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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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NASA NTRS2004

Mars Express: The Exploration of Phobos

The origin, structure and composition of Phobos are essentially still unresolved issue, with major outcomes for understanding the origin and evolution of the Solar system, and of the Mars system. Several missions have been designed with this unique body the only target. Is Phobos a captured small body (and in this case, can we identify the degree of differentiation such a small object has undergone ?), or is there any co-generic process with Mars involved ? Are there still volatile species trapped, and if so where, and in what form ? What are the reciprocal contributions of Mars and Phobos material accreted in the other body? The number of key clues for deciphering the early solar system processes, the Mars-Phobos binary evolution, and the role Phobos could play in the future of Mars exploration (including human expeditions), are numerous, and exciting for a large community. Part of the answers are in the high resolution coverage of this object (optical and IR, for composition variation), and in its full spectral analysis, from UV to thermal IR : Mars Express is the unique mission to provide this opportunity, and orbit 756, August 22, a totally unique opportunity to approach Phobos so closely. OMEGA should provide all across Stickney, the deepest accessible material, and over more than 20 km along, a spatial resolution less than 200 m, and assess the composition (and possibly their variations) wrt silicates (mafic materials), oxides, and eventually hydrated minerals and organics. By no means we should miss this opportunity: no one would understand the rationale not to turn the instruments ON while so close, and pointing them towards the Phobos surface.

Phobos↗
NASA NTRS1998

The Mars Express Subsurface Radar: Water and Ice Detection in the Polar Regions

The European Space Agency (ESA) will conduct a mission to Mars during the 2003 launch opportunity, called Mars Express. Much of the payload is similar to that of the failed Mars 96 orbiter, but a completely new instrument has been selected for the payload, the Subsurface Sounding Radar/Altimeter (SSRA). The SSRA experiment is a joint project between the University of Rome, the Jet Propulsion Laboratory, and Alenia Aerospazio, Italy. This paper describes the science objectives of the experiment, the instrument characteristics, and applications of the SSRA investigation to studies of the martian polar regions.

Plaut, J. J.↗
NASA NTRS2004

Coordinated Observations of Aeolian Features from the Mars Exploration Rovers (MER) and the Mars Express High Resolution Stereo Camera and Other Orbiters

Surface features associated with aeolian (wind) processes at the Mars Exploration Rover (MER) landing sites for Spirit (Gusev crater) and Opportunity (Sinus Meridiani) were observed from the surface and from orbit through coordinated observations by the rovers and the Mars Express orbiter High Resolution Stereo Camera and compared with features seen in other orbiter data and with wind vectors predicted by a numerical mesoscale model of the atmosphere.

Greeley, R.↗
NASA NTRS2005

Public Outreach and Archiving of Data from the High Resolution Stereo Camera Onboard Mars Express: 2004 The First Year

During the first year of operation, corresponding to the calendar year 2004, the HRSC imaging experiment onboard ESA's Mars Express mission recorded 23 Gigabyte of 8-bit compressed raw data. After processing, the amount of data increased to more than 344 Gigabyte of decompressed and radiometrically calibrated scientifically useable image products. Every six months these HRSC Level 2 data are fed into ESA's Planetary Science Archive (PSA) that sends all data also to the Planetary Data System (PDS) to ensure easy availability to the interested user. On their respective web portals, the European Space Agency published in cooperation with the Principal Investigator-Group at Freie Universitat Berlin and the German Space Agency (DLR) almost 40 sets of high-level image scenes and movies for PR needs that have been electronically visited many hundred thousand times.

Koehler, U.↗
NASA NTRS2005

High LMD GCM Resolution Modeling of the Seasonal Evolution of the Martian Northern Permanent Cap: Comparison with Mars Express OMEGA Observations

Analyses of imaging data from Mariner, Viking and MGS have shown that surface properties (albedo, temperature) of the northern cap present significant differences within the summer season and between Mars years. These observations include differential brightening and/or darkening between polar areas from the end of the spring to midsummer. These differences are attributed to changes in grain size or dust content of surface ice. To better understand the summer behavior of the permanent northern polar cap, we perfomed a high resolution modeling (approximately 1 deg x 1 deg.) of northern cap in the Martian Climate/water cycle as simulated by the Laboratoire de Meteorologie Dynamique (LMD) global climate model. We compare the predicted properties of the surface ice (ice thickness, temperature) with the Mars Express Omega summer observations of the northern cap. albedo and thermal inertia svariations model. In particular, albedo variations could be constrained by OMEGA data. Meteorological predictions of the LMD GCM wil be presented at the conference to interpret the unprecedently resolved OMEGA observations. The specific evolution of regions of interest (cap center, Chasma Boreal...) and the possibility of late summer global cap brightening will be discussed.

Levrard, B.↗
NASA NTRS2008

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

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

MEX↗
NASA NTRS2001

U.S. Participation in the Mars Express Mission

NASA will provide the antenna and RF subsystem to the MARSIS radar sounder. There are 11 U.S. Co-Investigators for the science investigations, and navigation and data archiving support are also provided. ASPERA-3 receives NASA Discovery Program funding. Additional information is contained in the original extended abstract.

Morrison, A. D.↗
NASA NTRS2004

Mars Express MARSIS Radar: A Prediction of the Effect of Overlying Ice on Detecting Polar Basal Lakes and Inter-Glacial Aquifers

The penetration of the MARSIS radar signal into the polar ice mass is modeled to determine the capability of the instrument to locate sub-glacial aquifers. As a ground penetrating radar, the orbiting MARSIS transmits a signal greater than 1 W between 1-5 MHz. In this work we will investigate the effect of ice conductive losses on the radar-detection of subsurface aquifers. Based on wave propagation analysis, it is found that for a bulk ice conductivity below 10-5 S/m, conductive losses in the medium are not significant. However, if the bulk ice conductivity is relatively large (greater than 10-5 S/m), the reflected signal from any deep aquifer will be absorbed as it propagates in the lossy ice medium limiting the probing depth.

Farrell, W. M.↗
NASA NTRS2005

Mars Express OMEGA Observations over Terra Meridiani

The OMEGA hyperspectral imager (0.35 to 5.08 micrometers) covered the hematite-bearing plains and underlying etched terrains of Terra Meridiani during several orbits with spatial resolutions ranging from several hundred meters to approximately 2 km. We extracted and analyzed surface reflectance spectra from OMEGA data for the approximately 864,000 square kilometers surrounding the Opportunity site. In this paper we focus on analysis of OMEGA orbit 485 data for the plains and etched terrains located to the northeast of the Opportunity landing site.

Arvidson, R. E.↗
NASA NTRS2005

Mars Express HRSC View of Western Olympus Mons: Evidence for Ice-bearing Deposit and High-Altitude Glaciation

This study is based on the geological analysis of the HRSC images taken on the orbit 0143 (12 m/px in nadir channel). The study area includes the western segment of Olympus Mons and the adjacent lowland plains (Fig. 1). Part of the volcano above the scarp is rather flat and is called "summit plateau" below. What is often called the volcano scarp is a slope classified into three morphologic types: Type 1 (S1 in Fig.1) is the steepest and dominated by ravines in its upper part and by talus beneath; Type 2 (S2) is intermediate in steepness and dominated by downslope trending linear depressions, part of which have channel-like morphology; and Type 3 (S3), is the most gentle and covered by lava flows, continuing from the summit plateau down to the lowland plains.

Basilevsky, A. T.↗