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Jutta ZIPFEL,
Christian SCHRÖDER,
Bradley L. JOLLIFF,
Ralf GELLERT,
Kenneth E. HERKENHOFF,
Rudolf RIEDER,
Robert ANDERSON,
James F. BELL III,
Johannes BRÜCKNER,
Joy A. CRISP, [......],
Timothy J. McCOY,
Harry Y. McSWEEN Jr,
Douglas W. MING,
Richard V. MORRIS,
Daniel S. RODIONOV,
Steven W. SQUYRES,
Heinrich WÄNKE,
Shawn P. WRIGHT,
Michael B. WYATT,
Albert S. YEN
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ABSTRACT: Abstract– The Opportunity rover of the Mars Exploration Rover mission encountered an isolated rock fragment with textural, mineralogical, and chemical properties similar to basaltic shergottites. This finding was confirmed by all rover instruments, and a comprehensive study of these results is reported here. Spectra from the miniature thermal emission spectrometer and the Panoramic Camera reveal a pyroxene-rich mineralogy, which is also evident in Mössbauer spectra and in normative mineralogy derived from bulk chemistry measured by the alpha particle X-ray spectrometer. The correspondence of Bounce Rock’s chemical composition with the composition of certain basaltic shergottites, especially Elephant Moraine (EET) 79001 lithology B and Queen Alexandra Range (QUE) 94201, is very close, with only Cl, Fe, and Ti exhibiting deviations. Chemical analyses further demonstrate characteristics typical of Mars such as the Fe/Mn ratio and P concentrations. Possible shock features support the idea that Bounce Rock was ejected from an impact crater, most likely in the Meridiani Planum region. Bopolu crater, 19.3 km in diameter, located 75 km to the southwest could be the source crater. To date, no other rocks of this composition have been encountered by any of the rovers on Mars. The finding of Bounce Rock by the Opportunity rover provides further direct evidence for an origin of basaltic shergottite meteorites from Mars.
Meteoritics & Planetary Science. 12/2010; 46(1):1 - 20.
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Richard V Morris,
Steven W Ruff,
Ralf Gellert,
Douglas W Ming,
Raymond E Arvidson, Benton C Clark,
D C Golden,
Kirsten Siebach,
Göstar Klingelhöfer,
Christian Schröder,
Iris Fleischer,
Albert S Yen,
Steven W Squyres
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ABSTRACT: Decades of speculation about a warmer, wetter Mars climate in the planet's first billion years postulate a denser CO2-rich atmosphere than at present. Such an atmosphere should have led to the formation of outcrops rich in carbonate minerals, for which evidence has been sparse. Using the Mars Exploration Rover Spirit, we have now identified outcrops rich in magnesium-iron carbonate (16 to 34 weight percent) in the Columbia Hills of Gusev crater. Its composition approximates the average composition of the carbonate globules in martian meteorite ALH 84001. The Gusev carbonate probably precipitated from carbonate-bearing solutions under hydrothermal conditions at near-neutral pH in association with volcanic activity during the Noachian era.
Science 07/2010; 329(5990):421-4. · 31.20 Impact Factor
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Andrew D Aubrey,
John H Chalmers,
Jeffrey L Bada,
Frank J Grunthaner,
Xenia Amashukeli,
Peter Willis,
Alison M Skelley,
Richard A Mathies,
Richard C Quinn,
Aaron P Zent, [......],
Diana L Blaney, Benton C Clark,
Max Coleman,
Beda A Hofmann,
Jean-Luc Josset,
Petra Rettberg,
Sally Ride,
François Robert,
Mark A Sephton,
Albert Yen
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ABSTRACT: The Urey organic and oxidant detector consists of a suite of instruments designed to search for several classes of organic molecules in the martian regolith and ascertain whether these compounds were produced by biotic or abiotic processes using chirality measurements. These experiments will also determine the chemical stability of organic molecules within the host regolith based on the presence and chemical reactivity of surface and atmospheric oxidants. Urey has been selected for the Pasteur payload on the European Space Agency's (ESA's) upcoming 2013 ExoMars rover mission. The diverse and effective capabilities of Urey make it an integral part of the payload and will help to achieve a large portion of the mission's primary scientific objective: "to search for signs of past and present life on Mars." This instrument is named in honor of Harold Urey for his seminal contributions to the fields of cosmochemistry and the origin of life.
Astrobiology 07/2008; 8(3):583-95. · 2.15 Impact Factor
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Albert S. Yen,
Ralf Gellert,
Christian Schröder,
Richard V. Morris,
James F Bell,
Amy T. Knudson, Benton C. Clark,
Douglas W. Ming,
Joy A. Crisp,
Raymond E. Arvidson, [......],
Harry Y McSween,
Lutz Richter,
Rudi Rieder,
Daniel Rodionov,
Larry Soderblom,
Steven W. Squyres,
Nicholas J. Tosca,
Alian Wang,
Michael Wyatt,
Jutta Zipfel
Nature 08/2005; · 36.28 Impact Factor
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Albert S. Yen,
Ralf Gellert,
Christian Schroder,
Richard V. Morris,
James F 3rd Bell,
Amy T. Knudson, Benton C. Clark,
Douglas W. Ming,
Joy A. Crisp,
Raymond E. Arvidson, [......],
Thanasis E. Economou,
Amitabha Ghosh,
Brian C. Hahn,
Kenneth E. Herkenhoff,
Larry A. Haskin,
Joel A. Hurowitz,
Bradley L. Joliff,
Jeffrey R. Johnson,
Gostar Klingelhofer,
Morten Bo Madsen
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ABSTRACT: The mineralogical and elemental compositions of the martian soil are indicators of chemical and physical weathering processes. Using data from the Mars Exploration Rovers, we show that bright dust deposits on opposite sides of the planet are part of a global unit and not dominated by the composition of local rocks. Dark soil deposits at both sites have similar basaltic mineralogies, and could reflect either a global component or the general similarity in the compositions of the rocks from which they were derived. Increased levels of bromine are consistent with mobilization of soluble salts by thin films of liquid water, but the presence of olivine in analysed soil samples indicates that the extent of aqueous alteration of soils has been limited. Nickel abundances are enhanced at the immediate surface and indicate that the upper few millimetres of soil could contain up to one per cent meteoritic material.
08/2005;
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Larry A Haskin,
Alian Wang,
Bradley L Jolliff,
Harry Y McSween, Benton C Clark,
David J Des Marais,
Scott M McLennan,
Nicholas J Tosca,
Joel A Hurowitz,
Jack D Farmer, [......],
James F Bell,
Kenneth Herkenhoff,
Phil R Christensen,
Steve Ruff,
Diana Blaney,
Steven Gorevan,
Nathalie A Cabrol,
Larry Crumpler,
John Grant,
Lawrence Soderblom
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ABSTRACT: Gusev crater was selected as the landing site for the Spirit rover because of the possibility that it once held a lake. Thus one of the rover's tasks was to search for evidence of lake sediments. However, the plains at the landing site were found to be covered by a regolith composed of olivine-rich basaltic rock and windblown 'global' dust. The analyses of three rock interiors exposed by the rock abrasion tool showed that they are similar to one another, consistent with having originated from a common lava flow. Here we report the investigation of soils, rock coatings and rock interiors by the Spirit rover from sol (martian day) 1 to sol 156, from its landing site to the base of the Columbia hills. The physical and chemical characteristics of the materials analysed provide evidence for limited but unequivocal interaction between water and the volcanic rocks of the Gusev plains. This evidence includes the softness of rock interiors that contain anomalously high concentrations of sulphur, chlorine and bromine relative to terrestrial basalts and martian meteorites; sulphur, chlorine and ferric iron enrichments in multilayer coatings on the light-toned rock Mazatzal; high bromine concentration in filled vugs and veins within the plains basalts; positive correlations between magnesium, sulphur and other salt components in trench soils; and decoupling of sulphur, chlorine and bromine concentrations in trench soils compared to Gusev surface soils, indicating chemical mobility and separation.
Nature 08/2005; 436(7047):66-9. · 36.28 Impact Factor
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Albert S Yen,
Ralf Gellert,
Christian Schröder,
Richard V Morris,
James F Bell,
Amy T Knudson, Benton C Clark,
Douglas W Ming,
Joy A Crisp,
Raymond E Arvidson, [......],
Harry Y McSween,
Lutz Richter,
Rudi Rieder,
Daniel Rodionov,
Larry Soderblom,
Steven W Squyres,
Nicholas J Tosca,
Alian Wang,
Michael Wyatt,
Jutta Zipfel
[show abstract]
[hide abstract]
ABSTRACT: The mineralogical and elemental compositions of the martian soil are indicators of chemical and physical weathering processes. Using data from the Mars Exploration Rovers, we show that bright dust deposits on opposite sides of the planet are part of a global unit and not dominated by the composition of local rocks. Dark soil deposits at both sites have similar basaltic mineralogies, and could reflect either a global component or the general similarity in the compositions of the rocks from which they were derived. Increased levels of bromine are consistent with mobilization of soluble salts by thin films of liquid water, but the presence of olivine in analysed soil samples indicates that the extent of aqueous alteration of soils has been limited. Nickel abundances are enhanced at the immediate surface and indicate that the upper few millimetres of soil could contain up to one per cent meteoritic material.
Nature 08/2005; 436(7047):49-54. · 36.28 Impact Factor
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Larry A. Haskin,
Alian Wang,
Bradley L. Jolliff,
Harry Y. McSween, Benton C. Clark,
David J. Des Marais,
Scott M. McLennan,
Nicholas J. Tosca,
Joel A. Hurowitz,
Jack D. Farmer, [......],
James F. Bell,
Kenneth Herkenhoff,
Phil R. Christensen,
Steve Ruff,
Diana Blaney,
Steven Gorevan,
Nathalie A. Cabrol,
Larry Crumpler,
John Grant,
Lawrence Soderblom
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[hide abstract]
ABSTRACT: Gusev crater was selected as the landing site for the Spirit rover because of the possibility that it once held a lake. Thus one of the rover's tasks was to search for evidence of lake sediments
Nature 07/2005; 436(7047):66-69. · 36.28 Impact Factor
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ABSTRACT: The neutron counter proposed here has a long history and was commercially available in a somewhat different form. This counter would be suitable for a rover or lander since it requires a rather long measuring time for each placement. It consists of two silicon wafer charged-particle counters with a layer of Li-6F deposited on the inner surface of one. The neutron detecting reaction is Li-6(n,H-3)He-4 in which the alpha particle and the triton are emitted from the Li-6 deposit back to back. If one of the detectors sees the alpha particle, the other will see the triton. This allows one to use a coincidence technique that virtually eliminates all background. The signals from each detector can be added together so that the total energy of the reaction, Q=4.6 MeV and the kinetic energy of the neutron, can be recorded.
02/1997;
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Timothy D Glotch,
Joshua L Bandfield,
Philip R Christensen,
Wendy M Calvin,
Scott M Mclennan, Benton C Clark,
A Deanne Rogers,
Steven W Squyres,
J L Bandfield,
P R Christensen,
W M Calvin,
S M Mclennan,
B C Clark,
A D Rogers,
S W Squyres
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ABSTRACT: 1] Analysis of Miniature Thermal Emission Spectrometer (Mini-TES) data has led to the recovery of a pure end-member spectral shape related to the light-toned outcrop observed at Meridiani Planum. Data from the MER Mössbauer spectrometer, APXS, and previous Mini-TES measurements were used to constrain a spectral library used to determine the mineralogy of the outcrop from this spectral shape. Linear deconvolution of the outcrop spectral shape suggests that it is composed primarily of Al-rich opaline silica, Mg-, Ca-, and Fe-bearing sulfates, plagioclase feldspar, nontronite, and hematite. Conversion of modeled mineralogy to chemistry shows good agreement with the chemical composition of the outcrops determined by APXS. Details of the analysis procedure and implications for the formation of the outcrop are discussed along with terrestrial analogs of the ancient environment at Meridiani. (2006), Mineralogy of the light-toned outcrop at Meridiani Planum as seen by the Miniature Thermal Emission Spectrometer and implications for its formation, J. Geophys. Res., 111, E12S03, doi:10.1029/2005JE002672.
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ABSTRACT: New data returned from the Mars Exploration Rover (MER) mission have revealed abundant evaporites in the sedimentary record at Meridiani Planum. A working hypothesis for Meridiani evaporite formation involves the evaporation of fluids derived from the weathering of martian basalt and subsequent diagenesis. On Earth, evaporite formation in exclusively basaltic settings is rare. However, models of the evaporation of fluids derived from experimentally weathering synthetic martian basalt provide insight into possible formation mechanisms. The thermodynamic database assembled for this investigation includes both Fe<sup>2+</sup> and Fe<sup>3+</sup> in Pitzer's ion interaction equations to evaluate Fe redox disequilibrium at Meridiani Planum. Modeling results suggest that evaporation of acidic fluids derived from weathering olivine-bearing basalt should produce Mg, Ca, and Fe-sulfates such as jarosite and melanterite. Calculations that model diagenesis by fluid recharge predict the eventual breakdown of jarosite to goethite as well as the preservation of much of the initial soluble evaporite component at modeled porosity values appropriate for relevant depositional environments (< 0.30). While only one of several possible formation scenarios, this simple model is consistent with much of the chemical and mineralogical data obtained on Meridiani Planum outcrop. Organismic and Evolutionary Biology
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Steven W. Squyres,
Andrew Herbert Knoll,
Raymond E. Arvidson,
James W. Ashley,
James F. III Bell,
Wendy M. Calvin,
Philip R. Christensen, Benton C. Clark,
Barabara A. Cohen,
Paulo Jr. de Souza, [......],
Ruogu Li,
Timothy J. McCoy,
Scott M. McLennan,
Douglas W. Ming,
Richard V. Morris,
James W. Jr Rice,
Christian Schröder,
Robert J. Sullivan,
Albert Yen,
R. Aileen Yingst
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ABSTRACT: The Mars rover Opportunity has explored Victoria crater, a ~750-meter eroded impact crater formed in sulfate-rich sedimentary rocks. Impact-related stratigraphy is preserved in the crater walls, and meteoritic debris is present near the crater rim. The size of hematite-rich concretions decreases up-section, documenting variation in the intensity of groundwater processes. Layering in the crater walls preserves evidence of ancient wind-blown dunes. Compositional variations with depth mimic those ~6 kilometers to the north and demonstrate that water-induced alteration at Meridiani Planum was regional in scope. Organismic and Evolutionary Biology Accepted Manuscript
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Nicholas Tosca,
Andrew Knoll,
Zoe Learner,
Albert S. Yen,
Robert Sullivan,
Steven W. Squyres,
Richard Morris,
Scott M. McLennan,
Jeffrey R. Johnson,
Kenneth E. Herkenhoff,
John P. Grotzinger,
Matthew P. Golombek,
Ralf Gellert, Benton C. Clark,
James F. III Bell,
William H. Farrand,
Bradley L. Jolliff
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ABSTRACT: Veneers and thicker rinds that coat outcrop surfaces and partially cemented fracture fills formed perpendicular to bedding document relatively late stage alteration of ancient sedimentary rocks at Meridiani Planum, Mars. The chemistry of submillimeter thick, buff-colored veneers reflects multiple processes at work since the establishment of the current plains surface. Veneer composition is dominated by the mixing of silicate-rich dust and sulfate-rich outcrop surface, but it has also been influenced by mineral precipitation, including NaCl, and possibly by limited physical or chemical weathering of sulfate minerals. Competing processes of chemical alteration (perhaps mediated by thin films of water or water vapor beneath blanketing soils) and sandblasting of exposed outcrop surfaces determine the current distribution of veneers. Dark-toned rinds several millimeters thick reflect more extensive surface alteration but also indicate combined dust admixture, halite precipitation, and possible minor sulfate removal. Cemented fracture fills that are differentially resistant to erosion occur along the margins of linear fracture systems possibly related to impact. These appear to reflect limited groundwater activity along the margins of fractures, cementing mechanically introduced fill derived principally from outcrop rocks. The limited thickness and spatial distribution of these three features suggest that aqueous activity has been rare and transient or has operated at exceedingly low rates during the protracted interval since outcropping Meridiani strata were exposed on the plains surface. Organismic and Evolutionary Biology
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Andrew Knoll,
Larry A. Soderblom,
Renate Rieder,
John W. Rice,
Richard V. Morris,
Harry Y McSween,
Scott M. McLennan,
Gostar Klingelhofer,
Jeffrey R. Johnson,
Ken E. Herkenhoff,
William H. Farrand,
Jeffrey Crisp, Benton C. Clark,
Philip R. Christensen,
Wendy Calvin,
James F. III Bell,
Raymond E. Arvidson,
John P. Grotzinger,
Steven W. Squyres
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ABSTRACT: Sedimentary rocks at Eagle crater in Meridiani Planum are composed of fine-grained siliciclastic materials derived from weathering of basaltic rocks, sulfate minerals (including magnesium sulfate and jarosite) that constitute several tens of percent of the rock by weight, and hematite. Cross-stratification observed in rock outcrops indicates eolian and aqueous transport. Diagenetic features include hematite-rich concretions and crystal-mold vugs. We interpret the rocks to be a mixture of chemical and siliciciastic sediments with a complex diagenetic history. The environmental conditions that they record include episodic inundation by shallow surface water, evaporation, and desiccation. The geologic record at Meridiani Planum suggests that conditions were suitable for biological activity for a period of time in martian history. Organismic and Evolutionary Biology
