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Compositional Variations in Sands of the Bagnold Dunes, Gale Crater, Mars, from Visible-Shortwave Infrared Spectroscopy and Comparison to Ground-Truth from the Curiosity Rover

Lapotre, M. G. A. and Ehlmann, B. L. and Minson, S. E. and Arvidson, R. E. and Ayoub, F. and Fraeman, A. A. and Ewing, R. C. and Bridges, N. T. (2017) Compositional Variations in Sands of the Bagnold Dunes, Gale Crater, Mars, from Visible-Shortwave Infrared Spectroscopy and Comparison to Ground-Truth from the Curiosity Rover. Journal of Geophysical Research. Planets, 122 (12). pp. 2489-2509. ISSN 2169-9097.

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During its ascent up Mount Sharp, the Mars Science Laboratory Curiosity rover traversed the Bagnold Dune Field. We model sand modal mineralogy and grain size at four locations near the rover traverse, using orbital shortwave infrared single-scattering albedo spectra and a Markov chain Monte Carlo implementation of Hapke's radiative transfer theory to fully constrain uncertainties and permitted solutions. These predictions, evaluated against in situ measurements at one site from the Curiosity rover, show that X-ray diffraction-measured mineralogy of the basaltic sands is within the 95% confidence interval of model predictions. However, predictions are relatively insensitive to grain size and are nonunique, especially when modeling the composition of minerals with solid solutions. We find an overall basaltic mineralogy and show subtle spatial variations in composition in and around the Bagnold Dunes, consistent with a mafic enrichment of sands with cumulative aeolian-transport distance by sorting of olivine, pyroxene, and plagioclase grains. Furthermore, the large variations in Fe and Mg abundances (~20 wt %) at the Bagnold Dunes suggest that compositional variability may be enhanced by local mixing of well-sorted sand with proximal sand sources. Our estimates demonstrate a method for orbital quantification of composition with rigorous uncertainty determination and provide key constraints for interpreting in situ measurements of compositional variability within Martian aeolian sandstones.

Item Type:Article
Related URLs:
URLURL TypeDescription
Lapotre, M. G. A.0000-0001-9941-1552
Ehlmann, B. L.0000-0002-2745-3240
Minson, S. E.0000-0001-5869-3477
Arvidson, R. E.0000-0002-2854-0362
Ayoub, F.0000-0002-7389-8400
Fraeman, A. A.0000-0003-4017-5158
Ewing, R. C.0000-0001-6337-610X
Bridges, N. T.0000-0002-6790-6793
Additional Information:© 2017 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 13 JUL 2016; Accepted 26 JAN 2017; Accepted article online 14 APR 2017; Published online 7 DEC 2017. We are indebted to the MSL Engineering and Science and Operations teams for collecting the in situ data, and Chi Ma of Caltech for compositional measurements of our basaltic-glass sample. We thank Alan Delamere and Rodney Heyd for their guidance on the use of HiRISE band ratios, and Christopher Edwards for providing us with the seamless color HiRISE mosaic shown in Figure 1a. Thanks to the CRISM Operations team for collecting the data set and to the CheMin team for rapid sharing of their results from MSL analyses on Mars. We also thank Tim Titus and Jessica Ball of the U.S. Geological Survey for informal reviews of our manuscript and Ralph Milliken and an anonymous reviewer for thorough reviews that improved our original manuscript. A portion of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. M.G.A.L. was partially funded by a NASA Earth and Space Science Fellowship (12-PLANET12F-0071) and from a MSL participating Scientist Program grant to B.L.E. A.A.F. also acknowledges funding from a MSL Participating Scientist Program grant. Data presented in this paper is or will be posted on the Planetary Data System (PDS).
Group:Astronomy Department
Funding AgencyGrant Number
Mars Science Laboratory (MSL)UNSPECIFIED
Subject Keywords:CRISM; spectroscopy; wind sorting; Mars; Bagnold Dunes; MCMC
Issue or Number:12
Record Number:CaltechAUTHORS:20170417-130229510
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Official Citation:Lapotre, M. G. A., B. L. Ehlmann, S. E. Minson, R. E. Arvidson, F. Ayoub, A. A. Fraeman, R. C. Ewing, and N. T. Bridges (2017), Compositional variations in sands of the Bagnold Dunes, Gale crater, Mars, from visible-shortwave infrared spectroscopy and comparison with ground truth from the Curiosity rover, J. Geophys. Res. Planets, 122, 2489–2509, doi:10.1002/2016JE005133
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:76603
Deposited By: Tony Diaz
Deposited On:24 Apr 2017 17:15
Last Modified:20 Apr 2020 08:47

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