The Latest from the Mars Exploration Rovers Spirit
- Slides: 20
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
MER Landing Sites: Gusev Crater (Spirit) and Meridiani Planum (Opportunity) http: //marsonweb. nasa. gov/landingsites/m er 2003/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: Fe 3 O 4 Hematite: Fe 2 O 3 Olivine: Fe 2 Si. O 4 Pyroxine: Ca. Fe. Si 2 O 6 Minerals tell about hydrological history, what chemical reactions were occurring
Measurements of mineral structure via the Mossbauer Effect
Radioisotope selection for MER • 57 Co -> 57 Fe* -> 57 Fe + 14. 4 ke. V • Iron dominant element in rocks, good mineralogical diagnostic • 57 Co 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, E 12, ROV 8
Transmission versus scattering Mossbauer Effect
MIMOS II experiment on MER
The MIMOS II Instrument
Mossbauer spectra of Mars rocks from MER
More Mossbauer spectra from Mars
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”