Venus Exploration Research Articles

Time-resolved remote Raman study of minerals under supercritical CO 2 and high temperatures relevant to Venus exploration

We report time-resolved (TR) remote Raman spectra of minerals under supercritical CO(2) (approx. 95 atm pressure and 423 K) and under atmospheric pressure and high temperature up to 1003 K at distances of 1.5 and 9 m, respectively. The TR Raman spectra of hydrous and anhydrous sulphates, carbonate and silicate minerals (e.g. talc, olivine, pyroxenes and feldspars) under supercritical CO(2) (approx. 95 atm pressure and 423 K) clearly show the well-defined Raman fingerprints of each mineral along with the Fermi resonance doublet of CO(2). Besides the CO(2) doublet and the effect of the viewing window, the main differences in the Raman spectra under Venus conditions are the phase transitions, the dehydration and decarbonation of various minerals, along with a slight shift in the peak positions and an increase in line-widths. The dehydration of melanterite (FeSO(4).7H(2)O) at 423 K under approximately 95 atm CO(2) is detected by the presence of the Raman fingerprints of rozenite (FeSO(4).4H(2)O) in the spectrum. Similarly, the high-temperature Raman spectra under ambient pressure of gypsum (CaSO(4).2H(2)O) and talc (Mg(3)Si(4)O(10)(OH)(2)) indicate that gypsum dehydrates at 518 K, but talc remains stable up to 1003 K. Partial dissociation of dolomite (CaMg(CO(3))(2)) is observed at 973 K. The TR remote Raman spectra of olivine, alpha-spodumene (LiAlSi(2)O(6)) and clino-enstatite (MgSiO(3)) pyroxenes and of albite (NaAlSi(3)O(8)) and microcline (KAlSi(3)O(8)) feldspars at high temperatures also show that the Raman lines remain sharp and well defined in the high-temperature spectra. The results of this study show that TR remote Raman spectroscopy could be a potential tool for exploring the surface mineralogy of Venus during both daytime and nighttime at short and long distances.

Evaluation of quasi-static fracture characteristics considering surface conditions of silicon nitride for a space component

ISAS/JAXA is now planning to adopt a thruster made of monolithic silicon nitride (SN282 manufactured by Kyocera Co.) onto a Venus exploration probe, PLANET-C, in replacement of conventional niobium heat-resistant alloy. Silicon nitride is still brittle and requires precise analysis on multiaxial thermal stresses induced during firing, though it has high toughness among other structural ceramics. This study evaluated quasi-static fracture characteristics of SN282 considering the surface conditions through compression-torsion biaxial fracture tests as well as the conventional four-point-bending tests. The samples were applied to the mechanical tests either as-ground or after annealing at 1300°C in air for 1 h, which formed an oxidation layer of more than 250nm on the specimen surface. Symmetry four-point-bending tests showed that annealing improves flexure strength and reduce the difference caused by grinding directions. Biaxial stress fracture tests showed the high compressive stress makes the influence of facial crack insensitive.

あかつきのセラミックスラスタ技術(航空宇宙材料フォーラム-航空宇宙システムの高度化に向けた最近の材料技術-,ものづくりにおける基礎研究と先端技術の融合)

あかつきのセラミックスラスタ技術(航空宇宙材料フォーラム-航空宇宙システムの高度化に向けた最近の材料技術-,ものづくりにおける基礎研究と先端技術の融合)

Flight Model Development of PLANET-C Telecommunication Subsystem

PLANET-C (PLC) is the mission of Japan Aerospace Exploration Agency (JAXA) for Venus exploration. It is a successor of HAYABUSA in the history of Japanese deep space missions and is expected to be the first Japanese planetary orbiter. The spacecraft will be launched in the summer of 2010 from Tanegashima Space Center. The mission has demanded new onboard telecommunication instruments. Among them are X-band digital transponder, high gain flat antenna, and low gain wider field of view antenna. Through their developments, new technologies such as deep space regenerative ranging adapted for JAXA ground stations have been successfully incorporated into the PLC system. They are now raedy for their first space-borne demonstration. We will discuss these telecommunication technologies newly introduced for the PLC mission.

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

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

Micrometeoroid impact on ceramic thin components for interplanetary probe

Abstract A new advanced ceramic thruster made of monolithic silicon nitride (Si3N4) is under development for the next interplanetary probe of PLANET-C Venus exploration mission in Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA). In order for secure operation of a spacecraft with a ceramic component onboard a real mission, the reliability against micrometeoroid impacts on the ceramic component has to be investigated in addition to the quasi-static mechanical and thermal analyses and verifications. First, the risk probability of the micrometeoroid impacts was evaluated by using an interplanetary flux model, and the risk evaluation in terms of impact energy was proposed by combining the velocity distribution with the flux model. The probability of impacts on the ceramic thruster during the mission was estimated with this model. Second, hypervelocity impact tests were performed with a two-stage light-gas gun. Three types of failure were observed: one was only a crater formed on the impact surface. Another type was crater formation on the front-face and spall fracture on the back-face and in the last type a perforation was formed in addition to cratering and spalling. The samples did not either shatter or breakdown for the impact energies tested in this study. The impact failure morphology observed in this study showed dependency on the plate thicknesses and the projectile kinetic energy. The energy-based risk evaluation together with the series of the hypervelocity impact tests indicated that the silicon nitride ceramic thruster onboard the interplanetary probe would have only a local damage and survive during the mission term.

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

The European Venus Explorer (EVE) mission was proposed to the European Space Agency in 2007, as an M-class mission under the Cosmic Vision Programme. Although it has not been chosen in the 2007 selection round for programmatic reasons, the EVE mission may serve as a useful reference point for future missions, so it is described here. It consists of one balloon platform floating at

Suzan-Lori Parks's Drama of Disinterment: A Transnational Exploration of Venus

This essay offers a transnational exploration of Suzan-Lori Parks's dis(re)memberment of Saartjie (Sarah) Baartman, a Khoisan woman from South Africa who was displayed in Europe in the 1800s under the appellation "The Hottentot Venus." Juxtaposing two simultaneous events—post-apartheid south Africa's efforts to repatriate baartman's remains, and the volatile American reception of Parks's play Venus —reveals the ways in which Parks's aesthetic, defined here as a "drama of disinterment," calls into question the notion that historical trauma is a wound that must be healed in the name of unity, the idea that reconciliation necessarily entails the establishment of an objective truth, and the assumption that the restoration of dignity is the goal of the recovery process.

Long-Term Characterization of 6H-SiC Transistor Integrated Circuit Technology Operating at 500 °C

ABSTRACTNASA has been developing very high temperature semiconductor integrated circuits for use in the hot sections of aircraft engines and for Venus exploration. This paper reports on long-term 500 °C electrical operation of prototype 6H-SiC integrated circuits based on epitaxial 6H-SiC junction field effect transistors (JFETs). As of this writing, some devices have surpassed 4000 hours of continuous 500 °C electrical operation in oxidizing air atmosphere with minimal change in relevant electrical parameters.

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

The Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) on board the ESA/Venus Express mission has technical specifications well suited for many science objectives of Venus exploration. VIRTIS will both comprehensively explore a plethora of atmospheric properties and processes and map optical properties of the surface through its three channels, VIRTIS-M-vis (imaging spectrometer in the 0.3–1 μm range), VIRTIS-M-IR (imaging spectrometer in the 1–5 μm range) and VIRTIS-H (aperture high-resolution spectrometer in the 2–5 μm range). The atmospheric composition below the clouds will be repeatedly measured in the night side infrared windows over a wide range of latitudes and longitudes, thereby providing information on Venus's chemical cycles. In particular, CO, H 2O, OCS and SO 2 can be studied. The cloud structure will be repeatedly mapped from the brightness contrasts in the near-infrared night side windows, providing new insights into Venusian meteorology. The global circulation and local dynamics of Venus will be extensively studied from infrared and visible spectral images. The thermal structure above the clouds will be retrieved in the night side using the 4.3 μm fundamental band of CO 2. The surface of Venus is detectable in the short-wave infrared windows on the night side at 1.01, 1.10 and 1.18 μm, providing constraints on surface properties and the extent of active volcanism. Many more tentative studies are also possible, such as lightning detection, the composition of volcanic emissions, and mesospheric wave propagation.

The solar wind interaction with Venus through the eyes of the Pioneer Venus Orbiter

Venus has no internal magnetic dynamo and thus its ionosphere and hot oxygen exosphere dominate the interaction with the solar wind. The solar wind at 0.72 AU has a dynamic pressure that ranges from 4.5 nPa (at solar max) to 6.6 nPa (at solar min), and its flow past the planet produces a shock of typical magnetosonic Mach number 5 at the subsolar point. At solar maximum the pressure in the ionospheric plasma is sufficient to hold off the solar wind at an altitude of 400 km above the surface at the subsolar point, and 1000 km above the terminators. The deflection of the solar wind occurs through the formation of a magnetic barrier on the inner edge of the magnetosheath, or shocked solar wind. Under typical solar wind conditions the time scale for diffusion of the magnetic field into the ionosphere is so long that the ionosphere remains field free and the barrier deflects almost all the incoming solar wind. Any neutral atoms of the hot oxygen exosphere that reach the altitude of the magnetosheath are accelerated by the electric field of the flowing magnetized plasma and swept along cycloidal paths in the antisolar direction. This pickup process, while important for the loss of the Venus atmosphere, plays a minor role in the deceleration and deflection of the solar wind. Like at magnetized planets, the Venus shock and magnetosheath generate hot electrons and ions that flow back along magnetic field lines into the solar wind to form a foreshock. A magnetic tail is created by the magnetic flux that is slowed in the interaction and becomes mass-loaded with thermal ions. The structure of the ionosphere is very much dependent on solar activity and the dynamic pressure of the solar wind. At solar maximum under typical solar wind conditions, the ionosphere is unmagnetized except for the presence of thin magnetic flux ropes. The ionospheric plasma flows freely to the nightside forming a well-developed night ionosphere. When the solar wind pressure dominates over the ionospheric pressure the ionosphere becomes completely magnetized, the flow to the nightside diminishes, and the night ionosphere weakens. Even at solar maximum the night ionosphere has a very irregular density structure. The electromagnetic environment of Venus has not been well surveyed. At ELF and VLF frequencies there is noise generated in the foreshock and shock. At low altitude in the night ionosphere noise, presumably generated by lightning, can be detected. This paper reviews the plasma environment at Venus and the physics of the solar wind interaction on the threshold of a new series of Venus exploration missions.

Venus Entry Probe Technology Reference Study

The Venus Entry Probe is one of ESA’s Technology Reference Studies (TRS). The purpose of the Technology Reference Studies is to provide a focus for the development of strategically important technologies that are of likely relevance for future scientific missions. The aim of the Venus Entry Probe TRS is to study approaches for low-cost in situ exploration of Venus and other planetary bodies with a significant atmosphere. In this paper, the mission objectives and an outline of the mission concept of the Venus Entry Probe TRS are presented.

Venus microsat explorer programme, an ESA technology reference study

The Venus microsat explorer programme (VMEP) is one of ESA's technology reference studies (TRSs). The purpose of the TRSs is to focus on the developments of strategically important technologies of likely relevance for future scientific missions. The aim of the VMEP is to study approaches for low cost in-situ exploration of Venus and other planetary bodies with a significant atmosphere. In this paper, the scientific objectives and an outline of the mission profile of the first phase of the VMEP are presented. Critical and enabling technologies identified by the TRS study will provide a guideline for future technology development activities that could be supported by ESA's Science Directorate.

Feasibility of generating a useful laser-induced breakdown spectroscopy plasma on rocks at high pressure: preliminary study for a Venus mission

Laser-induced breakdown spectroscopy (LIBS) is being developed for future use on landers and rovers to Mars. The method also has potential for use on probes to other planets, the Moon, asteroids and comets. Like Mars, Venus is of strong interest because of its proximity to earth, but unlike Mars, conditions at the surface are far more hostile with temperatures in excess of 700 K and pressures on the order of 9.1 MPa (90 atm). These conditions present a significant challenge to spacecraft design and demand that rapid methods of chemical data gathering be implemented. The advantages of LIBS (e.g. stand-off and very rapid analysis) make the method particularly attractive for Venus exploration because of the expected short operational lifetimes (≈2 h) of surface instrumentation. Although the high temperature of Venus should pose no problem to the analytical capabilities of the LIBS spark, the demonstrated strong dependence of laser plasma characteristics on ambient gas pressures below earth atmospheric pressure requires that LIBS measurements be evaluated at the high Venus surface pressures. Here, we present a preliminary investigation of LIBS at 9.1 MPa for application to the analysis of a basalt rock sample. The results suggest the feasibility of the method for a Venus surface probe and that further study is justified.

Atmospheric Flight on Venus: A Conceptual Design

A solar-powered aircraft system is proposed for the exploration of Venus. The atmosphere of Venus provides several advantages for flying a solar-powered aircraft. At the top of the cloud level, the solar intensity is comparable to or greater than terrestrial solar intensities. The atmospheric pressure makes flight much easier than on planets such as Mars. Also, the slow rotation of Venus allows an airplane to be designed for flight within continuous sunlight, eliminating the need for energy storage for nighttime flight. These factors make Venus a prime choice for a long-duration solar-powered aircraft. Fleets of solar-powered aircraft could provide an architecture for efficient and low-cost comprehensive coverage for a variety of scientific missions.

VEVA Discovery mission to Venus: exploration of volcanoes and atmosphere

Venus Exploration of Volcanoes and Atmosphere (VEVA) is a potential Discovery mission. It will provide a multidisciplinary investigation of the atmosphere and surface of Venus by returning the first-ever aerial photography of the surface and definitive, in situ determination of its atmospheric composition in the lower scale height. VEVA involves delivering an entry vehicle to Venus housing a payload consisting of an instrumented atmospheric sonde and a balloon–gondola system. After entry, the atmospheric sonde is released to fall to the surface, and the balloon package inflates, which arrests its descent at a 60-km float height. The balloon carries an instrumented gondola with battery power for 7 days as it circles Venus. The gondola carries four small imaging sondes for release and descent to the surface at different times during the 7-day mission. Data from the sondes are radioed to the gondola for relay to Earth.

The Planet Venus

Venus has long been referred to as Earth's sister planet. Shrouded in clouds, mystery, and myth,Venus has defied exploration up until the latter half of the 20th century when the planet was assaulted by an armada of spacecraft sent by the inhabitants of Earth. The Planet Venus by Mikhail Ya. Marov and David Grinspoon, both of whom are well known in the planetary community, is a chronological, technical account about mankind's exploration of Venus. It reviews various ideas and theories that have been developed about Venus, from the time of the earliest telescopic observations to the age of interplanetary missions.

Atlas of Venus

The 1990s have been a tremendously exciting time for exploration and science of the planet Venus, the nearest neighbor and, in many ways, near twin of the Earth. The Magellan spacecraft, launched in May 1989 for an August 1990 arrival, was a stunning success, imaging nearly the entire globe at subkilometer resolution. Before Magellan met its end in October 1994, adding its mass to the planet whose study had been its raison d'etre, its radar imager had transformed our view of the Venusian surface from a smattering of murky images and incomplete, grainy maps provided by earlier Russian probes to a crystal clear global portrait of a planet with a long, complex, and ongoing history of volcanism and tectonism.Aesthetically, the Magellan images are of superb quality and they contain a wonderful mix of the familiar and the exotic that will fuel Venus science for decades. A rich menagerie of volcanic features including vast plains of flood basalts, towering shield volcanoes, smaller “pancake domes” formed from more viscous magmas, and even volcanic “river channels” that wind across the plains for thousands of kilometers make Venus a dreamworld for planetary volcanologists. Other volcano‐tectonic features, such as the hundreds of crownlike circular “coronae” mapped around the planet, seem unique to Venus.

Planetary exploration by robotic aerovehicles

Planetary aerobots are a new type of telerobotic science platform that can fly and navigate in a dynamic 3-dimensional atmospheric environment, thus enabling the global in situ exploration of planetary atmospheres and surfaces. Aerobots are enabled by a new concept in planetary balloon altitude control, developed at JPL, which employs reversible-fluid changes to permit repeated excursions in altitude. The essential physics and thermodynamics ofreversible-fluid altitude control have been demonstrated in a series of altitude-control experiments conducted in the Earth's atmosphere, which are described. Aerobot altitude-control technology will be important in the exploration of seven planets and satellites in our solar system. Three of these objects—Venus, Mars, and the Saturnian satellite Titan—have accessible solid surfaces and atmospheres dominated by the dense gases nitrogen or carbon dioxide. They will be explored with aerobots using helium or hydrogen as their primary means of buoyancy. The other four planets—Jupiter, Saturn, Uranus, and Neptune—have deep atmospheres that are predominantly hydrogen. It may be possible to explore these atmospheres with aerobots inflated with atmospheric gas that is then radiatively heated from the hotter gaseous depths below. To fulfill their potential, aerobots to explore the planets will need autonomous state estimators to guide their observations and provide information to the altitude-control systems. The techniques of acquiring these data remotely are outlined. Aerobots will also use on board altitude control and navigation systems to execute complex flight paths including descent to the surface and exploiting differential wind velocities to access different latitude belts. Approaches to control of these systems are examined. The application of aerobots to Venus exploration is explored in some detail: The most ambitious mission described, the Venus Flyer Robot (VFR), would have the capability to make repeated short excursions to the high-temperature surface environment of Venus to acquire data and then return to the Earth-like upper atmosphere to communicate and recool its electronic systems. Finally a Planetary Aerobot Testbed is discussed which will conduct Earth atmospheric flights to validate autonomous-state-estimator techniques and flight-path-control techniques needed for future planetary missions.

Venus Exploration Forthcoming -Scientific View

As a mission after MAGELLAN, which is the NASA's next Venus explorer and will be launched in April 1989 for making a Radar map, a Venus exploration program is proposed here with the special interest in the origin and evolution of Venusian atmosphere. This program will make the exact measurements of the compositions of clouds and atmosphere under the cloud, the composition and temperature of the surface, and topography. By these measurements, we aim at: manifesting whether an ocean was present in the past, whether lots of water have escaped from Venus, whether the volcanic activity is/was present now/in the past, whether the plate tectonics is/was present, etc. We will also Study in detail the dynamics in the lower atmosphere, the origin of sulfur compounds, the history in the topographic structures, etc. In consequence, this program will use an orbiter and a balloon which will make a ground-base observation after the landing on the surface. More detailed description in English is available in the paper: A.Matsuzaki, ''Venus Exploration Relevant to Origin and Evolution of its Atmosphere Origin of Sulfur Dioxide as a Clue'', Proceedings of the 21 st ISAS Lunar and Planetary Symposium, July 7-9 1988, in press.