2 results
3 - Martian surface chemistry: APXS results from the Pathfinder landing site
- from Part II - Elemental Composition: Orbital and in situ Surface Measurements
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- By C. N. Foley, Department of Terrestrial Magnetism, Carnegie Institute of Washington, 5241 Broad Branch Road, NW Washington, DC 20015-1305, USA, T. E. Economou, Laboratory for Astrophysics & Space Res. University of Chicago, 933 East 56th Street, Chicago, IL 60637, USA, R. N. Clayton, Enrico Fermi Institute, 5640 S. Ellis Avenue, RI 440 Chicago, IL 60637, USA, J. Brückner, Geochemistry Department, Max Planck Institut für Chemie, PO Box 3060, Mainz D-55020, Germany, G. Dreibus, Cosmochemistry Deparment, Max Planck Institut für Chemie, PO Box 3060, Mainz D-55020, Germany, R. Rieder, Cosmochemistry Deparment, Max Planck Institut für Chemie, PO Box 3060, Mainz D-55020, Germany, H. Wänke, Abteilung Kosmochemie Max Planck Institut für Chemie, PO Box 3060, Mainz D-55020, Germany
- Edited by Jim Bell, Cornell University, New York
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- Book:
- The Martian Surface
- Published online:
- 10 December 2009
- Print publication:
- 05 June 2008, pp 33-57
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Summary
ABSTRACT
The Mars Pathfinder Alpha Proton X-ray Spectrometer (APXS) was utilized to determine the major and minor elemental abundances of rocks and soils at the 1997 landing site in Ares Vallis. The determined abundances suggest that: (1) the rocks are covered with various amounts of soil; (2) the Soil-Free Rock (SFR) chemistry is similar to that of an evolved SNC-like (SNC – Shergottite, Nakhlite, and Chassignite) igneous tholeiitic basalt-andesite to andesite that is minimally altered (possibly similar to Type 2 TES material); (3) the carbon content is below detection limits for all samples, implying < 5% as MgCO3 (Brückner et al., 1999); (4) the α-mode oxygen abundance indicates that mineral-bound water, above the value for igneous rocks, is present in some rocks and is therefore indicative of some nonigneous alteration and therefore possibly rock-rinds that obscure the petrology of the SFR; and (5) the Pathfinder soils are similar to the Viking fines and may be composed of mafic igneous material like the SNC meteorites and of volatiles deposited from volcanic emissions, as previously suggested by Clark (1993) for the Viking soils.
4 - Mars Exploration Rovers: chemical composition by the APXS
- from Part II - Elemental Composition: Orbital and in situ Surface Measurements
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- By J. Brückner, Geochemistry Department, Max Planck Institut für Chemie, PO Box 3060, Mainz D-55020, Germany, G. Dreibus, Cosmochemistry Deparment, Max Planck Institut für Chemie, PO Box 3060, Mainz D-55020, Germany, R. Gellert, Department of Physics, University of Guelph Guelph, ON N1G 2W1, Canada, S. W. Squyres, Department of Astronomy, Cornell University, 428 Space Sciences Building, Ithaca, NY 14853, USA, H. Wänke, Abteilung Kosmochemie Max Planck Institut für Chemie, PO Box 3060, Mainz D-55020, Germany, A. Yen, JPL/Caltech 4800 Oak Grove Road M/S 183-501 Pasadena, CA 91109-8099, USA, J. Zipfel, Forschungsinstitut und Naturmuseum Senckenberg Frankfurt/Main, D-60325, Germany
- Edited by Jim Bell, Cornell University, New York
-
- Book:
- The Martian Surface
- Published online:
- 10 December 2009
- Print publication:
- 05 June 2008, pp 58-102
-
- Chapter
- Export citation
-
Summary
ABSTRACT
The Alpha Particle X-Ray Spectrometers (APXSs) on board the Mars Exploration Rovers (MERs) determine the elemental compositions of Martian samples. Improvements to the version of the instrument flown on the Mars Pathfinder (MPF) mission allow, for the first time, in situ detection and quantification of trace elements such as nickel, zinc, and bromine. The APXS measurements are performed by placing the sensor head against or immediately above the sample surface. A wealth of compositional diversity has been discovered at the two MER landing sites. At Gusev crater, fresh rock surfaces in the plains resemble primitive basalts, while rocks in the Columbia Hills are significantly weathered and enriched in mobile elements such as phosphorus, sulfur, chlorine, and bromine. Sandstones cemented by sulfates as well as evidence for clay formation have also been found in the Columbia Hills. At Meridiani Planum, the layered sedimentary rocks were found to consist primarily of sulfates mixed with siliciclastic debris. Iron-rich spherules and their fragments, confirmed to be hematitic by the Mössbauer spectrometer (MB), are found armoring the soil bedforms as well as embedded in the outcrop rocks. A variety of unusual objects, including an iron-nickel meteorite and a likely ejecta fragment similar to a Martian meteorite, have also been discovered. The elemental compositions of soils analyzed at both sites are remarkably similar, indicative of global-scale homogenization or the similarity of the soil precursors.