Search results for "Composition of Mars"
showing 10 items of 17 documents
Geochemical and mineralogical indicators for aqueous processes in the Columbia Hills of Gusev crater, Mars
2006
[1] Water played a major role in the formation and alteration of rocks and soils in the Columbia Hills. The extent of alteration ranges from moderate to extensive. Five distinct rock compositional classes were identified; the order for degree of alteration is Watchtower ≅ Clovis > Wishstone ≅ Peace > Backstay. The rover's wheels uncovered one unusual soil (Paso Robles) that is the most S-rich material encountered. Clovis class rocks have compositions similar to Gusev plains soil but with higher Mg, Cl, and Br and lower Ca and Zn; Watchtower and Wishstone classes have high Al, Ti, and P and low Cr and Ni; Peace has high Mg and S and low Al, Na, and K; Backstay basalts have high Na and K comp…
In situ and experimental evidence for acidic weathering of rocks and soils on Mars
2006
Experimental data for alteration of synthetic Martian basalts at pH=0-1 indicate that chemical fractionations at low pH are vastly different from those observed during terrestrial weathering. Rock analyses from Gusev crater are well described by the relationships apparent from low pH experimental alteration data. A model for rock surface alteration is developed which indicates that a leached alteration zone is present on rock surfaces at Gusev. This zone is not chemically fractionated to a large degree from the underlying rock interior, indicating that the rock surface alteration process has occurred at low fluid-to-rock ratio. The geochemistry of natural rock surfaces analyzed by APXS is c…
Mössbauer mineralogy of rock, soil, and dust at Gusev crater, Mars: Spirit's journey through weakly altered olivine basalt on the plains and pervasiv…
2006
The Moessbauer spectrometer on Spirit measured the oxidation state of Fe, identified Fe-bearing phases, and measured relative abundances of Fe among those phases for surface materials on the plains and in the Columbia Hills of Gusev crater. Eight Fe-bearing phases were identified: olivine, pyroxene, ilmenite, magnetite, nanophase ferric oxide (npOx), hematite, goethite, and a Fe(3+)-sulfate. Adirondack basaltic rocks on the plains are nearly unaltered (Fe(3+)/Fe(sub T) Px), and minor npOx and magnetite. Columbia Hills basaltic rocks are nearly unaltered (Peace and Backstay), moderately altered (WoolyPatch, Wishstone, and Keystone), and pervasively altered (e.g., Clovis, Uchben, Watchtower, …
Bounce Rock-A shergottite-like basalt encountered at Meridiani Planum, Mars
2011
Additional co-authors: Thanasis ECONOMOU, Steven P. GOREVAN, Brian C. HAHN, Gostar KLINGELHOFER, Timothy J. McCOY, Harry Y. McSWEEN Jr, Douglas W. MING, Richard V. MORRIS, Daniel S. RODIONOV, Steven W. SQUYRES, Heinrich WANKE, Shawn P. WRIGHT, Michael B. WYATT, Albert S. YEN
The Spirit Rover's Athena science investigation at Gusev Crater, Mars.
2004
The Mars Exploration Rover Spirit and its Athena science payload have been used to investigate a landing site in Gusev crater. Gusev is hypothesized to be the site of a former lake, but no clear evidence for lacustrine sedimentation has been found to date. Instead, the dominant lithology is basalt, and the dominant geologic processes are impact events and eolian transport. Many rocks exhibit coatings and other characteristics that may be evidence for minor aqueous alteration. Any lacustrine sediments that may exist at this location within Gusev apparently have been buried by lavas that have undergone subsequent impact disruption.
Basaltic Rocks Analyzed by the Spirit Rover in Gusev Crater
2004
The Spirit landing site in Gusev Crater on Mars contains dark, fine-grained, vesicular rocks interpreted as lavas. Pancam and MiniâThermal Emission Spectrometer (Mini-TES) spectra suggest that all of these rocks are similar but have variable coatings and dust mantles. Magnified images of brushed and abraded rock surfaces show alteration rinds and veins. Rock interiors contain â¤25% megacrysts. Chemical analyses of rocks by the Alpha Particle X-ray Spectrometer are consistent with picritic basalts, containing normative olivine, pyroxenes, plagioclase, and accessory FeTi oxides. MoÌssbauer, Pancam, and Mini-TES spectra confirm the presence of olivine, magnetite, and probably pyroxene. The…
Mineralogy at Gusev Crater from the Mössbauer spectrometer on the Spirit Rover.
2004
Mössbauer spectra measured on Mars by the Spirit rover during the primary mission are characterized by two ferrous iron doublets (olivine and probably pyroxene) and a ferric iron doublet (tentatively associated to nanophase ferric iron oxide). Two sextets resulting from nonstoichiometric magnetite are also present, except for a coating on the rock Mazatzal, where a hematite-like sextet is present. Greater proportions of ferric-bearing phases are associated with undisturbed soils and rock surfaces as compared to fresh rock surfaces exposed by grinding. The ubiquitous presence of olivine in soil suggests that physical rather than chemical weathering processes currently dominate at Gusev crat…
The new Athena alpha particle X-ray spectrometer for the Mars Exploration Rovers
2003
[1] The new alpha particle X-ray spectrometer (APXS) is part of the Athena payload of the two Mars Exploration Rovers (MER). The APXS sensor head is attached to the turret of the instrument deployment device (IDD) of the rover. The APXS is a very light-weight instrument for determining the major and minor elemental composition of Martian soils, rocks, and other geological materials at the MER landing sites. The sensor head has simply to be docked by the IDD on the surface of the selected sample. X-ray radiation, excited by alpha particles and X rays of the radioactive sources, is recorded by a high-resolution X-ray detector. The X-ray spectra show elements starting from sodium up to yttrium…
Weathering of Fe-bearing minerals under Martian conditions, investigated by Mössbauer spectroscopy
2004
Abstract The surface of Mars is covered by weathered material. Mars' rusty red colour in particular is commonly ascribed to ferric iron-bearing minerals. The planet's surface is generally iron rich. Mossbauer spectroscopy is a powerful tool for quantitative mineralogical analysis of Fe-bearing minerals. Consequently, the miniaturized Mossbauer spectrometer MIMOS II is part of the payload of NASA's twin Mars Exploration Rovers “Spirit” and “Opportunity”, and ESA's ill-fated Mars Express lander “Beagle 2”. Both Mars Exploration Rovers are currently conducting successful surface operations on Mars. In this paper, we give a brief insight into mission operations with respect to the reconstructio…
Athena MIMOS II Mössbauer spectrometer investigation
2003
[1] Mossbauer spectroscopy is a powerful tool for quantitative mineralogical analysis of Fe-bearing materials. The miniature Mossbauer spectrometer MIMOS II is a component of the Athena science payload launched to Mars in 2003 on both Mars Exploration Rover missions. The instrument has two major components: (1) a rover-based electronics board that contains power supplies, a dedicated central processing unit, memory, and associated support electronics and (2) a sensor head that is mounted at the end of the instrument deployment device (IDD) for placement of the instrument in physical contact with soil and rock. The velocity transducer operates at a nominal frequency of ∼25 Hz and is equipped…