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ChemCam activities and discoveries during the nominal mission of the Mars Science Laboratory in Gale crater, Mars

Maurice, S. and Ehlmann, B. L. (2016) ChemCam activities and discoveries during the nominal mission of the Mars Science Laboratory in Gale crater, Mars. Journal of Analytical Atomic Spectrometry, 31 (4). pp. 863-889. ISSN 0267-9477. doi:10.1039/c5ja00417a.

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At Gale crater, Mars, ChemCam acquired its first laser-induced breakdown spectroscopy (LIBS) target on Sol 13 of the landed portion of the mission (a Sol is a Mars day). Up to Sol 800, more than 188 000 LIBS spectra were acquired on more than 5800 points distributed over about 650 individual targets. We present a comprehensive review of ChemCam scientific accomplishments during that period, together with a focus on the lessons learned from the first use of LIBS in space. For data processing, we describe new tools that had to be developed to account for the uniqueness of Mars data. With regard to chemistry, we present a summary of the composition range measured on Mars for major-element oxides (SiO_2, TiO_2, Al_2O_3, FeO_T, MgO, CaO, Na_2O, K_2O) based on various multivariate models, with associated precisions. ChemCam also observed H, and the non-metallic elements C, O, P, and S, which are usually difficult to quantify with LIBS. F and Cl are observed through their molecular lines. We discuss the most relevant LIBS lines for detection of minor and trace elements (Li, Rb, Sr, Ba, Cr, Mn, Ni, and Zn). These results were obtained thanks to comprehensive ground reference datasets, which are set to mimic the expected mineralogy and chemistry on Mars. With regard to the first use of LIBS in space, we analyze and quantify, often for the first time, each of the advantages of using stand-off LIBS in space: no sample preparation, analysis within its petrological context, dust removal, sub-millimeter scale investigation, multi-point analysis, the ability to carry out statistical surveys and whole-rock analyses, and rapid data acquisition. We conclude with a discussion of ChemCam performance to survey the geochemistry of Mars, and its valuable support of decisions about selecting where and whether to make observations with more time and resource-intensive tools in the rover's instrument suite. In the end, we present a bird's-eye view of the many scientific results: discovery of felsic Noachian crust, first observation of hydrated soil, discovery of manganese-rich coatings and fracture fills indicating strong oxidation potential in Mars' early atmosphere, characterization of soils by grain size, and wide scale mapping of sedimentary strata, conglomerates, and diagenetic materials.

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Ehlmann, B. L.0000-0002-2745-3240
Additional Information:© 2016 The Royal Society of Chemistry. Received 19th October 2015; Accepted 16th February 2016; First published online 16 Feb 2016. This work was supported in France by the French Space Agency (CNES), the Centre National de la Recherche Scientifique (CNRS), and many institutes and universities across the country. Collaboration with colleagues in the US was funded by NASA’s Mars Program Office.
Funding AgencyGrant Number
Centre National d'Études Spatiales (CNES)UNSPECIFIED
Centre National de la Recherche Scientifique (CNRS)UNSPECIFIED
Issue or Number:4
Record Number:CaltechAUTHORS:20160902-074327948
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:70135
Deposited By: Tony Diaz
Deposited On:02 Sep 2016 18:40
Last Modified:11 Nov 2021 04:24

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