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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 - the First European Mission to Venus  

Microsoft Academic Search

The ESA Venus Express mission is based on reuse of the Mars Express spacecraft and the payload available from the Mars Express and Rosetta missions. In less than 3 years the spacecraft was rebuilt with modifications to cope with harsh environment at Venus and fully tested. The Venus Express will be launched in the end of October 2005 from Baykonur

D. V. Titov; H. Svedhem

2005-01-01

3

A dynamic atmosphere revealed by the Venus Express mission  

NASA Astrophysics Data System (ADS)

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

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

4

Venus Express  

NASA Astrophysics Data System (ADS)

Venus Express has now orbited Venus for more than two Venus sidereal days, i.e. 486 Earth days. The spacecraft remains in an excellent condition and more than 1 Terabit of science data has been downlinked to ground. The data returned from the mission during this period has been of extraordinary quality and has already led to new insights in several fields. Venus Express is the first mission fully exploiting the infrared spectral windows in order to map the atmosphere in three dimensions. The observations show a highly dynamic atmosphere, including close-ups of the southern polar double vortex with quickly moving fine structures at several different altitudes. For most of the time the atmosphere can be divided into three distinctly different dynamic regions. - The equatorial region, dominated by a turbulent atmosphere mainly driven by convection, a mid latitude region dominated by a smooth laminar like flow, and the polar region dominated by a cold collar and a vast complex vortex system. The dynamics is mainly studied by the Virtis and VMC instruments. Several minor species at various depths of the atmosphere, including D/H ratios as function of altitude are being characterised by the spectrometer SpicaV and the Virtis high-res spectral channel. The upper atmosphere and plasma environment and interaction between these is studied by the Aspera instrument, the Magnetometer and radio science by occultation. This talk will give a brief report of the status of the mission, a summary of the major findings from the first part of the mission, including during the Messenger fly-by, and an outline of the plans for the future activities.

Svedhem, H.; Witasse, O.

2007-12-01

5

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

NASA Astrophysics Data System (ADS)

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

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

6

Manned Venus Orbiting Mission  

NASA Technical Reports Server (NTRS)

Manned orbiting stopover round trips to Venus are studied for departure dates between 1975 and 1986 over a range of trip times and stay times. The use of highly elliptic parking orbits at Venus leads to low initial weights in Earth orbit compared with circular orbits. For the elliptic parking orbit, the effect of constraints on the low altitude observation time on the initial weight is shown. The mission can be accomplished with the Apollo level of chemical propulsion, but advanced chemical or nuclear propulsion can give large weight reductions. The Venus orbiting mission weights than the corresponding Mars mission.

Willis, E. A., Jr.

1967-01-01

7

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.

8

Venus Aerobot Multisonde Mission  

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

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

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

11

Contributions to Comparative Climatology by Venus Express  

NASA Astrophysics Data System (ADS)

Venus Express is carrying six instruments dedicated to the study of the atmosphere of Venus and the interaction of the atmosphere with both the solar wind and the planetary surface. The spacecraft is orbiting in a highly elliptic polar orbit with an apocentre 66000 km above the South Pole and a pericentre about 250 km above the North Pole. The first two years of operation has taken place during the present solar minimum and the mission thus complements the Pioneer Venus mission well, both with respect to its orbit and to the phase of the solar cycle. A very important feature of Venus Express is its ability to probe the atmosphere in three dimensions by making use of the near-IR spectral windows. The early part of the mission has had the general objective of addressing a large number of questions, mainly related to atmospheric dynamics (3-D wind fields, cloud morphology, and the polar vortices), thermal structure, chemistry and escape. The instruments and mission parameters also lend themselves very well to studies related to problems of surface-atmosphere interaction and atmospheric evolution. With a large and still accumulating data base in all these areas, the focus of the mission can place increasing emphasis on addressing past and future climate change on Venus, leading to a better understanding of the comparative climatology of the terrestrial planets. This talk will summarize the most important results to date from Venus Express with relevance to climate studies, and will address some ongoing activities in this field.

Svedhem, H.; Witasse, O.; Taylor, F. W.

2008-12-01

12

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

13

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

14

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

NASA Astrophysics Data System (ADS)

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

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

2008-05-01

15

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

16

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

NASA Astrophysics Data System (ADS)

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 and electromagnetic fields affect the Venusian atmosphere? The ASPERA-4 instrument comprises four sensors; two ENA sensors, electron and ion spectrometers. The neutral particle imager (NPI) provides measurements of the integral ENA flux (0.1-60 keV) with no mass and energy resolution but relatively high angular resolution. The neutral particle detector (NPD) provides measurements of the ENA flux, resolving velocity (0.1-10 keV) and mass (H and O) with a coarse angular resolution. The electron spectrometer (ELS) is a standard top-hat electrostatic analyser in a very compact design. These three sensors are located on a scanning platform providing a 4? coverage. The instrument also contains an ion mass composition sensor, IMA (ion mass analyser). Mechanically, IMA is a separate unit electrically connected with the ASPERA-4 main unit. IMA provides ion measurements in the energy range 0.01-36 keV/ q for the main ion components H+, He++, He+, and the ion group with M/q20-80amu/q.

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

2007-10-01

17

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

18

Venus  

NSDL National Science Digital Library

This site 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. There are also many pictures and additional websites for more information.

2005-06-07

19

Mission concepts for Venus surface investigation  

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

20

Venus Atmospheric Circulation: Update after Venus Express  

NASA Astrophysics Data System (ADS)

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

Limaye, Sanjay

21

Venus entry probe technology reference mission  

NASA Astrophysics Data System (ADS)

The Venus Entry Probe is one of ESA's Technology Reference Missions (TRM). TRMs are model science-driven missions that are, although not part of the ESA science programme, able to provide focus to future technology requirements. This is accomplished through the study of several technologically demanding and scientifically meaningful mission concepts, which are strategically chosen to address diverse technological issues. The TRMs complement ESA's current mission specific development programme and allow the ESA Science Directorate to strategically plan the development of technologies that will enable potential future scientific missions. Key technological objectives for future planetary exploration include the use of small orbiters and in-situ probes with highly miniaturized and highly integrated payload suites. The low resource, and therefore low cost, spacecraft allow for a phased strategic approach to planetary exploration. The aim of the Venus Entry Probe TRM (VEP) is to study approaches for low cost in-situ exploration of the Venusian atmosphere. The mission profile consists of two minisats. The first satellite enters low Venus orbit. This satellite contains a highly integrated remote sensing payload suite primarily dedicated to support the in-situ atmospheric measurements of the aerobot. The second minisat enters deep elliptical orbit, deploys the aerobot, and subsequently operates as a data relay, data processing and overall resource allocation satellite. The micro-aerobot consists of a long-duration balloon that will analyze the Venusian middle cloud layer at an altitude of ˜ 55 km, where the environment is relatively benign (T = 20 C and p = 0.45 bars). The balloon will deploy a swarm of active ballast probes, which determine vertical profiles of selected properties of the lower atmosphere. In this presentation, the mission objectives and profile of the Venus Entry Probe TRM will be given as well as the key technological challenges.

van den Berg, M. L.; Falkner, P.; Atzei, A. C.; Phipps, A.; Mieremet, A.; Kraft, S.; Peacock, A.

22

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

23

The Magellan Venus radar mapping mission  

NASA Astrophysics Data System (ADS)

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

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

1990-06-01

24

Communications Transceivers for Venus Surface Missions  

NASA Technical Reports Server (NTRS)

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

Force, Dale A.

2004-01-01

25

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

26

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

27

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

28

Reassessment of planetary protection requirements for Venus missions  

NASA Astrophysics Data System (ADS)

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

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

29

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

30

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

31

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

32

The 2010 European Venus Explorer (EVE) mission proposal  

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

33

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

34

Venus Terminator Temperature Structure: Venus Express SOIR and VTGCM Comparisons  

NASA Astrophysics Data System (ADS)

The wavelength range probed by SOIR instrument on board Venus Express - 2.2 to 4.3 muµm - allows a detailed chemical inventory of the Venus atmosphere. In particular CO _{2} density vertical profiles are obtained from 70 to 170 km altitude. Temperature and total density profiles are deduced from the CO _{2} density profiles. These measurements show a striking permanent temperature minimum (at 125 km) and a weaker temperature maximum (over 100-115 km). 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 Venus atmospheric region probed by the SOIR instrument is very special as it acts as a transition region between two distinct dynamical regimes characterized by different flow patterns: the zonal retrograde flow below 70 km and the subsolar to antisolar circulation above 120 km. The study of CO, being mainly produced through the photodissociation of CO2 at high altitudes by solar ultraviolet radiation, can lead to significant information on the dynamics taking place in this region. New Venus Thermospheric General Circulation Model (VTGCM) simulations are conducted for conditions appropriate to these SOIR measurements. In particular, solar minimum or moderate fluxes are specified and mean values of eddy diffusion and wave drag parameters are utilized. Recent upgrades to the VTGCM code now include more realistic lower boundary conditions at 70 km near cloud tops. Model temperature profiles are extracted from the terminators that correspond to five latitude bins (0-30°, 30-60°, 60-70°, 70-80°, 80-90° latitude) presently used in the SOIR data analysis. Averaging of VTGCM temperature profiles in each of these bins (at morning and evening terminators) is conducted to match SOIR sampling. The features observed in the SOIR data provide detailed constraints for new empirical models and global circulation models of the Venus upper atmosphere. Comparisons of these SOIR and VTGCM temperature profiles are made. Most notably, the observed temperature minimum near 125 km and the weaker temperature maximum over 100-115 km are generally reproduced by the VTGCM at the correct pressure/altitude levels. However, magnitudes of simulated and measured temperatures are somewhat different. In addition, VTGCM evening terminator (ET) temperatures are simulated to be modestly warmer than corresponding morning terminator (MT) values, a result of stronger ET than MT zonal winds at/above about 130-140 km.

Vandaele, Ann C.; Bougher, Stephen; Brecht, Amanda; Mahieux, Arnaud; Drummond, Rachel; Robert, Severine; Wilquet, Valérie; Thomas, Ian; Schulte, Rick

35

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

36

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

37

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

38

Venus Terminator Temperature Structure: Venus Express SOIR and VTGCM Comparisons  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

39

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

40

Temperature Structure at Venus as Observed by Venus Express (SPICAV)  

NASA Astrophysics Data System (ADS)

The SPICAV/SOIR instrument on board ESA Venus Express orbiter is probing the upper atmosphere of Venus by the technique of stellar occultations in the UV, and solar occultations in the UV, visible, near IR and mean IR (2.4 to 4.2 µm). On the night side, occultations of bright UV stars allow to determine the density profile from CO2 absorption in the altitude range 80-140 km and the temperature, from the hydrostatic law. We have detected in many occasions a strong temperature inversion just above the mesopause (at 90-120 km), that we interpret as the result of adiabatic heating during air subsidence, in the day-side to night side upper atmosphere circulation. The temperature excess is 30-70 K at 100 km, but is rather variable. No clear pattern with local time, solar zenith angle, or latitude is obvious. The air subsidence is also evidenced from NO emissions (? and ? bands of NO) when N and O atoms (produced on the day side) recombine during air subsidence. A tentative correlation between the intensity of NO emission and temperature profiles will be presented. The haze top altitude may vary by up to 8 km in a few days, together with a given CO2 density. Some questions related to the retrieval of CO2 density and temperature in the infra-red in solar occultation will be addressed. The CO mixing ratio profile, showing a strong minimum at 80-90 km, will be discussed in terms of dynamics.

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

41

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

42

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

43

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

44

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

45

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

Microsoft Academic Search

Magellan, NASA's last geoscience mission to Venus, provided synthetic aperture radar (SAR) images at ~100-m resolution, topography at ~10-km resolution, and the gravity field at ~300-km resolution. Although that mission provided a major advance in our understanding of the planet, basic questions about the geologic history of Venus remain unresolved. For example, hypotheses on the planet's surface evolution range from

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

2009-01-01

46

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

47

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

NASA Astrophysics Data System (ADS)

We present the spatial distribution of air temperature on Venus' night side, as observed by the high spectral resolution channel of VIRTIS (Visible and Infrared Thermal Imaging Spectrometer), or VIRTIS-H, on board the ESA mission Venus Express. The present work extends the investigation of the average thermal fields in the northern hemisphere of Venus, by including the VIRTIS-H data. We show results in the pressure range of 100-4 mbar, which corresponds to the altitude range of 65-80 km. With these new retrievals, we are able to compare the thermal structure of the Venus' mesosphere in both hemispheres. The major thermal features reported in previous investigations, i.e. the cold collar at about 65-70°S latitude, 100 mbar pressure level, and the asymmetry between the evening and morning sides, are confirmed here. By comparing the temperatures retrieved by the VIRTIS spectrometer in the North and South we find that similarities exist between the two hemispheres. Solar thermal tides are clearly visible in the average temperature fields. To interpret the thermal tide signals (otherwise impossible without day site observations), we apply model simulations using the Venus global circulation model Venus GCM (Lebonnois, S., Hourdin, F., Forget, F., Eymet, V., Fournier, R. [2010b]. International Venus Conference, Aussois, 20-26 June 2010) of the Laboratoire de Météorologie Dynamique (LMD). We suggest that the signal detected at about 60-70° latitude and pressure of 100 mbar is a diurnal component, while those located at equatorial latitudes are semi-diurnal. Other tide-related features are clearly identified in the upper levels of the atmosphere.

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

2012-02-01

48

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

49

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

50

Climate change on Venus and future spacecraft mission priorities  

NASA Astrophysics Data System (ADS)

Weathering of surface minerals in the sulfur-rich lower atmosphere of Venus may well have played a significant role in the recent evolution of the planet's climate. SO 2 in the atmosphere is interesting because it is the primary precursor of Venus' bright H 2SO 4 /H 2O clouds, it is a greenhouse gas, it is most likely outgassed by volcanoes [Prinn, 1985], it probably reacts with the surface, and it is apparently much higher in abundance that would be expected from thermochemical equilibrium with the surface [Fegley and Treiman, 1992] (although interpretations of Vega 1 and 2 UV spectrometer data challenge the latter, see Bertaux et al., [1996]). Changes in the atmospheric abundance of SO 2 would be accompanied by alterations in the optical properties of the clouds and in the greenhouse effect, thereby affecting surface temperatures [Bullock and Grinspoon, 2001]. Fegley and Prinn , [1989] demonstrated e perimentally that the reaction CaCO3 +x SO 2 ==> CaSO 4 + CO proceeds rapidly under Venus-like conditions, and concluded that SO 2 and hence the H 2 SO 4 /H 2O clouds would disappear in 1.9 My unless SO 2 in the atmosphere were continually replenished by volcanic outgassing. Using a coupled chemical kinetic reaction-diffusion and climate model, [ Bullock and Grinspoon, 2001] calculated that volcanism must supply SO 2 to the atmosphere on approximately 30 My timescales in order to maintain clouds with their current optical properties. Clues to the nature of the recent Venus climate may be obtained by elucidating the sensitivity of cloud properties to changes in a mospheric SO 2 andt H 2O and by investigations into the styles and depths of chemical weathering at the surface. Future robotic spacecraft missions have the pot ential to provide significant insights into recent climate change on Venus and on the role that sulfur may have played. Among the most important and scientifically valuable investigations are: 1. High spectral, spatial, and temporal resolution near-IR i aging spectrometrym from Venus orbit in order to retrieve accurate SO 2, H 2O and CO abundances and variability beneath the clouds. Coupling gas abundance and variability to cloud morphology , cloud optical properties, and to atmospheric dynamics would enable a far better understanding of how clouds and climate respond to changing atmospheric chemistry. 2. Visible to near-IR high resolution images of the surface from 15-20 km in order to complement the global synthetic aperture radar imagery of the Magellan mission (e.g. [M o r o z, 2002]). Remaining scientific issues about Venus' geologic history, which is vigorously debated, may well be resolved by obtaining near-visual wavelength datasets of selected areas on Venus. These can be used to calibrate the global radar dataset in terms of surface properties and geomorphology. 3. Elemental and mineralogical analyses of the surface and subsurface, in order to establish both fundamental mineralogy and weathering products as a function of depth. Visual images of the surface by the Venera landers clearly show broken slabs a few cm in thickness [S u r k o v et al., 1984]. This provides hints as to the nature and extent of weathering of the surface. A detailed mineralogy of the top 10 cm of the surface would provide highly valuable information on the nature and rates of surface-atmosphere interactions and their possible role in alterations of atmospheric chemistry and climate. Although Venus is a difficult planet to study because of its shroud of sulfuric acid clouds and its otherwise harsh environment, it is the only planet that shares the similarity with Earth of having a climate that is actively modified by its geology . As the study of Earth's climate becomes of greater and greater significance to society, so too does the necessity of thinking of planetary climate 'outside the box'. The continued exploration of Venus is one of the most promising avenues to accomplish this. Bertaux, J.L., et al., J. Geophys. Res. , 101 , 12,709-12,745, 1996. Bullock, M.A., and D.H. Grinspoon, Icarus, 150 , 19-37, 2001. Fegley,

Bullock, M.; Grinspoon, D.

51

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

NASA Technical Reports Server (NTRS)

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

1975-01-01

52

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

53

IN-SITU AERIAL EXPLORATION OF VENUS BY BALLOON -SCIENCE OBJECTIVES AND MISSION ARCHITECTURE. K.H. Baines1  

E-print Network

IN-SITU AERIAL EXPLORATION OF VENUS BY BALLOON - SCIENCE OBJECTIVES AND MISSION ARCHITECTURE. K the trailblazing flights of the 1985 twin Soviet VEGA balloons, missions to fly in the skies of Venus have been will be discussed. Floating in Venus's rapid windstream near an altitude of 55 km, VALOR's balloon-borne science

Treiman, Allan H.

54

Venus Express: five years of atmospheric observations  

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

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

2011-10-01

55

The Scientific Exploration of Venus  

NASA Astrophysics Data System (ADS)

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

Taylor, Fredric W.

2014-12-01

56

First Results from Venus Express Aerobraking Campaign  

NASA Astrophysics Data System (ADS)

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

Svedhem, Håkan

57

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

58

Venus  

Microsoft Academic Search

Venus is Earth's nearest planetary neighbor, and has fascinated mankind since the dawn of history. Venus' clouds reflect most of the sunlight shining on the planet and make it the brightest object in the sky after the Sun and Moon. Venus is visible with the naked eye as an evening star until a few hours after sunset, or as a

B. Fegley Jr.

2003-01-01

59

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

60

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

61

Results of the Venus Express Aerobraking Campaign  

NASA Astrophysics Data System (ADS)

After a very successful mission orbiting Venus for more than 8 years, slowly the fuel is running out and the spacecraft will inevitably one day end up in the hot and acid atmosphere of the planet. Being near the end of the mission and in a position to accept some risk to the spacecraft we decided to take the opportunity to dip down deep into the atmosphere, to around 130 km, in a controlled manner, in order to make detailed in situ investigations of this for remote sensing instruments difficult to access region. The on board accelerometers gave direct measurements of the deceleration which in turn is directly proportional to the local atmospheric density. This provided an excellent way to study both the total density profile throughout the orbital arc in the atmosphere and small scale density variations in the region of the pericentre. The spacecraft behaved perfectly well throughout the whole campaign and provided a wealth of data both on the atmosphere and on the response of the spacecraft to the harsh environment with strong heat loads and some dynamic stress. At the time of the campaign the pericentre was located near the terminator at about 75 degrees Northern latitude. Aerobraking is a very efficient method of reducing the pericentre velocity and thereby reducing the apocentre altitude and the orbital period.The so called "walk-in" phase started at an altitude of 190 km on 17 May and the campaign ended on 11 July, after having reached a lowest altitude of 129.2 km. Subsequently, a series of orbit control manoeuvres lifted up the pericentre to 460 km altitude and the science activities were resumed after a thorough check-out of the spacecraft. We have detected a highly variable atmosphere, both on a day to day basis and within the individual pericentre passes. The duration of each pass was approximately 100 s and the maximum dynamic pressure achieved was more than 0.75 N/m2, probably a record for a spacecraft that continued its operation afterwards. The orbital period was reduced over the duration of the campaign changing from 24 hours to 22 hours 20 minutes.

Svedhem, Hakan; Müller-Wodarg, Ingo

2014-11-01

62

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

63

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

64

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

65

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

66

Climatology of the Venus upper haze as measured by SOIR on board Venus Express  

NASA Astrophysics Data System (ADS)

We recently demonstrated the potential of the SPICAV/SOIR suite of instruments onboard the Venus Express spacecraft to characterize the aerosols in the mesosphere of Venus from a data set of three selected orbits [1]. The wavelength dependence of the continuum is primarily due to the extinction caused by the aerosol particles of the upper haze and is directly related to the effective particle radius of the particles. Recent advances are presented here, showing that careful selection of diffraction orders (i.e. spectral windows) during solar occultations performed by the SOIR instrument [2, 3] could allow using only the SOIR channel to obtain information on the particle's size. The continuum of the SOIR spectra was obtained with the ASIMAT retrieval code [4]. The possibility to use the SOIR channel alone, instead of in combination with the SPICAV channels is important as it offers a larger data set, although less informative in terms of microphysical properties. Therefore, temporal and geographical variations of the vertical profiles of the aerosol extinction were investigated for a particular diffraction order. This spectral window was measured in many solar occultations and over a period of 3 years leading to good spatial and temporal coverages. 1. Wilquet, V., et al., Preliminary characterization of the upper haze by SPICAV/SOIR solar occultation in UV to mid-IR onboard Venus Express. J. Geophysical Research, 2009. 114(E00B42): p. doi:10.1029/2008JE003186. 2. Nevejans, D., et al., Compact high-resolution space-borne echelle grating spectrometer with AOTF based on order sorting for the infrared domain from 2.2 to 4.3 micrometer. Applied Optics, 2006. 45(21): p. 5191-5206. 3. Mahieux, A., et al., In-Flight performance and calibration of SPICAV SOIR on board Venus Express. Applied Optics, 2008. 47(13): p. 2252-65. 4. Mahieux, A., et al., Venus atmospheric densities and temperature profiles retrieved from SOIR solar occultations on board Venus Express. J . Geophys . Res . 2010. (submitted).

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

2010-05-01

67

Investigating Climate on Venus with Future Missions (Invited)  

NASA Astrophysics Data System (ADS)

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

Grinspoon, D. H.

2013-12-01

68

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

69

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.

70

Morphology of magnetic field in near-Venus magnetotail: Venus express observations  

NASA Astrophysics Data System (ADS)

of the magnetic field morphology in the near-Venus wake is essential to the studies of magnetotail dynamics and the planetary plasma escape. In this study we use the magnetic field measurements made by Venus Express during the period of April 2006 to December 2012 to investigate the global magnetic field morphology in the near-Venus magnetotail (0-3 Venusian radii, RV, down tail) in the frame of solar wind electric field coordinates. The hemisphere with electric field pointing toward/away is indicated as ±E hemisphere. It has been reported that the cross-tail field component has a hemispheric asymmetry in the Venusian magnetotail. We report here that this asymmetry should have been formed at the terminator and would transport tailward. In addition, we find that the draped magnetic field lines near both hemispheric flanks are directed equatorward in the region 0-1.5 RV down tail as it looks like "sinking" into Venus umbra. We estimate the thickness of the magnetotail current sheet and the current density at the sheet center. We find that the average half thickness of central current sheet near +E hemispheric flank (~460 km) is almost twice as thick as that near magnetic equatorial plane (~200 km), but the corresponding current densities at the sheet center are comparable (~6.0 nA/m2). As a result, the larger cross-tail field component found near the +E hemispheric flank suggests a stronger tailward j × B force, i.e., the more efficient tailward acceleration of plasma in this region, showing the agreement with previous observations of heavy ion outflow from Venus. In contrast, the average magnetic field structure near -E hemispheric flank is irregular, which suggests that dynamic activities, such as magnetic reconnection and magnetic field turbulence, preferentially appear there.

Rong, Z. J.; Barabash, S.; Futaana, Y.; Stenberg, G.; Zhang, T. L.; Wan, W. X.; Wei, Y.; Wang, X.-D.; Chai, L. H.; Zhong, J.

2014-11-01

71

Magellan - Early results from the Venus mapping mission  

NASA Technical Reports Server (NTRS)

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

72

Venus  

NASA Astrophysics Data System (ADS)

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

Fegley, B., Jr.

2003-12-01

73

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

74

The latest results on the energetic neutral atoms and plasma of Venus from the ASPERA-4 instrument of Venus Express  

NASA Astrophysics Data System (ADS)

The Venus Express mission carries the instrument ASPERA-4 Analyzer of Space Plasmas and Energetic Atom to perform for the first time comprehensive plasma measurements at Venus ASPERA-4 is a replica of the instrument ASPERA-3 for the Mars Express mission orbiting Mars for about 2 years The general scientific objective of the ASPERA-4 experiment is to study the solar wind - atmosphere interaction and characterize the plasma atmospheric escape through energetic neutral atom ENA imaging and in-situ ion and electron measurements The ASPERA-4 instrument comprises four sensors two ENA sensors and an electron and ion spectrometer The Neutral Particle Imager NPI provides measurements of the integral ENA flux in the energy range 0 1 - 60 keV with no mass and energy resolution but comparatively high angular resolution 4 6 deg x 11 5 deg The Neutral Particle Detector NPD provides measurements of the ENA flux in the energy range 0 1 - 10 keV resolving velocity and mass H and O with a coarse angular resolution The Electron Spectrometer ELS is a standard top-hat electrostatic analyzer in a very compact design with the high 8 energy resolution to perform photoelectron spectroscopy These three sensors are located on a scanning platform to cover ideally the full sphere Ion Mass Analyzer IMA provides ion measurements in the energy range 0 01 - 30 keV q for the main ion components 1 2 4 16 amu q and the group of molecular ions 20 - 80 amu q The instantaneous field of view is 4 6 deg x 360 deg Electrostatic sweeping performs the elevation 90 deg

Barabash, S.; Sauvaud, J.-A.; Aspera-4

75

Spectral inventory of the SOIR spectra onboard Venus Express  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

76

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

77

Galileo infrared observations of the atmosphere and surface of Venus: The potential for Venus Express  

NASA Astrophysics Data System (ADS)

Near infrared mapping spectrometer (NIMS) measurements obtained during Galileo's brief 1990 flyby show that infrared spectroscopy can be used to study numerous, diverse phenomena and altitude regimes at Venus, ranging in vertical extent from upper atmosphere down to, and including, the surface. To illustrate the great potential of Venus Express we summarize previous NIMS work (Carlson et al., Science 253, 1541, 1991; Special Issue of Planet. Space Sci, 41, No. 7, 1993; Roos-Serote et al, Icarus 114, 300, 1995) and present new analyses of surface and lower atmosphere observations. Venus’s upper atmosphere exhibits infrared carbon dioxide and carbon monoxide band emissions formed by resonance scattering of incident solar radiation as well as molecular oxygen band emission of photochemical origin. Thermal emission maps show warm high-altitude polar caps above cooler clouds. Discrete features of unknown cause are evident at mid-latitude cloud top levels. Spectral windows allow infrared sounding of the atmosphere below the clouds and characterization of the lower clouds, which are found to exhibit more spatial structure than higher altitude clouds. Motions of these lower altitude clouds were used to determine Hadley cell velocities while spectroscopic measurements were used to for sounding of carbon monoxide and water in the lower atmosphere below the clouds. Thermal radiation from the surface can be used to generate infrared-derived altimetry and to deduce opacity parameters for high-temperature and high-pressure carbon dioxide.

Carlson, R.; Baines, K.; Kamp, L.

2003-04-01

78

Magnetic fields in the Venus ionosphere: Dependence on the IMF direction—Venus express observations  

NASA Astrophysics Data System (ADS)

The structure of the magnetized ionosphere of Venus is investigated using the magnetometer and plasma (Analyzer of Space Plasmas and Energetic Atoms 4) data from the Venus Express spacecraft. Observations surveying the low-altitude (h ? 250 km) ionosphere were made at solar zenith angles ? 75°. The magnetic field permeating the Venus ionosphere at solar minimum conditions increases at low altitudes and reaches a maximum at an altitude of ˜200 km. The orientation of the magnetic field in the peak is almost insensible to the magnetic field direction in the solar wind. For both sector polarities of the IMF, the magnetic field vector has a dominant dawn-dusk component. The topology of the magnetic field also occurs different for different signs of the cross-flow component of the IMF revealing either a sudden straightening with liberation of the magnetic field stresses or a closing into a loop. We discuss different mechanisms of the peak formation including local magnetization, a weak intrinsic planetary field, a dipole field induced by eddy currents, a remnant origin, or giant flux ropes. All of them fail to explain most of the observed features. We suggest that a decoupling of ion and electron motion at low altitudes due to ion-neutral collisions results in currents which produce different field configurations depending on the IMF orientation.

Dubinin, E.; Fraenz, M.; Zhang, T. L.; Woch, J.; Wei, Y.

2014-09-01

79

Plasma environment of Venus: Comparison of Venus Express ASPERA-4 measurements with 3-D hybrid simulations  

NASA Astrophysics Data System (ADS)

We use data of the ASPERA-4 ion and electron spectrometers onboard Venus Express to determine the locations and shapes of the plasma boundaries (bow shock, ion composition boundary, and mantle) at Venus. We also investigate the variation of the terminator bow shock position as a function of the solar wind dynamic pressure and solar EUV flux. We compare the results with a 3-D hybrid simulation. In the hybrid model, ions are treated as individual particles moving in self-consistently generated electromagnetic fields and electrons are modeled as a massless charge neutralizing fluid. The planetary heavy ion plasma is generated by an oxygen ionosphere and exosphere adapted to a profile, which depends on the solar zenith angle (Chapman layer). A comparison between observations and simulations indicates that the hybrid model is able to produce an adequate picture of the global plasma environment at Venus. The positions of the plasma boundaries are well reproduced by the model but a significant disagreement appears in the absolute values of the considered parameters.

Martinecz, C.; Boesswetter, A.; FräNz, M.; Roussos, E.; Woch, J.; Krupp, N.; Dubinin, E.; Motschmann, U.; Wiehle, S.; Simon, S.; Barabash, S.; Lundin, R.; Zhang, T. L.; Lammer, H.; Lichtenegger, H.; Kulikov, Y.

2009-09-01

80

Plasma environment of Venus: Comparison of Venus Express ASPERA-4 measurements with 3-D hybrid simulations  

NASA Astrophysics Data System (ADS)

We use data of the ASPERA-4 ion and electron spectrometers onboard Venus Express to determine the locations and shapes of the plasma boundaries (bow shock, ion composition boundary, and mantle) at Venus. We also investigate the variation of the terminator bow shock position as a function of the solar wind dynamic pressure and solar EUV flux. We compare the results with a 3-D hybrid simulation. In the hybrid model, ions are treated as individual particles moving in self-consistently generated electromagnetic fields and electrons are modeled as a massless charge neutralizing fluid. The planetary heavy ion plasma is generated by an oxygen ionosphere and exosphere adapted to a profile, which depends on the solar zenith angle (Chapman layer). A comparison between observations and simulations indicates that the hybrid model is able to produce an adequate picture of the global plasma environment at Venus. The positions of the plasma boundaries are well reproduced by the model but a significant disagreement appears in the absolute values of the considered parameters.

Martinecz, C.; Boesswetter, A.; Fränz, M.; Roussos, E.; Woch, J.; Krupp, N.; Dubinin, E.; Motschmann, U.; Wiehle, S.; Simon, S.; Barabash, S.; Lundin, R.; Zhang, T. L.; Lammer, H.; Lichtenegger, H.; Kulikov, Y.

2009-03-01

81

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

82

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

83

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

84

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

85

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

NASA Astrophysics Data System (ADS)

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

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

2008-09-01

86

Venus Express bistatic radar: High-elevation anomalous reflectivity  

NASA Astrophysics Data System (ADS)

Magellan (MGN) bistatic radar observations in 1994 confirmed earlier Pioneer Venus reports of unusual Venus surface reflectivity and emissivity at elevations above 6054 km radius. They also revealed that the anomalous values of surface dielectric constant $\\varepsilon$ near Cleopatra Patera included a large imaginary component ($\\varepsilon$ ? -i 100) at 13 cm wavelength, consistent with a semiconducting surface material. The MGN observations were conducted using a linearly polarized wave, canted at 45° with respect to the plane of incidence and radiated by the MGN synthetic aperture radar antenna toward the specularly reflecting region of the mean planetary surface. In 2006 similar experiments were conducted using 13 cm circularly polarized transmissions from Venus Express (VEX). The VEX signal-to-noise ratio (SNR) was lower than that of MGN, but elevated ?$\\varepsilon$? has been inferred broadly over Maxwell Montes. A quasi-specular echo was detected near Cleopatra but with insufficient SNR to address the question of conductivity. An early failure of the VEX 13 cm radio system precludes further measurements with VEX.

Simpson, Richard A.; Tyler, G. Leonard; Häusler, Bernd; Mattei, Riccardo; Pätzold, Martin

2009-06-01

87

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

NASA Technical Reports Server (NTRS)

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

Kwok, J. H.

1984-01-01

88

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

NASA Astrophysics Data System (ADS)

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

2006-04-01

89

Mars Express Science Results and Goals for the Extended Mission  

NASA Astrophysics Data System (ADS)

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

Chicarro, A. F.

2006-08-01

90

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

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

91

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

92

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

NASA Astrophysics Data System (ADS)

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

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

2008-05-01

93

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

94

Investigation of the HDO/H2O ratio on Venus from SOIR solar occultations on board Venus Express  

NASA Astrophysics Data System (ADS)

The SOIR instrument performs solar occultation measurements in the IR region (2.2 - 4.3 ?m) at a resolution of 0.12 cm-1, the highest on board Venus Express. It combines an echelle spectrometer and an AOTF (Acousto-Optical Tunable Filter) for the order selection. The wavelength range probed by SOIR allows a detailed chemical inventory of the Venus atmosphere at the terminators in the upper mesosphere and lower thermosphere (70 to 170 km) with an emphasis on vertical distribution of the gases. H2O and HDO have been routinely monitored at various latitudes of the Venus terminator, using the temperature profiles obtained from the SOIR CO2 density profiles. The HDO/H2O ratios are obtained from an altitude region extending from 70 km up to 100 km, and show a vertical gradient. Observations made at the IRTF telescope in Hawaii in 2010 showed a disk-averaged mixing ratio of HDO is 0.22 ± 0.03 ppm for a representative height region of 62-67 km. Based on many previous H2O measurements, the HDO/H2O ratio is found to be 140 ± 20 times larger than the telluric ratio. This lies between the ratios of 120 ± 40 and 240 ± 25, respectively, reported for the 30-40 km region [De Bergh et al. 1991] by ground-based night-side spectroscopy and for the 80-100 km region by solar occultation measurement on board the Venus Express [Fedorova et al. 2008]. In addition to this, past observations at an altitude of 70 km show that HDO on Venus in the early evening shows a latitudinal structure, and HDO mixing ratio at higher latitude is two times larger that in the lower latitude regions. So there is probably a vertical distribution or/and a latitudinal structure. From measurements obtained by SOIR on Venus Express at the Venus terminator, the D/H ratio seems to be very variable, and we confirm that the D/H ratio is larger at higher altitude.

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

2012-04-01

95

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

96

Limb observations of CO2 and CO non-LTE emissions in the Venus atmosphere by VIRTIS/Venus Express  

NASA Astrophysics Data System (ADS)

We report and analyze here observations of strong infrared emissions from the limb of the Venus upper atmosphere during daytime, taken by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) aboard Venus Express. We focus on the measurements taken during the first 4 months of nominal operations. The emissions observed at 4.3 ?m and at 2.7 ?m are attributed to CO2 fluorescence of solar radiation and are detected up to about 160 km and 130 km, respectively, while the CO fluorescence at 4.7 ?m is observed up to about 120 km. The emissions are detected in both the channels of VIRTIS, at different spatial and spectral resolutions (resolving powers about 1800 and 400), for the periapsis and the apoapsis of the Venus Express orbit. From these data sets we built up 2-D maps of the emissions as well as vertical profiles, which are then studied in order to characterize their variations with geophysical parameters, like solar illumination and emission altitude. Several analyses are performed in order to understand the VIRTIS behavior, to determine systematic effects in the data, and to propose appropriate corrections. We also present comparisons with a theoretical nonlocal thermodynamic equilibrium (non-LTE) model of the Venus upper atmosphere. The agreement is very encouraging, in general, and the main variability observed in the data, with solar zenith angle and altitude, can be understood with the model. We conclude that the present data set opens brilliant perspectives for deriving densities and rotational temperatures in the upper mesosphere and lower thermosphere of Venus.

Gilli, G.; López-Valverde, M. A.; Drossart, P.; Piccioni, G.; Erard, S.; Cardesín Moinelo, A.

2009-03-01

97

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

98

Location of the bow shock and ion composition boundaries at Venus—initial determinations from Venus Express ASPERA-4  

NASA Astrophysics Data System (ADS)

For the first time since 1992 when the Pioneer Venus Orbiter (PVO) ceased to operate, there is again a plasma instrument in orbit around Venus, namely the ASPERA-4 flown on Venus Express (inserted into an elliptical polar orbit about the planet on April 11, 2006). In this paper we report on measurements made by the ion and electron sensors of ASPERA-4 during their first five months of operation and, thereby, determine the locations of both the Venus bow shock (BS) and the ion composition boundary (ICB) under solar minimum conditions. In contrast to previous studies based on PVO data, we employ a 3-parameter fit to achieve a realistic shape for the BS. We use a different technique to fit the ICB because this latter boundary cannot be represented by a conic section. Additionally we investigate the dependence of the location of the BS on solar wind ram pressure (based on ASPERA-4 solar wind data) and solar EUV flux (using a proxy from Earth).

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

2008-05-01

99

The first results from the ASPERA-4 instrument of Venus Express  

NASA Astrophysics Data System (ADS)

The Venus Express mission carries the instrument ASPERA-4 Analyzer of Space Plasmas and Energetic Atom to perform for the first time comprehensive plasma measurements at Venus ASPERA-4 is a replica of the instrument ASPERA-3 for the Mars Express mission orbiting Mars for about 2 years The general scientific objective of the ASPERA-4 experiment is to study the solar wind - atmosphere interaction and characterize the plasma atmospheric escape through energetic neutral atom ENA imaging and in-situ ion and electron measurements The ASPERA-4 instrument comprises four sensors two ENA sensors and an electron and ion spectrometer The Neutral Particle Imager NPI provides measurements of the integral ENA flux in the energy range 0 1 - 60 keV with no mass and energy resolution but comparatively high angular resolution 4 6 deg x 11 5 deg The Neutral Particle Detector NPD provides measurements of the ENA flux in the energy range 0 1 - 10 keV resolving velocity and mass H and O with a coarse angular resolution The Electron Spectrometer ELS is a standard top-hat electrostatic analyzer in a very compact design with the high 8 energy resolution to perform photoelectron spectroscopy These three sensors are located on a scanning platform to cover ideally the full sphere Ion Mass Analyzer IMA provides ion measurements in the energy range 0 01 - 30 keV q for the main ion components 1 2 4 16 amu q and the group of molecular ions 20 - 80 amu q The instantaneous field of view is 4 6 deg x 360 deg Electrostatic sweeping performs the elevation 90 deg

Barabash, S.; Sauvaud, J.-A.; Fedorov, A.; Aspera-4

100

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

101

Quantification of middle and lower cloud variability and mesoscale dynamics from Venus Express/VIRTIS observations at 1.74 ?m  

NASA Astrophysics Data System (ADS)

We present an analysis of VIRTIS-M-IR observations of 1.74 ?m emission from the nightside of Venus. The 1.74 ?m window in the near infrared spectrum of Venus is an ideal proxy for investigating the evolution of middle and lower cloud deck opacity of Venus because it exhibits good signal to noise due to its brightness, good contrast between bright and dark regions, and few additional sources of extinction beside the clouds themselves. We have analyzed the data from the first 407 orbits (equivalent to 407 Earth days) of the Venus Express mission to determine the magnitude of variability in the 1.74 ?m radiance. We have also performed an analysis of the evolution of individual features over a span of roughly 5-6 h on two successive orbits of Venus Express. We find that the overall 1.74 ?m brightness of Venus has been increasing through the first 407 days of the mission, indicating a gradual diminishing of the cloud coverage and/or thickness, and that the lower latitudes exhibited more variability and more brightening than higher latitudes. We find that individual features evolve with a time scale of about 30 h, consistent with our previous analysis. Analysis of the evolution and motion of the clouds can be used to estimate the mesoscale dynamics within the clouds of Venus. We find that advection alone cannot explain the observed evolution of the features. The measured vorticity and divergence in the vicinity of the features are consistent with evolution under the influence of significant vertical motions likely driven by a radiative dynamical feedback. We measure a zonal wind speed of around 65 m/s, and a meridional wind speed around 2.5 m/s by tracking the motion of the central region of the features. But we also find that the measured wind speeds depend strongly on the points chosen for the wind speed analysis.

McGouldrick, Kevin; Momary, Thomas W.; Baines, Kevin H.; Grinspoon, David H.

2012-02-01

102

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

103

Climatology of the neutral atmosphere as measured by SOIR on board Venus Express  

NASA Astrophysics Data System (ADS)

The SOIR instrument on board Venus Express performs solar occultation measurements in the IR region (2.2 - 4.3 µm) at a resolution of 0.12 cm-1, the highest on board Venus Express. It combines an echelle spectrometer and an AOTF (Acousto-Optical Tunable Filter) for the order selection [1, 2]. The wavelength range probed by SOIR allows a detailed chemical inventory of the Venus atmosphere above the cloud layer with an emphasis on vertical distribution of the [3, 4] H2O, HCl, HF, CO gases, as well as those of their isotopologues. Recent improvements of the retrieval method [5] allowed us to reinvestigate the vertical profiles of these minor constituents of the Venus mesosphere. In addition, the number of occultations dedicated to the above-mentioned molecules in combination with CO2 measurements (the major constituent of the Venus atmosphere) increased by more than 50 % during last year. The complete data set now covers 2.5 years with fairly good geographical coverage, although limited by the geometry of the orbit. We will present the climatology for some of the observed species. 1. Mahieux, A., et al., In-Flight performance and calibration of SPICAV SOIR on board Venus Express. Applied Optics, 2008. 47(13): p. 2252-65. 2. Nevejans, D., et al., Compact high-resolution space-borne echelle grating spectrometer with AOTF based on order sorting for the infrared domain from 2.2 to 4.3 micrometer. Applied Optics, 2006. 45(21): p. 5191-5206. 3. Fedorova, A., et al., HDO and H2O vertical distribution and isotopic ratio in the Venus mesosphere by Solar Occultation at Infrared spectrometer on board Venus Express. JGR, 2008. 113, E00B22: p. doi:10.1029/2008JE003146. 4. Vandaele, A.C., et al., Composition of the Venus mesosphere measured by SOIR on board Venus Express. J. Geophys. Res., 2008. 113, E00B23: p. doi:10.1029/2008JE003140. 5. Mahieux, A., et al., Venus atmospheric densities and temperature profiles retrieved from SOIR solar occultations on board Venus Express. J . Geophys . Res . 2010. (submitted).

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

2010-05-01

104

Future Exploration of Venus: Opportunities and Challenges  

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

105

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

106

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

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

107

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

108

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

109

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

110

Investigation of winds in Venus mesosphere by digital method using UV images from VMC aboard Venus Express.  

NASA Astrophysics Data System (ADS)

Investigation of winds at the top cloud layer is important for understanding the global circulation of the Venus atmosphere. The Venus Monitoring Camera (VMC) aboard Venus Express has acquired a huge number of UV (365 nm) images. UV images of top cloud layer are customary to obtain the wind velocity due to their high contrast. Visual estimation of wind velocities is a labor intensive procedure. Authors have developed a digital method to estimate velocities of shifts of cloud details. The method is based on analysis of correlations between two UV images acquired at different moments. The method takes into account the change of a correlation function due to latitudinal peculiarities of cloud morphology and eliminates image regions which are far from the sub-spacecraft point. The digital method provides with good vector coverage of the Venus day side (9-16 local time) from the equator to high latitudes. The best agreement between the digital and visual methods is observed at low latitudes (below 35S). The discrepancy at higher latitudes is related to complicated cloud morphology, namely domination of streaks, which increases errors in the zonal wind speed. The method is productive for long-scale circulation at the top cloud layer. Sizes of regions for correlation were chosen empirically as a trade-off of sensitivity against noise immunity and varies from 10x7.5 ° to 20x10 ° depending on grid step. 580 orbits covering ten Venus years have been processed by using the digital method. The database of shift vectors counts about 400000 records. The mean wind speed at low latitudes is about 100 m/s. Wind vector fields were obtained for every orbit. The zonal wind speed in the equatorial region exhibits short-period (about 4.8 days) and long-period variations (long-term trend). Vector field averaged by all orbits show deviations of the main stream up to 5 degrees poleward in the early afternoon (12.5-14.5h) at 45-55S. The mean absolute value of the wind speed increases from 59.38 m/s at 10-12h to 76.46 m/s at 12.5-14.5h at the same latitude interval.

Patsaeva, Marina; Khatuntsev, Igor; Ignatiev, Nikolai

2013-04-01

111

Unveiling Venus  

NASA Astrophysics Data System (ADS)

As of this writing, the USSR's Venus-exploration probes have accomplished atmospheric analyses at different altitudes in the Venus atmosphere, pressure and temperature readings, lightning observations, wind-velocity measurements, close-up terrain imaging, in situ rock and soil analyses, seismic measurements, and radar terrain-imaging from orbit. While NASA's accomplishments are fewer, the Magellan Venus Radar Mapper will furnish a wealth of new information beginning in August, 1990. Magellan will use the same antenna to both scan the Venus surface and transmit the resulting data back to earth at 268.8 kbit/sec. Magellan will cover up to 90 percent of the Venus surface in the course of its 'nominal' mission, lasting an entire Venusian day.

Bulloch, Chris

1989-06-01

112

High Temperature Mechanisms for Venus Exploration  

Microsoft Academic Search

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

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

2008-01-01

113

Scientific investigations of the Mars Express mission  

Microsoft Academic Search

The ESA Mars Express mission will be launched in May 2003 from Baikonur onboard a Russian Soyuz\\/Fregat launcher. The mission comprises an orbiter spacecraft to be placed in a quasi-polar martian orbit, with closest approach at 250 km and a mission lifetime of one martian year (687 days), and the small Beagle-2 probe to land at Isidis Planitia in December

A. F. Chicarro

2003-01-01

114

Correlations between Venus nightside near infrared emissions measured by VIRTIS/Venus Express and Magellan radar data  

NASA Astrophysics Data System (ADS)

Background The Venus Express Spacecraft images the nightside thermal emissions using the VIRTIS imaging spectrometer. At 1.02 micron thermal emission from the surface is penetrates the atmosphere but the signal is attenuated by scattering and absorption [1, 2]. Although the measured flux at top of the atmosphere is nonlinearly related to the original emission of the surface, it is still positively correlated with the product of surface temperature and surface emissivity [3]. The surface temperature of Venus is relatively well constrained as a monotonous function of altitude. Emissivity at 1 micron depends strongly on surface composition, in particular abundance of mafic minerals [3]. Mapping the thermal emission of the surface of Venus therefore supplements radar data as it allows to infer relative variation of surface composition. Data Processing This study examines the correlation of VIRTIS images showing a signal of the surface with all known parameters that govern radiance and applies semi empirical relations to remove the respective influences. 1. Stray sunlight is removed by subtraction of a spectrum template scaled to fit radiance at 1.4 ¹m [2] 2. Limb darkening is accounted for using a linear phase function consistent with results of radiative transfer modeling [4]. 3. Cloud opacity is determined from 1.31 ¹m and applied to 1.02 ¹m while accounting for multiple reflections between lower atmosphere and clouds [3]. Result is brightness temperature of thermal emission below the cloud deck but above the lowest 20 km of the atmosphere. 4. Influence of surface temperature and lower atmosphere absorption is determined by correlation of VIRTIS declouded brightness temperature and Magellan Topography data [5]. To further reduce the influence of cloud contrast and increase the signal of the surface, all suitable VIRTIS observations are map projected and stacked to create a map of the southern hemisphere of Venus. Observations and Interpretation As expected from the small diurnal, latitudinal and seasonal variations of temperature in the atmosphere of Venus, the map created from all retrieved brightness temperatures is highly correlated with Magellan altimetry (fig. 1). Local deviation from the globally averaged brightness to topography relation can be either ascribed to surface emissivity or unexpected temperature variations. Temperature variations e.g. due to active volcanism are unlikely to be persistent over the time of observations. The stacked data is here interpreted in terms of surface emissivity variation by removal of the influence of topography (fig. 2). The emissivity variation found is correlated with geomorphological features established from Magellan radar images. It is generally lower at tessera terrain. This might indicate felsic surface composition of tessera highlands, e.g. anorthosite or granite [6, 7]. Creation of felsic crust is unlikely under current conditions. Some, but not all volcanic edifices show increased emissivity. Large lava flows in the Lada terra - Lavinia planitia region also show an increased thermal emission. In particular Cavilaca and Juturna fluctus, emanating from Boala corona (70S 0E) inside Quetzalpetlatl corona, are characterized by an increased IR flux. This might be consistent with the large scale extrusive volcanism of ultramafic composition considered by [8] in the context of chemical differentiation in the upper mantle. Discussion These observations are however highly sensitive to errors in the altimetry applied. A known systematic error in the Magellan dataset stemming from spacecraft orbit determination uncertainty is qualitatively confirmed by comparison with VIRTIS data (see longitude -120 in fig. 1 and 2. Tessera terrain is known to strongly scatter radar waves which might influences accuracy of altimetry. An quantitative analysis and search for small scale systematic errors is in progress during the submission of this abstract. References [1] Lecacheux, J., P. Drossart, P. Laques, F. Deladerriere, and F. Colas (1993), Detection of the surface of Venus at 1.0 micromet

Mueller, N.; Helbert, J.; Hashimoto, G. L.; Tsang, C. C. C.; Erard, S.; Piccioni, G.; Drossart, P.

2008-09-01

115

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

116

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

NASA Astrophysics Data System (ADS)

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

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

117

The Venus ionosphere  

Microsoft Academic Search

Physical properties of the Venus ionosphere obtained by experiments on the US Pioneer Venus and the Soviet Venera missions are presented in the form of models suitable for inclusion in the Venus International Reference Atmosphere. The models comprise electron density (from 120 km), electron and ion temperatures, and relative ion abundance in the altitude range from 150 km to 1000

S. J. Bauer; L. M. Brace; H. A. Taylor Jr.; T. K. Breus; A. J. Kliore

1985-01-01

118

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

119

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

120

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

121

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

122

Atmospheric studies with the Mars Express mission  

Microsoft Academic Search

The Mars Express mission, including an orbiter sp acecraft and a small Beagle-2 lander, will be launched in 2003 by a Soyuz rocket from Baikonur. In addition to a wide variety of scientific objectives concerning the global coverage of the planet for studies of the surface geology and mineralogy, subsurface structure, and atmospheric circulation, composition and escape, as well as

A. Chicarro

2002-01-01

123

The Venus ionosphere  

NASA Technical Reports Server (NTRS)

Physical properties of the Venus ionosphere obtained by experiments on the US Pioneer Venus and the Soviet Venera missions are presented in the form of models suitable for inclusion in the Venus International Reference Atmosphere. The models comprise electron density (from 120 km), electron and ion temperatures, and relative ion abundance in the altitude range from 150 km to 1000 km for solar zenith angles from 0 to 180 deg. In addition, information on ion transport velocities, ionopause altitudes, and magnetic field characteristics of the Venus ionosphere, are presented in tabular or graphical form. Also discussed is the solar control of the physical properties of the Venus ionosphere.

Bauer, S. J.; Brace, L. M.; Taylor, H. A., Jr.; Breus, T. K.; Kliore, A. J.

1985-01-01

124

A solar storm observed from the Sun to Venus using the STEREO, Venus Express, and MESSENGER spacecraft  

NASA Astrophysics Data System (ADS)

The suite of SECCHI optical imaging instruments on the STEREO-A spacecraft is used to track a solar storm, consisting of several coronal mass ejections (CMEs) and other coronal loops, as it propagates from the Sun into the heliosphere during May 2007. The 3-D propagation path of the largest interplanetary CME (ICME) is determined from the observations made by the SECCHI Heliospheric Imager (HI) on STEREO-A (HI-1/2A). Two parts of the CME are tracked through the SECCHI images, a bright loop and a V-shaped feature located at the rear of the event. We show that these two structures could be the result of line-of-sight integration of the light scattered by electrons located on a single flux rope. In addition to being imaged by HI, the CME is observed simultaneously by the plasma and magnetic field experiments on the Venus Express and MESSENGER spacecraft. The imaged loop and V-shaped structure bound, as expected, the flux rope observed in situ. The SECCHI images reveal that the leading loop-like structure propagated faster than the V-shaped structure, and a decrease in in situ CME speed occurred during the passage of the flux rope. We interpret this as the result of the continuous radial expansion of the flux rope as it progressed outward through the interplanetary medium. An expansion speed in the radial direction of ˜30 km s-1 is obtained directly from the SECCHI-HI images and is in agreement with the difference in speed of the two structures observed in situ. This paper shows that the flux rope location can be determined from white light images, which could have important space weather applications.

Rouillard, A. P.; Davies, J. A.; Forsyth, R. J.; Savani, N. P.; Sheeley, N. R.; Thernisien, A.; Zhang, T.-L.; Howard, R. A.; Anderson, B.; Carr, C. M.; Tsang, S.; Lockwood, M.; Davis, C. J.; Harrison, R. A.; Bewsher, D.; Fränz, M.; Crothers, S. R.; Eyles, C. J.; Brown, D. S.; Whittaker, I.; Hapgood, M.; Coates, A. J.; Jones, G. H.; Grande, M.; Frahm, R. A.; Winningham, J. D.

2009-07-01

125

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

126

Solar wind interaction with Venus and impact on its atmosphere  

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

127

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

NASA Astrophysics Data System (ADS)

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

Haus, Rainer; Kappel, David; Arnold, Gabriele

2015-01-01

128

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

129

Venus Atmosphere Dynamics Workshop  

Microsoft Academic Search

There has been considerable renewed interest in modeling the dynamics of the Venus atmosphere and getting to the bottom of the problem of what drives the atmospheric superrotation and other observed phenomena such as the polar vortex. The renewal of modeling activity has been inspired by the development of highly capable computers and spacecraft missions that have recently visited Venus

G. Schubert; C. C. Covey

2007-01-01

130

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

131

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

NASA Astrophysics Data System (ADS)

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

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

2008-05-01

132

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

133

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

134

Technology perspectives in the future exploration of Venus  

NASA Astrophysics Data System (ADS)

Science goals to understand the origin, history and environment of Venus have been driving international space exploration missions for over 40 years. Today, Venus is still identified as a high priority science target in NASA's Solar System Exploration Roadmap, and clearly fits scientific objectives of ESA's Cosmic Vision Program in addition to the ongoing Venus Express mission, while JAXA is planning to launch its own Venus Climate Orbiter. Technology readiness has often been the pivotal factor in mission prioritization. Missions in all classes—small, medium or large—could be designed as orbiters with remote sensing capabilities, however, the desire for scientific advancements beyond our current knowledge point to in-situ exploration of Venus at the surface and lower atmosphere, involving probes, landers, and aerial platforms. High altitude balloons could circumnavigate Venus repeatedly; deep probes could operate for extended periods utilizing thermal protection technologies, pressure vessel designs and advancements in high temperature electronics. In situ missions lasting for over an Earth day could employ a specially designed dynamic Stirling Radioisotope Generator (SRG) power system, that could provide both electric power and active thermal control to the spacecraft. An air mobility platform, possibly employing metallic bellows, could allow for all axis control, long traversing and surface access at multiple desired locations, thus providing an advantage over static lander or rover based architectures. Sample return missions are also featured in all planetary roadmaps. The Venus exploration plans over the next three decades are anticipated to greatly contribute to our understanding of this planet, which subsequently would advance our overall knowledge about Solar System history and habitability.

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

135

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

136

Exploring Venus: Major scientific issues and directions  

NASA Astrophysics Data System (ADS)

Venus has been a prime target of space exploration since the launch of Venera-1 in 1961. In 1962, Mariner 2 determined that the surface of Venus is hot, providing the first confirmation of its immense greenhouse effect. Venus has now been visited by numerous flybys, orbiters, atmospheric probes, landers, and balloons! Magellan's radar pierced the planet-encircling clouds to provide a global map of the Venus surface. Table 1 lists the chronology of Venus missions. Despite the numerous missions, the Venus environment provides a difficult target, and many significant questions remain unanswered. The state of current knowledge, the open questions, and ways to address them are discussed in the following chapters.

Esposito, Larry W.; Stofan, Ellen R.; Cravens, Thomas E.

137

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

138

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

139

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

NASA Astrophysics Data System (ADS)

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

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

2008-05-01

140

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

NASA Technical Reports Server (NTRS)

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

Chin, Gordon

2011-01-01

141

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. PMID:24475166

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

2014-01-01

142

HDO and H2O vertical distributions and isotopic ratio in the Venus mesosphere by Solar Occultation at Infrared spectrometer on board Venus Express  

NASA Astrophysics Data System (ADS)

Vertical distributions of the molecular density and mixing ratios of H2O and HDO in the Venus mesosphere have been obtained using Solar Occultation at Infrared (SOIR), a high-resolution (with ?/?? ~ 20,000) echelle spectrometer on Venus Express. The atmosphere is sounded in solar occultation in the range of altitudes from 65 to 130 km. Simultaneous measurements of water vapor lines in the spectral range around 2.61 ?m (3830 cm-1) at altitudes between 70 and 110 km and HDO lines around 3.58 ?m (2715cm-1) at altitudes 70-95 km have been performed. During 1 1/2 years, from April 2006 to August 2007, 54 such measurements have been carried out at different locations of Venus from the north pole to middle south latitudes. Most of the observations at morning and evening terminator correspond to high northern latitudes. We report values of mixing ratio and isotopic ratio obtained for 22 of those measurements occurring in the northern polar area. The average value of the volume mixing ratio of H2O is 1.16 +/- 0.24 ppm and that of HDO is 0.086 +/- 0.020 ppm. A depletion in the mixing ratio for both H2O and HDO is observed at 85 km, which can be related to a depletion of CO2 density above (~95 km) and a possible temperature inversion at these altitudes. The vertical variation of HDO and H2O mixing ratio is within a factor of 2-3 for the analyzed set of observations. The temporal variations have been investigated, and no noticeable variability of H2O is reported at high northern altitudes. The average ratio of HDO/H2O obtained in this work, 240 +/- 25 times the terrestrial ratio, is higher (~1.5 times) than the value of 157 +/- 30 times terrestrial reported for the lower atmosphere. This could be explained by a lower photodissociation of HDO and/or a lower escape rate of D atoms versus H atoms.

Fedorova, A.; Korablev, O.; Vandaele, A.-C.; Bertaux, J.-L.; Belyaev, D.; Mahieux, A.; Neefs, E.; Wilquet, W. V.; Drummond, R.; Montmessin, F.; Villard, E.

2008-12-01

143

Pioneer Venus orbiter  

NASA Technical Reports Server (NTRS)

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

1974-01-01

144

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

145

A Study of Lower Atmosphere Dynamics And Search For Active Volcanism On Venus : Preliminary Work To Venus Express Mission  

NASA Astrophysics Data System (ADS)

Although Venusian lower atmosphere is optically unreachable from Earth, near IR spectro-imagery provides an interesting way to study it : night-side ground thermal emission is strong in the K-window, in which CO2 opacity is weak enough for other consituents to be detected. Our first results are abundance estimates for CO and OCS in function of latitude at several different longitudes. Whenever the S/N ratio is good enough, there appears to be a North/South asymmetry in CO distribution. Data were acquired at IRTF using SpeX spectro-imager, during Venusian quadratures in Feb. 2003 and in Aug. 2004 (more recently and not yet processed). The purpose of this work is to use these minor consituents as tracers to study the yet badly known dynamics of Venusian troposphere below the cloudy layers, as well as detecting ground-based sources of sulphured gases, thus helping in active volcanism detection.

Marcq, E.; Encrenaz, T.; Bézard, B.; Birlan, M.

2004-11-01

146

The Lavoisier mission : A system of descent probe and balloon flotilla for geochemical investigation of the deep atmosphere and surface of Venus  

NASA Astrophysics Data System (ADS)

Lavoisier mission is a joint effort of eight European countries and a technological challenge aimed at investigating the lower atmosphere and the surface of Venus. The mission consists of a descent probe and three balloons to be deployed below the cloud deck. Its main scientific objectives may be summarized as following : (i) composition of the deep atmosphere : noble gas (elemental/isotopic), molecular species (elemental/ isotopic), oxygen fugacity; vertical/horizontal/temporal variability; (ii) infrared spectroscopy and radiometry (molecular composition, radiative transfer); (iii) dynamics of the atmosphere : p, T, acceleration measurements, balloon localization through VLBI, meteorological events signed by acoustic waves, atmospheric mixing as imprinted on radioactive tracers; (iv) surface morphology and mineralogy through near infrared imaging on dayside, surface temperature through NIR imaging on nightside. Additional tentative objectives are search for (a) atmospheric electrical activity (optically, radioelectrically, acoustically), (b) crustal outgassing and/or volcanic activity : acoustic activity, horizontal/vertical distribution of radioactive tracers, (c) seismic activity : acoustic waves transmitted from crust to atmosphere, and (d) remanent and/or intrinsic magnetic field. Lavoisier was proposed to ESA in response to the F2/F3 mission Announcement of Opportunity at the beginning of 2000, but it was not selected for the assessment study. A wide international partnership was created for this occasion, including Finland (FMI), France (IPSL, MAGIE, Université Orsay, IPSN, INPG, CEA, IPGP, Obs. Paris-Meudon), Germany (MPAe, Univ. Muenster), Hungary (KFKI, Univ. Eotvos), Portugal (OAL), Russia (IKI), Spain (IAA), United Kingdom (Univ. Oxford).

Chassefière, E.; Berthelier, J. J.; Bertaux, J.-L.; Quèmerais, E.; Pommereau, J.-P.; Rannou, P.; Raulin, F.; Coll, P.; Coscia, D.; Jambon, A.; Sarda, P.; Sabroux, J. C.; Vitter, G.; Le Pichon, A.; Landeau, B.; Lognonné, P.; Cohen, Y.; Vergniole, S.; Hulot, G.; Mandéa, M.; Pineau, J.-F.; Bézard, B.; Keller, H. U.; Titov, D.; Breuer, D.; Szego, K.; Ferencz, Cs.; Roos-Serote, M.; Korablev, O.; Linkin, V.; Rodrigo, R.; Taylor, F. W.; Harri, A.-M.

147

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

148

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

NASA Astrophysics Data System (ADS)

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

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

2010-03-01

149

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

150

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

NASA Astrophysics Data System (ADS)

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

Ksanfomality, L. V.

2014-11-01

151

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

152

The Infrared Limb Darkening of Venus  

Microsoft Academic Search

The observed infrared limb darkening of Venus in the 8- to 13-micron interval and over the observed range in tz, the cosine of the Venus zenith angle, can be expressed as t , where a  0.5, according to two independent sets of measurements. Three general categories of models of the atmosphere and clouds of Venus are here proposed to

James B. Pollack; Carl Sagan

1965-01-01

153

Venus Atmosphere and Surface Explorer  

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

154

AMTEC radioisotope power system for the Pluto Express mission  

SciTech Connect

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

Ivanenok, J.F. III; Sievers, R.K. [Advanced Modular Power Systems, Inc., Ann Arbor, MI (United States)

1995-12-31

155

The geological mapping project of the Mars Express mission  

Microsoft Academic Search

The ESA mission Mars Express will send three instruments with geological mapping capability: HRSC, OMEGA, and MARSIS. The HRSC is a camera that will provide medium to high-resolution images (about 10m\\/pixel to 2m\\/pixel) in colour and stereo. OMEGA will provide maps of the surface mineralogy. MARSIS is a subsurface penetrating radar that will bring back data at depth in excess

G. G. Ori; A. di Iorio

2003-01-01

156

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

157

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

158

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

159

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

160

Venus Transit 2004  

NASA Astrophysics Data System (ADS)

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

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

2002-09-01

161

Return to Venus of the Japanese Venus Climate Orbiter AKATSUKI  

NASA Astrophysics Data System (ADS)

Japanese Venus Climate Orbiter/AKATSUKI was proposed in 2001 with strong support by international Venus science community and approved as an ISAS (The Institute of Space and Astronautical Science) mission soon after the proposal. The mission life we expected was more than two Earth years in Venus orbit. AKATSUKI was successfully launched at 06:58:22JST on May 21, 2010, 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' deployment was confirmed. After a successful cruise, the malfunction happened on the propulsion system during the Venus orbit insertion (VOI) on Dec. 7, 2010. The engine shut down before the planned reduction in speed to achieve. The spacecraft did not enter the Venus orbit but entered an orbit around the Sun with a period of 203 days. Most of the fuel still had remained, but the orbital maneuvering engine was found to be broken and unusable. However, we have found an alternate way of achieving orbit by using only the reaction control system (RSC). We had adopted the alternate way for orbital maneuver and three minor maneuvers in Nov. 2011 were successfully done so that AKATSUKI would meet Venus in 2015. We are considering several scenarios for VOI using only RCS.

Nakamura, Masato; Kawakatsu, Yasuhiro; Hirose, Chikako; Imamura, Takeshi; Ishii, Nobuaki; Abe, Takumi; Yamazaki, Atsushi; Yamada, Manabu; Ogohara, Kazunori; Uemizu, Kazunori; Fukuhara, Tetsuya; Ohtsuki, Shoko; Satoh, Takehiko; Suzuki, Makoto; Ueno, Munetaka; Nakatsuka, Junichi; Iwagami, Naomoto; Taguchi, Makoto; Watanabe, Shigeto; Takahashi, Yukihiro; Hashimoto, George L.; Yamamoto, Hiroki

2014-01-01

162

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

163

Chasing Venus  

NSDL National Science Digital Library

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

2009-05-20

164

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

165

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

166

Scientists Identify Exploration Goals for Venus  

NASA Astrophysics Data System (ADS)

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

Kumar, Mohi

2014-04-01

167

Optimizing Aerobot Exploration of Venus  

NASA Technical Reports Server (NTRS)

Venus Flyer Robot (VFR) is an aerobot; an autonomous balloon probe designed for remote exploration of Earth's sister planet in 2003. VFR's simple navigation and control system permits travel to virtually any location on Venus, but it can survive for only a limited duration in the harsh Venusian environment. To help address this limitation, we develop: (1) a global circulation model that captures the most important characteristics of the Venusian atmosphere; (2) a simple aerobot model that captures thermal restrictions faced by VFR at Venus; and (3) one exact and two heuristic algorithms that, using abstractions (1) and (2), construct routes making the best use of VFR's limited lifetime. We demonstrate this modeling by planning several small example missions and a prototypical mission that explores numerous interesting sites recently documented in the plane tary geology literature.

Ford, Kevin S.

1997-01-01

168

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

2008-07-01

169

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

NASA Astrophysics Data System (ADS)

Venus Express is an ESA spacecraft orbiting Venus since April 2006. The instrument VIRTIS acquires multispectral images in the range from 0.2 to 5 m wavelength. An analysis of VIRTIS images at the wavelengths of the atmospheric window at 1.02 m shows evidence for variation of surface emissivity on the southern hemisphere [Mueller et al. 2008]. Inferred surface emissivity is correlated to some extend with morphological units identified from radar images of the NASA/JPL Magellan mission [Tanaka et al. 1997]. Alpha and Phoebe Regios are highlands mostly composed of tessera terrain, which is defined as a region strongly deformed by compressive and extensional tectonism in at least two directions. In comparison to lowland plains and other less tectonized highlands, these regions generally emit less thermal radiation, which implies lower emissivity. A recent analysis of NIR data from the Galileo fly-by in 1990 finds, that highland regions on Venus on average have a lower emissivity than lowlands [Hashimoto et al. 2008]. As a significant part of Venus highlands in the area observed by Galileo is composed of tessera, this observation is consistent with the observation of Mueller et al. [2008]. In situ measurements by the Venera and Vega landers are at most places consistent with basaltic surface composition. The hypsometry of Venus is unimodal. Inferred lava viscosity of most volcanic features is low, consistent with basaltic composition. All these observations hint towards a crust mostly composed of basalt [Basilevsky et al 1997]. However, no landing site was on tessera terrain, tessera are hypsometrically elevated and the morphology is dominated by tectonic deformation. Among other arguments this leads to the hypothesis that tessera highlands crust is more abundant in feldspar and silica, comparable to lunar highlands or continents on Earth [Nikolaeva et al., 1992]. NIR mapping supports this hypothesis, although other interpretations of the NIR data can not be ruled out. Generation of felsic crust is unlikely under the current climatic and tectonic regime on Venus. The lunar highland crust is believed to be a remnant of an magma ocean [Taylor 1974]. Enrichment in silica as in the continental crust of Earth requires recycling of water into the mantle [Campbell and Taylor 1984]. The surface of Venus is extremely dry and Venus and crustal recycling by plate tectonics does not operate at present. Any crust with felsic bulk composition had to be created during the early history of the planet. In a stratigraphic analysis tessera terrain predates all units it is in contact with [Ivanov and Head 1996]. Tessera terrain is defined by an extensive history of tectonic deformation. Assuming that tessera highlands indeed represent less dense crustal blocks created early in the history of Venus, implications arise from their persistence on the surface of Venus regarding resurfacing mechanism, crustal recycling and thermal evolution. If tessera highlands are enriched in silica relative to basalt this implies existence of a primordial ocean on Venus [Hashimoto et al. 2008]. In either case Venus would even more closely resemble the Earth-Moon system than previously assumed, making Venus an excellent subject for general studies of earth-like planets. Basilevsky, A. T.,et al. (1997), The Resurfacing History of Venus, in Venus II, pp. 1047-1084. Hashimoto, et al. (2008), Galileo Near Infrared Mapping Spectrometer (NIMS) Data Suggests Felsic Highland Crust on Venus, JGR, in press. Ivanov, M. A., et al. (1996), Tessera terrain on Venus: A survey of the global distribution, characteristics, and relation to surrounding units from Magellan data, JGR, 101, 14,861-14,908. Mueller, N., et al. (2008), Venus surface thermal emission at one micrometer in VIRTIS imaging observations - evidence for variation of crust and mantle differentiation conditions, JGR , in press. Nikolaeva, O. V., et al. (1992), Evidence on the crustal dichotomy, pp. 129-139, Venus Geology, Geochemistry, and Geophysics - Research results from the USSR. Tanaka, K. L., et al. (1997), Phy

Müller, N.; Helbert, J.

2009-04-01

170

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

171

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

172

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.

173

Venus Atmospheric Maneuverable Platform (VAMP)  

NASA Astrophysics Data System (ADS)

Over the past years we have explored a possible new approach to Venus upper atmosphere exploration by applying recent Northrop Grumman (non-NASA) development programs to the challenges associated with Venus upper atmosphere science missions. Our concept is a low ballistic coefficient (<50 Pa), semibuoyant aircraft that deploys prior to entering the Venus atmosphere, enters the Venus atmosphere without an aeroshell, and provides a long-lived (months to years), maneuverable vehicle capable of carrying science payloads to explore the Venus upper atmosphere. VAMP targets the global Venus atmosphere between 55 and 70 km altitude and would be a platform to address VEXAG goals I.A, I.B, and I.C. We will discuss the overall mission architecture and concept of operations from launch through Venus arrival, orbit, entry, and atmospheric science operations. We will present a strawman concept of VAMP, including ballistic coefficient, planform area, percent buoyancy, inflation gas, wing span, vehicle mass, power supply, propulsion, materials considerations, structural elements, subsystems, and packaging. The interaction between the VAMP vehicle and the supporting orbiter will also be discussed. In this context, we will specifically focus upon four key factors impacting the design and performance of VAMP: 1. Science payload accommodation, constraints, and opportunities 2. Characteristics of flight operations and performance in the Venus atmosphere: altitude range, latitude and longitude access, day/night performance, aircraft performance, performance sensitivity to payload weight 3. Feasibility of and options for the deployment of the vehicle in space 4. Entry into the Venus atmosphere, including descent profile, heat rate, total heat load, stagnation temperature, control, and entry into level flight We will discuss interdependencies of the above factors and the manner in which the VAMP strawman's characteristics affect the CONOPs and the science objectives. We will show how the these factors provide constraints as well as enable opportunities for novel long duration scientific studies of the Venus upper atmosphere that support VEXAG goals I.A, I.B, and I.C.. We will also discuss how the VAMP platform itself can facilitate some of these science measurements.

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

2014-04-01

174

Portuguese Participation In The Mars Express/beagle2 Mission  

NASA Astrophysics Data System (ADS)

Three Portuguese groups responded to the European Space Agency (ESA) second an- nouncement of opportunities for the Mars Express Mission. Projects were submitted in the fields Atmosphere and Surface/Atmosphere Interaction, Exobiology and Geologi- cal Evolution. Contacts among the groups revealed large areas of potential interaction and a necessity of active data, methods and analysis interchange. The projects will be executed in the period 2002-2006, and aim to analyse the information that will be conveyed by instruments aboard the Mars Express Orbiter and Beagle 2 Lander. Our combined projects propose to yield seven products: the Mars Orbital Viewer U MOVie U ; an apparent thermal inertia (ATI) map; a high-resolution water stability map; a lithostructural map; a hydrological potential map; a local assessment of poten- tial biomarkers; a geological map of Mars. MOVie will be a virtual-reality addressable map of Mars, based on stereoscopic images from the HSRC camera. The ATI map will draw on data from both the OMEGA (VNIR band) and PFS (NIR/TIR band) instru- ments. This map will enrich the existing atmospheric circulation models and help in the discrimination of lithotypes and hydric potential. One of our main objectives is to address the question whether water release does occur in the present epoch, which will be done by analysing the water vapour content in the low atmosphere. Data ar- riving from Beagle 2 will also be the basis for the assessment of methane contents on low martian atmosphere and soil-adsorbed gases. Atmosphere, soil and rock compo- sition data from the lander will allow for the correction of remotely sensed spectra. Classification will proceed in two phases: first an expert system will evaluate point lithologies from mineral and rock spectra; then those point lithologies will be mapped onto the planetary surface by a self-organising neural network. Mathematical mor- phology operators will also be used to perform the classification of Mars surface by incorporating textural features, thus biasing the neural network into defining litho- logical patterns that correspond to regions with a higher hydric potential. The hydric potential map will draw on data from the lithostructural map, the water stability map and the MARSIS - microwave - instrument. Integration of all data will be achieved on the final geological map of Mars. The procedures developed in these projects will be reusable, with minor adjustements due to different instrumental setups, on other planetary missions, even for remote sensing of the Earth.

Alves, E. I.; Portuguese Mx Teams

175

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

176

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

177

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

178

Comparative analysis of Venus and Mars magnetotails  

NASA Astrophysics Data System (ADS)

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

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

2008-05-01

179

Magellan paints a portrait of Venus  

NASA Astrophysics Data System (ADS)

A brief review is made of some of the findings of the Magellan mission to Venus. Examples of the high-resolution radar images produced by Magellan are shown and discussed. The objectives of the planned extension of the Magellan mission are addressed.

Kerr, R. A.; Tancredi, G.; Gallardo, T.

1991-03-01

180

Pioneer Venus orbiter electron temperature probe  

NASA Technical Reports Server (NTRS)

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

Brace, Larry H.

1994-01-01

181

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.

182

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

183

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

184

Hypothetical flora and fauna of Venus  

NASA Astrophysics Data System (ADS)

Hypothetical habitability of some of extrasolar planets is a fundamental question of science. Some of exoplanets possess physical conditions close to those of Venus. Therefore, the planet Venus, with its dense and hot (735 K) oxygen-free atmosphere of CO2, having a high pressure of 9.2 MPa at the surface, can be a natural laboratory for this kind of studies. The only existing data on the planet's surface are still the results obtained by the Soviet VENERA landers in the 1970s and 1980s. The TV experiments of Venera-9 and 10 (October, 1975) and Venera-13 and 14 (March, 1982) delivered 41 panoramas of Venus surface (or their fragments). There have not been any similar missions to Venus in the subsequent 39 and 32 years. In the absence of new landing missions to Venus, the VENERA panoramas have been re-processed. The results of these missions are studied anew. A dozen of relatively large objects, from a decimeter to half a meter in size, with an unusual morphology have been found which moved very slowly or changed slightly their shape. Their emergence by chance could hardly be explained by noise. Certain unusual findings that have similar structure were found in different areas of the planet. This paper presents the last results obtained of a search for hypothetical flora and fauna of Venus.

Ksanfomality, L. V.

2014-12-01

185

Scientific Balloons for Venus Exploration  

NASA Astrophysics Data System (ADS)

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

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

186

An AOTF-based spectrometer for the studies of Mars atmosphere for Mars Express ESA mission  

Microsoft Academic Search

The SPICAM Light optical package on the ESA Mars Express mission is dedicated to the nadir and limb observations in the UV between 118 nm and 320 nm, and has originally included an IR solar occultation channel, an inheritance of the IR part of the SPICAM solar occultation instrument for Mars 96. Because of severe mass constrains of the mission

O. Korablev; J.-L. Bertaux; A. Grigoriev; E. Dimarellis; Yu. Kalinnikov; A. Rodin; C. Muller; D. Fonteyn

2002-01-01

187

Remote Raman - LIBS Geochemical Investigation under Venus Atmospheric Conditions  

Microsoft Academic Search

The extreme Venus surface temperature (740K) and atmospheric pressure (93 atm) creates a challenging environment for future lander missions. The scientific investigations capable of Venus geochemical observations must be completed within several hours of the landing before the lander will be overcome by the harsh atmosphere. A combined remote Raman - LIBS (Laser Induced Breakdown Spectroscopy) instrument is capable of

S. M. Clegg; J. E. Barefield; R. C. Wiens; A. K. Misra; S. K. Sharma

2008-01-01

188

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

189

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

190

Solar Wind Interaction with Venus  

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

191

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

192

Three-dimensional modelling of Venus photochemistry  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

193

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

NASA Astrophysics Data System (ADS)

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

Peralta, Javier; Ángel López-Valverde, Miguel; Gilli, Gabriella; Drossart, Pierre; Piccioni, Giuseppe

2010-05-01

194

Atmospheric tides on Venus. III - The planetary boundary layer  

NASA Technical Reports Server (NTRS)

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

Dobrovolskis, A. R.

1983-01-01

195

The magnetosheath and magnetotail of Venus  

NASA Astrophysics Data System (ADS)

The history of U.S. and Soviet space missions probing the magnetosheath and magnetotail of Venus is recalled; current models of solar-wind interaction with Venus are reviewed; and recommendations for further study of the existing data and for future space missions are discussed. Sections are devoted to the bow shock, ionopause, and neutral exosphere; the dayside and near-terminator magnetosheath (macroscopic properties, turbulence and waves, magnetic barrier, ion pickup theory, and the magnetosheath boundary layer); the near-planet wake and nightside magnetosheath; and the magnetotail (formation and configuration, magnetic-field observations, and plasma and plasma-wave observations). Extensive diagrams and graphs are provided.

Phillips, J. L.; McComas, D. J.

1991-02-01

196

Hinode Views the 2012 Venus Transit - Duration: 0:04.  

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...

197

Hinode Views the 2012 Venus Transit - Duration: 0:08.  

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...

198

Hinode Views the Transit of Venus - Duration: 0:48.  

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 ...

199

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

200

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

201

Mobile continents on Venus.  

NASA Astrophysics Data System (ADS)

The continental matter on Venus moves not only as large blocks (as is the case on Earth). It can also slide downwards as gigantic flows. This form or transportation of matter has been discovered only on Venus so far.

Sukhanov, A. L.

1989-11-01

202

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

203

Questions for the geologic exploration of Venus  

NASA Technical Reports Server (NTRS)

Venus is the last terrestrial planet to be mapped in the Solar System. This is an indication not of its relative importance for comparative planetary studies but of the previous lack of demonstrated, affordable technology. Venus is, in fact, the most important planet to study for improving our understanding of global terrestrial processes such as plate tectonics. The next NASA mission to Venus, in 1988, will map the planet at a resolution comparable to that of the Mars Mariner 9 mission. The objective is 70 percent coverage at 1 km per line pair or better. This is the minimum resolution that will allow analysis of tectonic, volcanic, aeolian, meteorite impact and other features. An altimeter will provide a global map of topography that will considerably improve our data base and, together with gravity field measurements, provide better interior geophysical models.

Saunders, R. S.

1984-01-01

204

Approach and challenges to science and mission planning for the European orbiter Mars Express  

Microsoft Academic Search

The paper focuses on the end-to-end science operations for the first and only European Mars mission to-date, describing the approaches to science and mission planning and the challenges imposed by the operations constraints. It includes the activities of the instrument and science planning teams to plan and process the collected data. The Mars Express spacecraft has been in orbit around

Erhard Rabenau; Michel Denis; Nicolas Altobelli

2012-01-01

205

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

206

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

207

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

208

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

E-print Network

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

M. Rengel; P. Hartogh; C. Jarchow

2008-09-16

209

Beagle 2: A proposed exobiology lander for ESA's 2003 Mars Express mission  

Microsoft Academic Search

The aim of the proposed Beagle 2 small lander for ESA's 2003 Mars Express mission is to search for organic material on and below the surface of Mars and to study the inorganic chemistry and mineralogy of the landing site. The lander will have a total mass of 60kg including entry, descent, and landing system. Experiments will be deployed on

M. R. Sims; C. T. Pillinger; I. P. Wright; J. Dowson; S. Whitehead; A. Wells; J. E. Spragg; G. Fraser; L. Richter; H. Hamacher; A. Johnstone; N. P. Meredith; C. de la Nougerede; B. Hancock; R. Turner; S. Peskett; A. Brack; J. Hobbs; M. Newns; A. Senior; M. Humphries; H. U. Keller; N. Thomas; J. S. Lingard; J. C. Underwood; N. M. Sale; M. F. Neal; G. Klingelhofer; T. C. Ng

1999-01-01

210

The High Resolution Stereo Camera (HRSC) Experiment onboard the European Mars Express (MEX) Mission  

Microsoft Academic Search

A major goal of the European Mars Express mission is to image the Martian surface at high spatial resolution, in stereo and in color. This task will be met by the High Resolution Stereo Camera (HRSC), a multiple-line pushbroom scanner. 9 CCD lines are mounted in parallel and simultaneously acquire images at high spatial resolution, in triple-stereo, in four colors

G. Neukum

2003-01-01

211

The High Resolution Stereo Camera (HRSC) Experiment On The European Mars Express Mission  

Microsoft Academic Search

Imaging Mars is one of the main goals of the European Mars Express mission and will be performed by the German High Resolution Stereo Camera (HRSC). The HRSC ex- periment is a pushbroom scanning instrument with 9 CCD line detectors mounted in parallel on the focal plane. Its unique feature is the ability to obtain nearly simul- taneously imaging data

G. Neukum; H. Hoffmann

2002-01-01

212

OPERATIONAL DETERMINATION OF TIE POINTS AND BUNDLE ADJUSTMENT OF HRSC IMAGES OF THE MARS EXPRESS MISSION  

Microsoft Academic Search

The pushbroom scanner HRSC (High Resolution Stereo Camera) onboard the European Mars Express mission is orbiting the planet Mars since January 2004 and delivers stereoscopic imagery with five panchromatic and four colour channels. This paper describes the process of improving the exterior orientation of the HRSC which is needed in order to derive high quality products such as high resolution

R. Schmidt; M. Spiegel; C. Heipke; G. Neukum

213

First observation of energetic neutral atoms in the Venus environment  

NASA Astrophysics Data System (ADS)

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

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

2008-05-01

214

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

215

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

216

Venus bowshock precursor  

NASA Technical Reports Server (NTRS)

Significant ion and electron flux enhancements immediately upstream of the Venus bowshock have been observed by the Electron Temperature Probe on the Pioneer Venus Orbiter. It is shown that mass loading of the solar wind by oxygen ions (without the effect of MHD turbulence) accounts for only about 3.5 percent of the observed effect. Evidence is presented that turbulence may play a nonnegligible role in the ion pickup process in front of the Venus bowshock.

Fontheim, Ernest G.; Brace, Larry H.

1990-01-01

217

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

218

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

219

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

220

Roadmap for Venus Exploration (rev. 3, Dec 5, 2013)  

E-print Network

a context for strategic planning and to facilitate future investigations and mission and technology. It was developed for the space science community by the Venus Exploration Analysis Group (VEXAG) to provide strategy comprising missions from all classes, coupled with strategic technology investments, will enable

Rathbun, Julie A.

221

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

222

Methods for the analysis of data from the Planetary Fourier Spectrometer on the Mars Express Mission  

Microsoft Academic Search

This work presents an algorithm for the scientific analysis of individual calibrated measurements from the Planetary Fourier spectrometer (PFS).The instrument, included in the scientific payload of the ESA Mars Express mission to Mars, acquires spectra in the range between 250 and 8200cm?1, with a sampling step of ?1cm?1 and an effective resolution of ?2cm?1. The observed radiance depends on several

Davide Grassi; N. I. Ignatiev; L. V. Zasova; A. Maturilli; V. Formisano; G. A. Bianchini; M. Giuranna

2005-01-01

223

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

224

Venus Transit 2004  

Microsoft Academic Search

December 6th, 1882 was the last transit of the planet Venus across the disk of the sun. It was heralded as an event of immense interest and importance to the astronomical community as well as the public at large. There have been only six such occurrences since Galileo first trained his telescope on the heavens in 1609 and on Venus

L. A. Mayo; S. F. Odenwald

2002-01-01

225

Venus - Ishtar gravity anomaly  

NASA Technical Reports Server (NTRS)

The gravity anomaly associated with Ishtar Terra on Venus is characterized, comparing line-of-sight acceleration profiles derived by differentiating Pioneer Venus Orbiter Doppler residual profiles with an Airy-compensated topographic model. The results are presented in graphs and maps, confirming the preliminary findings of Phillips et al. (1979). The isostatic compensation depth is found to be 150 + or - 30 km.

Sjogren, W. L.; Bills, B. G.; Mottinger, N. A.

1984-01-01

226

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.

227

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

228

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.

229

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

230

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

231

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

232

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

233

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

234

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

235

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

236

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

237

Plasma waves at Venus  

NASA Astrophysics Data System (ADS)

Many significant wave phenomena have been discovered at Venus with the plasma wave instrument on the Pioneer Venus Orbiter. It has been shown that whistler-mode waves in the magnetosheath of the planet may be an important source of energy for the topside ionosphere. Plasma waves are also associated with thickening of the ionopause current layer. Current-generated waves in plasma clouds may also provide anomalous resistance resulting in electron acceleration, possibly producing aurora. Ion-acoustic waves are observed in the bow shock, and appear to be a feature of the magnetotail boundary. Lastly, plasma waves have been cited as evidence for lightning on Venus.

Strangeway, R. J.

1991-02-01

238

On the possibility of plate tectonics on Venus  

NASA Astrophysics Data System (ADS)

Several arguments have been put forward suggesting that Venus has no plate tectonics. Some of these arguments are examined and it is suggested that because conditions on the surface of Venus are very different from those on Earth, the arguments should be reconsidered. It is shown that in the absence of an ocean, the differential hypsographic curve of earth would probably have only one mode, like that for Venus. It is shown that the atmosphere of Venus is quite capable of erosion, provided that near-surface velocities are about 1 m sec or more, and that therefore the oceanic areas on Venus, should they exist, are probably covered with some thickness of sediment. If sedimentation on Venus is at all rapid, it is likely that subduction zones could be filled up and made unrecognizable topographically. Because Venus does not have an ocean, and because its surface temperature is much greater than that on earth, ridge crests on Venus have a much smaller topographic expression than those on earth. If significant sedimentation occurs they would be completely unrecognizable topographically.

Brass, G. W.; Harrison, C. G. A.

1982-01-01

239

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

E-print Network

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

Barentsen, Geert

2013-01-01

240

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

241

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

242

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

243

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

244

The Atmosphere of Venus  

NASA Technical Reports Server (NTRS)

Topics considered at the conference included the dynamics, structure, chemistry, and evolution of the Venus atmosphere, as well as cloud physics and motion. Infrared, ultraviolet, and radio occultation methods of analysis are discussed, and atmospheric models are described.

Hansen, J. E. (editor)

1975-01-01

245

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.

246

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

247

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

248

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

249

The High Resolution Stereo Camera (HRSC) Experiment onboard the European Mars Express (MEX) Mission  

NASA Astrophysics Data System (ADS)

A major goal of the European Mars Express mission is to image the Martian surface at high spatial resolution, in stereo and in color. This task will be met by the High Resolution Stereo Camera (HRSC), a multiple-line pushbroom scanner. 9 CCD lines are mounted in parallel and simultaneously acquire images at high spatial resolution, in triple-stereo, in four colors and at five viewing angles. During the nominal mission, the HRSC will cover at least 50% of the Martian surface at 10-15 m/pixel, 70% at better than 30 m/pixel and 100% at better than 100 m/pixel resolution. The instrument is equipped with an additional super-resolution channel reaching a spatial resolution of up to 2 m/pixel. This channel is boresighted with the HRSC stereo scanner and will obtain nested-in images or image strips. Up to a few % of the Martian surface can be covered by the super-resolution channel during the mission. This channel will be of particular importance for highest-resolution coverage of landing sites such as planned for the Mars Express Beagle 2 site and the two Mars Surveyor 2003 rover sites. Scientifically, the HRSC experiment concentrates on the geological and climatological evolution of Mars with special emphasis on the role of water throughout the Martian history. An international team of 40 Co-Investigators from 28 scientific institutions and 10 countries will run the experiment and analyze the data over the two-year nominal mission with a possible extension over an additional two years. The data will be processed in such a way that they will be usable by the scientific community at large six months after receipt. The experiment hardware and software development is finished and the instrument is being assembled and tested at the ESA-MEX spacecraft. The launch of the mission is scheduled from Baikonur in late May 2003. First data from the cruise phase to Mars will be received in the June-July period of 2003.

Neukum, G.; HRSC Team

2003-04-01

250

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

251

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

252

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

NASA Astrophysics Data System (ADS)

7 years of continuous monitoring of Venus by ESA's Venus Express provided an opportunity to study dynamics of the atmosphere of Venus. Venus Monitoring Camera (VMC) [1] delivered the longest and the most complete so far set of UV images to study the cloud level circulation by tracking motion of the cloud features. We analyzed 130 orbits with manual cloud tracking and 600 orbits with digital correlation method. Here we present the latest update of our results. Total number of wind vectors derived in this work is approximately a half million. During Venus Express observations the mean zonal speed was in the range of 85-110 m/s. VMC observations indicated a long term trend for the zonal wind speed at low latitudes to increase. The origin of low frequency trend with a period about 3000 days is unclear. Fourier analysis [2-3] of revealed quasi-periodicities in the zonal circulation at low latitudes. 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 ±4.2 to ±17.4 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. Short term oscillations may be caused by wave processes in the mesosphere of Venus at the cloud top level. Wave number of the observed oscillations is 1. The second group is a long term periods caused by orbital motion of Venus (116 days, 224 days) and is related to the periodicity in VMC observations. Also VMC UV observations showed a clear diurnal pattern of the mean circulation. The zonal wind demonstrated semi-diurnal variations with minimum speed close to noon (11-14 h) and maxima in the morning (8-9 h) and in the evening (16-17 h). The meridional component clearly peaks in the early afternoon (13-15h) at latitudes near 50S. The minimum of the meridional wind is located at low latitudes in the morning (8-11h). References [1] Markiewicz W. J. et al.: Venus Monitoring Camera for Venus Express // Planet. Space Sci.. V.55(12). pp1701-1711. doi:10.1016/j.pss.2007.01.004, 2007. [2] Deeming T.J.: Fourier analysis with unequally-spaced data. Astroph. and Sp. Sci. V.36, pp137-158, 1975. [3] Terebizh, V.Yu. Time series analysis in astrophysics. Moscow: "Nauka," Glav. red. fiziko-matematicheskoi lit-ry, 1992. In Russian

Khatuntsev, Igor; Patsaeva, Marina; Ignatiev, Nikolai; Titov, Dmitri; Markiewicz, Wojciech J.

2013-04-01

253

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

254

The structure of the Venus ionosphere  

NASA Technical Reports Server (NTRS)

The morphology and temporal variability of the Venus ionosphere are characterized, reviewing the results of recent theoretical investigations, observations, and in situ measurements, especially by the Pioneer Venus Orbiter (PVO). Consideration is given to the Pioneer mission and orbit evolution, early radio occultation profiles of ionospheric N(e), the mean structure and thermal balance of the ionosphere, the ion composition and its dawn-dusk asymmetry, the small-scale spatial structure on the nightside, latitudinal and seasonal variations, solar-cycle effects, suprathermal electrons and superthermal ions, and the global configuration and stability of the ionopause. Data from a single PVO passage through the ionotail are discussed in detail, examining the implications for ion escape and the solar-cycle and short-term variability. The differences among the terrestrial, Martian, and Venusian ionospheres are outlined; the PVO data base is described; and the sources of measurement error are indicated.

Brace, L. H.; Kliore, A. J.

1991-01-01

255

Automating the Hunt for Volcanoes on Venus  

E-print Network

Our long-term goal is to develop a trainable tool for locating patterns of interest in large image databases. Toward this goal we have developed a prototype system, based on classical filtering and statistical pattern recognition techniques, for automatically locating volcanoes in the Magellan SAR database of Venus. Training for the specific volcano-detection task is obtained by synthesizing feature templates (via normalization and principal components analysis) from a small number of examples provided by experts. Candidate regions identified by a focus of attention (FOA) algorithm are classified based on correlations with the feature templates. Preliminary tests show performance comparable to trained human observers. 1 Introduction Many geological studies use surface features to deduce processes that have occurred on a planet. The recent JPL Magellan mission, which was successful in imaging over 95% of the surface of Venus with synthetic aperture radar (SAR), has provided planetary s...

M.P. Burl; U. M. Fayyad; P. Perona; P. Smyth

1994-01-01

256

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

257

Wireless Seismometer for Venus  

NASA Technical Reports Server (NTRS)

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

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

2014-01-01

258

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

259

Venus ionopause during solar minimum  

NASA Astrophysics Data System (ADS)

Pioneer Venus ion composition measurements are used to study the Venus ionosphere during solar minimum. It is suggested that the topside electron density profile at Venus during solar minimum has two distinct regimes. One beween 140 and 180 km is dominated by O2(+) ions which are in photochemical equilibrium. The other regime is above 180 km and is dominated by O(+) ions which are disturbed by the solar wind induced plasma transport. For Pioneer Venus, Mariner 10, and Venera 9 and 10 data, it is found that Venus exhibits a photodynamical type of ionopause during solar minimum.

Mahajan, K. K.; Mayr, H. G.

1989-12-01

260

Venus ionopause during solar minimum  

NASA Technical Reports Server (NTRS)

Pioneer Venus ion composition measurements are used to study the Venus ionosphere during solar minimum. It is suggested that the topside electron density profile at Venus during solar minimum has two distinct regimes. One beween 140 and 180 km is dominated by O2(+) ions which are in photochemical equilibrium. The other regime is above 180 km and is dominated by O(+) ions which are disturbed by the solar wind induced plasma transport. For Pioneer Venus, Mariner 10, and Venera 9 and 10 data, it is found that Venus exhibits a photodynamical type of ionopause during solar minimum.

Mahajan, K. K.; Mayr, H. G.

1989-01-01

261

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

262

Present status of Venus  

SciTech Connect

The TRISTAN e/sup +/e/sup -/ collider came into operation in the last October. The first beam collision was confirmed with the VENUS detector on November 19, '86. Then the authors observed 56 Bhabha events and 16 hadronic events for the integrated luminosity of 93 nb/sup -1/ at ..lambda..s = 50 GeV. R-value obtained by a preliminary quick analysis is 5.7+-1.6. Here they report the present status and the results of the VENUS experiment.

Sugimoto, S.

1987-08-01

263

Variability of the Venus Oxygen Airglow  

NASA Astrophysics Data System (ADS)

We have obtained spatially resolved near-IR spectroscopic observations of the night-side of Venus through the last three inferior conjunctions using IRIS2 on the Anglo-Australian 3.9m telescope and CASPIR on the 2.3m ANU telescope. The data are used to investigate the extreme variability of the spatial distribution and intensity of the O2 airglow emission feature at 1.27 microns. The airglow emission was very strong in September 2002, and much weaker in July 2004. Substantial night-to-night variations are also seen in both the intensity and spatial distribution of the emission. The emission is typically brightest near the anti-solar point, consistent with an upper atmosphere circulation in the form of a tidal flow from day-side to night-side. However, there are substantial variations from this typical pattern, with plumes of emission sometimes extending over long distances, and reaching regions close to the terminator. The Venus O2 airglow provides a probe of the chemistry and dynamics of the Venus upper atmosphere. These and earlier ground-based observations help to provide context for the more detailed studies that will be possible by the Venus Express spacecraft.

Bailey, Jeremy A.; Meadows, V. S.; Chamberlain, S.; Simpson, A.; Crisp, D.

2006-09-01

264

An analysis of AMTEC, multi-cell ground-demo for the Pluto/Express mission  

SciTech Connect

Results of recent tests of an 8-cell, AMTEC ground-demo are analyzed and the performance of individual cells compared. The ground-demo produced a peak electric power of 27 W{sub e} at an output voltage of 16 V, when tested at hot and cold side temperatures of 1123 K and 553 K. The electric power output and terminal voltage of the individual cells, however, differed by as much as 25%, from 2.94 to 3.76 W{sub e}, and 1.73 to 2.21 V, respectively. These variations were attributed to differences in: (a) contact resistance between electrode / BASE / current collector; (b) current (or electrons) leakage between anode and cathode electrodes through the metal-ceramic braze joint between BASE tubes and support plate; and (c) the charge-exchange polarization losses. Model's predictions compared very well with measured voltage and electric power output of individual cells and of the ground-demo. At the operating conditions for the Pluto/Express spacecraft (T{sub hot} {approximately} 1200 K, T{sub cd} {approximately} 573 K), the best performing ground-demo cell would have delivered 5 W{sub e} at an output voltage of 3 V. These values, however, are still significantly lower than those needed to meet the Pluto/Express mission power requirements (8.2 W{sub e} at 3.5 V, per cell).

Tournier, J.M.; El-Genk, M.S.

1998-07-01

265

Development of a Pioneer Venus expert scheduling system  

NASA Technical Reports Server (NTRS)

An Expert System has been developed to perform a substantial part of the science planning for NASA's Pioneer Venus spacecraft. The program performs functions that have been traditionally performed by operations personnel ('orbit builders'), and attempts to directly duplicate their methods and techniques. Output from the program is formatted to correspond to the previously hand-generated worksheets, in order to ease program validation as well as operator acceptance. Pioneer Venus mission operations are described in detail followed by a description of the expert system implementation.

Rosenthal, Donald A.; Jackson, Robert W.

1988-01-01

266

Fundamental issues in the geology and geophysics of venus.  

PubMed

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

Solomon, S C; Head, J W

1991-04-12

267

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

268

Observe how radar was used to map Venus  

NSDL National Science Digital Library

This series of five animations summarizes how the Magellan Radar Mapping Mission created a map of Venus. High school students can see that dense cloud cover obscured the planet's surface and how radar was used to penetrate the clouds and measure the topography. The animations also demonstrate how the images were captured in long strips and sent back to Earth. Sample image strips are shown, as well as the final product: a rotating map of Venus. Movie controls allow students to repeat, pause, or step through the animation, which can give students more time to analyze the images. Copyright 2005 Eisenhower National Clearinghouse

TERC. Center for Earth and Space Science Education

2003-01-01

269

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

270

Plains Tectonics on Venus  

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

271

Windblown dust on Venus  

Microsoft Academic Search

The threshold frictional velocity necessary to initiate grain movement on the Venus surface is 1 to 2 cm\\/s. Particles smaller than 30 or 40 microns in effective diameter will also be so moved and suspended at the threshold of movement. Theoretical arguments and Venera 8 Doppler measurements suggest marginally that dust should not be raised at the Venera 8 landing

Carl Sagan

1975-01-01

272

Venus in 3D  

NASA Astrophysics Data System (ADS)

Stereographic images of the surface of Venus which enable geologists to reconstruct the details of the planet's evolution are discussed. The 120-meter resolution of these 3D images make it possible to construct digital topographic maps from which precise measurements can be made of the heights, depths, slopes, and volumes of geologic structures.

Plaut, J. J.

1993-08-01

273

Venus rack cooling system  

SciTech Connect

A rack cooling system for the VENUS detector has been developed. It uses forced-air cooling and has enough cooling power for crates with as much as 1500 watts of power consumption. The design and the cooling performance for FASTBUS crates are reported.

Tanaka, R.; Arai, Y.; Ishihara, N.

1986-02-01

274

Morphotectonics of Venus  

NASA Technical Reports Server (NTRS)

Venus topography can be mapped morphostructurally to reveal nested hierarchical patterns of quasi-circular upland/lowland complexes. These patterns are interpreted as surficial effects of hierarchically structured, long-acting mantle convection. Beta Regio, Alpha Regio, and Artemis illustrate this process of dynamical interaction between the deforming lithosphere and the convecting mantle.

Finn, V. J.; Baker, V. R.; Dolginov, A. Z.

1993-01-01

275

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

276

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

277

Venus - Sinuous Channel  

NASA Technical Reports Server (NTRS)

This full resolution radar mosaic from Magellan at 49 degrees south latitude, 273 degrees east longitude of an area with dimensions of 130 by 190 kilometers (81 by 118 miles), shows a 200 kilometer (124 mile) segment of a sinuous channel on Venus. The channel is approximately 2 kilometers (1.2 miles) wide. These channel-like features are common on the plains of Venus. In some places they appear to have been formed by lava which may have melted or thermally eroded a path over the plains' surface. Most are 1 to 3 kilometers (0.6 to 2 miles) wide. They resemble terrestrial rivers in some respects, with meanders, cutoff oxbows, and abandoned channel segments. However, Venus channels are not as tightly sinuous as terrestrial rivers. Most are partly buried by younger lava plains, making their sources difficult to identify. A few have vast radar-dark plains units associated with them, suggesting large flow volumes. These channels appear to be older than other channel types on Venus, as they are crossed by fractures and wrinkle ridges, and are often buried by other volcanic materials. In addition, they appear to run both upslope and downslope, suggesting that the plains were warped by regional tectonism after channel formation. Resolution of the Magellan data is about 120 meters (400 feet).

1991-01-01

278

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

279

Storms On Venus: Lightning-induced Chemistry And Predicted Products  

NASA Astrophysics Data System (ADS)

Observations by many spacecraft that have visited Venus over the last 40 years appear to confirm the presence of lightning storms in the Venus atmosphere. Recent observations by Venus Express indicate that lightning frequency and power is similar to that on Earth. While storms are occurring, energy deposition by lightning into Venus atmospheric constituents will immediately dissociate molecules into atoms, ions and plasma from the high temperatures in the lightning column (>30,000 K) and the associated shock waves and heating, after which these atom and ion fragments will recombine during cooldown to form new sets of molecules. Lightning will re-sort the atoms of C,O,S,N,H to create highly energetic new products. Spark and discharge experiments in the literature suggest that lightning effects on the main atmospheric molecules CO2, N2, SO2, H2SO4 and H2O will yield new molecules such as mixed carbon oxides (CnOm), mixed sulfur oxides (SnOm), oxygen (O2), elemental sulfur (Sn), nitrogen oxides (NO, N2O, NO2, NO3), sulfuric acid clusters (HnSmOx-.aHnSmOx e.g. HSO4-.mH2SO4), polysulfur oxides, carbon soot, and also halogen oxides from HCl or HF and other exotic species. Many of these molecular species may be detectable by instruments onboard Venus Express. We explore the diversity of new products likely created in the storm clouds on Venus.

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

2012-10-01

280

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

281

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.

282

Pioneer Mars 1979 mission options  

NASA Technical Reports Server (NTRS)

A preliminary investigation of lower cost Mars missions which perform useful exploration objectives after the Viking/75 mission was conducted. As a study guideline, it was assumed that significant cost savings would be realized by utilizing Pioneer hardware currently being developed for a pair of 1978 Venus missions. This in turn led to the additional constraint of a 1979 launch with the Atlas/Centaur launch vehicle which has been designated for the Pioneer Venus missions. Two concepts, using an orbiter bus platform, were identified which have both good science potential and mission simplicity indicative of lower cost. These are: (1) an aeronomy/geology orbiter, and (2) a remote sensing orbiter with a number of deployable surface penetrometers.

Friedlander, A. L.; Hartmann, W. K.; Niehoff, J. C.

1974-01-01

283

Signs of hypothetical fauna of Venus  

NASA Astrophysics Data System (ADS)

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

Ksanfomality, Leonid V.

2014-04-01

284

Magellan - Initial analysis of Venus surface modification  

NASA Technical Reports Server (NTRS)

Images of the Venus surface provided by the Magellan mission make it possible to see the fine-scale features diagnostic of weathering, erosion, and deposition. These include ejecta deposits extending up to 1000 km to the west of several impact craters, windblown deposits, features containing both obstacles and a source of particulate material, and evidence for degradation by atmosphere-surface interactions and mass movements. Initial Magellan observations pertaining to the nature, rate, and history of surficial processes are analyzed. Emphasis is placed on radar imaging, but results from radiometry and altimetry observations are also discussed.

Arvidson, R. E.; Baker, V. R.; Elachi, Charles; Saunders, R. S.; Wood, J. A.

1991-01-01

285

Venus transit 2004: An international education program  

NASA Astrophysics Data System (ADS)

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

Mayo, L.; Odenwald, S.

2003-04-01

286

Doublet craters on Venus  

NASA Astrophysics Data System (ADS)

Of the impact craters on Earth larger than 20 km in diameter, 10-15% (3 out of 28) are doublets, having been formed by the simultaneous impact of two well-separated projectiles. The most likely scenario for their formation is the impact of well-separated binary asteroids. If a population of binary asteroids is capable of striking the Earth, it should also be able to hit the other terrestrial planets as well. Venus is a promising planet to search for doublet craters because its surface is young, erosion is nearly nonexistent, and its crater population is significantly larger than the Earth's. After a detailed investigation of single craters separated by less than 150 km and "multiple" craters having diameters greater than 10 km, we found that the proportion of doublet craters on Venus is at most 2.2%, significantly smaller than Earth's, although several nearly incontrovertible doublets were recognized. We believe this apparent deficit relative to the Earth's doublet population is a consequence of atmospheric screening of small projectiles on Venus rather than a real difference in the population of impacting bodies. We also examined "splotches," circular radar reflectance features in the Magellan data. Projectiles that are too small to form craters probably formed these features. After a careful study of these patterns, we believe that the proportion of doublet splotches on Venus (14%) is comparable to the proportion of doublet craters found on Earth (10-15%). Thus, given the uncertainties of interpretation and the statistics of small numbers, it appears that the doublet crater population on Venus is consistent with that of the Earth.

Cook, Cheryl M.; Melosh, H. Jay; Bottke, William F.

2003-09-01

287

Pioneer Mars 1979 mission options  

NASA Technical Reports Server (NTRS)

Two mission concepts utilizing modified Pioneer Venus hardware are presented as relatively low-cost alternatives for scientific exploration of Mars in 1979. Mission A would perform in situ aeronomy measurements in the Martian ionosphere and include several remote sensing instruments capable of geological surface mapping at low altitudes. The initial high eccentricity orbit would be allowed to decay in an adaptive mode. Mission B would sequentially deploy (from an orbiter bus), four, nondestructing surface penetrometers carrying instrumentation to investigate soil density, composition and chemistry, subsurface water, and perhaps seismology. Mission B is more expensive than mission A, since it requires more extensive hardware modifications and systems development.

Niehoff, J. C.; Friedlander, A. L.

1974-01-01

288

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

289

Mariner Venus/Mercury 1973 solar radiation force and torques  

NASA Technical Reports Server (NTRS)

The need for an improvement of the mathematical model of the solar radiation force and torques for the Mariner Venus/Mercury spacecraft arises from the fact that this spacecraft will be steering toward the inner planets (Venus and Mercury), where, due to the proximity of the Sun, the effect of the solar radiation pressure is much larger than it was on the antecedent Mariner spacecraft, steering in the opposite direction. Therefore, although the model yielded excellent results in the case of the Mariner 9 Mars Orbiter, additional effects of negligible magnitudes for the previous missions of the Mariner spacecraft should now be included in the model. This study examines all such effects and incorporates them into the already existing model, as well as using the improved model for calculation of the solar radiation force and torques acting on the Mariner Venus/Mercury spacecraft.

Georgevic, R. M.

1974-01-01

290

The loss of ions from Venus through the plasma wake S. Barabash1  

E-print Network

signature of the ion pick-up process6 . The comprehensive plasma package on Venus Express comprises an ionLETTERS The loss of ions from Venus through the plasma wake S. Barabash1 , A. Fedorov2 , J. J- chemistry2 , and although the bulk of O and O2 are gravitationally bound, heavy ions have been observed

California at Berkeley, University of

291

Schistosoma mansoni: Structural and biochemical characterization of two distinct Venus Kinase Receptors  

Microsoft Academic Search

Venus Kinase Receptors (VKRs) are atypical transmembrane proteins composed of an extracellular Venus FlyTrap module linked through a single helix to a tyrosine kinase domain similar to that of insulin receptors. This structure was first described in Schistosoma mansoni, then in a selected range of invertebrates, including many insects. The preferential expression of VKRs in larvae and gonads suggested their

Nadege Gouignard; Mathieu Vanderstraete; Katia Cailliau; Arlette Lescuyer; Edith Browaeys; Colette Dissous

292

Models of Venus atmosphere (1972)  

NASA Technical Reports Server (NTRS)

Criteria were developed in the following areas: environment, structures, guidance and control, and chemical propulsion. Quantitative data for the Venus atmosphere were obtained from earth-based observations and from spacecraft which have entered the Venus atmosphere or passed within several planetary radii of the planet. The models provide the temperature, pressure, and density profiles required to perform basic aerodynamic analyses. A set of engineering models are provided for the Venus atmosphere, based on theory and measured data available in January 1972.

1972-01-01

293

Tectonics and composition of Venus  

SciTech Connect

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

Anderson, D.L.

1980-01-01

294

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

295

Aerobraking at Venus: A science and technology enabler  

NASA Astrophysics Data System (ADS)

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

Hibbard, Kenneth; Glaze, Lori; Prince, Jill

2012-04-01

296

The new face of Venus  

NASA Astrophysics Data System (ADS)

The Magellan data on the Venus landscape which revealed volcanoes, shining mountains, relaxing plateaus, and craters on the surface of about 500 C, with an atmospheric pressure 90 times that of earth, are discussed. Venus is considered to be a planet that is both incredibly similar and dissimilar to earth. Venus might not exhibit plate tectonism but it might be dominated by catastrophes. The greenhouse around Venus has operated for at least the last 500 million years. The Magellan data revealed channels extending for thousands of kilometers, beautiful outflows surrounding impact craters, and odd volcanic constructs like the steep-sided domes.

Stofan, E. R.

1993-08-01

297

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

298

On the Frequency of Potential Venus Analogs from Kepler Data  

E-print Network

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

Kane, Stephen R; Domagal-Goldman, Shawn D

2014-01-01

299

Venus Mobile Explorer with RPS for active cooling: A feasibility study  

Microsoft Academic Search

This paper presents the findings from a study to evaluate the feasibility of a radioisotope power system (RPS) combined with active cooling to enable a long-duration venus surface mission. On-board power with active cooling technology featured prominently in both. the national research council's decadal survey and in the 2006 NASA solar system exploration roadmap as mission enabling for the exploration

Stephanie D. Leifer; Jacklyn R. Green; Tibor S. Balint; Ram Manvi

2009-01-01

300

Venus: Its Great Transition  

NASA Astrophysics Data System (ADS)

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

Lenardic, A.; Kaula, W. M.

1996-03-01

301

Mars Express - ESA sets ambitious goals for the first European mission to Mars  

NASA Astrophysics Data System (ADS)

Mars has always fascinated human beings. No other planet has been visited so many times by spacecraft. And still, it has not been easy to unveil its secrets. Martian mysteries seem to have increased in quantity and complexity with every mission. When the first spacecraft were sent - the Mariner series in 1960s - the public was expecting an Earth ‘twin’, a green, inhabited planet full of oceans. Mariner shattered this dream by showing a barren surface. This was followed by the Viking probes which searched for life unsuccessfully in 1976. Mars appeared dry, cold and uninhabited: the Earth’s opposite. Now, two decades later, modern spacecraft have changed that view, but they have also returned more questions. Current data show that Mars was probably much warmer in the past. Scientists now think that Mars had oceans, so it could have been a suitable place for life in the past. “We do not know what happened to the planet in the past. Which process turned Mars into the dry, cold world we see today?” says Agustin Chicarro, ESA’s Mars Express project scientist. “With Mars Express, we will find out. Above all, we aim to obtain a complete global view of the planet - its history, its geology, how it has evolved. Real planetology!” Mars Express will reach the Red Planet by the end of December 2003, after a trip of just over six months. Six days before injection into its final orbit, Mars Express will eject the lander, Beagle 2, named after the ship on which Charles Darwin found inspiration to formulate his theory of evolution. The Mars Express orbiter will observe the planet and its atmosphere from a near-polar orbit, and will remain in operation for at least a whole Martian year (687 Earth days). Beagle 2 will land in an equatorial region that was probably flooded in the past, and where traces of life may have been preserved. The Mars Express orbiter carries seven advanced experiments, in addition to the Beagle 2 lander. The orbiter’s instruments have been built by group of scientific institutes from all over Europe, plus Russia, the United States, Japan and China. These instruments are a subsurface sounding radar; a high-resolution camera, several surface and atmospheric spectrometers, a plasma analyzer and a radio science experiment. The high-resolution camera will image the entire planet in full colour, in 3D, at a resolution of up to 2 metres in selected areas. One of the spectrometers will map the mineral composition of the surface with great accuracy. The missing water Data from some of the instruments will be key to finding out what happened with the water which was apparently so abundant in the past. For instance, the radar altimeter will search for subsurface water and ice, down to a depth of a few kilometres. Scientists expect to find a layer of ice or permafrost, and to measure its thickness. Other observations with the spectrometers will determine the amount of water remaining in the atmosphere. They will also tell whether there is a still a full ‘water cycle’ on Mars, for example how water is deposited in the poles and how it evaporates, depending on the seasons. "These data will determine how much water there is left. We have clear evidence for the presence of water in the past, we have seen dry river beds and sedimentary layers, and there is also evidence for water on present-day Mars. But we do not know how much water there is. Mars Express will tell us,” says Chicarro. The search for life The instruments on board Beagle 2 will investigate the geology and the climate of the landing site. But, above all, it will look for signs of life. Contrary to the Viking missions, Mars Express will search for evidence for both present and past life. Scientists are now more aware that a few biological experiments are not enough to search for life - they will combine many different types of tests to help discard contradictory results. To ‘sniff’ out direct evidence of past or present biological activity, Beagle 2’s ‘nose’ is a gas analysis package. This will determine whether carbonate mineral

2003-05-01

302

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.

303

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

304

Venus - Dead or alive?  

NASA Technical Reports Server (NTRS)

In situ nightside electric field observations from the Pioneer Venus Orbiter have been interpreted as evidence of extensive lightning in the lower atmosphere of Venus. The scenario, including proposed evidence of clustering of lightning over surface highland regions, has encouraged the acceptance of currently active volcanic output as part of several investigations of the dynamics and chemistry of the atmosphere and the geology of the planet. However, the correlation between the 100-hertz electric field events attributed to lightning and nightside ionization troughs resulting from the interaction of the solar wind with the ionosphere indicates that the noise results from locally generated plasma instabilities and not from any behavior of the lower atmosphere. Furthemore, analysis of the spatial distribution of the noise shows that it is not clustered over highland topography, but rather occurs at random throughout the latitude and longitude regions sampled by the orbiter during the first 5 years of operation, from 1978 to 1984. Thus the electric field observations do not identify lightning and do not provide a basis for inferring the presence of currently active volcanic output. In the absence of known evidence to the contrary, it appears that Venus is no longer active.

Taylor, Harry A., Jr.; Cloutier, Paul A.

1986-01-01

305

Pioneer Venus Orbiter contributions to a revised Venus reference ionosphere  

Microsoft Academic Search

The original Venus International Reference Atmosphere (VIRA) included an empirical model of the Venusian ionosphere (Bauer et al. 1985) which was based primarily on in situ and radio occultation measurements made by the Pioneer Venus Orbiter (PVO) in 1979 and 1980, a time of very high solar activity. The solar cycle variations of in situ parameters could not be determined

L. H. Brace; J. M. Grebowsky; A. J. Kliore

1997-01-01

306

ABSTRACTS FOR THE VENUS GEOSCIENCE TUTORIAL AND VENUS  

E-print Network

Administration Hosted by the U. S. Geological Survey LPI Contribution No. 708 #12;Compiled in 1989 by the Lunar. Cover: Radar image of Maxwell Montes, Venus. (Courtesy Arecibo Observatory) #12;PREFACE This volumeSouthern Guinevere Planitia, Venus, Based on Analyses of Goldstone Radar Data R. E. Arvidson, J. J. Plaut, R. F

Rathbun, Julie A.

307

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

308

Ballistic mode Mercury orbiter mission opportunity handbook  

NASA Technical Reports Server (NTRS)

Significant payloads in Mercury orbit can be achieved through use of high-thrust, chemical propulsion systems on ballistic trajectories. Interplanetary trajectory characteristics are presented, for Venus swingbys to Mercury, were multiple revolutions about the sun are allowed on each leg to provide low energy mission in 1977, 1980, 1985 and 1988. Guidance and navigation results are shown for each opportunity. Additionally, the use of midcourse maneuvers and multiple Venus swingbys are explored as means of further reducing the energy requirements.

Hollenbeck, G. R.; Roos, D. G.; Lewis, P. S.

1973-01-01

309

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

310

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

311

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

312

Venus Surface Sample Return: A Weighty High-Pressure Challenge  

NASA Technical Reports Server (NTRS)

A mission to return a sample to Earth from the surface of Venus faces a multitude of multidisciplinary challenges. In addition to the complications inherent in any sample return mission, Venus presents the additional difficulties of a deep gravity well essentially equivalent to Earth's and a hot-house atmosphere which generates extremes of high temperature, density, and pressure unmatched at any other known surface in the solar system. The Jet Propulsion Laboratory of the California Institute of Technology recently conducted a study to develop an architecture for such a mission; a major goal of this study was to identify technology developments which would need to be pursued in order to make such a mission feasible at a cost much less than estimated in previous. The final design of this mission is years away but the study results presented here show our current mission architecture as it applies to a particular mission opportunity, give a summary of the engineering and science trades which were made in the process of developing it, and identify the main technology development efforts needed.

Sweetser, Ted; Cameron, Jonathon; Chen, Gun-Shing; Cutts, Jim; Gershman, Bob; Gilmore, Martha S.; Hall, Jeffrey L.; Kerzhanovich, Viktor; McRonald, Angus; Nilsen, Erik

1999-01-01

313

Venus-intercepting meteoroid streams  

NASA Astrophysics Data System (ADS)

This study is motivated by the possibility of determining the large-body meteoroid flux at the orbit of Venus. Towards this end, we attempt to estimate the times at which enhanced meteoric activity might be observed in the planet's atmosphere. While a number of meteoroid streams are identified as satisfying common Earth and Venus intercept conditions, it is not clear from the Earth-observed data if these streams contain large-body meteoroids. A subset of the Taurid Complex objects may produce fireball-rich meteor showers on Venus. A total of 11 short-period, periodic comets and 46 near-Earth asteroids approach the orbit of Venus to within 0.1 au, and these objects may have associated meteoroid streams. Comets 27P/Crommelin and 7P/Pons-Winnecke are identified as candidate parents to possible periodic meteor showers at the orbit of Venus.

Beech, Martin

1998-02-01

314

Solar Wind Driven Plasma Fluxes from the Venus Ionosphere  

NASA Astrophysics Data System (ADS)

SOLAR WIND DRIVEN PLASMA FLUXES FROM THE VENUS IONOSPHERE H. Pérez-de-Tejada (1), R. Lundin (2), H. Durand-Manterola (1), S. Barabash (2), T. L. Zhang (3), J. A., Sauvaud (4), and M. Reyes-Ruiz (5) 1 - Institute of Geophysics, UNAM, México, D. F. 2 - Swedish Institute of Space Physics, Kiruna, Sweden 3 - Space Research Institute, Graz, Austria 4 - CESR, Toulouse, France 5 - Institute of Astronomy, UNAM, Ensenada, México Measurements 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 being driven by magnetic forces but by the kinetic energy of the solar wind. Beams of planetary O+ ions with those properties have been detected in several orbits of the Venus Express through the wake as the spacecraft traverses by the noon-midnight plane along its near polar trajectory. The momentum flux of the O+ ions leads to superalfvenic flow conditions. It is suggested that such O+ ion beams are produced in the vicinity of the magnetic polar regions of the Venus ionosphere where the solar wind erodes the local plasma leading to plasma channels that extend downstream from those regions.

Perez De Tejada, H. A.; Lundin, R. N.; Zhang, T.; Sauvaud, J. A.; Reyes-Ruiz, M.

2012-12-01

315

Modeling the distribution of H2O and HDO in the upper atmosphere of Venus  

NASA Astrophysics Data System (ADS)

The chemical and dynamical processes in the upper atmosphere of Venus are poorly known. Recently obtained vertical profiles of trace species from the Venus Express mission, such as HCl, H2O, and HDO, provide new information to constrain these processes. Here, we simulate these profiles, using the model we have developed and described in a related paper by Yung et al. (2008), with special emphasis on the modeling of H2O and HDO. A new mechanism, the photo-induced isotopic fractionation effect (PHIFE) of H2O and HCl, is incorporated into our model. The observed enhancement of HDO could be attributed to (1) preferential destruction of H2O relative to HDO via PHIFE and (2) escape of hydrogen that enhances the abundance of D and hence its parent molecule HDO. Over a wide range of the sensitivity of the results to the changes of the two mechanisms, we find that the observed profiles of HDO and H2O profiles cannot be explained satisfactorily by current knowledge of chemical and dynamical processes in this region of the atmosphere. Several conjectures to tackle the problems are discussed.

Liang, Mao-Chang; Yung, Yuk L.

2009-02-01

316

Plasma vortices, lateral forcing, and the superrotating Venus atmosphere  

NASA Astrophysics Data System (ADS)

New observations from Venus Express (VEX) show the existence of a large-scale vortex-like ion flow pattern in the Venus plasma tail. The flow pattern is characterized by besides a dominating antisunward flow, also a lateral flow component of solar wind (H+) and ionospheric (O+) ions. The lateral flow component is directed opposite to the Venus orbital motion. A test of the energy and momentum balance between solar wind H+ and ionospheric O+ indicates that the energy and momentum delivered to O+ is proportional to the loss of energy and momentum by solar wind H+. The combined antisunward and lateral H+ and O+ flow wraps over the planetary atmosphere, from the terminator into the nightside. The net lateral flow near Venus is in the direction of the Venus atmospheric superrotation. Further down in the Venus plasma tail the flow display a circular motion around the central tail axis. The general agreement in direction between the nightside ion flow over the Northern hemisphere, and the retrograde motion of the Venus atmosphere, implies a cause-effect relation between the ionospheric O+ flow and the atmospheric neutral flow. This underlying connection is further strengthened by the fact the the O+ flow velocity in the 200-300 km altitude range follows the same power law curve as that fitted to the atmospheric zonal wind velocity profile [1]. The combined ion + neutral wind profile therefore implies momentum balance between the ionospheric and atmospheric retrograde flow. The fact that the O+ flow is driven by solar wind forcing leaves us with the question: Is the superrotating upper atmosphere at Venus a consequence of solar wind forcing? Is the ion flow capable of accelerating, and maintaining, a superrotating upper atmosphere at Venus? Combining ion data [2] with a fluid dynamic model of the energy and momentum transfer of ions to neutrals we find that this is certainly possible. The ionospheric O+ energy and momentum observed is sufficient to accelerate, and maintain superrotating velocites, after a few million years - minute compared to evolutionary time scales of a planet. [1] Schubert G., C. Covey, A. Del Genio, L.S. Elson et al., J. Geophys. Res., 85, 8007-8025, 1980 [2] Lundin, R.; Barabash, S.; Futaana, Y.; Sauvaud, J.-A.; Fedorov, A.; Perez-de-Tejada, H., Ion flow and momentum transfer in the Venus plasma environment, Icarus, 215, 751-758, 2011

Lundin, R.; Barabash, S.; Futaana, S.; Holmstrom, M.; Perez-de-Tejada, H.; Sauvaud, J.-A.

2012-04-01

317

Mesoscale roughness of Venus  

NASA Technical Reports Server (NTRS)

The global distribution of multi-kilometer (approx. 9 km) length scale 'roughness' (hereafter mesoscale roughness or MR) on Venus can be estimated from the Magellan global altimetry dataset (GxDR) and then compared with MR data derived for Earth from 5' ETOP5 data and for Mars (from USGS Mars DTM dataset). The mesoscale roughness parameter (MR) represents the RMS variance in meters of the actual planetary surface topography relative to the best fitting tangent plane defined on the basis of a 3x3 pixel sliding window. The best-fit plane was computed using a least-squares solution which minimizes delta H, the sum of the squares of the differences between the 9 local elevation values (H(sub i)), and the elevation of best-fit plane at the same grid location. Using the best-fit plane and delta H, we have computed the RMS 'roughness' var(delta R), where this parameter is always minimized on the basis of its calculation using least squares. We have called this 'ruggedness' parameter the Mesoscale Roughness (MR) because it is directly related to the high-frequency variance of topography after mesoscale slopes and tilts (i.e., for Venus, the baseline over which MR is computed (dx) is approx. 8.8 km and dx for Earth is approx. 9.3 km) are removed. As such, MR represents the degree to which a planetary surface is more rugged than approximately 10 km scale facets or tilts. It should not be confused with the radar 'RMS Roughness' parameter computed at 0.1 to 10 m length scales on the basis of the Magellan radar altimeter echo. We will use our MR parameter to investigate the global ruggedness properties of Venus as they relate to geological provinces and in comparison with the spatial pattern of MR for Earth and Mars.

Garvin, J. B.; Frawley, James J.

1994-01-01

318

Pioneer Venus gas chromatography of the lower atmosphere of Venus  

NASA Technical Reports Server (NTRS)

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

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

1980-01-01

319

Venus: A World of Water and Life  

NASA Astrophysics Data System (ADS)

Author: John Ditkof Institution: University Wisconsin-Madison 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.

2012-12-01

320

The monopropellant hydrazine propulsion subsystem for the Pioneer Venus spacecraft  

NASA Technical Reports Server (NTRS)

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

Barker, F. C.

1979-01-01

321

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

PubMed

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

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

2007-11-29

322

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

NASA Astrophysics Data System (ADS)

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

Launius, Roger D.

2012-09-01

323

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

PubMed Central

Both Venus and Mars have captured the human imagination during the twentieth century as possible abodes of life. Venus had long enchanted humans—all the more so after astronomers realized it was shrouded in a mysterious cloak of clouds permanently hiding the surface from view. It was also the closest planet to Earth, with nearly the same size and surface gravity. These attributes brought myriad speculations about the nature of Venus, its climate, and the possibility of life existing there in some form. Mars also harbored interest as a place where life had or might still exist. Seasonal changes on Mars were interpreted as due to the possible spread and retreat of ice caps and lichen-like vegetation. A core element of this belief rested with the climatology of these two planets, as observed by astronomers, but these ideas were significantly altered, if not dashed during the space age. Missions to Venus and Mars revealed strikingly different worlds. The high temperatures and pressures found on Venus supported a “runaway greenhouse theory,” and Mars harbored an apparently lifeless landscape similar to the surface of the Moon. While hopes for Venus as an abode of life ended, the search for evidence of past life on Mars, possibly microbial, remains a central theme in space exploration. This survey explores the evolution of thinking about the climates of Venus and Mars as life-support systems, in comparison to Earth. PMID:25371106

Launius, Roger D.

2012-01-01

324

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

NASA Astrophysics Data System (ADS)

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

325

Chemical reactions between Venus' surface and atmosphere - An update. (Invited)  

NASA Astrophysics Data System (ADS)

The surface of Venus, at ~740K, is hot enough to allow relatively rapid chemical reactions between it and the atmosphere, i.e. weathering. Venus chemical weathering has been explored in detail [1], to the limits of available data. New data from Venus Express (VEx) and new ideas from exoplanets have sparked a modest renewal of interest in Venus weathering. Venus' surface cannot be observed in visible light, but there are several NIR ';windows' through its atmosphere that allow surface imaging. The VIRTIS spectrometer on VEx viewed the surface through one window [2]; emissivity variations among lava flows on Imdr and Themis Regios have been explained as varying degrees of weathering, and thus age [3]. The VMC camera on VEx also provides images through a NIR window, which suggest variable degrees of weathering on some basaltic plains [4]. Indirect evidence for weathering may come from varying SO2 abundance at Venus' cloud tops; repeated rapid increases and gradual declines may represent volcanic eruptions followed by weathering to form sulfate minerals [5]. Continued geochemical modeling relevant to Venus weathering is motivated by expolanet studies [6]. Models have been extended to hypothetical exo-Venuses of different temperatures and surface compositions [7]. The idea that Venus' atmosphere composition can be buffered by reaction with its surface was explored in detail, and the derived constraint extended to other types of planets [8]. Several laboratories are investigating Venus weathering, motivated in part by the hope that they can provide real constraints on timescales of Venus volcanism [3]. Aveline et al. [9] are extending early studies [10] by reacting rocks and minerals with concentrated SO2 (to accelerate reaction rates to allow detectability of products). Kohler et al. [11] are investigating the stability of metals and chalcogenides as possible causes of the low-emissivity surfaces at high elevations. Berger and Aigouy [12] studied rock alteration on a hypothetical early Venus with a water-rich atmosphere. Martin et al. [13] investigated the fate of weathered rock when heated (by igneous or impact events). Our understanding of Venus' geological history is stymied by a lack of data - spacecraft observations of and/or at its surface. VMC on VEx may continue to provide new data on surface emissivity, but their interpretation is inherently ambiguous. Laboratory experiments seem the most promising approach - attempting to quantify rates of weathering and thus volcanism [3], and (with luck) framing significant problems that can be directly answered by spacecraft observations. [1] Fegley B.Jr. et al. (1997) In Venus II. U. Ariz. Press. p. 591. [2] Helbert J. et al. (2008) GRL 35, L11201. [3] Smrekar S.E et al. (2010) Science 328, 605-608. [4] Basilevsky A.T. et al. (2012) Icarus 217, 434-450. [5] Marcq E. et al. (2013) Nature Geoscience 6, 25-28. [6] Kane S.R. et al. (2013) Astrophysical J. 770, L20. [7] Schaefer L. & Fegley B.Jr. (2011) Astrophysical J. 729, 6. [8] Treiman A.H. & Bullock M.A. (2012) Icarus 217, 534-541. [9] Aveline D.C. et al. (2011) Lunar Planet. Sci. Conf. 42, Abstr. #2165. [10] Fegley B.Jr. & Prinn R.G. (1989) Nature 337, 55-58. [11] Kohler E. et al. (2012) Lunar Planet. Sci. Conf. 43, Abstr. #2749. [12] Berger G. & Aigouy T. (2011) Lunar Planet. Sci. Conf. 42, Abstr. #1660. [13] Martin A.M. et al. (2012) Earth Planet. Sci. Lett. 331-332, 291-304.

Treiman, A. H.

2013-12-01

326

Short Large-Amplitude Magnetic Structures (SLAMS) at Venus  

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

327

Stagnation Point Radiative Heating Relations for Venus Entry  

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

328

Mirror mode structures near Venus and Comet P/Halley  

NASA Astrophysics Data System (ADS)

In this paper, we study where mirror mode structures are generated near unmagnetized solar system bodies (Venus and comet P/Halley measured in situ by Venus Express and Giotto). To estimate the location of the mirror mode source region at Venus, we apply a turbulent diffusion model of mirror mode structures, which has already been successfully tested in planetary magnetosheaths (Earth, Jupiter, Saturn). It enables us to estimate the distance between the measured location of the mirror mode and the origin of the mirror mode structure through the mirror mode size. We find that the scenario of mirror mode excitation at the bow shock with subsequent convection and diffusion downstream to the magnetopause is valid for Venus. In the cometary case, however, we find that the size of the mirror mode structure is comparable to the gyroradius of water group ions. This suggests local production of mirror mode structures in the cometary magnetosheath, most likely through fresh ion pickup, as opposed to the convection and diffusion mechanism at Venus.

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

2014-06-01

329

The high-resolution stereo camera (HRSC) experiment on Mars Express: Instrument aspects and experiment conduct from interplanetary cruise through the nominal mission  

Microsoft Academic Search

ESA's Mars Express has successfully completed its nominal mission of one Martian year covering about 25% of the surface in stereo and color with resolutions up to 10m\\/pixel by its high-resolution stereo camera (HRSC). Mars Express is now in its extended mission phase, during which much of the remaining part of the Martian surface is envisaged to be covered in

R. Jaumann; G. Neukum; T. Behnke; T. C. Duxbury; K. Eichentopf; J. Flohrer; S. v. Gasselt; B. Giese; K. Gwinner; E. Hauber; H. Hoffmann; A. Hoffmeister; U. Köhler; K.-D. Matz; T. B. McCord; V. Mertens; J. Oberst; R. Pischel; D. Reiss; E. Ress; T. Roatsch; P. Saiger; F. Scholten; G. Schwarz; K. Stephan; M. Wählisch

2007-01-01

330

HST Observations of Mars and Venus Supra-thermal Thermospheric Oxygen  

NASA Astrophysics Data System (ADS)

The loss of water from Venus and Mars is an ongoing topic of study in planetary astronomy. One method for considering this loss is to examine the loss of volatiles, specifically hydrogen and oxygen, from the thermospheres of the two planets. One process by which oxygen atoms escape the Mars atmosphere is by a creation of a suprathermal population of oxygen from the dissociative recombination of O2+, the dominant ion in the Mars and Venus ionospheres. On Venus, the same process occurs, but due to the larger planetary mass the suprathermal corona has not been observed as an escape mechanism by itself. Observations of hot oxygen in the Venus atmosphere date back as far as 1978 (Bertaux et al.), though observational confirmation of the hot population of Mars was only published as recently as 2011 (Feldman et al.) Re-analysis of the understanding of the Venus thermosphere has been performed after Venus Express results seemed to contrast to the Pioneer Venus observations (Lichtenegger et al., 2009). The observations presented in this work were taken of Mars using HST STIS and a low-resolution grating in 2007 and of Venus using HST STIS and an echelle grating in November 2013. The UV spectroscopic observations of resonantly-scattered sunlight from the 1304 Å oxygen emission are compared with modeled thermospheric populations.Comparisons are made with previous data sets and modeled populations, in order to better describe the temporal variation of the suprathermal neutral oxygen populations.

Carveth, Carol; Clarke, John T.; Chaufray, Jean-Yves; Bertaux, Jean-Loup

2014-06-01

331

Recent hotspot volcanism on Venus from VIRTIS emissivity data.  

PubMed

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

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

2010-04-30

332

The Pioneer Venus Orbiter: 11 years of data. A laboratory for atmospheres seminar talk  

NASA Technical Reports Server (NTRS)

The Pioneer Venus Orbiter has been in operation since orbit insertion on December 4, 1978. For the past 11 years, it has been acquiring data in the salient features of the planet, its atmosphere, ionosphere, and interaction with the solar wind. A few of the results of this mission are summarized and their contribution to our general understanding of the planet Venus is discussed. Although Earth and Venus are often called twin planets, they are only superficially similar. Possessing no obvious evidence of plate tectonics, lacking water and an intrinsic magnetic field, and having a hot, dense carbon dioxide atmosphere with sulfuric acid clouds makes Venus a unique object of study by the Orbiter's instruments.

Kasprzak, W. T.

1990-01-01

333

The International VEGA "Venus-Halley" (1984-1986) Experiment: Description and Scientific Objectives  

NASA Technical Reports Server (NTRS)

The Venus-Halley (Vega) project will provide a unique opportunity to combine a mission over Venus with a transfer flight to Halley's comet. This project is based on three research goals: (1) to study the surface of Venus; (2) to study the air circulation on Venus and its meteorological parameters; and (3) to study Halley's comet. The objective of the study of Halley's comet is to: determine the physical characteristics of its nucleus; define the structure and dynamics of the coma around the nucleus; define the gas composition near the nucleus; investigate the dust particle distribution as a function of mass at various distances from the nucleus; and investigate the solar wind interaction with the atmosphere and ionosphere of the comet.

1985-01-01

334

Systems design study of the Pioneer Venus spacecraft. Appendices to volume 1, sections 3-6 (part 1 of 3). [design of Venus probe windows  

NASA Technical Reports Server (NTRS)

The design is described of the Venus probe windows, which are required to measure solar flux, infrared flux, aureole, and cloud particles. Window heating and structural materials for the probe window assemblies are discussed along with the magnetometer. The command lists for science, power and communication requirements, telemetry sign characteristics, mission profile summary, mass properties of payloads, and failure modes are presented.

1973-01-01

335

Mantle plumes on Venus revisited  

NASA Astrophysics Data System (ADS)

The Equatorial Highlands of Venus consist of a series of quasicircular regions of high topography, rising up to about 5 km above the mean planetary radius. These highlands are strongly correlated with positive geoid anomalies, with a peak amplitude of 120 m at Atla Regio. Shield volcanism is observed at Beta, Eistla, Bell, and Atla Regiones and in the Hathor Mons-Innini Mons-Ushas Mons region of the southern hemisphere. Volcanos have also been mapped in Phoebe Regio and flood volcanism is observed in Ovda and Thetis Regiones. Extensional tectonism is also observed in Ovda and Thetis Regiones. Extensional tectonism is also observed in many of these regions. It is now widely accepted that at least Beta, Atla, Eistla, and Bell Regiones are the surface expressions of hot, rising mantel plumes. Upwelling plumes are consistent with both the volcanism and the extensional tectonism observed in these regions. The geoid anomalies and topography of these four regions show considerable variation. Peak geoid anomalies exceed 90 m at Beta and Atla, but are only 40 m at Eistla and 24 m at Bell. Similarly, the peak topography is greater at Beta and Atla than at Eistla and Bell. Such a range of values is not surprising because terrestrial hotspot swells also have a side range of geoid anomalies and topographic uplifts. Kiefer and Hager used cylindrical axisymmetric, steady-state convection calculations to show that mantle plumes can quantitatively account for both the amplitude and the shape of the long-wavelength geoid and topography at Beta and Atla. In these models, most of the topography of these highlands is due to uplift by the vertical normal stress associated with the rising plume. Additional topography may also be present due to crustal thickening by volcanism and crustal thinning by rifting. Smrekar and Phillips have also considered the geoid and topography of plumes on Venus, but they restricted themselves to considering only the geoid-topography ratio and did not examine either the geoid and topography amplitudes separately or the shapes of anomalies.

Kiefer, Walter S.

1992-12-01

336

Transforming Venus by induced overturn  

NASA Astrophysics Data System (ADS)

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, the introduction of life, initial habitability, and long-term developments.

Smith, Alexander G.

1989-12-01

337

Transits Of Venus: 1639, 1761, 1769, 1874, 1882, 2004, And 2012  

NASA Astrophysics Data System (ADS)

Transits of Venus are exceedingly rare predictable astronomical events, with only six having been observed since Jeremiah Horrox corrected Johannes Kepler's Rudolphine Tables and observed the transit of 1639. Edmond Halley's 1716 method of finding the size and scale of the Solar System and thus of the Universe led to hundreds of 18th-century and 19th-century transit-of-Venus expeditions for each event. I discuss the history and importance of the transit observations, and how spacecraft observations of the 1999 transit of Mercury, repeated at the 2003 and 2006 transits, led to the solution of the black-drop effect problem that had prevented Halley's method from reaching its desired accuracy and thus solution of the noble problem of astronomy to find the size and scale of the solar system. Other spacecraft observations of the 2004 transit of Venus have led to an analysis of how Venus's atmosphere becomes visible for about 25 minutes before second contact and after third contact, and links with prior historical claims, mostly invalid, to have discovered Venus's atmosphere at transits. Total-solar-irradiance spacecraft observations at the 2004 Venus transit link to exoplanet discoveries with NASA's aptly named Kepler Mission and ESA's CoRoT. I further link previous transit observations to planned observations for the June 5/6, 2012, Venus transit and the May 9, 2016, Mercury transit, together providing a historical basis for 22nd-century astronomers preparing to observe the December 10, 2117, Venus transit. My observations at the 2004 and 2012 transits of Venus were and will be supported in large part by grants from the Committee for Research and Exploration of the National Geographic Society. My solar observations were supported in part by NASA grant NNG04GK44G for work with the TRACE spacecraft and NASA Marshall grant NNX10AK47A and planetary work supported in part by NNX08AO50G from NASA Planetary Astronomy.

Pasachoff, Jay M.

2012-01-01

338

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

339

Clouds and aerosols on Venus: an overview  

NASA Astrophysics Data System (ADS)

The past decade demonstrated significant progress in understanding of the Venus cloud system. This paper gives a summary of new observations and modelling efforts that will form the basis for a relevant chapter in the Venus III book. Venus Express observations reveal significant latitudinal variations and temporal changes in the global cloud top morphology [1]. The cloud top altitude varies from ~72 km in the low and middle latitudes to ~64 km in the polar region, correlated with decrease of the aerosol scale height from 4 ± 1.6 km to 1.7 ± 2.4 km marking a vast polar depression [2, 3]. UV imaging shows the middle latitudes and polar regions in unprecedented detail. The eye of the Southern polar vortex was found to be a strongly variable feature with complex morphology and dynamics [4]. Solar and stellar occultations give access to a vertical profiling of the light absorption by the aerosols in the upper haze. The aerosol loading in the mesosphere of Venus investigated by SPICAV experiment onboard Venus Express between 2006 and 2010 was highly variable on both short and long time scales. The extinction at a given altitude can vary with a factor of 10 for occultations separated by a few Earth days. The extinction at a given altitude is also significantly lower towards the poles (by a factor 10 at least) compared to the values around the equator, while there is apparently no correlation between the extinction and the latitude in the region comprised between ±40° around the equator [5]. Based on Mie theory and on the observed spectral dependence of light extinction in spectra recorded simultaneously in the UV (SPICAV-UV), in the near IR (SPICAV-IR), and in the short-and midwavelength IR (SPICAV-SOIR), the size distribution of aerosols in the upper haze of Venus was retrieved, assuming H2SO4/water composition of the droplets [6]. The optical model includes H2SO4 concentrations from 60 to 85%. A number of results are strikingly new: (1) an increase of the H2SO4 concentration with a decreasing altitude (from 70-75% at about 90 km to 85% at 70 km of altitude) and (2) Many SOIR/SPICAV data cannot be fitted when using size distributions found in the literature, with an effective radius below 0.3 ?m and a variance of about 2. The scale height of the upper haze is found to be 6.9 ± 5.1 km. The lower & middle cloud layers - those at 48 - 60 km altitudes - are difficult to observe, as they are hidden by upper clouds. Nevertheless, both nightside near-IR sounding and radio occultation has provided valuable insight into cloud processes in this region. Near IR sounding reveals the morphology of the lower/middle clouds 'backlit' by thermally emitted photons from the lower atmosphere. The morphology of these clouds changes on timescales of order of 24 hours [7]. The vertically integrated cloud optical depth is twice as great in the polar collar (at 75 degrees latitude) compared to low latitudes. Spectral band ratio analysis, if interpreted strictly in terms of Mode 1 / 2 / 2' / 3 particles of H2SO4:H2O mixtures, the acidity of the cloud particles is found to be higher near the polar collar and in regions of optically thick cloud [8]. Particles in the centre of the polar vortex exhibit anomalously high band ratios so are significantly larger and/or of different composition than those at low latitudes [9]. Radio occultation from Venus Express confirms that the atmosphere is in convective equilibrium from 50-60 km [10]. Sulphuric acid vapour profiles calculated from the absorption of the radio signals show an atmosphere saturated with sulphuric acid in the cloud layer [11]. Both of these results are consistent with the understanding of convective condensational cloud at altitudes of 50-60 km. Microphysical simulations of the aerosol populations in the atmosphere of Venus have received a boost from the recent exploration of particle properties carried out by various teams using Venus Express over the last decade or so. Numerous groups are applying separate models to the coupled problems of the Venus clouds. Quasi-periodic variabilit

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

2014-04-01

340

Pioneer Venus 1978  

NASA Technical Reports Server (NTRS)

An orbiter and a multiprobe spacecraft will be sent to Venus in 1978 to conduct a detailed examination of the planet's atmosphere and weather. The spin-stabilized multiprobe spacecraft consists of a bus, a large probe and three identical small probes, each carrying a complement of scientific instruments. The large probe will conduct a detailed sounding of the lower atmosphere, obtaining measurements of the clouds, atmospheric structure, wind speed, and atmospheric composition. Primary emphasis will be placed on the planet's energy balance and clouds. The three small probes will provide information on the circulation pattern of the lower atmosphere. The probe bus will provide data on the upper atmosphere and ionosphere down to an altitude of about 120 km. The orbiter is designed to globally map the atmosphere, ionosphere, and the solar wind/ionosphere interaction. In addition, it will utilize radar mapping techniques to study the surface.

1976-01-01

341

NASA CONNECT: Venus Transit  

NSDL National Science Digital Library

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

2004-01-01

342

Oxygen Chemistry and Airglow in Venus' Atmosphere  

NASA Astrophysics Data System (ADS)

Airglow in a planetary atmosphere is diagnostic of the combined effects of transport, both vertical and horizontal, and chemistry. Airglow emission on the night side in the OH(3-2, 2-1, 2-0, and 1-0), O2(c-X and a-X), and NO(C-A) bands has been reported in the past two years based on observations by VIRTIS on Venus Express [1,2,3]. Previous observations had also identified airglow emission in the O2(a-X) band on the day side [4]. Vertical profiles from limb observations indicate the OH and O2 nightglow emissions are typically most intense at 95-100 km altitude [1,5] while the NO nightglow emission is most intense at about 110 km altitude [2]. All of these airglow emissions are directly or indirectly connected to the atomic oxygen abundance at these altitudes and vertical profiles of the O2(a-X) nightglow emission as observed by VIRTIS on Venus Express have been used to infer the atomic oxygen profile [6]. The expected connections among these day and night side airglow emissions based on photochemical modelling will be discussed along with their implications for oxygen chemistry in the 90-110 km altitude range in Venus' atmosphere. This work was partially supported by the Australian Research Council. [1] Piccioni et al, A&A 483, L29, 2008 [2] García Muñoz et al, PNAS 106, 985, 2009 [3] García Muñoz et al, JGR, in revision, 2009 [4] Connes et al, ApJ 233, L29, 1979 [5] Piccioni et al, JGR 114, E00B38, 2009 [6] Gérard et al, GRL 35, L02207, 2008

Mills, Franklin P.; Garcia Munoz, A.; Yung, Y. L.; Allen, M.; Piccioni, G.; Drossart, P.

2009-09-01

343

Venus - First Radar Test  

NASA Technical Reports Server (NTRS)

After traveling more than 1.5 billion kilometers (948 million miles), the Magellan spacecraft was inserted into orbit around Venus on Aug. 10, 1990. This mosaic consists of adjacent pieces of two Magellan image strips obtained on Aug. 16 in the first radar test. The radar test was part of a planned In Orbit Checkout sequence designed to prepare the Magellan spacecraft and radar to begin mapping after Aug. 31. The strip on the left was returned to the Goldstone Deep Space Network station in California; the strip to the right was received at the DSN in Canberra, Australia. A third station that will be receiving Magellan data is located near Madrid, Spain. Each image strip is 20 km (12 miles) wide and 16,000 km (10,000 miles) long. This mosaic is a small portion 80 km (50 miles) long. This image is centered at 21 degrees north latitude and 286.8 degrees east longitude, southeast of a volcanic highland region called Beta Regio. The resolution of the image is about 120 meters (400 feet), 10 times better than previous images of the same area of Venus, revealing many new geologic features. The bright line trending northwest southeast across the center of the image is a fracture or fault zone cutting the volcanic plains. In the upper left corner of the image, a multiple ring circular feature of probable volcanic origin can be seen, approximately 4.27 km (2.65 miles) across. The bright and dark variations seen in the plains surrounding these features correspond to volcanic lava flows of varying ages. The volcanic lava flows in the southern half of the image have been cut by north south trending faults. This area is similar geologically to volcanic deposits seen on Earth at Hawaii and the Snake River Plains in Idaho.

1990-01-01

344

A spatial domain Stokes flow model for the gravity and topography of the middle latitudes of Venus  

NASA Technical Reports Server (NTRS)

A novel modeling technique is developed and applied to the long-wavelength gravity, topography, and internal density structure of Venus. The focus of this study is to employ data on the gravity and topography of Venus, which are obtained from the Pioneer Venus Orbiter mission, to enhance understanding some key aspects of the internal structure of the planet. A modeling strategy utilizing 'stokeslets' or basic units of slow viscous flow (governed by the Stokes equations) to duplicate the observed gravity and topography is implemented.

Bills, Bruce G.; Fischer, Mfark A.

1992-01-01

345

ENA diagnostic of the solar wind interaction with Mars and Venus  

NASA Astrophysics Data System (ADS)

Charge - exchange of the solar wind ions flowing around non-magnetized Mars and Venus on their exospheres results in hydrogen energetic neutral atom (ENA) emissions. Accelerated planetary ions may also experience charge - exchange resulting in planetary ENAs, mainly oxygen. The ENAs carry information on the ion distribution functions integrated over the line-of-sight and are used for remote sensing of the original plasma populations. The ASPERA-3/4 instruments (Analyzer of Space Plasmas and Energetic Atoms) onboard Mars Express and Venus Express missions performed the first-ever measurements of ENAs from these bodies in the energy range 100 eV - 10 keV. ENAs are mostly emitted by the magnetospheath plasma flowing around the induced magnetosphere. Due to lower gravity the Martian exosphere extends further in the magnetosheath than at Venus that makes Mars a “brighter ENA source”. We thus focus mostly on Mars and only briefly discuss ENA observations at Venus. ENA emissions from an elementary emitting volume in the magnetosheath are highly anisotropic and occur along the tangential line to the stream-line in this point. That makes impossible to obtain a global ENA image of the object from a single vantage point contrary to, for example, “classical” ENA imaging of the terrestrial ring current. At Mars the statistically obtained emission pattern shows an increase in the ENA flux perpendicular to the sun direction resembling a thick layer or a wall. The emissions coming mostly from the sub-solar point show an increase in the direction opposite to the convective electric field indicating the induced magnetosphere boundary is not cylindrically symmetric and closer to planet in this direction. Measurements of ENAs turned out to be an effective way to reveal the global dynamics of an induced magnetosphere. Arrival of an interplanetary shock to Mars and the associated compression of the induced magnetosphere are clearly detected as an abrupt termination of the ENA signal because the ENA wall suddenly moved away from the spacecraft. When the spacecraft stays sufficiently long inside the ENA wall, oscillations of the ENA signal with a period of 30 sec - few min (~0.01 Hz) can be observed. The oscillations of the similar frequency are observed in the electron and ion fluxes in the magnetosheath as well as magnetic field. Their physics is not understood. Mars Express/ASPERA-3 detected a slight increase of the ENA emissions above the magnetic anomalies. It may be related to the increase of the neutral densities above these regions. Contrary to the predictions, Mars Express/ASPERA-3 did not detect any oxygen ENAs. That allowed to provide upper limits for the hydrogen exospheric densities which turned out to be much lower at the solar minimum than expected. Finally, we introduce a few “exotic” ideas of using ENAs for studies the near-Venus and near-Mars space. Using ENAs backscattered from the atmosphere one may obtain global precipitating maps. Using the neutral solar wind passing through the upper atmosphere at the terminate region, one may realize neutral solar wind occultation geometry and use the ENA signal variation for the upper atmosphere profiling.

Barabash, Stas

346

Venus - Computer Simulated Global View of the Northern Hemisphere  

NASA Technical Reports Server (NTRS)

The northern hemisphere is displayed in this global view of the surface of Venus. The north pole is at the center of the image, with 0 degrees, 90 degrees, 180 degrees, 270 degrees east longitudes at the 6, 3, 12, and 9 o'clock positions, respectively, of an imaginary clock face. Magellan synthetic aperture radar mosaics from the three eight-month cycles of Magellan radar mapping are mapped onto a computer-simulated globe to create this image. Magellan obtained coverage of 98 percent of the surface of Venus. Remaining gaps are filled with data from previous missions, (the Soviet Venera 15 and 16 radar and Pioneer Venus Orbiter altimetry) and data from Earth-based radar observations from the Arecibo radio telescope. Simulated color is used to enhance small-scale structures. The simulated hues are based on color images recorded by the Venera 13 and 14 landing craft. Maxwell Montes, the planet's highest mountain at 11 kilometers (6.6 miles) above the average elevation, is the bright feature in the lower center of the image. Other terrain types visible in this image include tessera, ridge belts, lava flows, impact craters and coronae. The image was produced by the Solar System Visualization Project and the Magellan Science team at the Jet Propulsion Laboratory Multimission Image Processing Laboratory. The Magellan mission is managed by JPL for NASA's Office of Space Science.

1993-01-01

347

PERFORMANCE OF AUTOMATIC TIE POINT EXTRACTION USING HRSC IMAGERY OF THE MARS EXPRESS MISSION  

Microsoft Academic Search

ABSTRACT: InJanuary 2004 the first European interplanetary spacecraft, Mars Express, was inserted successfully into a Martian orbit. The multiline scanner HRSC (High Resolution Stereo Camera) on board ,of Mars Express will image most of the ,surface of Mars ,in colour and stereoscopically in high resolution. The Institute of Photogrammetry and GeoInformation (IPI), University of Hannover, has created software for the

C. Heipke; R. Schmidt; G. Neukum

348

Atmospheric evolution on Venus Bruce Fegley, Jr.  

E-print Network

·2 H2O) at ~45 to ~70 km altitude continuously shrouds Venus' surface from our view. The clouds also1 Atmospheric evolution on Venus Bruce Fegley, Jr. Planetary Chemistry Laboratory Department and Ancient Environments Edited by Vivien Gornitz January 2004 #12;2 ATMOSPHERIC EVOLUTION ON VENUS Overview

Fegley Jr., Bruce

349

Biologically Closed Electrical Circuits in Venus Flytrap  

Microsoft Academic Search

The Venus flytrap (Dionaea muscipula Ellis) is a marvel of plant electrical, mechanical, and biochemical engineering. The rapid closure of the Venus flytrap upper leaf in about 0.1 s is one of the fastest movements in the plant kingdom. We found earlier that the electrical stimulus between a midrib and a lobe closes the Venus flytrap upper leaf without mechanical

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

2009-01-01

350

Venus tectonics: another Earth or another Mars  

Microsoft Academic Search

The presence of presumably primordial large craters has led to the suggestion that Venus may have a thick lithosphere like that of Mars despite its similarities to Earth in size and density. However, crust and upper mantle temperatures on Venus are very likely higher than on Earth so that a dry Venus could have a lithosphere with a thickness similar

George E. McGill

1979-01-01

351

Pioneer Venus gas chromatography of the lower atmosphere of Venus  

SciTech Connect

A gas chromatograph mounted in the Pioneer Venus sounder probe measured the chemical composition of the atmosphere of Venus at three altitudes. Ne, N/sub 2/, O/sub 2/, Ar, CO, H/sub 2/O, SO/sub 2/, and CO/sub 2/ were measured, and upper limits set for H/sub 2/, COS, H/sub 2/S, CH/sub 4/, Kr, N/sub 2/O, C/sub 2/H/sub 4/, C/sub 2/H/sub 6/, and C/sub 3/H/sub 8/. Simulation studies have provided indirect evidence for sulfuric acid--like droplets and support the possibility of water vapor at altitudes of 42 and 24 km. The paper discusses the implications of these results for the origin, evolution, and present state of Venus' atmosphere.

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

1980-12-30

352

Electrical memory in Venus flytrap.  

PubMed

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 exact electrical charge utilized by the D. muscipula Ellis to facilitate the trap closing and investigated electrical short memory in the Venus flytrap. As soon as the 8 microC charge for a small trap or a 9 microC charge for a large trap is transmitted between a lobe and midrib from the external capacitor, the trap starts to close at room temperature. At temperatures 28-36 degrees C a smaller electrical charge of 4.1 microC is required to close the trap of the D. muscipula. The cumulative character of electrical stimuli points to the existence of short-term electrical memory in the Venus flytrap. We also found sensory memory in the Venus flytrap. When one sustained mechanical stimulus was applied to only one trigger hair, the trap closed in a few seconds. PMID:19356999

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

2009-06-01

353

Episodic plate tectonics on Venus  

NASA Technical Reports Server (NTRS)

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

Turcotte, Donald

1992-01-01

354

Geologic map of the Carson Quadrangle (V-43), 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 had the objectives of (1) improving knowledge of the geologic processes, surface properties, and geologic history of Venus by analysis of surface radar characteristics, topography, and morphology and (2) improving knowledge of the geophysics of Venus by analysis of venusian gravity. The Magellan spacecraft carried a 12.6-cm radar system to map the surface of Venus. The transmitter and receiver systems were used to collect three datasets: synthetic aperture radar (SAR) images of the surface, passive microwave thermal emission observations, and measurements of the backscattered power at small angles of incidence, which were processed to yield altimetric data. Radar imaging and altimetric and radiometric mapping of the venusian surface were done in mission cycles 1, 2, and 3, from September 1990 until September 1992. Ninety-eight percent of the surface was mapped with radar resolution of approximately 120 meters. The SAR observations were projected to a 75-m nominal horizontal resolution; these full-resolution data compose the image base used in geologic mapping. The primary polarization mode was horizontal-transmit, horizontal-receive (HH), but additional data for selected areas were collected for the vertical polarization sense. Incidence angles varied from about 20° to 45°. High-resolution Doppler tracking of the spacecraft was done from September 1992 through October 1994 (mission cycles 4, 5, 6). High-resolution gravity observations from about 950 orbits were obtained between September 1992 and May 1993, while Magellan was in an elliptical orbit with a periapsis near 175 kilometers and an apoapsis near 8,000 kilometers. Observations from an additional 1,500 orbits were obtained following orbitcircularization in mid-1993. These data exist as a 75° by 75° harmonic field.

Bender, Kelly C.; Senske, David A.; Greeley, Ronald

2000-01-01

355

Dual Balloon Concept for Lifting Payloads from the Surface of Venus  

NASA Technical Reports Server (NTRS)

Introduction: Two high-rated Venus mission concepts proposed in the National Science Foundation Decadal Survey require a balloon to lift payloads from Venusian surface to high altitudes: Venus Surface Sample Return (VESSR) and Venus In-Situ Explorer (VISE). In case of VESSR the payload is a canister with the surface sample plus a Venus ascent vehicle (VAV), which is a rocket that takes the sample into orbit for rendezvous with an Earth return vehicle. VISE is envisioned as a more limited precursor mission where the surface sample is only taken to high altitudes so that non time-critical analyses can be performed. From the balloon point of view, the only difference between these two missions is that the VESSR payload to be lifted is very much larger than VISE because of the inclusion of the VAV. A key problem is that at the time the decadal survey was published, no high temperature balloon technology existed to implement either mission. Prior technology development efforts had concentrated on a single balloon that could operate across the entire 0-60 km altitude range, tolerating both the sulfuric acid aerosols and the extreme temperatures of -10 to +460 C. However, this problem was unsolved because no combination of sufficiently lightweight balloon material and manufacturing (seaming) technology was ever found to tolerate the high temperatures at the surface.

Kerzhanovich, Viktor V.; Yavrouian, A. H.; Hall, J. L.; Cutts, J. A.

2005-01-01

356

Limb Altitude and the Southern Hemispheric Vortex Observed by Venus Monitoring Camera on VEX Orbiter  

NASA Astrophysics Data System (ADS)

The Venus Monitoring Camera (VMC) on European Space Agency's Venus Express orbiter has been collecting almost daily images at four wavelengths (365, 550, 980 and 1050 nm) since June 2006 with a few gaps during solar conjunctions. These data provide a nearly continuous record of the southern vortex (Limaye at al. 2009) that spans the entire hemisphere and reveal a dynamic, constantly evolving structure and showing a range of dynamical instability features in the central region. These instability features are also seen in the near infrared observations from the VIRTIS instrument on Venus Express (Luz et al. 2011). Some similarities between the Venus hemispheric vortex and a tropical cyclone have been previously noted (Suomi and Limaye, 1981; Limaye et al., 2009; 2011) and more have been discovered from the VMC observations. While the details of the spatial structure of the vortex is easily observed from the imaging observations at ultraviolet (VMC) and near infrared wavelengths (VIRTIS), the vertical structure is more difficult to determine from Venus Express. Here we present inferences about the vertical level obtained from the visible limb of the planet in VMC images. The altitude of the limb has been measured using full or near full disk images and depicts the altitude of the Venus cloud cover which comprises the vortex circulation. By precisely locating the limb location by fitting each limb profile in the VMC images, the average latitudinal profile of the limb altitude has been estimated. Although the pixel size of the images used is ~ 30-45 km, the large number of images (> 25,000) provides a very large sample of limb altitude determinations at each latitude between the equator and about 60° S latitude enabling sub-pixel variations of the limb altitude. The latitudinal profile of the limb altitude is similar to that inferred from the near infrared observations from VIRTIS (Ignatiev et al., 2009; Cottini et al., 2012) - high in low latitudes and low in polar latitudes and is consistent with the vortex structure. References Cottini, V., N.I. Ignatiev, G. Piccioni, P. Drossart, D. Grassi, W.J. Markiewicz (2012), Water vapor near the cloud tops of Venus from Venus Express/VIRTIS dayside data, Icarus, 217, 561-569. Ignatiev, N.I., D. V. Titov, G. Piccioni, P. Drossart, W. J. Markiewicz, V. Cottini, Th. Roatsch, M. Almeida, and N. Manoel, (2009), Altimetry of the Venus cloud tops from the Venus Express observations, J. Geophys. Res., DOI: 10.1029/2008JE003320. Limaye, S.S., J.P. Kossin, C. Rozoff, G. Piccioni, D.V. Titov, W.K. Markiewicz (2009) Vortex circulation on Venus: dynamical similarities with terrestrial hurricanes, Geophys. Res.Lett., 36, L04204, doi:10.1029/2008GL036093. Limaye, S., R.J. Krauss, D. Santek and W. Markiewicz (2011), Global Cloud Organization and Motions on Venus from the Venus Monitoring Camera on Venus Express, EPSC Abstracts, Vol. 6, EPSC-DPS2011-1230, 2011.T@ Luz, D., et al., "Venus's Southern Polar Vortex Reveals Precessing Circulation", published online on Science Express, 7 April 2011. DOI:10.1126/science.1201629. Suomi, V. E., and S. S. Limaye (1978), Venus: Further evidence of vortex circulation, Science, 201, 1009- 1011.

Limaye, Sanjay; Krauss, Robert; Markiewicz, Wojciech

2013-04-01

357

Venus - Rhea Mons Volcano  

NASA Technical Reports Server (NTRS)

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

1990-01-01

358

Thermal Structure of Venus Night-Side Atmosphere as Seen by Ground-Based Heterodyne Observations at 10?m  

NASA Astrophysics Data System (ADS)

The structure of Venus atmosphere has been the target of intense studies in the past decade. The recent space mission Venus Express (VEX) has shed light on many open question concerning the thermal and dynamical behavior of its atmosphere. In the vicinity of the imminent shut down of the space craft, the importance of ground-based observations increases significantly. We want to introduce a new and unique opportunity to retrieve temperature profiles from the Venusian night-side atmosphere, using ground-based observation techniques. The application of heterodyne spectroscopy in the infrared enables the capability to resolve single molecular ro-vibrational transition features. Pressure broadened CO2 absorption lines, observable on the Venusian night side, have proven to be a good tracer for analyzing the predominant temperature. The profiles originate from the altitude region between the cloud top at ~65km (~100hPa) and 95km (~0.1hPa). With a spectral limited altitude resolution of 5.3km, vertical profiles can be variably deduced on various position on the planet. Initial results from two observing campaigns in March (A) and May (B) 2012 will be presented. During campaign A, Venus was shortly after maximum Eastern elongation and about 45% illuminated, while on campaign B, the Planet was close to its latest transit and thus almost completely dark. At each campaign, two different locations on the planet were investigated, by probing the CO2 P(12) transition at 10.5?m. A comparison to space-based data, including a coordinated observation with VEX, performed during campaign B, and the spatial variability of the temperature profiles are under investigation.

Stangier, Tobias; Sornig, Manuela; Hewagama, Tilak; Tellmann, Silvia; Pätzold, Martin; Krause, Pia; Kostiuk, Theodor; Livengood, Timothy

2014-05-01

359

Clouds of Venus. Input to VIRA.  

NASA Astrophysics Data System (ADS)

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

Ignatiev, Nikolay; Zasova, Ludmila

2012-07-01

360

Evidence for lightning on Venus  

NASA Technical Reports Server (NTRS)

Lightning is an interesting phenomenon both for atmospheric and ionospheric science. At the Earth lightning is generated in regions where there is strong convection. Lightning also requires the generation of large charge-separation electric fields. The energy dissipated in a lightning discharge can, for example, result in chemical reactions that would not normally occur. From an ionospheric point of view, lightning generates a broad spectrum of electromagnetic radiation. This radiation can propagate through the ionosphere as whistler mode waves, and at the Earth the waves propagate to high altitudes in the plasmasphere where they can cause energetic particle precipitation. The atmosphere and ionosphere of Venus are quite different from those on the Earth, and the presence of lightning at Venus has important consequences for our knowledge of why lightning occurs and how the energy is dissipated in the atmosphere and ionosphere. As discussed here, it now appears that lightning occurs in the dusk local time sector at Venus.

Strangeway, R. J.

1992-01-01

361

Biologically closed electrical circuits in venus flytrap.  

PubMed

The Venus flytrap (Dionaea muscipula Ellis) is a marvel of plant electrical, mechanical, and biochemical engineering. The rapid closure of the Venus flytrap upper leaf in about 0.1 s is one of the fastest movements in the plant kingdom. We found earlier that the electrical stimulus between a midrib and a lobe closes the Venus flytrap upper leaf without mechanical stimulation of trigger hairs. The Venus flytrap can accumulate small subthreshold charges and, when the threshold value is reached, the trap closes. Here, we investigated the electrical properties of the upper leaf of the Venus flytrap and proposed the equivalent electrical circuit in agreement with the experimental data. PMID:19211696

Volkov, Alexander G; Carrell, Holly; Markin, Vladislav S

2009-04-01

362

Hotspots on Venus: Possible recent activity at Themis Regio  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

363

Planetary missions using microspacecraft technology  

NASA Technical Reports Server (NTRS)

Some of the planetary missions using microspacecraft of mass on the order of 10 kg which are presently being considered at JPL are discussed. The primary benefits offered by this type of spacecraft is the small and relatively inexpensive launch vehicles and short program development schedules. A mission presently considered by the Asteroid Investigation with Microspacecraft (AIM) study is described with special attention given to the spacecraft configuration; the AIM mission will launch three spacecraft from a single Pegasus vehicle, achieving separate flybys for three near-earth asteroids. Attention is also given to the salient features of the Mars Rover Sample Return mission, the Venus Atmospheric Sounder, and the Comet Nucleus Mission, for which the application of microspacecraft technology is considered.

Short, Kendra L.; Jones, Ross M.; Salvo, Christopher G.; Mostert, Robert N.

1992-01-01

364

Venus - Global surface radio emissivity  

NASA Technical Reports Server (NTRS)

Observations of thermal radio emission from the surface of Venus, made by the Pioneer Venus radar mapper at a wavelength of 17 cm, show variations that are dominated by changes in surface emissivity. The regions of lowest emissivity (0.54 + or - 0.05 for the highland areas of Aphrodite Terra and Theia Mons) correspond closely to regions of high radar reflectivity reported earlier. These results support the inference of inclusions of material with high electrical conductivity in the surface rock of these areas.

Ford, P. G.; Pettengill, G. H.

1983-01-01

365

The mobile continents of Venus  

NASA Astrophysics Data System (ADS)

The structure of mobile continents in the northern hemisphere of Venus is examined on the basis of Venera 15 and 16 photographs. The relationship between block motion and subduction is considered, and the characteristics of the observed 'parquet' structure are described. This structure is shown to have certain analogies on other terrestrial planets. It is concluded that the continental matter of Venus might have been displaced via two processes, involving the motion of small and large plates, accompanied by clumping and shallow subduction on their boundaries, as well as through the formation of large gravity-induced landslides and fluxes.

Sukhanov, Aleksei L.

1989-11-01

366

Largest impact craters on Venus  

NASA Technical Reports Server (NTRS)

High-resolution radar images from the Magellan spacecraft have allowed us to perform a detailed study on 25 large impact craters on Venus with diameters from 70 to 280 km. The dimension of these large craters is comparable with the characteristic thickness of the venusian lithosphere and the atmospheric scale height. Some physical parameters for the largest impact craters on Venus (LICV), such as depth, ring/diameter ratio, and range of ballistic ejecta deposits, have been obtained from the SAR images and the altimetry dataset produced by MIT. Data related to each of these parameters is discussed.

Ivanov, B. A.; Weitz, C. M.; Basilevsky, A. T.

1992-01-01

367

Ionospheric magnetic fields at Venus and Mars  

NASA Astrophysics Data System (ADS)

Mars Global Surveyor (MGS) and Venus Express(VEX) spacecraft have provided us a wealth of insitu observations of characteristics of induced magnetospheres of Mars and Venus at low altitudes during the periods of solar minimum. At such conditions the interplanetary magnetic field (IMF) penetrates deeply inside the ionosphere while the solar wind is terminated at higher altitudes. We present the measurements made by MGS and VEX in the ionospheres of both planets which reveal similar features of the magnetization. The arising magnetic field pattern occurs strongly asymmetrical with respect to the direction of the cross-flow component of the IMF revealing either a sudden straightening of the field lines with a release of the magnetic field stresses or a sudden rotation of the magnetic field vector with a reversal of the sign of the cross-flow component. Such an asymmetrical response is observed at altitudes where the motion of ions and electrons is decoupled and collisional effects become important for generation of the electric currents Asymmetry in the field topology significantly modifies a plasma transport to the night side.

Dubinin, E.; Fraenz, M.; Zhang, T. L.; Woch, J.; Wei, Y.

2014-04-01

368

Exploring Mercury: Scientific Results from the MESSENGER Mission  

E-print Network

#12;Exploring Mercury: Scientific Results from the MESSENGER Mission Larry R. Nittler Carnegie-Cahill · MESSENGER Science Team, Engineers, Mission Operations (APL) #12;Mars Mercury · Naked-eye planet, but very difficult to observe due to proximity to Sun May 12, 2011, from NZ (M. White, Flickr) Mercury Venus Jupiter

Rhoads, James

369

A survey of hot flow anomalies at Venus  

NASA Astrophysics Data System (ADS)

We present the first survey of hot flow anomalies (HFAs) at the bow shock of Venus, expanding on our recent initial case study. A 3.06 sol (774 Earth day) survey of Venus Express magnetometer, ion spectrometer, and electron spectrometer data was undertaken in order to identify Cytherian HFAs. Seven events were discovered, corresponding to a statistical frequency ?1.2±0.8 per day, approximately the same rate as at the Earth. All seven HFAs were centered on a discontinuity in the solar wind, with inward pointing motional electric fields on at least one side, and exhibited electron and ion perturbations consistent with heating. For one event the calculation of continuous electron moments is possible, revealing that electron temperature increased from ?2×105 K to 8×105 K in the HFA core (comparable to terrestrial and Kronian HFA observations), and density increased from ?1 cm-3 to ~2?2.5 cm-3 in the bounding compression regions. Cytherian HFAs were found to be physically smaller (0.4?1.7 Venus radii (RV)) than their terrestrial or Kronian counterparts, although are much larger when compared to the overall size of the system (?130% of the subsolar bow shock distance), and occur very close (1.5?3.0RV) to the planet. Thus, we hypothesize that HFAs have a much more dominant role in the dynamics of the induced magnetosphere of Venus relative to the magnetospheres of magnetized planets.

Collinson, G. A.; Sibeck, D. G.; Masters, A.; Shane, N.; Zhang, T. L.; Fedorov, A.; Barabash, S.; Coates, A. J.; Moore, T. E.; Slavin, J. A.; Uritsky, V. M.; Boardsen, S.; Sarantos, M.

2014-02-01

370

Venus - Ovda Regio  

NASA Technical Reports Server (NTRS)

This image covers much of Ovda Regio, which forms the western part of Aphrodite Terra. It covers an area about 2,250 kilometers (1,386 miles) wide by 1,300 kilometers (800 miles) north to south, and ranges in latitude from 8 degrees north to 12 degrees south and in longitude from 62 degrees east to 90 degrees east. Ovda Regio is a highland region that rises over 4 kilometers (2.5 miles) above the surrounding plain. Magellan images show a complex surface, with several generations of structures. A pervasive fabric of irregular broad domes and ridges and associated curvilinear valleys was flooded by lava, then fractured. The circular feature surrounded by dark lava flows in the western part of the image is a caldera, or large volcanic collapse pit. Late-stage extension created long graben, or fault-bounded valleys, is best seen near the center of the image. The northern boundary of Ovda Regio is a steep, curvilinear mountain belt made up of long, narrow, rounded ridges. These ridges are similar in appearance to folded mountain belts on Earth. Several impact craters, such as the circular features on the western margin of the image, are scattered across the area. The bright area in the southeast part of the image indicates the presence of a radar-reflective mineral such as pyrite. Most of the highland areas on Venus display a similar bright signal. Each pixel of this image covers an area on the surface 675 meters (2,215 feet) across, representing a 9- times reduction in resolution compared to full-scale resolution data.

1991-01-01

371

Pancakelike domes on Venus  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

372

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

NASA Technical Reports Server (NTRS)

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

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

2014-01-01

373

Magnetic fields in Venus nightside ionospheric holes - Collected Pioneer Venus Orbiter magnetometer observations  

NASA Technical Reports Server (NTRS)

The magnetic fields detected by the Pioneer Venus Orbiter (PVO) magnetometer within the electron density depletions called 'holes' in the nightside ionosphere are typically larger and more organized than the fields in the surrounding ionosphere. Moreover, they have substantial sunward/antisunward components which cause them to appear as near-radial fields near the antisolar point. The collection of observations presented here illustrate the variety of appearances of the fields in holes. Some new results which summarize their average properties, their dependence on solar wind conditions, and their lack of geographical control are aslo presented. These results are potentially pertinent to the interpretation of data from the PVO entry at the end of 1992 and from the impending Mars Obsever mission, which will probe the magnetic fields in the low-altitude wake of weakly magnetized Mars.

Luhmann, J. G.; Russell, D. S.

1992-01-01

374

How the Venus flytrap snaps  

Microsoft Academic Search

The rapid closure of the Venus flytrap (Dionaea muscipula) leaf in about 100ms is one of the fastest movements in the plant kingdom. This led Darwin to describe the plant as ``one of the most wonderful in the world''. The trap closure is initiated by the mechanical stimulation of trigger hairs. Previous studies have focused on the biochemical response of

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

2005-01-01

375

Phlogopite Decomposition, Water, and Venus  

NASA Technical Reports Server (NTRS)

Venus is a hot and dry planet with a surface temperature of 660 to 740 K and 30 parts per million by volume (ppmv) water vapor in its lower atmosphere. In contrast Earth has an average surface temperature of 288 K and 1-4% water vapor in its troposphere. The hot and dry conditions on Venus led many to speculate that hydrous minerals on the surface of Venus would not be there today even though they might have formed in a potentially wetter past. Thermodynamic calculations predict that many hydrous minerals are unstable under current Venusian conditions. Thermodynamics predicts whether a particular mineral is stable or not, but we need experimental data on the decomposition rate of hydrous minerals to determine if they survive on Venus today. Previously, we determined the decomposition rate of the amphibole tremolite, and found that it could exist for billions of years at current surface conditions. Here, we present our initial results on the decomposition of phlogopite mica, another common hydrous mineral on Earth.

Johnson, N. M.; Fegley, B., Jr.

2005-01-01

376

The Approaching Transit of Venus  

Microsoft Academic Search

IN NATURE of the 4th of January last Mr. J. Carpenter gives an interesting sketch of the arrangements in progress for observing the forthcoming Transit of Venus. He states that French and German astronomers have decided on establishing a station of observation at Muscat (Mascate) or at some place between that nasty little port and Teheran. Now, as a point

J. J. Farie

1872-01-01

377

Earth/Venus Rotation Movie  

NSDL National Science Digital Library

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

2005-09-01

378

A high resolution gravity model for Venus - GVM-1  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

379

The effect of dys-1 mutation on miRNA expression profile in Caenorhabditis elegans during Shenzhou-8 mission  

NASA Astrophysics Data System (ADS)

microRNAs (miRNAs) is reported to be sensitive to radiation exposure and altered gravity, involved in a variety of biological processes through negative regulation of gene expression. Dystrophin-like dys-1 gene is expressed and required in muscle tissue, which plays a vital role in mechanical transduction when gravity varies. In the present study, we investigated the effect of dys-1 mutation on miRNA expression profile in Caenorhabditis elegans (C. elegans) under space radiation associated with microgravity (R+M) and radiation alone (R) environment during Shenzhou-8 mission. We performed miRNA microarray analysis in dys-1 mutant and wide-type (WT) of dauer larvae and found that 27 miRNAs changed in abundance after spaceflight. Compared with WT, there was different miRNA expression pattern in different treatments in dys-1 mutant. Cel-miR-796 and miR-124 were reversely expressed under R+M and R environment in WT and dys-1 mutant, respectively, indicating they might be affected by microgravity. Mutation of dys-1 remarkably reduced the number of altered miRNAs under space environment, resulting in the decrease of genes in biological categories of “body morphogenesis”, “behavior”, “cell adhesion” and so on. Particularly, we found that those genes controlling regulation of locomotion in WT were lost in dys-1 mutant, while genes in positive regulation of developmental process only existed in dys-1 mutant. miR-796 was predicted to target genes ace-1 and dyc-1 that are functionally linked to dys-1. Integration analysis of miRNA and mRNA expression profile revealed that miR-56 and miR-124 were involved in behavior and locomotion by regulating different target genes under space environment, among which nep-11, deb-1, C07H4.1 and F11H8.2 might be associated with neuromuscular system. Our findings suggest that dys-1 could cause alteration of miRNAs and target genes, involved in regulating the response of C. elegans to space microgravity in neuromuscular system. This research will provide new insight for better understanding of the mechanism in microgravity-induced muscular dystrophy.

Xu, Dan; Sun, Yeqing; Gao, Ying; Xing, Yanfang

380

Geophysical models of Western Aphrodite-Niobe region: Venus  

NASA Technical Reports Server (NTRS)

The new topography and gravitational field data for Venus expressed in spherical harmonics of degree and order up to 50 allow us to analyze the crust-mantle boundary relief and stress state of the Venusian lithosphere. In these models, we consider models in which convection is confined beneath a thick, buoyant lithosphere. We divide the convection regime into an upper mantle and lower mantle component. The lateral scales are smaller than on Earth. In these models, relative to Earth, convection is reflected in higher order terms of the gravitational field. On Venus geoid height and topography are highly correlated, although the topography appears to be largely compensated. We hypothesize that Venus topography for those wavelengths that correlate well with the geoid is partly compensated at the crust-mantle boundary, while for the others compensation may be distributed over the whole mantle. In turn the strong sensitivity of the stresses to parameters of the models of the external layers of Venus together with geological mapping allows us to begin investigations of the tectonics and geodynamics of the planet. For stress calculations we use a new technique of space- and time-dependent Green's response functions using Venus models with rheologically stratified lithosphere and mantle and a ductile lower crust. In the basic model of Venus the mean crust is 50-70 km thick, the density contrast across the crust-mantle boundary is in the range from 0.3 to 0.4 g/cm(exp -3). The thickness of a weak mantle zone may be from 350 to 1000 km. Strong sensitivity of calculated stress to various parameters of the layered model of Venus together with geological mapping and analysis of surface tectonic patterns allow us to investigate the tectonics and geodynamics of the planet. The results are presented in the form of maps of compression-extension and maximum shear stresses in the lithosphere and maps of crust-mantle boundary relief, which can be presented as a function of time. We have modeled the region of Western Aphrodite and the Niobe plains to get reasonable depths of compensation. Crust mantle boundary relief is calculated for Western Aphrodite-Niobe relative to a mean crustal thickness of 50 km. The calculations include the consequences of simple crust models and more complicated models with a weak, ductile lower crust, a strong upper mantle and a weak lower mantle layer.

Marchenkov, K. I.; Saunders, R. S.; Banerdt, W. B.

1993-01-01

381

Volcanism of Venus: Insights from the VMC data analysis  

NASA Astrophysics Data System (ADS)

The analysis of the Venera 15/16 and Magellan data led to an understanding of Venus geology which may be described as a time sequence of material and structural units and features [e.g., (Basilevsky and Head, 1995, 2000; Ivanov and Head, 2011]. Dominant among them are various volcanic plains and volcanic constructs whose morphologies indicate a low viscosity for the lavas composing them suggesting mostly basaltic composition [e.g., Head et al., 1992; Crumpler et al., 1997]. This is supported by the analyses of surface composition at the Venera-Vega sites [e.g., Surkov, 1986]. However, some volcanic features of Venus could be composed of nonbasaltic lavas [e.g., Pavri et al., 1992; Crumpler et al., 1997; Ivanov and Head, 1999] but this suggestion needs more study. Based on the analysis of the characteristics of impact crater populations on Venus [e.g., McKinnon et al., 1997] as well as on the analysis of the unit superposition/embayment relations [Basilevsky and Head, 1996, 2000, 2006; Collins et al., 1999] it was shown that the widespread regional volcanic plains formed close to the beginning of morphologically visible history of this planet that is 0.5-1 b.y. ago. Later in time, volcanic activity on Venus continued in different areas at different times, including very close to the present. No conclusive evidence of ongoing volcanic activity has yet been found, although some indications of very recent volcanic events have been published [Bondarenko et al., 2010; Smrekar et al., 2010]. Analysis of the data taken by the Venus Monitoring Camera (VMC) onboard of Venus Express, which has two NIR, one visible and one UV channels, allowed to revealed some promising results on the questions of nonbasaltic volcanism [e.g., Basilevsky et al., 2012] and the ongoing volcanic activity on Venus [e.g., Shalygin et al., 2014]. The VMC results presented in the context of characteristics of Venusi volcanism will be the main emphasis of the talk.

Bazilevskiy, Alexander; Ignatiev, Nikolay; Markiewicz, Wojciech; Head, James; Titov, Dmitrij; Shalygin, Eugene V.

382

Science questions for the Magellan continuing mission  

NASA Technical Reports Server (NTRS)

Magellan has completed two mapping cycles around the planet Venus, returning high resolution synthetic aperture images and altimetry data of over 95 percent of the planet's surface. Venus is dominated by low lying volcanic plains with an impact crater population indicating an average surface age of about 500 million years. Highland regions either tend to be characterized by volcanic shield complexes and rifting or by complex ridged terrain. Successful as the primary mission of Magellan has been, significant scientific questions remain to be addressed with imaging and gravity data that will be collected over the next several years.

Saunders, R. S.; Stofan, E. R.

1992-01-01

383

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

PubMed

Vitellogenin (Vg) and lipophorin (Lp) are lipoproteins which play important roles in female reproductive physiology of insects. Both are actively taken up by growing oocytes and especially Vg and its receptor are considered as female-specifically expressed. The finding that the fat body of in honey bee (Apis mellifera) drones synthesizes Vg and is present in hemolymph has long been viewed as a curiosity. The recent paradigm change concerning the role played by Vg in honey bee life history, especially social division of labor, has now led us to investigate whether a physiological constellation similar to that seen in female reproduction may also be represented in the male sex. By means of Western blot analysis we could show that both Vg and Lp are present in the reproductive tract of adult drones, including the accessory (mucus) glands, but apparently are not secreted. Furthermore, we analyzed the transcript levels of the genes encoding these proteins (vg and lp), as well as their putative receptors (Amvgr and Amlpr) in fat body and accessory glands. Whereas lp, vg and Amlpr transcript levels decreased with age in both tissues, Amvgr mRNA levels increased with age in fat body. To our knowledge this is the first report that vitellogenin and its receptor are co-expressed in the reproductive system of a male insect. We interpret these findings as a cross-sexual transfer of a social physiological trait, associated with the rewiring of the juvenile hormone/vitellogenin circuitry that occurred in the female sex of honey bees. PMID:20