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Published March 2015 | Published
Journal Article Open

Organic molecules in the Sheepbed Mudstone, Gale Crater, Mars

Abstract

The Sample Analysis at Mars (SAM) instrument on board the Mars Science Laboratory Curiosity rover is designed to conduct inorganic and organic chemical analyses of the atmosphere and the surface regolith and rocks to help evaluate the past and present habitability potential of Mars at Gale Crater. Central to this task is the development of an inventory of any organic molecules present to elucidate processes associated with their origin, diagenesis, concentration, and long-term preservation. This will guide the future search for biosignatures. Here we report the definitive identification of chlorobenzene (150–300 parts per billion by weight (ppbw)) and C_2 to C_4 dichloroalkanes (up to 70 ppbw) with the SAM gas chromatograph mass spectrometer (GCMS) and detection of chlorobenzene in the direct evolved gas analysis (EGA) mode, in multiple portions of the fines from the Cumberland drill hole in the Sheepbed mudstone at Yellowknife Bay. When combined with GCMS and EGA data from multiple scooped and drilled samples, blank runs, and supporting laboratory analog studies, the elevated levels of chlorobenzene and the dichloroalkanes cannot be solely explained by instrument background sources known to be present in SAM. We conclude that these chlorinated hydrocarbons are the reaction products of Martian chlorine and organic carbon derived from Martian sources (e.g., igneous, hydrothermal, atmospheric, or biological) or exogenous sources such as meteorites, comets, or interplanetary dust particles.

Additional Information

© 2015. The Authors. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made. Received 3 OCT 2014; Accepted 13 FEB 2015; Accepted article online 4 MAR 2015; Published online 21 MAR 2015. This work could not have been conducted without the continuous support of the SAM and MSL operations, engineering, and scientific teams. NASA provided support for the development and operation of SAM. SAM-GC was supported by funds from the French Space Agency (CNES). C.F. acknowledges the NPP program. C.F., D.P.G., K.E.M., J.L.E., R.E.S., J.P.D., and M.G.M. acknowledge support from the MSL Participating Scientist Program. Data from these SAM experiments are archived in the Planetary Data System (pds.nasa.gov).

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August 22, 2023
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