Characterization of hydrogen in basaltic materials with laser‐induced breakdown spectroscopy (LIBS) for application to MSL ChemCam data
Abstract
The Mars Science Laboratory rover, Curiosity, is equipped with ChemCam, a laser‐induced breakdown spectroscopy (LIBS) instrument, to determine the elemental composition of nearby targets quickly and remotely. We use a laboratory sample set including prepared mixtures of basalt with systematic variation in hydrated mineral content and compositionally well‐characterized, altered basaltic volcanic rocks to measure hydrogen by characterizing the H‐alpha emission line in LIBS spectra under Martian environmental conditions. The H contents of all samples were independently measured using thermogravimetric analysis. We found that H peak area increases with weight percent H for our laboratory mixtures with basaltic matrices. The increase is linear with weight percent H in the mixtures with structurally bound H up to about 1.25 wt.% H and then steepens for higher H‐content samples, a nonlinear trend not previously reported but potentially important for characterizing high water content materials. To compensate for instrument, environmental, and target matrix‐related effects on quantification of H content from the LIBS signal, we examined multiple normalization methods. The best performing methods utilize O 778‐ and C 248‐nm emission lines. The methods return comparable results when applied to ChemCam data of H‐bearing materials on Mars. The calibration and normalization methods tested here will aid in investigations of H by LIBS on Mars with ChemCam and SuperCam. Further laboratory work will aid quantification across different physical matrices and heterogeneous textures because of differences we observed in H in pelletized and natural rock samples of the same composition.
Additional Information
© 2018 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 15 OCT 2017; Accepted 1 JUL 2018; Accepted article online 10 JUL 2018; Published online 11 AUG 2018. We thank Mark Davis, from Caltech Chemical Engineering, and his lab group, in particular Kramer Brand and Marat Orazov, for assisting us in using their thermogravimetric analysis instrument. The authors gratefully recognize the work of Rhonda McInroy in collecting LIBS measurements at LANL. We also thank Agnes Cousin for helpful discussions. Thanks to George Rossman for help in sample selection, acquisition, and preparation. The work at Caltech was supported by a NASA MSL Participating Scientist Program grant to B. L. Ehlmann and a National Science Foundation Graduate Research Fellowship grant DGE‐1144469 to N. H. Thomas. Work at LANL and the instrument facilities were supported by the NASA MSL project. O. F., P.‐Y. M., J. L., O. G., and S. M. participation to MSL and ChemCam is supported by CNES. We would also like to acknowledge the assistance of the editors and two anonymous reviewers in improving this manuscript. All ChemCam data used in this paper are publicly available on the PDS. Some of our supporting data have been previously published in Anderson et al. (2017); all spectra are included as supporting information.Attached Files
Published - Thomas_et_al-2018-Journal_of_Geophysical_Research__Planets.pdf
Supplemental Material - jgre20980-sup-0001-2017je005467_s01.pdf
Supplemental Material - jgre20980-sup-0002-2017je005467_s01.docx
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Additional details
- Eprint ID
- 87677
- DOI
- 10.1029/2017JE005467
- Resolver ID
- CaltechAUTHORS:20180710-072709015
- NASA
- NSF Graduate Research Fellowship
- DGE-1144469
- Centre National d'Études Spatiales (CNES)
- Created
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2018-07-10Created from EPrint's datestamp field
- Updated
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2021-11-15Created from EPrint's last_modified field
- Caltech groups
- Astronomy Department, Division of Geological and Planetary Sciences