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  • 11
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    Cementation and Aqueous Alteration of a Sandstone Unit Under Acidic Conditions in Gale Crater, Mars (2016)
    In:  CASI
    Details
    Publikationsdatum: 2019-07-13
    Beschreibung: The Curiosity rover landed on Mars in August 2012 to explore the sedimentary history and to assess the habitability of Gale Crater. After 1200 sols of surface operations and over 12 km of traverse distance, the mineralogy of 10 samples has been determined by the CheMin X-ray diffractometer (XRD) and the chemical composition of nearly 300 targets has been established by the Alpha Particle X-ray Spectrometer (APXS). Light-toned fracture zones containing elevated concentrations of silica have been studied by Curiosity's instruments to determine the nature of the fluids that resulted in the enrichment of SiO2. Multiple fluid exposures are evident, and the chemistry and mineralogy data indicate at least two aqueous episodes may have occurred under acidic conditions.
    Schlagwort(e): Lunar and Planetary Science and Exploration
    Materialart: JSC-CN-35221 , Lunar and Planetary Science Conference; Mar 21, 2016 - Mar 25, 2016; The Woodlands, TX; United States
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  • 12
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    Diagenesis in the Murray Formation, Gale Crater, Mars (2016)
    In:  CASI
    Details
    Publikationsdatum: 2019-07-13
    Beschreibung: The Mars Science Laboratory (MSL) Curiosity rover began investigating the rocks of Mt. Sharp in September 2014. The Murray formation is the lowermost unit, which is mostly comprised of finely laminated mudstones, suggesting these sediments were deposited in a lacustrine environment. It is important to characterize the geochemical and mineralogical trends throughout the Murray Fm to interpret the aqueous conditions of the ancient lake, the sources of the lake sediments, and post-depositional alteration processes. Four samples have been drilled from the Murray Fm so far: Confidence Hills, Mojave 2, and Telegraph Peak were collected from the Pahrump Hills member - the basal portion of the Murray Fm, and Buckskin was collected in the Marias Pass region (Fig. 1). The drill fines were delivered to the instruments inside the rover, including the CheMin instrument, a combination X-ray diffractometer and X-ray fluorescence spectrometer. Rietveld refinements and FULLPAT analyses of 1D CheMin XRD patterns were performed to determine quantitative abundances of minerals and amor-phous phases and the unit cell parameters of minerals present in abundances greater than 4-5 wt.%.
    Schlagwort(e): Lunar and Planetary Science and Exploration
    Materialart: JSC-CN-35225 , Lunar and Planetary Science Conference; Mar 21, 2016 - Mar 25, 2016; The Woodlands, TX; United States
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  • 13
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    Mineralogy of the Pahrump Hills Region, Gale Crater, Mars (2015)
    In:  CASI
    Details
    Publikationsdatum: 2019-07-19
    Beschreibung: The Pahrump Hills region of Gale crater is a approximately 12 millimeter thick section of sedimentary rocks in the Murray formation, interpreted as the basal geological unit of Mount Sharp. The Mars Science Laboratory, Curiosity, arrived at the Pahrump Hills in September, 2014, and performed a detailed six-month investigation of the sedimentary structures, geochemistry, and mineralogy of the area. During the campaign, Curiosity drilled and delivered three rock samples to its internal instruments, including the CheMin XRD/XRF. The three targets, Confidence Hills, Mojave 2, and Telegraph Peak, contain variable amounts of plagioclase, pyroxene, iron oxides, jarosite, phyllosilicates, and X-ray amorphous material. Hematite was predicted at the base of Mount Sharp from orbital visible/near-IR spectroscopy, and CheMin confirmed this detection. The presence of jarosite throughout Pahrump Hills suggests the sediments experienced acid-sulfate alteration, either in-situ or within the source region of the sediments. This acidic leaching environment is in stark contrast to the environment preserved within the Sheepbed mudstone on the plains of Gale crater. The minerals within Sheepbed, including Fe-saponite, indicate these sediments were deposited in a shallow lake with circumneutral pH that may have been habitable.
    Schlagwort(e): Lunar and Planetary Science and Exploration
    Materialart: JSC-CN-33260 , 2015 Goldschmidt Conference; Aug 16, 2015 - Aug 21, 2015; Prague; Czechoslovakia
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  • 14
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    Aerogel as a Sample Collector and Sample Mount for Transmission XRD Analysis (2001)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-07-17
    Beschreibung: Silica aerogel can be used for dust collection and in situ X-ray analysis. Aerogels can be less absorbing than Be, and it is feasible to obtain X-ray transmission factors 〉50% using typical aerogels together with a 100-micrometer Be backing foil. Additional information is contained in the original extended abstract.
    Schlagwort(e): Lunar and Planetary Science and Exploration
    Materialart: Lunar and Planetary Science XXXII; LPI-Contrib-1080
    Format: text
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  • 15
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    The Amorphous Composition of Three Mudstone Samples from Gale Crater: Implications for Weathering and Diagenetic Processes on Mars (2017)
    In:  CASI
    Details
    Publikationsdatum: 2019-07-19
    Beschreibung: The Mars Science Laboratory rover, Curiosity, is exploring the lowermost formation of Gale crater's central mound. Within this formation, three samples named Marimba, Quela, and Sebina have been analyzed by the CheMin X-ray diffractometer and the Alpha Particle X-ray Spectrometer (APXS) to determine mineralogy and bulk elemental chemistry, respectively. Marimba and Quela were also analyzed by the SAM (Sample Analysis at Mars) instrument to characterize the type and abundance of volatile phases detected in evolved gas analyses (EGA). CheMin data show similar proportions of plagioclase, hematite, and Ca-sulfates along with a mixture of di- and trioctahedral smectites at abundances of approximately 28, approximately 16, and approximately 18 wt% for Marimba, Quela, and Sebina. Approximately 50 wt% of each mudstone is comprised of X-ray amorphous and trace crystalline phases present below the CheMin detection limit (approximately 1 wt%). APXS measurements reveal a distinct bulk elemental chemistry that cannot be attributed to the clay mineral variation alone indicating a variable amorphous phase assemblage exists among the three mudstones. To explore the amorphous component, the calculated amorphous composition and SAM EGA results are used to identify amorphous phases unique to each mudstone. For example, the amorphous fraction of Marimba has twice the FeO wt% compared to Quela and Sebina yet, SAM EGA data show no evidence for Fe-sulfates. These data imply that Fe must reside in alternate Fe-bearing amorphous phases (e.g., nanophase iron oxides, ferrihydrite, etc.). Constraining the composition, abundances, and proposed identity of the amorphous fraction provides an opportunity to speculate on the past physical, chemical, and/or diagenetic processes which produced such phases in addition to sediment sources, lake chemistry, and the broader geologic history of Gale crater.
    Schlagwort(e): Lunar and Planetary Science and Exploration
    Materialart: JSC-CN-40602 , Geological Society of America (GSA) 2017 Annual Meeting; Oct 22, 2017 - Oct 25, 2017; Seattle, WA; United States
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  • 16
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    Amorphous Phase Characterization Through X-Ray Diffraction Profile Modeling: Implications for Amorphous Phases in Gale Crater Rocks and Soils (2018)
    In:  CASI
    Details
    Publikationsdatum: 2019-08-13
    Beschreibung: The CheMin X-ray diffraction instrument on the Mars Science Laboratory rover has analyzed 18 rock and soil samples in Gale crater. Diffraction data allow for the identification of major crystalline phases based on the positions and intensities of well-defined peaks and also provides information regarding amorphous and poorly-ordered materials based on the shape and positions of broad scattering humps. The combination of diffraction data, elemental chemistry from APXS (Alpha Particle X-ray Spectrometer) and evolved gas analyses (EGA) from SAM (Sample Analysis at Mars) help constrain possible amorphous materials present in each sample (e.g., glass, opal, iron oxides, sulfates) but are model dependent. We present a novel method to characterize amorphous material in diffraction data and, through this approach, aim to characterize the phases collectively producing the amorphous profiles in CheMin diffraction data. This method may be applied to any diffraction data from samples containing X-ray amorphous materials, not just CheMin datasets, but we re-strict our discussion to Martian-relevant amorphous phases and diffraction data measured by CheMin or CheMin-like instruments.
    Schlagwort(e): Lunar and Planetary Science and Exploration
    Materialart: JSC-E-DAA-TN53573 , LPI Contrib. No. 2083 , Lunar and Planetary Science Conference; Mar 19, 2018 - Mar 23, 2018; The Woodlands, Tx; United States
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  • 17
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    The Mineralogical Record of Ancient Fluvio-Lacustrine Environments in Gale Crater as Measured by the MSL CheMin Instrument (2019)
    In:  CASI
    Details
    Publikationsdatum: 2019-08-21
    Beschreibung: The Mars Science Laboratory Curiosity rover landed in Gale crater in August 2012 to investigate early Hesperian-aged sedimentary rocks on the lower slopes of Aeolis Mons (i.e., Mount Sharp) that show variations in phyllosilicates, hematite, and sulfates from orbital reflectance spectroscopy, suggesting changes in ancient aqueous environments. During the Eighth International Conference on Mars in July 2014, Curiosity was still traversing the Bradbury group on the plains of Gale crater (Aeolis Palus) and had only analyzed four samples in its internal laboratories. Soon after Mars 8, Curiosity began its investigation of Mount Sharp and has since driven through ~350 m of vertical stratigraphy, the majority of which is part of the Murray formation. The Murray fm is comprised primarily of laminated mudstone with occasional sandstone and heterolithic facies and represents a long-lived fluvio-lacustrine environment. Curiosity has analyzed 13 drilled rock samples from the Murray formation and 4 from the ancient eolian Stimson fm with the Chemistry and Mineralogy (CheMin) instrument. Here, we discuss the mineralogy of all fluvio-lacustrine samples analyzed to date and what these results tell us about sources of the sediments, aqueous environments, and habitability of ancient Gale crater.
    Schlagwort(e): Lunar and Planetary Science and Exploration
    Materialart: JSC-E-DAA-TN72364 , International Conference on Mars; Jul 22, 2019 - Jul 25, 2019; Pasadena, CA; United States
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  • 18
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    Mineralogy by X-ray Diffraction on Mars: The Chemin Instrument on Mars Science Laboratory (2014)
    In:  CASI
    Details
    Publikationsdatum: 2019-08-13
    Beschreibung: To obtain detailed mineralogy information, the Mars Science Laboratory rover Curiosity carries CheMin, the first X-ray diffraction (XRD) instrument used on a planet other than Earth. CheMin has provided the first in situ XRD analyses of full phase assemblages on another planet.
    Schlagwort(e): Lunar and Planetary Science and Exploration
    Materialart: JSC-CN-31342 , International Conference on Mars; Jul 14, 2014 - Jul 18, 2014; Pasadena, CA; United States
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  • 19
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    Astrobiological Significance of Definitive Mineralogical Analysis of Martian Surface Samples Using the CheMin XRD/XRF Instrument (2004)
    In:  CASI
    Details
    Publikationsdatum: 2019-07-13
    Beschreibung: The search for evidence of habitability, or of extant or extinct life on Mars, will initially be a search for evidence of past or present conditions supportive of life. The three key requirements for the emergence of life are thought to be liquid water; a suitable energy source; and chemical building blocks. CheMin is a miniaturized XRD/XRF (X-Ray diffraction / X-ray fluorescence) instrument which has been developed for definitive mineralogic analysis of soils and rocks on the Martian surface. The CheMin instrument can provide information that is highly relevant to each of these habitability requirements as summarized below.
    Schlagwort(e): Man/System Technology and Life Support
    Materialart: Mars Astrobiology Science and Technology Workshop; Sep 07, 2004 - Sep 12, 2004; Washington, DC; United States
    Format: text
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  • 20
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    Characterizing the Phyllosilicate Component of the Sheepbed Mudstone in Gale Crater, Mars Using Laboratory XRD and EGA (2014)
    In:  CASI
    Details
    Publikationsdatum: 2019-07-13
    Beschreibung: The Curiosity rover investigated the mineralogy of the Sheepbed mudstone member of the Yellowknife Bay formation in Gale crater. Data from the Chemistry and Mineralogy (CheMin) X-ray diffractometer (XRD) helped identify phyllosilicates in the two drilled samples, John Klein and Cumberland. These patterns showed peaks at low angles, consistent with (001) peaks in 2:1 swelling phyllosilicates [1]. Evolved gas analyses (EGA) by the Sample Analysis at Mars (SAM) instrument of these samples confirmed the presence of phyllosilicates through the release of H2O at high temperatures, consistent with dehydroxylation of octahedral OH in phyllosilicates [2]. CheMin data for the phyllosilicates at John Klein and Cumberland show that they are structurally similar in that their (02l) peaks are near 22.5 deg 2theta, suggesting both samples contain trioctahedral 2:1 phyllosilicates [1]. However, the positions of the (001) peaks differ: the phyllosilicate at John Klein has its (001) peak at 10 Angstroms, whereas the phyllosilicate at Cumberland has an (001) peak at 14 Angstroms. Such differences in (001) dspacings can be ascribed to the type of cation in the interlayer site [3]. For example, large monovalent cations (e.g., K(+)) have low hydration energies and readily lose their H2O of hydration, whereas small divalent cations (e.g., Mg(2+)) have high energies of hydration and retain H2O in the phyllosilicate interlayers [3,4]. The goal of this study is to determine whether differences in the interlayer cation composition can explain the CheMin data from John Klein and Cumberland and to use this knowledge to better understand phyllosilicate formation mechanisms.
    Schlagwort(e): Lunar and Planetary Science and Exploration
    Materialart: JSC-CN-30371 , Lunar and Planetary Science Conference; Mar 17, 2014 - Mar 21, 2014; The Woodlands, TX; United States
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