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Laser-Induced Breakdown Spectroscopy (LIBS) characterization of granular soils: Implications for ChemCam analyses at Gale crater, Mars

David, G. and Meslin, P.-Y. and Dehouck, E. and Gasnault, O. and Cousin, A. and Forni, O. and Berger, G. and Lasue, J. and Pinet, P. and Wiens, R. C. and Maurice, S. and Fronton, J.-F. and Rapin, W. (2021) Laser-Induced Breakdown Spectroscopy (LIBS) characterization of granular soils: Implications for ChemCam analyses at Gale crater, Mars. Icarus, 365 . Art. No. 114481. ISSN 0019-1035. doi:10.1016/j.icarus.2021.114481.

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The Curiosity rover has been characterizing mineralogical and chemical compositions of Gale crater soils on Mars since 2012. Given its sub-millimeter scale of analysis, the ChemCam instrument is well suited to study the composition of soil constituents. However, the interpretation of LIBS data on soils in the martian environment is complicated by the large diversity of particle sizes (from dust to sand), combined with the unknown physical arrangement of their mineral constituents (i.e., the type of grain mixtures). For example, martian soils contain a significant amount of X-ray amorphous materials whose physical form remains unclear. In this study, we reproduced martian soil analyses in the laboratory to understand how the LIBS technique can provide specific insights into the physical and chemical properties of granular soils. For this purpose, different types of samples were studied with various ranges of grain sizes, mimicking two possible mixtures that may occur in martian soils: mechanical mixtures of two populations of grains made of distinct chemical compositions; and material forming a compositionally distinct coating at the surface of grains. Our results, also supported by in situ ChemCam data, demonstrate that both the sizes and the type of mixture of soil particles have a strong influence on the LIBS measurement. For mechanical mixtures of two populations of grains larger than 125–250 μm, the scatter of the data provides information about the chemical composition of the end-members. On the other hand, the chemistry recorded by LIBS for grains with surface coatings is fully dominated by the outer material for grains smaller than 500 μm in diameter. This is due to the small penetration depth of the laser (~0.3–1.5 μm per shot), combined with the ejection of small grains at each shot, which leads to a constant replenishment of fresh material. This experimental work will thus improve our understanding of martian soils analyzed by ChemCam, and more broadly, will benefit LIBS studies of granular materials.

Item Type:Article
Related URLs:
URLURL TypeDescription ItemNASA Planetary Data System
David, G.0000-0002-2719-1586
Meslin, P.-Y.0000-0002-0703-3951
Dehouck, E.0000-0002-1368-4494
Gasnault, O.0000-0002-6979-9012
Cousin, A.0000-0001-7823-7794
Forni, O.0000-0001-6772-9689
Berger, G.0000-0003-4806-5594
Lasue, J.0000-0001-9082-4457
Pinet, P.0000-0002-1933-5631
Wiens, R. C.0000-0002-3409-7344
Maurice, S.0000-0001-5702-8002
Rapin, W.0000-0003-4660-8006
Additional Information:© 2021 Elsevier Inc. Received 3 March 2020, Revised 19 February 2021, Accepted 15 April 2021, Available online 21 April 2021. We are grateful to the MSL science and engineering teams who operate the rover. ChemCam instrument development, operations and science support in the US were funded by the NASA Mars Exploration Program. ChemCam and MSL are supported in France by the Centre National d'Etudes Spatiales (CNES). All the ChemCam data used in this paper are released and can be found on the Planetary Data System ( Laboratory LIBS experiments were conducted at Institut de Recherche en Astrophysique et Planétologie (IRAP) in Toulouse, France. We acknowledge the Agence Nationale de la Recherche (ANR) under the program ANR-16-CE31-0012 entitled “Mars-PRIME” for helping collaborative efforts and support for this study. Declaration of Competing Interest: None.
Funding AgencyGrant Number
Centre National d'Études Spatiales (CNES)UNSPECIFIED
Agence Nationale pour la Recherche (ANR)ANR-16-CE31-0012
Subject Keywords:Martian soil; Laser-Induced-Breakdown spectroscopy; Granular media; Planetary pedology; Independent Component analysis
Record Number:CaltechAUTHORS:20210715-201635481
Persistent URL:
Official Citation:G. David, P.-Y. Meslin, E. Dehouck, O. Gasnault, A. Cousin, O. Forni, G. Berger, J. Lasue, P. Pinet, R.C. Wiens, S. Maurice, J.-F. Fronton, W. Rapin, Laser-Induced Breakdown Spectroscopy (LIBS) characterization of granular soils: Implications for ChemCam analyses at Gale crater, Mars, Icarus, Volume 365, 2021, 114481, ISSN 0019-1035, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:109853
Deposited By: Tony Diaz
Deposited On:15 Jul 2021 20:37
Last Modified:15 Jul 2021 20:37

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