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The Latest from the Mars Exploration Rovers. Spirit at Gusev Crater. Primary goal of Mars exploration: Search for water on Mars. Summary: Orbital photography shows evidence for water on ancient Mars. Also evidence for large standing bodies of water.
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Summary: Orbital photography shows evidence for water on ancient Mars Also evidence for large standing bodies of water
MER Landing Sites: Gusev Crater (Spirit) and Meridiani Planum (Opportunity) http://marsonweb.nas.nasa.gov/landingsites/mer2003/mocs
MER Landing sites: Gusev crater (Spirit) and Meridiani Planum (Opportunity)
Landing Sites for Spirit and Opportunity Spirit Opportunity
Mineralogy: Key to hydrological history of Mars • Magnetite: Fe3O4 • Hematite: Fe2O3 • Olivine: Fe2SiO4 • Pyroxine: CaFeSi2O6 Minerals tell about hydrological history, what chemical reactions were occurring
Radioisotope selection for MER • 57Co -> 57Fe* -> 57Fe + 14.4 keV • Iron dominant element in rocks, good mineralogical diagnostic • 57Co has half life of 271 days. A challenge for interplanetary missions
How does Mossbauer Effect tell you about mineral structure of Mars rocks? Klingelhoefer et al 2003, JGR 108, E12, ROV 8
Results from MER spacecraft • Evidence of water at Meridiani from the outset: haematite chondrules, sedimentary rocks with chemically weathered compositions: “there are other possible scenarios; they all require liquid water and acidic conditions”. • Early results from Gusev seemed to argue against water; high abundance of pristine olivine. “the ubiquitous presence of olivine in the soil suggests that physical rather than chemical weathering processes…”
Recent results from MER (cont) • More recent results from Gusev, coatings on rock with 2-5 times high S & Cl concentrations than interior, crystalline haematite. • “The physical and chemical characteristics provide evidence for limited by unequivocal interaction between water and the volcanic rocks of the Gusev plains”