2002 Annual Science Report
Arizona State University Reporting | JUL 2001 – JUN 2002
Exploring Mars for Past or Present Life
Mars Global Surveyor Thermal Emission Spectrometer (TES) data continue to provide new information pertinent to the role of water in mineralogical processes on Mars. Although no large-scale carbonate deposits have yet been detected, spectral evidence has been observed for H2O bearing minerals in Martain dust. Newly observed spectral details of the dust indicate that zeolites are a possible candidate for the aqueous mineral component. A search for spectral matches to the SNC or Martian meteorites yielded positive results. An excellent match with the spectrum of the ALH84001 meteorite was found in Eos Chasma within the Valles Marineris. (Eos chasma had been previously short-listed as a potential landing site for the 2003 Mars Exploration Rover (MER) rover mission). An important result of this work is that very little of the current surface of Mars matches the spectral character of the SNCs, possibly indicating a change in magmatic processes over Martian geologic history. TES data continue to be used to refine the candidate landing sites for the 2003 MER mission. The Sinus Meridiani hematite deposit, discovered with TES data, remains a top choice for one of the two rovers. Newly acquired Mars Odyssey Thermal Emission Imaging System (THEMIS) images also are being used to characterize the candidate landing sites. The geologic details of the hematite site are revealed with stunning clarity using the infrared images produced by THEMIS, putting into context the geologic setting of the hematite deposit.
Building on postdoctoral studies of collaborator Jeff Moersch, Masters student Alice Baldridge (Advisor Farmer) developed detailed mineralogical ground truth for remotely sensed Mars analog sites in the Badwater Basin of Death Valley. In collaboration with Moersch, we used spectral mapping tools (Environment for Visualizing Images (ENVI)) to analyze MODIS ASTER instrument (MASTER) (mid-infrared spectral) scenes and identify the locations of pure end-member pixels. To establish ground truth, we sampled all of the pure end member carbonate, sulfate and silicate pixels for laboratory analysis of mineralogy. We then applied a number of methods (X-ray diffraction (XRD), microprobe, SEM/EDS, thin section petrography and point counting), and lab spectral analysis (using the TES analog instrument), plus ground-based spectroscopy to identify mineralogy. To aid in spectral identifications, we developed a mid-infrared (IR) spectral library for evaporates. This information was added to ASU’s Spectral Library for use by the TES and THEMIS project teams who are presently mapping Mars. This spectral library also included mineralogical information from XRD, microprobe, EDS/SEM and basic petrographic descriptions. The results of the ground truth study were presented at Geological Society of America (GSA) and American Geophysical Union (AGU) meeting last Fall, and they comprised a Master’s thesis completed by Alice Baldridge in the Spring. The results of this study established thresholds for the detection of evaporite minerals (especially carbonates, sulfates and silicates) in the Badwater Basin. The results of the study suggest that at the coarse spatial of the TES instrument (3 km/pixel), detection of carbonates and sulfates would be unlikely. However, at the enhanced spatial resolution of THEMIS (100 m/pixel), both carbonates and sulfates should be easily detected, provided they are present at abundances exceeding ~15%. The results of this two part study are currently being prepared for publication with a planned submission in the Fall.
Under the direction of Co-I Farmer, Masters student Meredith Payne has used Viking and Mars Observer Camera (MOC) imaging to identify a half dozen sites adjacent to the North Polar cap of Mars, where very recent volcano-ice interactions and associated hydrothermal processes appear to have operated. Integrated data sets from Viking, the MOC and the Mars Observer Laser Altimeter (MOLA) were used to construct geologic maps, topographic profiles of suspect volcanic features and three-dimensional Digital Elevation Models (DEMs) of sites using ARC Info, ARC View and other analytical tools. We tested alternative hypotheses for the origin of the suspect volcanic and hydrothermal landforms at each site using morphometric comparisons with terrestrial analogs of known origin in Iceland, western North America and Arizona. Results of the study were presented at the GSA/Geological Society of London (GSL) meeting in Edinburgh last summer and at the GSA and AGU meetings last Fall, and they comprise a Masters thesis to be completed by Meredith Payne in late July.
PROJECT MEMBERS:Philip Christensen
RELATED OBJECTIVES:Objective 8.0
Search for evidence of ancient climates, extinct life and potential habitats for extant life on Mars.