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NASA NTRS2007

Contingency Operations during Failure of Inertial Attitude Acquisition Due to Star Tracker Blinding for Three-Axes-Stabilized Interplanetary Spacecraft

The three interplanetary ESA missions Mars-Express, Rosetta and Venus-Express (launched 2003, 2004 and 2005 resp.) are three-axes stabilized spacecraft (s/c) that estimate their inertial attitude (i.e. the attitude of the s/c w.r.t. the inertial frame) using measurements from a redundant set of star trackers (STR). Each s/c is equipped with four reaction wheels, a reaction control system based on thrusters and a redundant set of ring laser gyroscopes (gyros). The STR h/w layout of the three s/c is identical whereas there is a difference in the star pattern recognition algorithm of Rosetta which uses five neighbouring stars around a central star instead of star triads. The Rosetta algorithm has been implemented to cope with the presence of false stars which are expected to be seen during operations around the comet. The attitude acquisition capability from lost in space is different also in terms of AOCMS: The survival mode of Rosetta which is entered upon STR failure is presented. The AOCMS of Mars- and Venus-Express manages temporary STR outages during sky occultation by the planet not even by using redundancy. Though, a blinding of both STR during cruise lasting for the order of days confronts the ground operators with the limits of the AOCMS design. The operations and analyses that have been planned and partially been performed to compensate for the outage of the STR are demonstrated for Mars-Express. The caution measures taken before Venus orbit insertion of Venus-Express are detailed.

Keil, Joachim↗
NASA NTRS2007

Science in Exploration: From the Moon to Mars and Back Home to Earth

NASA is embarking on a grand journey of exploration that naturally integrates the past successes of the Apollo missions to the Moon, as well as robotic science missions to Mars, to Planet Earth, and to the broader Universe. The US Vision for Space Exporation (VSE) boldly lays out a plan for human and robotic reconnaissance of the accessible Universe, starting with the surface of the Moon, and later embracing the surface of Mars. Sustained human and robotic access to the Moon and Mars will enable a new era of scientific investigation of our planetary neighbors, tied to driving scientific questions that pertain to the evolution and destiny of our home planet, but which also can be related to the search habitable worlds across the nearby Universe. The Apollo missions provide a vital legacy for what can be learned from the Moon, and NASA is now poised to recapture the lunar frontier starting with the flight of the Lunar Reconnaissance Orbiter (LRO) in late 2008. LRO will provide a new scientific context from which joint human and robotic exploration will ensue, guided by objectives some of which are focused on the grandest scientific challenges imaginable : Where did we come from? Are we alone? and Where are we going? The Moon will serve as an essential stepping stone for sustained human access and exploration of deep space and as a training ground while robotic missions with ever increasing complexity probe the wonders of Mars. As we speak, an armada of spacecraft are actively investigating the red planet both from orbit (NASA's Mars Reconnaissance Orbiter and Mars Odyssey Orbiter, plus ESA's Mars Express) and from the surface (NASA's twin Mars Exploration Rovers, and in 2008 NASA's Phoenix polar lander). The dramatically changing views of Mars as a potentially habitable world, with its own flavor of global climate change and unique climate records, provides a new vantage point from which to observe and question the workings of our own planet Earth. By 2010 NASA will have its first mobile analytical laboratory operating on the surface of Mars (Mars Science Laboratory) in search of potentially subtle expressions of past life or at least of life-hospitable environments. Meanwhile back here on Planet Earth, NASA will be continuing to implement an increasingly comprehensive program of robotic missions that address major issues associated with global climate variability, and the "state variables" that affect the quality of human life on our home planet. Ultimately, the fmits of NASA's emergent program of Exploration (VSE) will provide never-beforepossible opportunities for scientific leadership and advancement, culminating in a new state of awareness from which to better plan for the sustainability of life on Earth and for extending Earth life to the Moon and eventually to Mars. As NASA nears its 50th anniversary, the unimaginable and unexpected wealth of strategic knowledge its missions have generated about Earth, the Universe, and our local Solar System boggles the mind and serves as a legacy of knowledge for Educators to inspire future generations.

Garvin, James B.↗
NASA NTRS2005

Lunar and Planetary Science XXXVI, Part 13

Contents include the following: A Fast, Non-Destructive Method for Classifying Ordinary Chondrite Falls Using Density and Magnetic Susceptibility. An Update on Results from the Magnetic Properties Experiments on the Mars Exploration Rovers, Spirit and Opportunity. Measurement Protocols for In Situ Analysis of Organic Compounds at Mars and Comets. Piping Structures on Earth and Possibly Mars: Astrobiological Implications. Uranium and Lead in the Early Planetary Core Formation: New Insights Given by High Pressure and Temperature Experiments. The Mast Cameras and Mars Descent Imager (MARDI) for the 2009 Mars Science Laboratory. MGS MOC: First Views of Mars at Sub-Meter Resolution from Orbit. Analysis of Candor Chasma Interior Layered Deposits from OMEGA/MEX Spectra. Analysis of Valley Networks on Valles Marineris Plateau Using HRSC/MEX Data. Solar Abundance of Elements from Neutron-Capture Cross Sections. Preliminary Evaluation of the Secondary Ion/Accelerator Mass Spectrometer, MegaSIMS. Equilibrium Landforms in the Dry Valleys of Antarctica: Implications for Landscape Evolution and Climate Change on Mars. Continued Study of Ba Isotopic Compositions of Presolar Silicon Carbide Grains from Supernovae. Paleoenviromental Evolution of the Holden-Uzboi Area. Stability of Magnesium Sulfate Minerals in Martian Environments. Tungsten Isotopic Constraints on the Formation and Evolution of Iron Meteorite Parent Bodies. Migration of Dust Particles and Volatiles Delivery to the Inner Planets. On the Sitting of Trapped Noble Gases in Insoluble Organic Matter of Primitive Meteorites. Trapping of Xenon Upon Evaporation-Condensation of Organic Matter Under UV Irradiation: Isotopic Fractionation and Electron Paramagnetic Resonance Analysis. Stability of Water on Mars. A Didactic Activity. Analysis of Coronae in the Parga Chasma Region, Venus. Photometric and Compositional Surface Properties of the Gusev Crater Region, Mars, as Derived from Multi-Angle, Multi-Spectral Investigation of Mars Express HRSC Data. Mapping Compositional Diversity on Mars: Spatial Distribution and Geological Implications. A New Simulation Chamber for Studying Planetary Environments. Folded Structure in Terra Sirenum. Mars. Nitrogen-Noble Gas Static Mass Spectrometry of Genesis Collector Materials. Neon Isotope Heterogeneity in the Terrestrial Mantle: Implication for the Acquisition of Volatile Elements in Terrestrial Planets. The Cosmic Clock, the Cycle of Terrestrial Mass Extinctions.

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NASA NTRS2005

Lunar and Planetary Science XXXVI, Part 17

The following topics were discussed: A Model for the Formation of Paterae on Io; LIBS-based Detection of As, Br, C, Cl, P, and S in the VUV Spectral Region in a Mars Atmosphere; Mass Independent Sulfur in Achondrites: Possible Evidence of Photochemistry in the Solar Nebula; Grain Size-dependent Viscosity and Oceans in Icy Satellites; Claritas Paleolake Studied from the MEX HRSC Data; Mars Express HRSC Colors of White Rock, Arabia, Mars; Lava and Flows of the Arcadia Region of Mars; Isotopic Composition of Lunar Soils and the Early Differentiation of the Moon; Trace Element Analysis of Lunar Soils by ICP-MS; Highly Siderophile Elements and Osmium Isotope Systematics in Ureilites: Are the Carbonaceous Veins Primary Components?; Evaporative Evolution of Martian Brines Based on Halogens in Nakhlites and MER Samples; Io from High-Resolution Galileo PPR Data Taken Simultaneously with SSI or NIMS Observations; Loki, Io: Groundbased Observations and a Model for Periodic Overturn; Deconstructing a Few Myths in the Interpretation of Satellite-Altitude Crustal Magnetic Field: Examples from Mars Global Surveyor; Semi-Autonomous Rover Operations: A Mars Technology Program Demonstration; Rotational Studies of Asteroids with Small Telescopes; Mineralogy and Temperature-induced Spectral Investigations of A-type Asteroids 246 Asporina and 446 Aeternitas; and Thermal History Calculations Versus Full Convection Models: Application to the Thermal Evolution of Mercury. Recent Solar-Proton Fluxes

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NASA NTRS2010

Biotoxicity of Mars Analog Soils: Microbial, Dispersal into Desiccated Soils Versus Emplacement in Salt or Ice Inclusions Fluids

Recent evidence from the Opportunity and Spirit rovers and the Mars Express mission suggests that the soils on Mars might be very high in biotoxic materials including sulfate salts, chlorides, and acidifying agents. Yet, very little is known about how the chemistries of Mars soils might affect the survival and growth of terrestrial microorganisms. The primary objectives of the research included: (1) prepare and characterize Mars analog soils amended with potential biotoxic levels of sulfates, chlorides, and acidifying minerals; and (2) use the simulants to conduct a series of toxicology assays to determine if terrestrial microorganisms from spacecraft can survive direct exposure to the biotoxic soils.

Schuerger, A. C.↗
NASA NTRS2012

Relay Support for the Mars Science Laboratory and the Coming Decade of Mars Relay Network Evolution

In the past decade, an evolving network of Mars relay orbiters has provided telecommunication relay services to the Mars Exploration Rovers, Spirit and Opportunity, and to the Mars Phoenix Lander, enabling high-bandwidth, energy-efficient data transfer and greatly increasing the volume of science data that can be returned from the Martian surface, compared to conventional direct-to-Earth links. The current relay network, consisting of NASA's Odyssey and Mars Reconnaissance Orbiter and augmented by ESA's Mars Express Orbiter, stands ready to support the Mars Science Laboratory, scheduled to arrive at Mars on Aug 6, 2012, with new capabilities enabled by the Electra and Electra-Lite transceivers carried by MRO and MSL, respectively. The MAVEN orbiter, planned for launch in 2013, and the ExoMars/Trace Gas Orbiter, planned for launch in 2016, will replenish the on-orbit relay network as the current orbiter approach their end of life. Currently planned support scenarios for this future relay network include an ESA EDL Demonstrator Module deployed by the 2016 ExoMars/TGO orbiter, and the 2018 NASA/ESA Joint Rover, representing the first step in a multimission Mars Sample Return campaign.

MAVEN↗
NASA NTRS2003

Optical Depth Retrievals from HRSC Stereo Images

Mars Express is due to arrive in orbit around Mars during the last days of 2003. A primary task of its mission is to map Mars in stereo with the High Resolution Stereo Camera (HRSC) at a spatial resolution of up to 12 m. The Martian atmosphere contains large amounts of dust and other aerosols that scatter light and influence the images. Therefore, image analysis requires careful consideration of these atmospheric effects. An essential parameter to consider is the optical depth. It will be possible to map the optical depth of the Martian atmosphere from HRSC stereo images by analyzing contrast differences. Software to this purpose has been developed at the Max-Planck Institute for Aeronomy in Lindau Germany. We present examples of optical depth-retrievals from airborne HRSC-A images of a region in the French Alps.

N M Hoekzema↗
NASA NTRSDate not supplied

3-μm Spectroscopy of Phobos and Deimos

The origin of the Martian moons Phobos and Deimos is still not well understood and two scenarios have been proposed for their formation: in-situ and captured asteroid[1]. The in-situ scenario suggested that Phobos and Deimos were formed from Martian materials by co-accretion with Mars[2] or re-accretion of Mars (e.g.,[3],[4],[5]). The captured asteroid scenario proposed that Phobos and Deimos were formed from captured primitive materials originating from the outer solar system[6, 7]. Previous telescopic data have revealed significant information about Phobos’ and Deimos’ spectral properties [8,9,10,11]. Additionally, spacecraft and spec-trometers such as Observatoire pour la Mineralogie, L’Eau, Les Glaces et l’Activité (OMEGA) onboard Mars Express and the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) onboard Mars Reconnaissance Orbiter (MRO) collected visible to near-infrared imaging spectroscopic data of both Phobos and Deimos [12, 13,14,15]. Results from these investigations show that the two moons are moderately low albedo objects with no significant diagnostic absorptions of common ferrous minerals such as olivine and pyroxene. All these ground-and space-based spectroscopic studies of Phobos and Deimos included a spectral range that did not go beyond ~3.5 μm. Here we present spectra of Phobos and Deimos that cover the ~0.7-4 μmrange to search for signatures of hydrated minerals, organics, and carbonates.

D Takir↗
NASA NTRS2008

Mars Ozone Absorption Line Shapes from Infrared Heterodyne Spectra Applied to GCM-Predicted Ozone Profiles and to MEX/SPICAM Column Retrievals

We present the application of infrared heterodyne line shapes of ozone on Mars to those produced by radiative transfer modeling of ozone profiles predicted by general circulation models (GCM), and to contemporaneous column abundances measured by Mars Express SPICAM. Ozone is an important tracer of photochemistry Mars' atmosphere, serving as an observable with which to test predictions of photochemistry-coupled GCMs. Infrared heterodyne spectroscopy at 9.5 microns with spectral resolving power >1,000,000 is the only technique that can directly measure fully-resolved line shapes of Martian ozone features from the surface of the Earth. Measurements were made with Goddard Space Flight Center's Heterodyne instrument for Planetary Wind And Composition (HIPWAC) at the NASA Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii on February 21-24 2008 UT at Ls=35deg on or near the MEX orbital path. The HIPWAC observations were used to test GCM predictions. For example, a GCM-generated ozone profile for 60degN 112degW was scaled so that a radiative transfer calculation of its absorption line shape matched an observed HIPWAC absorption feature at the same areographic position, local time, and season. The RMS deviation of the model from the data was slightly smaller for the GCM-generated profile than for a line shape produced by a constant-with-height profile, even though the total column abundances were the same, showing potential for testing and constraining GCM ozone-profiles. The resulting ozone column abundance from matching the model to the HIPWAC line shape was 60% higher than that observed by SPICAM at the same areographic position one day earlier and 2.5 hours earlier in local time. This could be due to day-to-day, diurnal, or north polar region variability, or to measurement sensitivity to the ozone column and its distribution, and these possibilities will be explored. This work was supported by NASA's Planetary Astronomy Program.

Fast, Kelly E.↗
NASA NTRS2004

Lunar and Planetary Science XXXV: Mars All Over: Geologic Mapping

The titles presented in this session include: 1) 'Geology of Noachian Martian Highlands Surrounding the Gusev Crater'; 2) 'The History of Deposition and Nature of Material in Hellas Basin, Mars'; 3) 'Geologic Mapping of the Medusae Fossae Formation on Mars'; 4) 'Geology of the Aram Chaos from MGS-Mars Odyssey Missions and Mars Express HRSC Data'; 5) 'Toward a Comprehensive Stratigraphic Column of Mars'; 6 'The Olympus Mons Aureole Deposits: Constraints on Emplacement Scenarios Based on Remotely Sensed Data'.

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NASA NTRS2004

Lunar and Planetary Science XXXV: Missions and Instruments: Hopes and Hope Fulfilled

The titles in this section include: 1) Mars Global Surveyor Mars Orbiter Camera in the Extended Mission: The MOC Toolkit; 2) Mars Odyssey THEMIS-VIS Calibration; 3) Early Science Operations and Results from the ESA Mars Express Mission: Focus on Imaging and Spectral Mapping; 4) The Mars Express/NASA Project at JPL; 5) Beagle 2: Mission to Mars - Current Status; 6) The Beagle 2 Microscope; 7) Mars Environmental Chamber for Dynamic Dust Deposition and Statics Analysis; 8) Locating Targets for CRISM Based on Surface Morphology and Interpretation of THEMIS Data; 9) The Phoenix Mission to Mars; 10) First Studies of Possible Landing Sites for the Phoenix Mars Scout Mission Using the BMST; 11) The 2009 Mars Telecommunications Orbiter; 12) The Aurora Exploration Program - The ExoMars Mission; 13) Electron-induced Luminescence and X-Ray Spectrometer (ELXS) System Development; 14) Remote-Raman and Micro-Raman Studies of Solid CO2, CH4, Gas Hydrates and Ice; 15) The Compact Microimaging Spectrometer (CMIS): A New Tool for In-Situ Planetary Science; 16) Preliminary Results of a New Type of Surface Property Measurement Ideal for a Future Mars Rover Mission; 17) Electrodynamic Dust Shield for Solar Panels on Mars; 18) Sensor Web for Spatio-Temporal Monitoring of a Hydrological Environment; 19) Field Testing of an In-Situ Neutron Spectrometer for Planetary Exploration: First Results; 20) A Miniature Solid-State Spectrometer for Space Applications - Field Tests; 21) Application of Laser Induced Breakdown Spectroscopy (LIBS) to Mars Polar Exploration: LIBS Analysis of Water Ice and Water Ice/Soil Mixtures; 22) LIBS Analysis of Geological Samples at Low Pressures: Application to Mars, the Moon, and Asteroids; 23) In-Situ 1-D and 2-D Mapping of Soil Core and Rock Samples Using the LIBS Long Spark; 24) Rocks Analysis at Stand Off Distance by LIBS in Martian Conditions; 25) Evaluation of a Compact Spectrograph/Detection System for a LIBS Instrument for In-Situ and Stand-Off Detection; 26) Analysis of Organic Compounds in Mars Analog Samples; 27) Report of the Organic Contamination Science Steering Group; 28) The Water-Wheel IR (WIR) - A Contact Survey Experiment for Water and Carbonates on Mars; 29) Mid-IR Fiber Optic Probe for In Situ Water Detection and Characterization; 30) Effects of Subsurface Sampling & Processing on Martian Simulant Containing Varying Quantities of Water; 31) The Subsurface Ice Probe (SIPR): A Low-Power Thermal Probe for the Martian Polar Layered Deposits; 32) Deploying Ground Penetrating Radar in Planetary Analog Sites to Evaluate Potential Instrument Capabilities on Future Mars Missions; 33) Evaluation of Rock Powdering Methods to Obtain Fine-grained Samples for CHEMIN, a Combined XRD/XRF Instrument; 34) Novel Sample-handling Approach for XRD Analysis with Minimal Sample Preparation; 35) A New Celestial Navigation Method for Mars Landers; 36) Mars Mineral Spectroscopy Web Site: A Resource for Remote Planetary Spectroscopy.

Source record↗
NASA NTRS2005

ESA's Mars Program: European Plans for Mars Exploration

A viewgraph presentation on the European Space Agency Mars Exploration Program is shown. The topics include: 1) History:Mars Exploration in Europe; 2) A few preliminary results from Mars Express; 3) A new instrument:Radar MARSIS; and 4) European Mars Exploration in the future?

Forget, Francois↗
NASA NTRS2010

Abstracts of the Annual Meeting of Planetary Geologic Mappers, Flagstaff, AZ, 2010

Topics covered include: Detailed Analysis of the Intra-Ejecta Dark Plains of Caloris Basin, Mercury; The Formation and Evolution of Tessera and Insights into the Beginning of Recorded History on Venus: Geology of the Fortuna Tessera Quadrangle (V-2); Geologic Map of the Snegurochka Planitia Quadrangle (V-1): Implications for the Volcanic History of the North Polar Region of Venus; Geological Map of the Fredegonade (V-57) Quadrangle, Venus: Status Report; Geologic Mapping of V-19; Geology of the Lachesis Tessera Quadrangle (V-18), Venus; Comparison of Mapping Tessera Terrain in the Phoebe Regio (V-41) and Tellus Tessera (V-10) Quadrangles; Geologic Mapping of the Devana Chasma (V-29) Quadrangle, Venus; Geologic Mapping of the Aristarchus Plateau Region on the Moon; Geologic Mapping of the Lunar South Pole Quadrangle (LQ-30); The Pilot Lunar Geologic Mapping Project: Summary Results and Recommendations from the Copernicus Quadrangle; Geologic Mapping of the Nili Fossae Region of Mars: MTM Quadrangles 20287, 20282, 25287, 25282, 30287, and 30282; Geologic Mapping of the Mawrth Vallis Region, Mars: MTM Quadrangles 25022, 25017, 25012, 20022, 20017, and 20012; Evidence for an Ancient Buried Landscape on the NW Rim of Hellas Basin, Mars; New Geologic Map of the Argyre Region of Mars: Deciphering the Geologic History Through Mars Global Surveyor, Mars Odyssey, and Mars Express Data; Geologic Mapping in the Hesperia Planum Region of Mars; Geologic Mapping of the Meridiani Region of Mars; Geologic Mapping in Southern Margaritifer Terra; Geology of -30247, -35247, and -40247 Quadrangles, Southern Hesperia Planum, Mars; The Interaction of Impact Melt, Impact-Derived Sediment, and Volatiles at Crater Tooting, Mars; Geologic Map of the Olympia Cavi Region of Mars (MTM 85200): A Summary of Tactical Approaches; Geology of the Terra Cimmeria-Utopia Planitia Highland Lowland Transitional Zone: Final Technical Approach and Scientific Results; Geology of Libya Montes and the Interbasin Plains of Northern Tyrrhena Terra, Mars: First Year Results and Second Year Work Plan; Mars Global Geologic Mapping Progress and Suggested Geographic-Based Hierarchal Systems for Unit Grouping and Naming; Progress in the Scandia Region Geologic Map of Mars; Geomorphic Mapping of MTMS -20022 and -20017; Geologic Mapping of the Medusae Fossae Formation, Mars, and the Northern Lowland Plains, Venus; Volcanism on Io: Results from Global Geologic Mapping; Employing Geodatabases for Planetary Mapping Conduct - Requirements, Concepts and Solutions; and Planetary Geologic Mapping Handbook - 2010.

Bleamaster, Leslie F., III↗
NASA NTRS2013

Mars: A Planet with a Dynamic Climate System

Mars is a well-observed planet. Since the 1960s orbiters, landers, rovers, and earth-based telescopic observations show that its climate system is dynamic. Its dynamic nature, largely the result of atmosphere-surface interactions, is most obvious in the seasonal cycles of dust, water, and carbon dioxide that define the planet's climate system. These cycles are linked through the global circulation and MGS, Odyssey, Phoenix, MER, Mars Express, MRO, and now MSL have continuously observed them at Mars for the past 16 years. Their observations show that while the seasonal cycles are largely annually repeatable, there are interannual variations. Planet-encircling dust storms, for example, are quasi-triennial and originate over a broader range of seasons and locations than previously thought. Water moves from pole-to-pole each year in a largely, but not precisely, repeatable pattern that suggests but does not demand non-polar surface reservoirs. And the seasonal CO2 polar caps grow and retreat in a very predictable way with only minor deviations from year-to-year in spite of significant differences in atmospheric dust content. These behaviors suggest a complicated but robust coupled system in which these cycles interact to produce the greatest interannual variability in the dust cycle and least variability in the CO2 cycle. The nature of these interactions is the subject of ongoing research, but clouds, both water ice and CO2 ice, now appear to play a bigger role than believed at the end of the 20th century. There may also be some long-term trends in these cycles as there is evidence from imaging data, for example, that the south polar residual cap may not be stable on decadal to centennial time scales. On even longer time scales, the discovery of as much as 5 mb global equivalent of buried CO2 ice near the south pole, the detection of vast quantities of subsurface water ice at very shallow depths in midlatitudes of both hemispheres, and the presence of remnant glacial features at almost all latitudes, strongly suggests the possibility of significant climate change associated with orbital variations. Some of the major questions these data raise concern how closed the seasonal cycles are and which reservoirs are gaining or loosing, the cause of the large interannual variability of the dust cycle and how it couples to the water and CO2 cycles, and the mechanisms for the origin of past glacial activity and the emplacement and removal of subsurface ice. While many of these questions can be addressed with continued research based on existing data, new observations focused on atmosphere surface-interactions would provide valuable constraints on how dust, water, and CO2 move between the surface and atmosphere.

CO2 cycles↗
NASA NTRS2010

Relay Telecommunications for the Coming Decade of Mars Exploration

Over the past decade, an evolving network of relay-equipped orbiters has advanced our capabilities for Mars exploration. NASA's Mars Global Surveyor, 2001 Mars Odyssey, and Mars Reconnaissance Orbiter (MRO), as well as ESA's Mars Express Orbiter, have provided telecommunications relay services to the 2003 Mars Exploration Rovers, Spirit and Opportunity, and to the 2007 Phoenix Lander. Based on these successes, a roadmap for continued Mars relay services is in place for the coming decade. MRO and Odyssey will provide key relay support to the 2011 Mars Science Laboratory (MSL) mission, including capture of critical event telemetry during entry, descent, and landing, as well as support for command and telemetry during surface operations, utilizing new capabilities of the Electra relay payload on MRO and the Electra-Lite payload on MSL to allow significant increase in data return relative to earlier missions. Over the remainder of the decade a number of additional orbiter and lander missions are planned, representing new orbital relay service providers and new landed relay users. In this paper we will outline this Mars relay roadmap, quantifying relay performance over time, illustrating planned support scenarios, and identifying key challenges and technology infusion opportunities.

Edwards, C.↗
NASA NTRS2003

The Ability to Probe the Martian Polar Subsurface Via Ground-penetrating Radar

Ground-penetrating radar (GPR) offers the exciting possibility of remote sensing below the Martian surface for trapped aquifers. A GPR is currently heading to Mars onboard Mars Express (MEX) and a GPR is in consideration to be onboard Mars Reconnaissance Orbiter (MRO) in 2005. While such orbital systems offer great potential for polar stratigraphy studies, their ability to penetrate deep into the Martian polar ice is a function of both the intervening ionospheric density and the overlying ground ice conductivity. The influence of both signal-altering layers will be discussed. Polar Ice and Water: Clifford1,2 has suggested

Farrell, W. M.↗
NASA NTRS2006

Sulfates on Mars: Indicators of Aqueous Processes

Recent analyses by MER instruments at Meridiani Planum and Gusev crater and the OMEGA instrument on Mars Express have provided detailed information about the presence of sulfates on Mars [1,2,3]. We are evaluating these recent data in an integrated multi-disciplinary study of visible-near-infrared, mid-IR and Mossbauer spectra of several sulfate minerals and sulfate-rich analog sites. Our analyses suggest that hydrated iron sulfates may account for features observed in Mossbauer and mid-IR spectra of Martian soils [4]. The sulfate minerals kieserite, gypsum and other hydrated sulfates have been identified in OMEGA spectra in the layered terrains in Valles Marineris and Terra Meridiani [2]. These recent discoveries emphasize the importance of studying sulfate minerals as tracers of aqueous processes. The sulfate-rich rock outcrops observed in Meridiani Planum may have formed in an acidic environment similar to acid rock drainage environments on Earth [5]. Because microorganisms typically are involved in the oxidation of sulfides to sulfates in terrestrial sites, sulfate-rich rock outcrops on Mars may be a good location to search for evidence of past life on that planet. Whether or not life evolved on Mars, following the trail of sulfate minerals will lead to a better understanding of aqueous processes and chemical weathering.

Bishop, Janice L.↗
NASA NTRS2005

The Effect of Impacts on the Martian Climate

Evidence for the presence of liquid water early in Mars history continues to accumulate. The most recent evidence for liquid water being pervasive early in Mars history is the discoveries of sulfate and gypsum layers by the Mars Exploration Rovers and Mars Express. However, the presence of liquid water at the surface very early in Mars history presents a conundrum. The early sun was most likely approximately 75% fainter than it is today. About 65-70 degrees of greenhouse warming is needed to bring surface temperatures to the melting point of water. To date climate models have not been able to produce a continuously warm and wet early Mars. This may be a good thing as there is morphological and mineralogical evidence that the warm and wet period had to be relatively short and episodic. The rates of erosion appear to correlate with the rate at which Mars was impacted thus an alternate possibility is transient warm and wet conditions initiated by large impacts. It is widely accepted that even relatively small impacts (approximately 10 km) have altered the past climate of Earth to such an extent as to cause mass extinctions. Mars has been impacted with a similar distribution of objects. The impact record at Mars is preserved in the abundance of observable craters on it surface. Impact induced climate change must have occurred on Mars.

Colaprete, A.↗