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  • 1
    Publication Date: 2013-06-01
    Description: Observations by the Mars Science Laboratory Mast Camera (Mastcam) in Gale crater reveal isolated outcrops of cemented pebbles (2 to 40 millimeters in diameter) and sand grains with textures typical of fluvial sedimentary conglomerates. Rounded pebbles in the conglomerates indicate substantial fluvial abrasion. ChemCam emission spectra at one outcrop show a predominantly feldspathic composition, consistent with minimal aqueous alteration of sediments. Sediment was mobilized in ancient water flows that likely exceeded the threshold conditions (depth 0.03 to 0.9 meter, average velocity 0.20 to 0.75 meter per second) required to transport the pebbles. Climate conditions at the time sediment was transported must have differed substantially from the cold, hyper-arid modern environment to permit aqueous flows across several kilometers.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Williams, R M E -- Grotzinger, J P -- Dietrich, W E -- Gupta, S -- Sumner, D Y -- Wiens, R C -- Mangold, N -- Malin, M C -- Edgett, K S -- Maurice, S -- Forni, O -- Gasnault, O -- Ollila, A -- Newsom, H E -- Dromart, G -- Palucis, M C -- Yingst, R A -- Anderson, R B -- Herkenhoff, K E -- Le Mouelic, S -- Goetz, W -- Madsen, M B -- Koefoed, A -- Jensen, J K -- Bridges, J C -- Schwenzer, S P -- Lewis, K W -- Stack, K M -- Rubin, D -- Kah, L C -- Bell, J F 3rd -- Farmer, J D -- Sullivan, R -- Van Beek, T -- Blaney, D L -- Pariser, O -- Deen, R G -- MSL Science Team -- New York, N.Y. -- Science. 2013 May 31;340(6136):1068-72. doi: 10.1126/science.1237317.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Planetary Science Institute, Tucson, AZ 85719, USA. williams@psi.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23723230" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2013-12-11
    Description: Sedimentary rocks examined by the Curiosity rover at Yellowknife Bay, Mars, were derived from sources that evolved from an approximately average martian crustal composition to one influenced by alkaline basalts. No evidence of chemical weathering is preserved, indicating arid, possibly cold, paleoclimates and rapid erosion and deposition. The absence of predicted geochemical variations indicates that magnetite and phyllosilicates formed by diagenesis under low-temperature, circumneutral pH, rock-dominated aqueous conditions. Analyses of diagenetic features (including concretions, raised ridges, and fractures) at high spatial resolution indicate that they are composed of iron- and halogen-rich components, magnesium-iron-chlorine-rich components, and hydrated calcium sulfates, respectively. Composition of a cross-cutting dike-like feature is consistent with sedimentary intrusion. The geochemistry of these sedimentary rocks provides further evidence for diverse depositional and diagenetic sedimentary environments during the early history of Mars.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉McLennan, S M -- Anderson, R B -- Bell, J F 3rd -- Bridges, J C -- Calef, F 3rd -- Campbell, J L -- Clark, B C -- Clegg, S -- Conrad, P -- Cousin, A -- Des Marais, D J -- Dromart, G -- Dyar, M D -- Edgar, L A -- Ehlmann, B L -- Fabre, C -- Forni, O -- Gasnault, O -- Gellert, R -- Gordon, S -- Grant, J A -- Grotzinger, J P -- Gupta, S -- Herkenhoff, K E -- Hurowitz, J A -- King, P L -- Le Mouelic, S -- Leshin, L A -- Leveille, R -- Lewis, K W -- Mangold, N -- Maurice, S -- Ming, D W -- Morris, R V -- Nachon, M -- Newsom, H E -- Ollila, A M -- Perrett, G M -- Rice, M S -- Schmidt, M E -- Schwenzer, S P -- Stack, K -- Stolper, E M -- Sumner, D Y -- Treiman, A H -- VanBommel, S -- Vaniman, D T -- Vasavada, A -- Wiens, R C -- Yingst, R A -- MSL Science Team -- New York, N.Y. -- Science. 2014 Jan 24;343(6169):1244734. doi: 10.1126/science.1244734. Epub 2013 Dec 9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Geosciences, State University of New York, Stony Brook, NY 11794, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24324274" target="_blank"〉PubMed〈/a〉
    Keywords: Bays ; Calcium Sulfate/analysis/chemistry ; Chlorine/analysis/chemistry ; *Exobiology ; Extraterrestrial Environment/*chemistry ; Ferrosoferric Oxide/analysis/chemistry ; Geologic Sediments/*chemistry ; Halogens/analysis/chemistry ; Hydrogen-Ion Concentration ; Iron/analysis/chemistry ; Magnesium/analysis/chemistry ; *Mars ; Silicates/analysis/chemistry ; Water/chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2014-12-18
    Description: Reports of plumes or patches of methane in the martian atmosphere that vary over monthly time scales have defied explanation to date. From in situ measurements made over a 20-month period by the tunable laser spectrometer of the Sample Analysis at Mars instrument suite on Curiosity at Gale crater, we report detection of background levels of atmospheric methane of mean value 0.69 +/- 0.25 parts per billion by volume (ppbv) at the 95% confidence interval (CI). This abundance is lower than model estimates of ultraviolet degradation of accreted interplanetary dust particles or carbonaceous chondrite material. Additionally, in four sequential measurements spanning a 60-sol period (where 1 sol is a martian day), we observed elevated levels of methane of 7.2 +/- 2.1 ppbv (95% CI), implying that Mars is episodically producing methane from an additional unknown source.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Webster, Christopher R -- Mahaffy, Paul R -- Atreya, Sushil K -- Flesch, Gregory J -- Mischna, Michael A -- Meslin, Pierre-Yves -- Farley, Kenneth A -- Conrad, Pamela G -- Christensen, Lance E -- Pavlov, Alexander A -- Martin-Torres, Javier -- Zorzano, Maria-Paz -- McConnochie, Timothy H -- Owen, Tobias -- Eigenbrode, Jennifer L -- Glavin, Daniel P -- Steele, Andrew -- Malespin, Charles A -- Archer, P Douglas Jr -- Sutter, Brad -- Coll, Patrice -- Freissinet, Caroline -- McKay, Christopher P -- Moores, John E -- Schwenzer, Susanne P -- Bridges, John C -- Navarro-Gonzalez, Rafael -- Gellert, Ralf -- Lemmon, Mark T -- MSL Science Team -- New York, N.Y. -- Science. 2015 Jan 23;347(6220):415-7. doi: 10.1126/science.1261713. Epub 2014 Dec 16.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA. chris.r.webster@jpl.nasa.gov. ; NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA. ; University of Michigan, Ann Arbor, MI 48109, USA. ; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA. ; Institut de Recherche en Astrophysique et Planetologie, UPS-OMP, CNRS, 31028 Toulouse, France. ; California Institute of Technology, Pasadena, CA 91125, USA. ; Instituto Andaluz de Ciencias de la Tierra [Consejo Superior de Investigaciones Cientificas (CSIC)-Universidad de Granada], Granada, Spain. Division of Space Technology, Lulea University of Technology, Kiruna, Sweden. ; Centro de Astrobiologia, Instituto Nacional de Tecnica Aeroespacial-CSIC, Madrid, Spain. ; Department of Astronomy, University of Maryland, College Park, MD 20742, USA. ; University of Hawaii, Honolulu, HI 96822, USA. ; Carnegie Institution of Washington, Washington, DC 20015, USA. ; Jacobs Technology, NASA Johnson Space Center, Houston, TX 77058, USA. ; Laboratoire Inter-Universitaires Des Systemes Atmospheriques (LISA), UMR CNRS 7583, Paris, France. ; NASA Ames Research Center, Mountain View, CA 94035, USA. ; York University, Toronto, Ontario M3J 1P3, Canada. ; The Open University, Milton Keynes MK7 6AA, UK. ; Space Research Centre, University of Leicester, Leicester LE1 7RH, UK. ; Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Mexico City 04510, Mexico. ; University of Guelph, Guelph, Ontario N1G 2W1, Canada. ; Texas A&M University, College Station, TX 77843, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25515120" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 4
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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