technique. ENAs incident on a start surface at a grazing angle of 15^o are reflected and cause secondary electron emission. The secondary electrons are transported to an MCP assembly, which gives the START signal. The reflected ENAs hit the stop surface and again produce the secondary electrons used to generate the STOP signal. The time-of-flight measurements give ENA velocity and are used to identify mass (H or O). Coincidence technique as well as properties of the START and STOP surface coating provide UV suppression to the level sufficient to achieve the required signal-to-noise ratio. The results of the flight model calibrations will be presented and analyzed.

Grigoriev, A.; Barabash, S.; Fedorov, A.; Wurz, P.; Grande, M.; Curtis, C.; Maggi, M.; Dierker, C.; Npd Team

2003-04-01

238

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

239

Variable Venus  

NSDL National Science Digital Library

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

240

Venus mapping  

NASA Technical Reports Server (NTRS)

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.

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

1991-01-01

241

Venus Climate Sensitivity  

NASA Astrophysics Data System (ADS)

The sensitivity of the Earth's climate to changes in atmospheric carbon dioxide is often expressed as the net change in radiative forcing, in W/m2, due to a doubling of carbon dioxide concentration. Feedbacks due to consequent changes in water vapor abundance, clouds, and surface ice act to magnify or suppress the net change in radiative forcing due to doubling of atmospheric carbon dioxide. For example, for the net change in radiative energy balance of ?H is ?H=?F/?[CO2 ] ?[CO2] + ?F/?T ?T + ?F/?[H2O] ?[H2O]/?T ?T + So/4 ??/?T ?T where F is the flux at the top of the atmosphere, [CO2] and [H2O] are the concentrations of carbon dioxide and water vapor in the atmosphere, So is the solar flux, and ? is the planetary albedo. The first term on the right is the direct effect of atmospheric carbon dioxide concentration on the outgoing thermal flux. The second term represents the adjustment to outgoing flux that results solely from changes in atmospheric temperature. The third term is the water vapor greenhouse term, and the fourth is the response the Earth's albedo to changes in temperature. Radiative balance is established when ?H --> 0. The sensitivity of Venus' climate due to perturbations in atmospheric constituents can be expressed in a similar manner. This analysis is useful for assessing the changes in surface temperature that result from volcanic activity, and the long term effects of the loss of volatiles to space or to reactions with the surface. I will discuss the change in radiative forcing of Venus' climate due to alteration of atmospheric water vapor abundance. As with carbon dioxide in the Earth's atmosphere, changes in Venus' atmospheric water vapor have both direct and indirect climate forcing effects. The analogous linearized climate sensitivity equation for Venus will be discussed, with an emphasis on the nature of the feedback each term represents.

Bullock, M.

2012-12-01

242

Variations and Effects of the Venusian Bow Shock from VEX Mission  

NASA Astrophysics Data System (ADS)

The upper atmosphere of Venus is not shielded by planetary magnetic field from direct interaction with the solar wind. The interaction of shocked solar wind and the ionosphere results in ionopause. Magnetic barrier, the inner region of dayside magnetosheath with the dominated magnetic pressure deflects the solar wind instead of the ionopause at solar maximum. Therefore, the structure and interaction of venusian ionosphere is very complex. Although the Venus Express (VEX) arrived at Venus in April 2006 provides more knowledge on the Venusian ionosphere and plasma environment, compared to Pioneer Venus Orbiter (PVO) with about 14 years of observations, some important details are still unknown (e.g., long Venusian bow shock variations and effects). In this paper, the bow shock positions of Venus are determined and analyzed from magnetometer (MAG) and ASPERA-4 of the Venus Express mission from May 28, 2006 to August 17, 2010. Results show that the altitude of BS was mainly affected by SZA (solar zenith angle) and Venus bow shocks inbound and outbound are asymmetry.

Xue, Yansong; Jin, Shuanggen

2014-04-01

243

Distant bow shock and magnetotail of Venus: magnetic field and plasma wave observations  

Microsoft Academic Search

An examination of the magnetic field and plasma wave data obtained by the Pioneer Venus orbiter in the wake region behind Venus discloses a well developed bow shock whose location is similar to that observed on previous missions in contrast to the dayside bow shock. Venus also has a well developed magnetotail in which the field strength is enhanced over

C.T. Russell; J. G. Luhmann; R. C. Elphic; F. L. Scarf

1981-01-01

244

Hot Flow Anomalies at Venus  

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

245

Investigating gravity waves evidences in the Venus upper atmosphere  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

246

Measurements Needed to Understand Superrotation and Circulation in the Venus Atmosphere  

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

247

The Plains of Venus  

NASA Astrophysics Data System (ADS)

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 725×375 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.

Sharpton, V. L.

2013-12-01

248

Venus: Water and Life  

NASA Astrophysics Data System (ADS)

Amphiboles that contain the hydroxide ion form only in the presence of water and this fact has become the way for scientists to prove that Venus was once a water world. Though, tremolite is considered the main mineral to look for, it requires life that is analogous to the ancient life here on Earth for it to form. Dolomite is the main ingredient for the formation of this low grade metamorphic mineral and without it would be very difficult for tremolite to form, unless there is another process that is unknown to science. Venus is known to have extensive volcanic features (over 1600 confirmed shield volcanoes dot its surface) and with little erosion taking place; a mineral that is associated with volcanism and forms only in the presence of water should be regarded as the main goal. Hornblende can form via volcanism or a metamorphic process but requires water for initial formation. The European Space Agency is currently trying to determine whether or not the continents on Venus' surface are made of granite, as they argue granite requires water for formation. Either way, computer models suggest that any oceans that formed on the surface would have lasted at best 2 billion years, as the surface is estimated to be only 800 million years old, any hornblende that would have formed is more than likely going to be deep underground. To find this mineral, as well as others, it would require a mission that has the ability to drill into the surface, as the easiest place to do this would be on the mountain peaks in the Northern Hemisphere on the Ishtar Terra continent. Through the process of uplift, any remaining hornblende may have been exposed or very near exposed to the surface. Do to the amount of fluorine in the atmosphere and the interaction between this and the lithosphere, the hydroxyl ions may have been replaced with fluorine turning the hornblende into the more stable fluoro-hornblende. To further add to the mystery of Venus is the unusual atmospheric composition. The presence of both sulfur dioxide and hydrogen sulfide demand further research as these gases are not being replenished by any geologic activity. Both of these compounds are found is sufficient quantity in the cloud decks, but are almost nonexistent at the surface, further supporting the idea of a chemical reaction/process in the atmosphere. There are particles that have been detected in the atmosphere that seem to be absorbing UV radiation is also located at these same altitudes. Finding tremolite on Venus would only further excite the possibility that we are not alone in the universe. Could life on Venus be related to life here on Earth? Where in the Solar System did life originate? These are questions that would need serious thought if such an event took place. Finding hornblende on Venus would give further support to several theories, but finding tremolite would change everything.

Ditkof, J. F.

2013-05-01

249

Solar Powered Flight on Venus  

NASA Technical Reports Server (NTRS)

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.

Colozza, Anthony; Landis, Geoff (Technical Monitor)

2004-01-01

250

High Temperature, Wireless Seismometer Sensor for Venus  

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

251

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

NASA Technical Reports Server (NTRS)

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.

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

2000-01-01

252

Venus nitric oxide nightglow mapping from SPICAV nadir observations  

NASA Astrophysics Data System (ADS)

Nitric oxide ? (190-240 nm) and ? (255-270 nm) bands have been observed on the Venus nightside with Venus Express SPICAV instrument operated in the nadir mode. These ultraviolet emissions arise from the de-excitation of NO molecules created by radiative recombination of O(3P) and N(4S) atoms. These atoms are produced on the dayside of the planet through photodissociation of CO2 and N2 molecules and are transported to the nightside by the global subsolar to antisolar circulation. We analyze a wide dataset of nadir observations obtained since 2006 to determine the statistical distribution of the NO nightglow and its variability. Individual observations show a great deal of variability and may exhibit multiple maxima along latitudinal cuts. We construct and compare a global NO map with the results obtained during the Pioneer-Venus mission and with the recently observed O2(a1?g) nightglow distribution. The NO airglow distribution shows a statistical bright region extending from 01:00 to 03:30 local time and 25°S to 10°N, very similar to the Pioneer results obtained 35 years earlier during maximum solar activity conditions. The shift from the antisolar point and the difference with the O2 airglow indicate that superrotating zonal winds are statistically weak near 97 km, but play an important role near 115 km. We compare these results with other evidence for superrotation in the thermosphere and point out possible sources of momentum transfer.

Stiepen, A.; Gérard, J.-C.; Dumont, M.; Cox, C.; Bertaux, J.-L.

2013-09-01

253

High Temperature Mechanisms for Venus Exploration  

NASA Astrophysics Data System (ADS)

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.

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

254

X-Band Microwave Radiometry as a Tool for Understanding the Deep Atmosphere of Venus  

NASA Astrophysics Data System (ADS)

Understanding the composition, structure, and spatial variability of the deep Venus atmosphere, including the boundary layer, is a key future direction identified in the Decadal Review. While only Mariner 2 carried a microwave radiometer for the expressed purpose of evaluating the Venus atmosphere, subsequent missions to Venus and other planets have used radar receivers in a "passive mode" to map the microwave emission from both surfaces and atmospheres. Additionally, successful mapping of microwave emissions from the atmospheres of Venus and the outer planets using earth-based antenna arrays have given unique insights into the composition and variability of such atmospheres. In the past two decades, multiple observations of Venus have been made at X band (3.6 cm) using the Jansky Very Large Array (VLA), and maps have been created of the 3.6 cm emission from Venus. Since the emission morphology is related both to surface features and to the deep atmospheric absorption from CO2 and SO2 (see, e.g., Butler et al., Icarus 154, 2001), emission measurements can be used to give unique information regarding the deep atmosphere, once surface effects are removed. Since surface emissivities measured at the 12.6 cm wavelength by the Magellan mission can be extrapolated to 3.6 cm (see, e.g., Tryka and Muhleman, JGR(Planets) 197, 1992), the residual effects due to deep atmospheric variability can potentially be detected, as they were for higher altitudes at shorter wavelengths (1.3 cm and 2.0 cm, Jenkins et.al., Icarus 158, 2002). As results from this study show, the limited resolution and sensitivity of earth-based measurements make detection of moderate atmospheric variability somewhat difficult. However, the higher sensitivity and resolution provided by an orbiting X-Band radiometer can provide important insights into the variability and structure of the Venus boundary layer. As shown in the figure, the vertical resolution of X-Band radiometry compares well with IR sounding of the deep atmosphere of Venus.

Steffes, P. G.; Devaraj, K.; Butler, B. J.

2013-12-01

255

Venus Aerobot Surface Science Imaging System (VASSIS)  

NASA Technical Reports Server (NTRS)

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.

Greeley, Ronald

1999-01-01

256

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)

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.

Cardesín Moinelo, Alejandro

2010-04-01

257

Lada Terra: A 'new' hotspot on Venus  

NASA Astrophysics Data System (ADS)

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

Smrekar, S. E.; Brown, N.

2012-12-01

258

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

NASA Technical Reports Server (NTRS)

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.

1973-01-01

259

Dynamics of Escaping Planetary Ions from Mars and Venus in a Global Hybrid Simulation  

NASA Astrophysics Data System (ADS)

We study the solar wind induced ion escape at Mars and Venus in a global hybrid simulation. Using the HYB hybrid model for planetary-solar wind interactions we analyze the energization and dynamics of planetary ions with different masses in plasma environments of these planets. Further, we study hemispheric plasma asymmetries in the direction of the solar wind convection electric field and between the magnetic dawn and dusk hemispheres associated with the flow-aligned component of the interplanetary magnetic field (IMF). We consider the physics of the asymmetries in a hybrid model and we also discuss the importance of the asymmetries for in situ plasma observations such as those made by Mars Express and Venus Express as well as the forthcoming MAVEN mission.

Jarvinen, R.; Luhmann, J. G.; Brain, D. A.; Kallio, E. J.

2013-12-01

260

Astrobiology and Venus Exploration  

Microsoft Academic Search

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

D. H. Grinspoon; M. A. Bullock

2005-01-01

261

LIPs on Venus  

Microsoft Academic Search

Venus, a planet similar to Earth in heat budget lacks plate tectonics, yet displays ample evidence of extensive volcanic and tectonomagmatic processes, including regions large enough to be considered LIPs. Thus Venus provides an excellent opportunity to examine large-scale magmatic processes outside a plate tectonic framework. I discuss four groups of Venus’ largest tectonomagmatic provinces: volcanic rises, large coronae (Artemis,

Vicki L. Hansen

2007-01-01

262

The atmosphere of Venus  

Microsoft Academic Search

The investigations of Venus take a special position in planetary researches. It was just the atmosphere of Venus where first measurements in situ were carried out by means of the equipment delivered by a space probe (Venera 4, 1967). Venus appeared to be the first neighbor planet whose surface had been seen by us in the direct nearness made possible

V. I. Moroz

1981-01-01

263

Neutral Mass Spectrometry for Venus Atmosphere and Surface  

NASA Technical Reports Server (NTRS)

The nature of the divergent evolution of the terrestrial planets Venus, Earth, and Mars is a fundamental problem in planetary science that is most relevant to understanding the characteristics of small planets we are likely to discover in extrasolar systems and the number of such systems that may support habitable environments. For this reason, the National Research Council's Decadal Survey gives Venus exploration high priority. That report was the basis of the NASA selection of Venus as one of four prime mission targets for the recently initiated New Frontiers Program. If the Decadal Survey priorities are to be realized, in situ Venus exploration must remain a high priority. Remote sensing orbital and in situ atmospheric measurements from entry probe or balloon platforms might be realized under the low cost Discovery missions while both atmospheric and landed surface measurements are envisioned with the intermediate class missions of the New Frontiers Program.

Mahaffy, Paul

2004-01-01

264

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

NASA Astrophysics Data System (ADS)

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 "Ramón y Cajal” contract from MEC.

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

2009-09-01

265

Solar wind interactions with Venus and Mars: a comparative study  

NASA Astrophysics Data System (ADS)

Due to the lack of a significant global magnetic field, the ionospheres of Venus and Mars stand off the solar wind and form a bow shock close to the planet, an induced magnetosphere, and an ionopause. Depending on the relative strength of the thermal pressure in the ionosphere and the dynamic pressure in the solar wind, the lower ionosphere can be in unmagnetized or magnetized states when the interplanetary fields are shielded above the ionopause or penetrate below. Magnetic flux ropes, which are bundles of twisted field lines, form in the lower ionosphere as small structures with diameters of a few kilometers or large structures with diameters of hundreds of kilometers. The data from Venus Express and Mars Global Surveyor missions are investigated to understand the formation of these structures and their effects in these ionospheres. On the topside of the ionosphere, particles originated from the planet are accelerated by the electro-magnetic force in the solar wind and carried away in a process called ion pickup. The pickup process and particle escape rate are examined using observations of ion cyclotron waves in the magnetic field data of these missions.

Wei, H.; Russell, C. T.; Zhang, T.

2013-05-01

266

Mars Human Exploration Reference Mission  

Microsoft Academic Search

This presentation proposes the next steps for human exploration of Mars. The presentation reviews the reasons for human exploration of Mars. Two different trajectories are proposed: (1) for a long stay mission, and (2) for a short term mission, which could also include a swing by Venus. A reference mission scenario is investigated, which includes forward deployment of two cargo

Bret Drake

1998-01-01

267

Evolution of Science Operations after 10 years of the Mars Express Mission  

NASA Astrophysics Data System (ADS)

The Mars Express mission was launched in June 2003 and has been providing great amounts of data since its arrival to Mars in Christmas 2003, covering a wide range of science objectives at all levels, from the surface and sub-surface geology, atmosphere dynamics and composition, up to the interaction with the magnetosphere and the characterization of the Martian sytem including its two moons, Phobos and Deimos. In these last 10 years, the Mars Express Science Operations Center has been responsible for the coordination of the scientific requirements and the implementation of the science plan, aiming to obtain the maximum scientific return of the mission while respecting the operational constraints. In this contribution we will show some of the operational challenges of the mission, focusing on the improvements and adaptations of the past years, not only in terms of technical and scientific requirements which have been varying with time, but also the optimization of the interfaces with all the teams involved.

Cardesin Moinelo, Alejandro; Martin, Patrick

2013-10-01

268

Giant Flux Ropes Observed in the Magnetized Ionosphere at Venus  

NASA Astrophysics Data System (ADS)

The Venus ionospheric response to solar and solar wind variations is most evident in its magnetic field properties. Early Pioneer Venus observations during the solar maximum revealed that the Venus ionosphere exhibits two magnetic states depending on the solar wind dynamic pressure conditions: magnetized ionosphere with large-scale horizontal magnetic field; or unmagnetized ionosphere with numerous small-scale thin structures, so-called flux ropes. Here we report yet another magnetic state of Venus' ionosphere, giant flux ropes in the magnetized ionosphere, using Venus Express magnetic field measurements during solar minimum. These giant flux ropes all have strong core fields and diameters of hundreds of kilometers, which is about the vertical dimension of the ionosphere. This finding represents the first observation of these giant flux ropes at Venus. The cause of these giant flux ropes remains unknown and speculative.

Zhang, Tielong; baumjohann, Wolfgang; Teh, Wai-Leong; Nakamura, Rumi; Russell, Christopher; Luhmann, Janet; Glassmeier, Karl-Heinz; Dubinin, Edik; Wei, Yong; Du, Aimin; Balikhin, Michael

2013-04-01

269

Giant flux ropes observed in the magnetized ionosphere at Venus  

NASA Astrophysics Data System (ADS)

The Venus ionospheric response to solar and solar wind variations is most evident in its magnetic field properties. Early Pioneer Venus observations during the solar maximum revealed that the Venus ionosphere exhibits two magnetic states depending on the solar wind dynamic pressure conditions: magnetized ionosphere with large-scale horizontal magnetic field; or unmagnetized ionosphere with numerous small-scale thin structures, so-called flux ropes. Here we report yet another magnetic state of Venus' ionosphere, giant flux ropes in the magnetized ionosphere, using Venus Express magnetic field measurements during solar minimum. These giant flux ropes all have strong core fields and diameters of hundreds of kilometers, which is about the vertical dimension of the ionosphere. This finding represents the first observation of these giant flux ropes at Venus. The cause of these giant flux ropes remains unknown and speculative.

Zhang, T. L.; Baumjohann, W.; Teh, W. L.; Nakamura, R.; Russell, C. T.; Luhmann, J. G.; Glassmeier, K. H.; Dubinin, E.; Wei, H. Y.; Du, A. M.; Lu, Q. M.; Wang, S.; Balikhin, M.

2012-12-01

270

Signs of Life on Venus  

NASA Astrophysics Data System (ADS)

The search for "habitable zones" in extrasolar planetary systems is based on the premise of "normal" physical conditions in a habitable zone, i.e. pressure, temperature range, and atmospheric composition similar to those on the Earth. However, one should not exclude completely the possibility of the existence of life at relatively high temperatures, despite the fact that at the first glance it seems impossible. The planet Venus with its dense, hot (735 K), oxigenless CO2 - atmosphere and high 92 bar-pressure at the surface could be the natural laboratory for the studies of this type. Amid exoplanets, celestial bodies with the physical conditions similar to the Venusian can be met. The only existing data of actual close-in observations of Venus' surface are the results of a series of missions of the soviet VENERA landers which took place the 1970's and 80's in the atmosphere and on the surface of Venus. For 36 and 29 years since these missions, respectively, I repeatedly returned to the obtained images of the Venus' surface in order to reveal on them any unusual objects observed in the real conditions of Venus. The new analysis of the Venus' panoramas was based on the search of unusual elements in two ways. Since the efficiency of the VENERA landers maintained for a long time they produced a large number of primary television panoramas during the lander's work. Thus, one can try to detect: (a) any differences in successive images (appearance or disappearance of parts of the image or change of their shape), and understand what these changes are related to (e.g., wind), and whether they are related to hypothetical habitability of a planet. Another sign (b) of the wanted object is their morphological peculiarities which distinguishes them from the ordinary surface details. The results of VENERA-9 (1975) and VENERA -13 (1982) are of the main interest. A few relatively large objects ranging from a decimeter to half meter and with unusual morphology were observed in some images, but were absent in the other or altered their shape. What sources of energy, in principle, could be used by life in the high temperature oxigenless atmosphere? The objects found are large enough, they are not micro-organisms. It is most natural to assume that, like on Earth, Venusian fauna is heterotrophic, and the source of its life is hypothetical autotrophic flora. There is enough light for flora's photosynthesis. Since the critical temperature of water on Venus is about 320°C and the temperature at the surface is about 460°C, the metabolism of organisms on Venus (if any) should be built without water, on the basis of some other liquid medium. Based on data analyzed it has been suggested that because of the limited energy capacity of the Venusian fauna, the temporal characteristics of their physical actions can be much longer than that of the Earth.

Ksanfomality, L.

2012-04-01

271

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

NASA Technical Reports Server (NTRS)

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.

Dorfman, S. D.

1973-01-01

272

Stirling Cooler Designed for Venus Exploration  

NASA Technical Reports Server (NTRS)

Venus having an average surface temperature of 460 degrees Celsius (about 860 degrees Fahrenheit) and an atmosphere 150 times denser than the Earth's atmosphere, designing a robot to merely survive on the surface to do planetary exploration is an extremely difficult task. This temperature is hundreds of degrees higher than the maximum operating temperature of currently existing microcontrollers, electronic devices, and circuit boards. To meet the challenge of Venus exploration, researchers at the NASA Glenn Research Center studied methods to keep a pressurized electronics package cooled, so that the operating temperature within the electronics enclosure would be cool enough for electronics to run, to allow a mission to operate on the surface of Venus for extended periods.

Landis, Geoffrey A.; Mellott, Kenneth D.

2004-01-01

273

Exoplanets and Formation of Planetary Systems: Studies With Esa Science Missions  

Microsoft Academic Search

Several space missions from the ESA Science Horizons 2000 Programme address key questions on the formation\\/evolution of planetary systems and on the study of ex- oplanets: - How do solar systems form ? (with HST, ISO, NGST, FIRST\\/Herschel, Rosetta, Gaia) - Geological evolution of terrestrial planets (with Living planet, Mars- express, SMART-1, Venus-express, Bepi-Colombo) - History and Role of impacts

B. H. Foing

2002-01-01

274

Expendable Cooling for a One-Day Venus Lander  

NASA Astrophysics Data System (ADS)

A thermal architecture of a Venus lander mission using an expendable coolant system has been developed to enable a day-long surface mission. The system uses an aqua-ammonia mixture to provide cooling of the electronics and the pressure vessel.

Pauken, M. T.; Fernandez, C. J.; Jeter, S. M.

2014-06-01

275

Nature of the magnetic flux ropes in the Venus ionosphere  

SciTech Connect

The onset of gutter instability at the moving, accelerating ionopause on Venus may allow magnetic flux tubes of solar wind to penetrate the interior of the ionosphere. As the ionospheric ions cross the lateral tube walls, an axial current of solar-wind electrons will enter, twisting the field lines into a rope. Such a mechanism would explain data recorded on the Pioneer Venus mission.

Dubinin, E.M.; Izrailevich, P.L.; Podgornyi, I.M.; Shkol'nikova, S.I.

1980-03-01

276

The Planet Venus  

NSDL National Science Digital Library

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

2007-05-12

277

Phases of Venus Model  

NSDL National Science Digital Library

The EJS Venus Phases model illustrates the phases of Venus as predicted by either the Copernican system of the Ptolemaic system (the Copernican system is the default). One window shows Earth, Sun, and Venus on its Copernican orbit. Venus is shown as a disk with the side facing the sun colored yellow (since it reflects the sun's light) and the other side colored dark gray (since that side is dark). Playing the simulation puts all moving objects (Venus and Earth/Sun) in motion. Another window shows what Venus would look at this position, when viewed from Earth through a telescope. A menu option displays another window showing Galileo's drawings of his telescope observations of Venus. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting "Open Ejs Model" from the pop-up menu item. EJS Phases of Venus model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_astronomy_VenusPhases.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models for astronomy are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Timberlake, Todd

2009-08-18

278

Colonization of Venus  

NASA Technical Reports Server (NTRS)

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.

Landis, Geoffrey A.

2003-01-01

279

Explosive propulsion applications. [to future unmanned missions  

NASA Technical Reports Server (NTRS)

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.

Nakamura, Y.; Varsi, G.; Back, L. H.

1974-01-01

280

Venus round trip using solar sail  

NASA Astrophysics Data System (ADS)

Trajectory optimization and simulation is performed for Venus round trip (VeRT) mission using solar sail propulsion. Solar gravity is included but atmospheric drag and shadowing effects are neglected in the planet-centered escape and capture stages. The spacecraft starts from the Geostationary orbit (GEO) at a predetermined time to prepare a good initial condition for the Earth-Venus transfer, although the launch window is not an issue for spacecraft with solar sails. The Earth-Venus phase and the return trip are divided into three segments. Two methods are adopted to maintain the mission trajectory for the VeRT mission and then compared through a numerical simulation. According to the first approach, Planet-centered and heliocentric maneuvers are modeled using a set of blended analytical control laws instead of the optimal control techniques. The second procedure is the Direct Attitude Angle Optimization in which the attitude angles of the solar sail are adopted as the optimization variables during the heliocentric transfer. Although neither of the two methods guarantees a globally optimal trajectory, they are more efficient and will produce a near-optimal solution if employed properly. The second method has produced a better result for the minimum-time transfer of the VeRT mission demonstrating the effectiveness of the methods in the preliminary design of the complex optimal interplanetary orbit transfers.

Zhu, KaiJian; Zhang, RongZhi; Xu, Dong; Wang, JiaSong; Li, ShaoMin

2012-08-01

281

Bursty escape fluxes in plasma sheets of Mars and Venus  

NASA Astrophysics Data System (ADS)

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

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

2012-01-01

282

The Planetary Fourier Spectrometer (PFS) onboard the European Mars Express mission  

Microsoft Academic Search

The Planetary Fourier Spectrometer (PFS) for the Mars Express mission is an infrared spectrometer optimised for atmospheric studies. This instrument has a short wave (SW) channel that covers the spectral range from 1700 to 8200.0cm-1 (1.2–5.5?m) and a long-wave (LW) channel that covers 250–1700cm-1 (5.5–45?m). Both channels have a uniform spectral resolution of 1.3cm-1. The instrument field of view FOV

V. Formisanoa; F. Angrilli; G. Arnold; S. Atreya; G. Bianchini; D. Biondi; A. Blanco; M. I. Blecka; A. Coradini; L. Colangeli; A. Ekonomov; F. Esposito; S. Fonti; M. Giuranna; D. Grassi; V. Gnedykh; A. Grigoriev; G. Hansen; H. Hirsh; I. Khatuntsev; A. Kiselev; N. Ignatiev; A. Jurewicz; E. Lellouch; J. Lopez Moreno; A. Marten; A. Mattana; A. Maturilli; E. Mencarelli; M. Michalska; V. Moroz; B. Moshkin; F. Nespoli; Y. Nikolsky; R. Orfei; P. Orleanski; V. Orofino; E. Palomba; D. Patsaev; G. Piccioni; M. Rataj; R. Rodrigo; J. Rodriguez; M. Rossi; B. Saggin; D. Titov; L. Zasova

2005-01-01

283

Volcanoes on Venus  

NSDL National Science Digital Library

Visitors can read about the characteristics of volcanism on Venus and how it differs from volcanism on Earth. A map showing the locations and types of volcanic structures on the surface of Venus is provided, along with links to other related topics.

284

The Nine Planets: Venus  

NSDL National Science Digital Library

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

Arnett, Bill

285

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

286

Hybrid modelling studies of solar wind interactions at Venus and Mars  

NASA Astrophysics Data System (ADS)

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.

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

2013-09-01

287

Study On The Upper Atmosphere Of Venus At The Terminator  

NASA Astrophysics Data System (ADS)

Observations have been made using the SOIR instrument aboard the Venus Express (VEx) mission characterizing the temperature and carbon dioxide profiles at the terminators. Using the Venus Thermospheric General Circulation Model (VTGCM), these profiles can also be modeled at the terminators for many latitudes. For this research, the SOIR and VTGCM profiles are averaged in the following northern latitude bins; 0-30, 30-60, 70-80, 80-90. Using the data from SOIR and outputs from the VTGCM, one can determine how well the current model reproduces the observations at the terminator. In the current VTGCM model, the temperature maximum and minimums characteristic of the data profiles are the same if not very similar with the exception of the magnitude of these characteristic features. The SOIR data tends to reveal more extreme maximum and minimum temperatures as compared to the simulated VTGCM values. Some assumptions made in the data processing technique used to determine the SOIR profile retrievals may not be valid. This causes temperatures around 125 km and above 140 km to not be as accurately represented. VTGCM thermal balance plots help address this problem. In addition, these balances provide insight as to why the model may not be in complete agreement with these SOIR profiles while also determining any missing physical processes that are not included in the current VTGCM framework. Data-model comparisons will also be considered for variable VTGCM parameters, including solar minimum and moderate fluxes as well as extremes of the wave drag parameter yielding minimum and maximum terminator winds. Using the VTGCM model in correspondence with data collected from the SOIR instrument, this study will characterize the overall climate at the Venus terminators and give insight into the physical mechanisms responsible.

Fischer, Johanna-Laina; Bougher, S. W.; Hicks, G. A.; Brecht, A. S.; Parkinson, C.; Mahieux, A.; Wilquet, V.; Vandaele, A.; Bertaux, J.

2012-10-01

288

Finite Gyroradius Effects Observed in Pickup Oxygen Ions at Venus  

NASA Technical Reports Server (NTRS)

On the dayside of Venus, the hot oxygen corona extending above the ionopause is the principal source of pickup oxygen ions. The ions are born here and picked up by the ionosheath plasma as it is deflected around the planet. These pickup ions have been observed by the Orbiter Plasma Analyzer (OPA) throughout the Pioneer Venus Orbiter (PVO) mission. They were observed over a region extending from their dayside source to great distances downstream (about 10 Venus radii), in the solar wind wake, as PVO passed through apoapsis. Finite gyroradius effects in the velocity distribution of the oxygen pickup ions are expected in the source region because the gyroradius is several times larger than the scale height of the hot oxygen source. Such effects are also expected in those regions of the ionosheath where the scale lengths of the magnetic field and the ambient plasma velocity field are less than the pickup ion gyroradius. While explicitly accounting for the spatial distribution of the hot oxygen source, an analytic expression for the pickup oxygen ion velocity distribution is developed to study how it is affected by finite gyroradii. The analysis demonstrates that as the gyroradius increases by factors of three to six above the hot oxygen scale height, the peak of the pickup oxygen ion flux distribution decreases 25 to 50% below the maximum allowed speed, which is twice the speed of the ambient plasma times the sine of the angle between the magnetic field and the flow velocity. The pickup oxygen ion flux distribution observed by OPA is shown to follow this behavior in the source region. It is also shown that this result is consistent with the pickup ion distributions observed in the wake, downstream of the source, where the flux peaks are usually well below the maximum allowed speed.

Hartle, Richard E.; Intriligator, Devrie; Grebowsky, Joseph M.; Einaudi, Franco (Technical Monitor)

2000-01-01

289

Atmosphere/mantle coupling and feedbacks on Venus  

NASA Astrophysics Data System (ADS)

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.

Gillmann, Cedric; Tackley, Paul

2014-06-01

290

Exploring the Planets: Venus  

NSDL National Science Digital Library

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

291

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

292

South-polar features on Venus similar to those near the north pole  

Microsoft Academic Search

Venus has no seasons, slow rotation and a very massive atmosphere, which is mainly carbon dioxide with clouds primarily of sulphuric acid droplets. Infrared observations by previous missions to Venus revealed a bright `dipole' feature surrounded by a cold `collar' at its north pole. The polar dipole is a `double-eye' feature at the centre of a vast vortex that rotates

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

2007-01-01

293

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

SciTech Connect

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.

Pasachoff, Jay M. [Williams College-Hopkins Observatory, 33 Lab Campus Drive, Williamstown, MA 01267 (United States); Schneider, Glenn [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Widemann, Thomas [Observatoire de Paris-LESIA, 92190 Meudon (France)

2011-04-15

294

Evolution of Venus: Current knowledge and future prospects  

NASA Astrophysics Data System (ADS)

Venus is commonly thought to have experienced a transition, early in its history, from a wet, more Earth-like environment to its currently highly desiccated state. A more recent global transition is indicated by the sparse, randomly distributed and relatively pristine crater population, which implies a rapid decrease in volcanic resurfacing rate between 300 and 1000 Myr ago. The accompanying precipitous decline in outgassing rate would have caused large climate changes and globally synchronous plains deformation. These two transitions may have been causally related, as the loss of atmospheric water through evaporation, photodissociation and H escape caused the transition from plate tectonics to single plate behavior, and the cessation of subducting hydrated sediments caused the desiccation of the mantle and consequent loss of an asthenosphere. New data from Venus Express can help test these ideas by refining the timescale for water loss, constraining current outgassing rates, and improving models of climate, cloud formation and atmospheric dynamics, thus improving the sophistication of evolutionary climate models. I will discuss these efforts and review relevant plans for future missions.

Grinspoon, David

295

System design of the Pioneer Venus spacecraft. Volume 2: Science  

NASA Technical Reports Server (NTRS)

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.

Acheson, L. K.

1973-01-01

296

Loss of hydrogen and oxygen from the upper atmosphere of Venus  

NASA Astrophysics Data System (ADS)

Atmospheric escape from the upper atmosphere of Venus is mainly influenced by the loss of hydrogen and oxygen caused by the interaction of solar radiation and particle flux with the unprotected planetary environment. Because one main aim of the ASPERA-4 particle/plasma and VEX-MAG magnetic field experiments on board of ESA's forthcoming Venus Express mission is the investigation of atmospheric erosion processes from the planet's ionosphere-exosphere environment, we study the total loss of hydrogen and oxygen and identified the efficiency of several escape mechanisms involved. For the estimation of pick up loss rates we use a gas dynamic test particle model and obtained average loss rates for H+, and O+ pick up ions of about 1×1025s-1 and about 1.6×1025s-1, respectively. Further, we estimate ion loss rates due to detached plasma clouds, which were observed by the pioneer Venus orbiter and may be triggered by the Kelvin-Helmholtz instability of about 0.5-1×1025s-1. Thermal atmospheric escape processes and atmospheric loss by photo-chemically produced oxygen atoms yield negligible loss rates. Sputtering by incident pick up O+ ions give O atom loss rates in the order of about 6×1024s-1. On the other hand, photo-chemically produced hot hydrogen atoms are a very efficient loss mechanism for hydrogen on Venus with a global average total loss rate of about 3.8×1025s-1, which is in agreement with Donahue and Hartle [1992. Solar cycle variations in H+ and D+ densities in the Venus ionosphere: implications for escape. Geophys. Res. Lett. 12, 2449-2452] and of the same order but less than the estimated H+ ion outflow on the Venus nightside of about 7.0×1025s-1 due to acceleration by an outward electric polarization force related to ionospheric holes by Hartle and Grebowsky [1993. Light ion flow in the nightside ionosphere of Venus. J. Geophys. Res. 98, 7437-7445]. Our study indicates that on Venus, due to its larger mass and size compared to Mars, the most relevant atmospheric escape processes of oxygen involve ions and are caused by the interaction with the solar wind. The obtained results indicate that the ratio between H/O escape to space from the Venusian upper atmosphere is about 4, and is in a much better agreement with the stoichiometrically H/O escape ratio of 2:1, which is not the case on Mars. However, a detailed analysis of the outflow of ions from the Venus upper atmosphere by the ASPERA-4 and VEX-MAG instruments aboard Venus Express will lead to more accurate atmospheric loss estimations and a better understanding of the planet's water inventory.

Lammer, H.; Lichtenegger, H. I. M.; Biernat, H. K.; Erkaev, N. V.; Arshukova, I. L.; Kolb, C.; Gunell, H.; Lukyanov, A.; Holmstrom, M.; Barabash, S.; Zhang, T. L.; Baumjohann, W.

2006-11-01

297

Inner solar system sample return missions using solar electric propulsion  

Microsoft Academic Search

This study evaluated the effects of solar electric propulsion (SEP) and PowerSail solar array technology on four sample return missions. These missions, to the Moon, Mars, Mercury, and Venus, were compared against previous Jet Propulsion Laboratory (JPL) studies. Compared to these baselines, PowerSail\\/SEP missions in general had longer trip times, though the Venus mission was of similar duration. Costs for

Ryan D. McDaniel; Swati Mohan; Jaime Juarez

2003-01-01

298

Sensor Amplifier for the Venus Ground Ambient  

NASA Technical Reports Server (NTRS)

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.

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

2006-01-01

299

Salt tectonics on Venus  

SciTech Connect

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.

Wood, C.A.; Amsbury, D.

1986-05-01

300

Pioneer Venus Data Analysis  

NASA Technical Reports Server (NTRS)

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.

Jones, Douglas E.

1996-01-01

301

Pioneer Venus Data Analysis  

NASA Astrophysics Data System (ADS)

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.

Jones, Douglas E.

1996-03-01

302

Venus Gravity Handbook  

NASA Technical Reports Server (NTRS)

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.

Konopliv, Alexander S.; Sjogren, William L.

1996-01-01

303

Magellan Mission Planning and Orbital Operations.  

National Technical Information Service (NTIS)

NASA's Magellan mission to understand the geological and geophysical processes that have shaped the planet Venus is reviewed. Through synthetic aperture radar, radiometric, altimetric, and gravity measurements, the scientific community hopes to improve it...

J. S. Carter A. M. Tavormina

1991-01-01

304

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

USGS Publications Warehouse

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).

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

2008-01-01

305

The thermal balance of the lower atmosphere of Venus  

NASA Technical Reports Server (NTRS)

The temperature near the surface of Venus (now established at 730 K) is remarkably high in view of Venus's cloud cover which causes the planet to absorb even less sunlight than does Earth. Early attempts to understand the thermal balance that leads to this unusual state were hindered by the lack of basic information regarding the composition, temperature-pressure structure, cloud properties, and wind field of the lower atmosphere. A series of successful space missions have measured many of the above quantities that control the transfer of heat in Venus's lower atmosphere. The relevant observational data are summarized and the attempts to understand the thermal balance of Venus's atmosphere below the cloud tops are reviewed. The data indicate that sufficient sunlight penetrates to deep atmospheric levels and is trapped by the large thermal opacity of the atmosphere to essentially account for the high temperatures observed.

Tomasko, M. G.

1981-01-01

306

The puzzling hydrogen corona at Venus  

NASA Astrophysics Data System (ADS)

Although the existence of a hydrogen exosphere around Venus has been established already by the Mariner 5 flyby in 1967, the density and extension of the venusian hydrogen corona is still an open question. It is expected that the hydrogen population consists of a cold part in the lower exosphere and a hot part at higher altitudes. Although the hydrogen exosphere becomes most directly noticeable by means of Lyman-? observations, pick-up planetary hydrogen ions can also be detected through proton cyclotron waves. We present results of magnetic field observations aboard Venus Express, indicating permanent ionization and pick-up of hydrogen by the solar wind upstream of the planetary bow shock up to several planetary radii. In addition, the results of Monte Carlo simulations of the hot hydrogen corona at Venus are shown, suggesting lower neutral densities than those derived from magnetic field observations. The reason for this discrepancy is yet an open issue.

Lichtenegger, H.; Delva, M.; Gröller, H.; Bertucci, C.

2013-09-01

307

Transits of Venus and Mercury as muses  

NASA Astrophysics Data System (ADS)

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

Tobin, William

2013-11-01

308

Solar Airplane Concept Developed for Venus Exploration  

NASA Technical Reports Server (NTRS)

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.

Landis, Geoffrey A.

2004-01-01

309

Venus Deep Nightside Magnetic Fields Revisited  

NASA Astrophysics Data System (ADS)

We reexamined the near-Venus deep nightside magnetic fields observed by the Pioneer Venus Orbiter(PVO) over two decades ago. This analysis was in part inspired by recent discussions of the possibilities of identifying a weak planetary dynamo or remanent magnetic field, and in part by the availability of numerical simulations of weak field plasma interactions using the BATS-R-US MHD code. The data were first scrutinized for statistically significant regions of radial field in the near-midnight low altitude wake from the prime mission periapsis of ~150km up to about 450 km. Radial field 'maps' were constructed for a range of altitudes in both solar wind interaction and planetary geographical coordinate systems. The results suggested the presence of weak radial fields above ~250km that show a persistent North-South sign bias. This behavior is not seen at the lowest altitudes probed, and is present regardless of the interplanetary magnetic field sector. The MHD simulations provided basic pictures of what might be expected for a hypothetical planet with a weak but still detectable dipole field that is comparable to the solar wind interaction-related draped interplanetary field. These show similar tendencies, illustrating that models are essential to the interpretation of potential weak intrinsic field signatures at planets such as Venus. Further modeling specific to Venus is needed to make further progress.

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

2011-12-01

310

10. The surface and interior of venus  

USGS Publications Warehouse

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.

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

311

Large Volcanic Edifices and Rises on Venus: The Benefits of Improved Topography and Gravity Data  

NASA Astrophysics Data System (ADS)

Venus is a volcanological laboratory, replete with edifices and rises that offer potentially deep insights into its evolution. However, this potential can only be realized with improved topography and gravity data, requiring a new orbital mission.

McGovern, P. J.

2014-05-01

312

Long-Lived, Maneuverable, Semi-Buoyant Platform for Venus Upper Atmosphere Exploration  

NASA Astrophysics Data System (ADS)

This presentation discusses the continued development of the Northrop Grumman/L’GARDE team’s long-lived, maneuverable platform to explore the Venus upper atmosphere. It focuses on the overall mission architecture and concept of operations.

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

2014-06-01

313

Pioneer Venus data analysis for the retarding potential analyzer  

NASA Technical Reports Server (NTRS)

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.

Knudsen, William C.

1993-01-01

314

SOHO Sees Venus' Approach  

NASA Video Gallery

This video taken by the Solar and Heliospheric Observatory (SOHO) shows the Sun's corona and Venus' approach for the transit. This was taken with the Extreme ultraviolet Imaging Telescope (EIT) in ...

315

Venus Transit 2004  

NSDL National Science Digital Library

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

316

Venus fly trap  

NSDL National Science Digital Library

Time-lapse photos or video show progressions from the start of an event to the end of the event. These time-lapse photos illustrate the growth of a single Venus fly trap. Biological processes require time.

Paul Lenz (None;)

2006-01-26

317

The Planet Venus.  

National Technical Information Service (NTIS)

The available information on Venus, and the methods by which this information was derived are presented. Topics discussed include: general information, investigation by classical astronomy, radio astronomy and radar methods, infrared spectroscopy, and aut...

V. A. Bronshten

1972-01-01

318

Mercury, Venus, and Earth!  

NSDL National Science Digital Library

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

Bschiffer

2009-10-21

319

Plate tectonics on Venus  

NASA Technical Reports Server (NTRS)

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.

Anderson, D. L.

1981-01-01

320

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

321

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

PubMed Central

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

2010-01-01

322

11. Pioneer venus experiment descriptions  

Microsoft Academic Search

This concluding paper of a special issue of Space Science Reviews, devoted to the exploration of Venus and the Pioneer Venus Program, contains brief engineering descriptions of the experiments to be integrated into the Orbiter and Multiprobe scientific payloads.

L. Colin; D. M. Hunten

1977-01-01

323

Venus - False Color of Eistla Regio  

NASA Technical Reports Server (NTRS)

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

1992-01-01

324

Venus - False Color of Bereghinya Planitia  

NASA Technical Reports Server (NTRS)

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

1992-01-01

325

The solar wind interaction with Venus  

NASA Technical Reports Server (NTRS)

The Pioneer Venus Orbiter (PVO) mission has played a key role in establishing the nature of the solar wind interaction with Venus. Although earlier probes had determined that Venus presented an obstacle much smaller than the size of earth's magnetosphere to the solar wind, they did not carry out in situ measurements pertaining to solar wind interaction studies at low enough altitudes to determine why. They also did not provide datasets of sufficient duration to study the variability of the interaction of both short (one day) and long (solar cycle) timescales. The first 600 of the nearly 5000 orbits of PVO magnetometer data have been used to determine a very low upper limit on the intrinsic dipolar magnetic moment of Venus. The consequence of that low magnetic moment is that the solar wind interacts directly with the upper atmosphere and ionosphere. Relative to a dipolar field obstacle, the ionospheric obstacle is rather incompressible. A bow shock is observed to stand in front of the nearly Venus-sized ionospheric obstacle at a comparatively steady subsolar altitude of approximately 1.5 R(v) (Venus radii). This shock decelerates the supersonic solar wind plasma so that it can flow around the obstacle. It was found to change its average position in the terminator plane from about 2.4 R(v) to 2.1 R(v) as the solar cycle progressed from the 1978 orbit insertion near solar maximum through the 1986-87 solar minimum, and back again during the latest solar activity increase. Between the bow shock and the ionosphere proper, the slowed solar wind plasma flow diverges near the subsolar point and makes its way across the terminator where it reaccelerates and continues anti-Sunward. The solar wind magnetic field, which is in effect frozen into the flowing plasma, is distorted in this 'magnetosheath' region so that it appears to hang up or drape over the dayside ionosphere before it slips around with the flow. These features of the solar wind interaction are also seen when the obstacle is a dipole magnetic field, but there are two important distinctions. In the wake of the Venus obstacle one finds an induced magnetic tail composed of varying interplanetary fields rather than the constant fields of intrinsic origin. This magnetotail is further seen to be populated by Heavy (0+) ions that are evidently escaping from the planet at significant (approximately 10(exp -25) s(exp -1)) rates. These heavy ions are also observed in the dayside magnetosheath. The interpretation is that ions are produced by both photoionization and solar wind electron impact ionization of the upper neutral atmosphere that extends into the magnetosheath.

Luthmann, J. G.

1992-01-01

326

Quantifying shapes of volcanoes on Venus  

NASA Technical Reports Server (NTRS)

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

Garvin, J. B.

1994-01-01

327

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

USGS Publications Warehouse

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.

Campbell, Bruce A.; Clark, David A.

2006-01-01

328

The structure of Venus' middle atmosphere and ionosphere  

Microsoft Academic Search

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 (50-90km) and the remarkably variable structure of the ionosphere. Observations become increasingly

M. Pätzold; B. Häusler; M. K. Bird; S. Tellmann; R. Mattei; S. W. Asmar; V. Dehant; W. Eidel; T. Imamura; R. A. Simpson; G. L. Tyler

2007-01-01

329

Solar wind-driven plasma fluxes from the Venus ionosphere  

NASA Astrophysics Data System (ADS)

conducted with the ASPERA-4 instrument and the magnetometer of the Venus Express spacecraft show that the kinetic pressure of planetary O+ ion fluxes measured in the Venus wake can be significantly larger than the local magnetic pressure, and as a result, those ions are not solely being driven by magnetic forces but also by the kinetic energy of the solar wind. Beams of planetary O+ ions with those properties have been detected in several orbits of the Venus Express through the Venus wake as the spacecraft traverses by the noon-midnight plane along its near-polar trajectory. The momentum flux of the O+ ions leads to superalfvenic flow conditions. It is suggested that such O+ ion beams are produced in the vicinity of the magnetic polar regions of the Venus ionosphere where the solar wind erodes the local plasma leading to plasma channels that extend downstream from those regions. The distribution of the number of cases where superalfvenic and subalfvenic conditions are measured along the Venus Express trajectory leads to dominant values when the total kinetic plasma pressure (including that of the solar wind protons) and the magnetic pressure are comparable, thus suggesting a possible equipartition of energy between the plasma and the magnetic field.

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

2013-12-01

330

Lunar and Planetary Science XXXV: Venus  

NASA Technical Reports Server (NTRS)

The session "Venus" included the following reports:Is It Possible to Detect Magnetic Materials on Venus with Bistatic Radar Probing?; Airfall Crater Deposits on the Surface of Venus: Do We See Them in the Venera Panoramas?; Rift System Architecture on Venus; Constraints on Deformation Belt Evolution on Venus; An Admittance Survey of Large Volcanoes on Venus: Implications for Volcano Growth; Crustal Thickening Above a Convecting Mantle with Application to Venus and Mars; Geological Mapping of Venus: Interpretation of Geologic History and Assessment of; Directional and Non-Directional Models; Ages of Venusian Ridge Belts Relative to Regional Plains; and Plumes as a Mechanism for Equilibrium Resurfacing of Venus.

2004-01-01

331

Project Venus 2004  

NSDL National Science Digital Library

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

2008-02-08

332

Scattering by Venus' surface  

NASA Technical Reports Server (NTRS)

During 1992, Magellan altimetry echoes were processed to yield scattering functions sigma(sub o)(phi) over near-nadir angles phi less than or equal to 10 deg from some 2000 Venus orbits. SAR image strips acquired simultaneously at oblique angles were also reduced to give scattering functions but over a few deg of incidence angle in the range 15 less than or equal to phi less than or equal to 45 deg. By sorting, the altimetry and SAR results can be combined to give composite scattering functions for much of Venus' surface. The data in hand should allow definition of such composite functions for 70-80 percent of Venus at resolutions of 20 km--approximately one million separate functions.

Simpson, R. A.; Tyler, G. L.; Maurer, M. J.; Holmann, E.; Wong, P. B.

1993-01-01

333

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

NASA Astrophysics Data System (ADS)

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

Hart, Richard; Russell, Christopher; Zhang, Tielong

2014-05-01

334

Ice caps on venus?  

PubMed

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

Libby, W F

1968-03-01

335

Fundamental issues in the geology and geophysics of Venus  

NASA Astrophysics Data System (ADS)

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

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

1991-04-01

336

Comparisons between the ionospheres of Venus and Mars  

NASA Astrophysics Data System (ADS)

The ionospheres of Venus and Mars are remarkably similar in many ways. The V2 layer at Venus and M2 layer at Mars are produced when extreme ultraviolet solar photons ionize atmospheric CO2. Peak ionospheric densities occur in these layers. The V1 layer at Venus and M1 layer at Mars are produced by deeper penetrating solar soft X-rays and subsequent electron collision ionization. Here we compare the properties of these analogous layers using radio occultation data from the Venus Express spacecraft and the Mars Global Surveyor spacecraft. We compare how the peak altitudes and peak densities of each layer depend on solar zenith angle. We also compare how the peak densities of each layer vary with solar flux. We report the results of our analysis and discuss the implications of our findings with regard to terrestrial planet ionospheres.

Girazian, Z. R.; Tarrh, A.; Fallows, K.; Withers, P.; Haeusler, B.; Paetzold, M.; Tellmann, S.

2012-12-01

337

Sampling the Cloudtop Region on Venus  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

338

Venus - Simulated Color of Leda Planitia  

NASA Technical Reports Server (NTRS)

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

1992-01-01

339

Phases of Venus  

NSDL National Science Digital Library

This simple animation illustrates how we observe the phases of Venus. As the planet revolves around the Sun, there are times of the year when it is observed completely lit up by the star and times when we only get it's dark side. The user can change the inclination of the observing plane, allowing a better understanding of the process.

Fowler, Michael; Timmins, Michael

2007-12-28

340

Mercury and Venus  

NSDL National Science Digital Library

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

Integrated Teaching And Learning Program

341

The Tectonics of Venus  

Microsoft Academic Search

Solid Venus has several differences from solid Earth: a mild variation in topography, with marked departures of some kilometres confined to less than 10% of the surface; no interconnected system of ridges, such as would be associated with a spreading lithospheric boundary layer; a high correlation of gravity with topography; and a ratio of gravity to topography implying compensation depths

William M. Kaula

1994-01-01

342

Venus - Lessons for earth  

NASA Technical Reports Server (NTRS)

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.

Hunten, D. M.

1992-01-01

343

The terraforming of Venus  

Microsoft Academic Search

Methods are considered for the 'terraforming' modification of Venusian environmental conditions. It is noted that Venus cannot be terraformed by microbiological means alone, and that the massive importation of such materials as H2 from various regions of the solar system will have to be instituted; recent impact erosion research on atmospheres appears to preclude this as an option. More fundamentally,

M. J. Fogg

1987-01-01

344

Pioneer Venus probe design  

NASA Technical Reports Server (NTRS)

The summary provides descriptions for a set of probes designed to explore an inner rather than an outer planet, and designed to survive to 100 bars rather than 10 bars. The probes carry a variety of scientific instruments and their supporting integrated subsystems are adjusted to Venus environmental conditions.

Nolte, L. J.

1974-01-01

345

Tectonic activity on Venus  

NASA Astrophysics Data System (ADS)

Models for the dominant mode of lithospheric heat transport on Venus are considered. The results of quantitative tests of the plate-divergence model for Aphrodite Terra are reviewed, and problems of this model are discussed. Other models addressed include those which emphasize the mantle flow field, a thick crust, and 'heat pipes'.

Solomon, S. C.; Grimm, R. E.

1988-01-01

346

The geology of Venus  

NASA Astrophysics Data System (ADS)

This paper summarizes the emerging picture of the surface of Venus provided by high-resolution earth-based radar telescopes and orbital radar altimetry and imaging systems. The nature and significance of the geological processes operating there are considered. The types of information needed to complete the picture are addressed.

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

347

Second Venus spacecraft set for launch  

NASA Technical Reports Server (NTRS)

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.

1978-01-01

348

Transit of Venus  

NSDL National Science Digital Library

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

349

The Venus nitric oxide night airglow: Model calculations based on the Venus thermospheric general circulation model  

SciTech Connect

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.

Bougher, S.W. (Univ. of Arizona, Tucson (United States)); Gerard, J.C. (Univ. de Liege, Ougree-Liege (Belgium)); Stewart, A.I.F.; Fesen, C.G. (Univ. of Colorado, Boulder (United States))

1990-05-01

350

Planetary Ion fluxes in the Venus Wake  

NASA Astrophysics Data System (ADS)

Measurements conducted with the ASPERA-4 instrument and the magnetometer of the Venus Express spacecraft show that the kinetic pressure of planetary O+ ions measured in the Venus wake can be significantly larger than the local magnetic pressure and, as a result, those ions are not being driven by magnetic forces but by the kinetic energy of the solar wind. Beams of planetary O+ ions with those properties have been detected in several orbits of the Venus Express through the wake as the spacecraft traverses by the noon-midnight plane along its near polar trajectory. Peak values of the kinetic pressure of the O+ ions are sufficient to produce superalfvenic flow conditions. It is suggested that such O+ ion beams are eroded from the magnetic polar regions of the Venus ionosphere where the solar wind carves out plasma channels that extend downstream from those regions. Issues related to the acceleration of planetary ions as the solar wind interacts with the Venus ionosphere are related to the energetics of the plasma. When the kinetic pressure of the particle populations involved in the interaction is smaller than the local magnetic pressure the latter will be dominant and hence the particles will follow trajectories dictated by the magnetic field. Such conditions should occur by the magnetic barrier that is formed over the dayside Venus ionosphere where the interplanetary magnetic fluxes pile up thus leading to enhanced values of the magnetic field intensity. Different conditions are expected when the kinetic pressure of the plasma is larger than the local magnetic pressure. In this case the latter will be convected by the particle fluxes as it occurs in the superalfvenic solar wind. Plasma conditions applicable to the planetary ions that stream in the Venus wake and that have been removed from the Venus ionosphere can be examined using the plasma and magnetic field data obtained from the Venus Express (VEX) measurements. A suitable example is provided by the plasma and the magnetic pressure profiles that were obtained from the data in orbit 123 on August 22-2006 and that are reproduced in Figure 1. The profiles in the lower panel show that the peak kinetic pressure of the O+ ions becomes substantially larger than the local magnetic pressure (between 01:48 UT and 02:00 UT) and also that within a wide region of the wake (between ~02:00 UT and ~02:25 UT) the kinetic pressure becomes smaller than the magnetic pressure. Values of the ratio of the kinetic to the magnetic pressure that are obtained from both profiles are given in the upper panel to show that in the region where the peak kinetic pressure of the O+ ions are measured that ratio is substantially larger than one thus indicating that the local ions move under superalfvenic conditions. The opposite is true in other regions of the wake where values of that ratio are smaller than one and thus the plasma is subalfvenic.

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

2012-09-01

351

The Oldest Rocks on Venus: the Importance of Tessera Terrain for Venus Exploration (Invited)  

NASA Astrophysics Data System (ADS)

Venus tessera terrain is a major, yet unsampled, tectonic unit on Venus characterized by multiple sets of intersecting compressional and extensional structures. Tessera terrain is temporally, morphologically, and perhaps also compositionally unique on Venus. Stratigraphic studies of tessera terrain establish that they consistently appear locally, and perhaps even globally, as the oldest material on a planet with an average surface crater retention age of ~500 million years. Thus, the tesserae provide the best chance to access rocks that are derived from the first 80% of the history of the planet, an era obscured by the emplacement of voluminous (presumably basaltic) plains. Analysis of Magellan imagery, topography and gravity data show that tessera terrain is characterized by higher strain rates and a thinner lithosphere than at present and thus records an extinct geodynamical era on Venus. Yet very little is understood about the number, morphology and stratigraphy of geologic units within tessera terrain, nor mass wasting processes operating on the surface. Improved radar imagery at the 5-25 m scale, and optical images below the clouds (<1 km) and at the surface will help assess the geologic processes operating in the pre-plains era. Such data products are also essential for judicious landing site selection, since tessera meter-scale roughness will limit landing site safety and sample access. Improved topography data are required to quantify the deformation recorded by ubiquitous tesserae structures that are finer than Magellan resolution. Tessera terrain is unsampled, but recent analyses of radiance from the surface at 1 micron using instruments on Venus Express and Galileo are consistent with felsic compositions for tesserae. Silicic compositions likely require both water and a plate recycling mechanism (e.g., subduction) for formation. The high D/H ratio of the Venus atmosphere is consistent with the loss of a significant inventory of water over the history of the planet. Felsic tesserae may herald from an ancient water-rich Venus, perhaps with an ocean and potentially habitable. Further assessment of tessera composition requires more comprehensive 1 micron radiance measurements from orbital, near-surface and surface platforms and in-situ measurement of mineralogy and chemistry. Radiance data need tobe supported by improved laboratory measurements of the emissivity of relevant rocks and weathering products in a Venus environment. Venus weathering experiments also support the interpretation of in situ analyses at the surface of Venus and may constrain sampling strategy. If confirmed, felsic tesserae would be critical targets for sample return due to their potential to include ancient rocks and/or minerals formed in the presence of water (e.g., zircons). In sum, the tesserae are the oldest materials exposed on the Venus surface and are the best candidates for containing ancient rocks and for comprising evolved compositions. They uniquely and critically constrain the geochemistry, geodynamics and history of water on Venus through time.

Gilmore, M. S.; Glaze, L. S.

2013-12-01

352

Distant bow shock and magnetotail of Venus: magnetic field and plasma wave observations  

SciTech Connect

An examination of the magnetic field and plasma wave data obtained by the Pioneer Venus orbiter in the wake region behind Venus discloses a well developed bow shock whose location is similar to that observed on previous missions in contrast to the dayside bow shock. Venus also has a well developed magnetotail in which the field strength is enhanced over magetosheath values and in which the magnetic field is aligned approximately with the solar wind direction. The boundary between magnetosheath and magnetotail is also marked by a change in the plasma wave spectrum.

Russell, C.T.; Luhmann, J.G.; Elphic, R.C.; Scarf, F.L.

1981-07-01

353

Venus - Multiple Views of High-level Clouds  

NASA Technical Reports Server (NTRS)

This series of pictures shows four views of the planet Venus obtained by Galileo's Solid State Imaging System at ranges of 1.4 to 2 million miles as the spacecraft receded from Venus. The pictures in the top row were taken about 4 and 5 days after closest approach; those in the bottom row were taken about 6 days out, 2 hours apart. In these violet-light images, north is at the top and the evening terminator to the left. The cloud features high in the planet's atmosphere rotate from right to left, from the limb through the noon meridian toward the terminator, traveling all the way around the planet once every four days. The motion can be seen by comparing the last two pictures, taken two hours apart. The other views show entirely different faces of Venus. These photographs are part of the 'Venus global circulation' sequence planned by the imaging team. The Galileo Project is managed for NASA's Office of Space Science and Applications by the Jet Propulsion Laboratory; its mission is to study Jupiter and its satellites and magnetosphere after multiple gravity-assist flybys at Venus and Earth.

1990-01-01

354

Venus surface properties deduced from radar and radiometry  

NASA Technical Reports Server (NTRS)

The brightness of surface features on side looking radar images of Venus is determined by many factors: the angles of incidence and reflection, polarization, surface geometry and composition, and so forth. The contribution from surface properties themselves can only be deduced by combining several types of measurement. For instance, without additional information, it is impossible to distinguish the effects of changes in surface roughness from those in dielectric constant. In common with the Moon and Mars, the surface of Venus appears to scatter radar waves in two ways: small-scale surface inhomogeneities, i.e., those smaller than the incident wavelength, depolarize and scatter the energy over a wide range of angles. The Pioneer Venus radar mapper experiment made three overlapping sets of measurements of the equatorial region of Venus from 15 deg S latitude to 45 deg N; the backscatter cross section at a range of incidence angles, the shape and intensity of radar echoes from the nadir, and the microwave brightness temperature of the surface. These techniques developed during the analysis of Pioneer Venus data will be used during the Magellan mission to extract measurements of surface slopes and dielectric constants over all areas covered by the SAR and altimeter antennae, with a resolution of about 10 km. A knowledge of the mechanisms that govern surface scattering will also be useful in the analysis of higher resolution side looking radar images, particularly in distinguishing the effects of changing roughness from those caused by a long range surface tilt or changing dielectric constant.

Ford, P. G.

1989-01-01

355

Studies of the atmosphere of Venus by means of spacecraft: Solved and unsolved problems  

Microsoft Academic Search

Many spacecraft were used for exploration of the atmosphere of Venus. Their list consists of 25 items, including fly-by missions, orbiters, descent and landing probes and even balloons. VENERA-4 (1967) was near the beginning of this list, providing the first time in situ experiments on other planet. It started a long sequence of successful Soviet Venera missions. However after the

V. I. Moroz

2002-01-01

356

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

NASA Technical Reports Server (NTRS)

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

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

2009-01-01

357

Making the Venus Concept Watch 1.0  

NASA Astrophysics Data System (ADS)

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

Balint, Tibor S.; Melchiorri, Julian P.

2014-08-01

358

Magellan unveils Venus  

SciTech Connect

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

Lerner, E.J.

1991-07-01

359

Lightning on Venus  

NASA Technical Reports Server (NTRS)

On the night side of Venus, the plasma wave instrument on the Pioneer-Venus Orbiter frequently detects strong and impulsive low-frequency noise bursts when the local magnetic field is strong and steady and when the field is oriented to point down to the ionosphere. The signals have characteristics of lightning whistlers, and an attempt was made to identify the sources by tracing rays along the B-field from the Orbiter down toward the surface. An extensive data set strongly indicates a clustering of lightning sources near the Beta and Phoebe Regios, with additional significant clustering near the Atla Regio at the eastern edge of Aphrodite Terra. These results suggest that there are localized lightning sources at or near the planetary surface.

Scarf, F. L.

1985-01-01

360

Impact craters on Venus  

NASA Technical Reports Server (NTRS)

Compared with volcanism and tectonism, impact cratering on Venus has played an overall minor role in sculpting the present-day landscape. The study of Venus impact craters is vital to help place the chronology of the geologic features on the surface in the context of the planet's geological evolution. The degradation of impact craters also provides information on surface and interior processes, particularly alteration by tectonism and volcanism. Through orbit 1422, Magellan mapped about 450 impact craters, with diameters ranging from 2 to 275 km, within an area of about 226 million sq km, or 49 percent of the planet's surface. These craters and their associated deposits show surprisingly little evidence of degradation at the 75 m/pixel resolution of the Magellan SAR. Remarkably few craters in the Magellan images appear to be in the process of being buried by volcanic deposits or destroyed by tectonic activity.

Schaber, G. G.

1991-01-01

361

Venus methane and water  

NASA Technical Reports Server (NTRS)

Data collected by the Pioneer Venus Large Probe Neutral Mass Spectrometer are presented and discussed. Results indicate the presence of a large amount of methane in the Venus atmosphere from 60 km to the surface. Deuterium transfer from atmospheric HDO to poorly deuterated methane may account for the puzzling apparent gradient in the water vapor mixing ration below 10 km. Deuterium transfer within the mass spectrometer may cause reduction in the apparent ratio of HDO to H2O. Accounting for the deuterium atoms leads to a revised water vapor mixing ratio of 28 ppm. Arguments against the methane detected being purely atmospheric are overwhelming. The methane may have been generated by a reaction between a highly deuterated atmospheric constituent and a poorly deuterated instrumental contaminant.

Donahue, Thomas M.; Hodges, R. R., Jr.

1993-01-01

362

The downward flux of O(+) over the nightside of Venus  

NASA Technical Reports Server (NTRS)

We have constructed a map of the downward flux of O(+) over the nightside of Venus at high and low solar activities through a combination of modeling and analysis of Pioneer Venus ion mass spectrometer data. O(+) density profiles were obtained for almost 40 inbound or outbound segments of orbits from the first 2 years of the mission and about 40 more in the recent reentry phase of the mission. We have determined the nearly linear relationship between the 0(+) maximum density and the downward O(+) flux for several solar zenith angles and local times by constructing models of the nightside ionosphere of Venus for a range of downward ion fluxes at the upper boundaries. We find that the largest downward fluxes occur near the terminators, and the fluxes fall off sharply toward the antisolar point. Although the standard deviations in the data are large, there is a suggestion of a local maximum near 155 deg, and the location of this maximum correlates fairly well with structure in the peak electron density as a function of solar zenith angle reported for the Pioneer Venus radio occulation experiment. The average downward ion flux is inferred to be about 1.7 x 10(exp 8)/sq cm/sec over the nightside hemisphere at solar maximum and a factor of 7 less at moderately low solar activity.

Brannon, J. J.; Fox, J. L.

1994-01-01

363

Evaluation of Long Duration Flight on Venus  

NASA Technical Reports Server (NTRS)

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

Landis, Geoffrey A.; Colozza, Anthony J.

2006-01-01

364

Ice On Venus  

NSDL National Science Digital Library

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

365

Three ages of Venus  

NASA Technical Reports Server (NTRS)

A central question for any planet is the age of its surface. Based on comparative planetological arguments, Venus should be as young and active as the Earth (Wood and Francis). The detection of probable impact craters in the Venera radar images provides a tool for estimating the age of the surface of Venus. Assuming somewhat different crater production rates, Bazilevskiy et al. derived an age of 1 + or - 0.5 billion years, and Schaber et al. and Wood and Francis estimated an age of 200 to 400 million years. The known impact craters are not randomly distributed, however, thus some area must be older and others younger than this average age. Ages were derived for major geologic units on Venus using the Soviet catalog of impact craters (Bazilevskiy et al.), and the most accessible geologic unit map (Bazilevskiy). The crater counts are presented for (diameters greater than 20 km), areas, and crater densities for the 7 terrain units and coronae. The procedure for examining the distribution of craters is superior to the purely statistical approaches of Bazilevskiy et al. and Plaut and Arvidson because the bins are larger (average size 16 x 10(6) sq km) and geologically significant. Crater densities define three distinct groups: relatively heavily cratered (Lakshmi, mountain belts), moderately cratered (smooth and rolling plains, ridge belts, and tesserae), and essentially uncratered (coronae and domed uplands). Following Schaber et al., Grieve's terrestrial cratering rate of 5.4 + or - 2.7 craters greater than 20 km/10(9) yrs/10(6) sq km was used to calculate ages for the geologic units on Venus. To improve statistics, the data was aggregated into the three crater density groups, deriving the ages. For convenience, the three similar age groups are given informal time stratigraphic unit names, from youngest to oldest: Ulfrunian, Sednaian, Lakshmian.

Wood, Charles A.; Coombs, Cassandra R.

1989-01-01

366

Venus - Adivar Crater  

NASA Technical Reports Server (NTRS)

Many of the impact craters of Venus revealed by Magellan have characteristics unlike craters on any other planetary body. This 30-kilometer (18.6-mile) diameter crater, named Adivar crater for the Turkish educator and author Halide Adivar (1883-1964), is located just north of the western Aphrodite highland (9 degrees north latitude, 76 degrees east longitude). Surrounding the crater rim is ejected material which appears bright in the radar image due to the presence of rough fractured rock. A much broader area has also been affected by the impact, particularly to the west of the crater. Radar-bright materials, including a jet-like streak just west of the crater, extend for over 500 kilometers (310 miles) across the surrounding plains. A darker streak, in a horseshoe or paraboloidal shape, surrounds the bright area. Radar-dark (i.e., smooth) paraboloidal streaks were observed around craters in earlier Magellan images, but this is a rare bright crater streak. These unusual streaks, seen only on Venus, are believed to result from the interaction of crater materials (the meteoroid, ejecta, or both) and high-speed winds in the upper atmosphere. The precise mechanism that produces the streaks is poorly understood, but it is clear that the dense atmosphere of Venus plays an important role in the cratering process.

1991-01-01

367

Ion escape from Venus using statistical distribution functions  

NASA Astrophysics Data System (ADS)

We use more than three years of data from the ASPERA-4 instrument onboard Venus Express to compile statistical distribution functions of ion flux in and around induced magnetosphere of Venus. We present samples of statistical distribution functions, as well average flux patterns in the near Venus space based on the statistical distribution functions. The statistical distribution functions allows for a compensation of biased sampling regarding both position and angular coverage of the instrument. Protons and heavy ions (mass/charge > 16) are the major ion species escaping from Venus. The escape is due to acceleration of planetary ions by energy transfer from the solar wind. The ion escape appears to exclusively take place in the induced magnetotail region and no heavy ions are present in the magnetosheath. Protons of solar wind origin are travelling around the planet and penetrating the tail, resulting in a mix of planetary and solar wind protons inside the induced magnetosphere boundary. The escape rates of ions inside the tail agree with results from recent published studies, where other analysis methods have been used. We also compare our results for Venus with a recent study of ion escape from Mars, where the same analysis method has been applied to data from the ASPERA-3 instrument on Mars Express. Both Mars and Venus are unmagnetized planets and are expected to interact similarly with the solar wind. On Mars the heavy ions are seen escaping in both the magnetosheath and tail regions as opposed to Venus where escape only takes place inside the tail. A possible explanation is that the magnetosphere of Mars is smaller compared to the ion gyroradius, making it easier for the ions to pass through the induced magnetosphere boundary. On both planets the escape rates of heavy ions in the tail are constant with increasing tail distance, verifying that the ions are leaving the planet in this region.

Nordstrom, T.; Stenberg, G.; Nilsson, H.; Barabash, S.; Futaana, Y.

2012-04-01

368

Survey of the spectral properties of turbulence in the solar wind, the magnetospheres of Venus and Earth, at solar minimum and maximum  

NASA Astrophysics Data System (ADS)

In the framework of the European FP7 project STORM ("Solar system plasma Turbulence: Observations, inteRmittency and Multifractals") we analyze the properties of turbulence in various regions of the solar system, for the minimum and respectively maximum of the solar activity. The main scientific objective of STORM is to advance the understanding of the turbulent energy transfer, intermittency and multifractals in space plasmas. Specific analysis methods are applied on magnetic field and plasma data provided by Ulysses, Venus Express and Cluster, as well as other solar system missions (e.g. Giotto, Cassini). In this paper we provide an overview of the spectral properties of turbulence derived from Power Spectral Densities (PSD) computed in the solar wind (from Ulysses, Cluster, Venus Express) and at the interface of planetary magnetospheres with the solar wind (from Venus Express, Cluster). Ulysses provides data in the solar wind between 1992 and 2008, out of the ecliptic, at radial distances ranging between 1.3 and 5.4 AU. We selected only those Ulysses data that satisfy a consolidated set of selection criteria able to identify "pure" fast and slow wind. We analyzed Venus Express data close to the orbital apogee, in the solar wind, at 0.72 AU, and in the Venus magnetosheath. We investigated Cluster data in the solar wind (for time intervals not affected by planetary ions effects), the magnetosheath and few crossings of other key magnetospheric regions (cusp, plasma sheet). We organize our PSD results in three solar wind data bases (one for the solar maximum, 1999-2001, two for the solar minimum, 1997-1998 and respectively, 2007-2008), and two planetary databases (one for the solar maximum, 2000-2001, that includes PSD obtained in the terrestrial magnetosphere, and one for the solar minimum, 2007-2008, that includes PSD obtained in the terrestrial and Venus magnetospheres and magnetosheaths). In addition to investigating the properties of turbulence for the minimum and maximum of the solar cycle we also analyze the spectral similarities and differences between fast and slow wind turbulence. We emphasize the importance of our data survey and analysis in the context of understanding the solar wind turbulence, the exploitation of data bases and as a first step towards developing a (virtual) laboratory for studying solar system plasma turbulence. Research supported by the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement no 313038/STORM, and a grant of the Romanian Ministry of National Education, CNCS - UEFISCDI, project number PN-II-ID-PCE-2012-4-0418.

Echim, Marius M.

2014-05-01

369

Venus Reveals Its Secrets (Collection of Articles).  

National Technical Information Service (NTIS)

The book tells about the next stage of the Soviet program for the investigation of the planet Venus with the aid of the automatic space stations, 'Venus-5' and 'Venus-6'. The reader can follow the whole history of man's investigations of Venus, beginning ...

1970-01-01

370

Pioneer Venus radar mapper experiment  

USGS Publications Warehouse

Altimetry and radar scattering data for Venus, obtained from 10 of the first 13 orbits of the Pioneer Venus orbiter, have disclosed what appears to be a rift valley having vertical relief of up to 7 kilometers, as well as a neighboring, gently rolling plain. Planetary oblateness appears unlikely to exceed 112500 and may be substantially smaller. Copyright ?? 1979 AAAS.

Pettengill, G. H.; Ford, P. G.; Brown, W. E.; Kaula, W. M.; Keller, C. H.; Masursky, H.; Mcgill, G. E.

1979-01-01

371

The magnetic barrier at Venus  

Microsoft Academic Search

The magnetic barrier at Venus is a region within which the magnetic pressure dominates all other pressure contributions. The barrier is formed in the inner region of the dayside magnetosheath to transfer solar wind momentum flux to the ionosphere. Passes through the dayside magnetosheath and ionopause with Pioneer Venus have allowed us to probe the magnetic barrier directly. These passes

T. L. Zhang; J. G. Luhmann; C.T. Russell

1991-01-01

372

Venus Atmospheric Maneuverable Platform (VAMP)  

NASA Astrophysics Data System (ADS)

VAMP is a long lived, semi-buoyant, atmospheric “rover” that deploys in orbit, enters the Venus atmosphere and flies in the Venus atmosphere between 55 and 70 km for up to one year as a platform to address VEXAG goals I.A, I.B, and I.C.

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

2014-05-01

373

Stagnant lid convection on Venus  

Microsoft Academic Search

The effect of strongly temperature-dependent viscosity on convection in the interior of Venus is studied systematically with the help of finite element numerical models. For viscosity contrasts satisfying experimental constraints on the rheology of rocks, Venus is likely to be in the regime of stagnant lid convection. This regime is characterized by the formation of a slowly creeping, very viscous

V. S. Solomatov; L.-N. Moresi

1996-01-01

374

Electrical memory in Venus flytrap  

Microsoft Academic Search

Electrical signaling, memory and rapid closure of the carnivorous plant Dionaea muscipula Ellis (Venus flytrap) have been attracting the attention of researchers since the XIX century. The electrical stimulus between a midrib and a lobe closes the Venus flytrap upper leaf in 0.3 s without mechanical stimulation of trigger hairs. Here we developed a new method for direct measurements of the

Alexander G. Volkov; Holly Carrell; Andrew Baldwin; Vladislav S. Markin

2009-01-01

375

The thermal conditions of Venus  

NASA Technical Reports Server (NTRS)

Models of Venus' thermal evolution are examined. The following subject areas are covered: (1) modified approximation of parameterized convection; (2) description of the model; (3) numerical results and asymptotic solution of the MAPC equations; (4) magnetism and the thermal regime of the cores of Earth and Venus; and (5) the thermal regime of the Venusian crust.

Zharkov, Vladimir N.; Solomatov, V. S.

1991-01-01

376

Transforming Venus by induced overturn  

Microsoft Academic Search

A scenario for terraforming Venus is proposed, in which the terraforming occurs through the controlled impact of bodies of water ice and industrial slag obtained from the outer solar system. The economic background and motivation for the scenario are noted. Consideration is given to the terraforming materials, increasing the rotational rate of Venus, patterns of impact, the carbonation of rocks,

Alexander G. Smith

1989-01-01

377

Venus: Interaction with Solar Wind  

NASA Astrophysics Data System (ADS)

The solar wind interaction with VENUS provides the archetypal interaction of a flowing magnetized PLASMA with a PLANETARY IONOSPHERE. Mars interacts with the solar wind in much the same way as does Venus, while the rotating plasma in the Saturnian magnetosphere is believed to interact similarly with its moon, Titan (see SATURN: MAGNETOSPHERE INTERACTION WITH TITAN). The interaction of the Jovian ...

Russell, C.; Luhmann, J.; Murdin, P.

2002-07-01

378

Particulate gravity currents on Venus  

Microsoft Academic Search

Canali are moderately sinuous channels, typically a few kilometers wide and hundreds of kilometers long, that occur principally on the plains of Venus. Plausible hypotheses for their formation include the following: open channels cut by exotic, low-viscosity lavas; roofed-over basaltic lava channels; or water on a cooler, wetter ancient Venus. Although it is accepted that a fluid cut these channels,

Dave Waltham; Kevin T. Pickering; Veronica J. Bray

2008-01-01