Organic molecules in the Sheepbed Mudstone, Gale Crater, Mars

C. Freissinet, D. P. Glavin, P. R. Mahaffy, K. E. Miller, J. L. Eigenbrode, R. E. Summons, A. E. Brunner, A. Buch, C. Szopa, P.D. Archer Jr, H. B. Franz, S. K. Atreya, W. B. Brinckerhoff, M. Cabane, P. Coll, P. G. Conrad, D. J. Des Marais, J. P. Dworkin, A. G. Fairén, P. FrançoisJ. P. Grotzinger, S. Kashyap, I. L. ten Kate, L. A. Leshin, C. A. Malespin, M. G. Martin, J. F. Martin-Torres, A. C. McAdam, D. W. Ming, R. Navarro-González, A. A. Pavlov, B. D. Prats, S. W. Squyres, A. Steele, J. C. Stern, D. Y. Sumner, B. Sutter, M. -P. Zorzano, MSL Science Team

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The Sample Analysis at Mars (SAM) instrument [Mahaffy et al., 2012] onboard the Mars Science Laboratory (MSL) 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 [Grotzinger et al., 2012]. 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 [Summons et al., 2011]. Here we report the definitive identification of chlorobenzene (150–300 parts per billion by weight (ppbw)) and C2 to C4 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.
Original languageEnglish
Pages (from-to)495-514
Number of pages20
JournalJournal of Geophysical Research - Planets
Issue number3
Early online date21 Mar 2015
Publication statusPublished - Mar 2015

Bibliographical note

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 (


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