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Degradation at the InSight Landing Site, Homestead Hollow, Mars: Constraints from Rock Heights and Shapes

Grant, J. A. and Wilson, S. A. and Golombek, M. and Trussell, A. and Warner, N. H. and Williams, N. and Weitz, C. M. and Gengl, H. and Deen, R. (2021) Degradation at the InSight Landing Site, Homestead Hollow, Mars: Constraints from Rock Heights and Shapes. . (Unpublished)

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Rock heights and three-dimensional shapes around the InSight lander in Homestead hollow, Mars, provide new constraints on modification of the degraded 27 m in diameter impact crater and are a tool for characterizing degradation on regolith-covered lava plains on Mars. Decreasing average rock height and increasing percentage of fragments where height comprises the short axis from outside to within the hollow supports significant ejecta deflation accompanied by infilling of the interior. Rock relief outside the hollow is compared with expectations of pristine ejecta thickness and indicates up to ~40 cm of near-rim early deflation (decreasing to a few cm out to one diameter) can account for the predicted eolian component of infilling and that other eolian infilling sources are not required. Scattered rocks in the hollow are ejecta from subsequent nearby impacts and their mostly buried expression is consistent with subsequent long-term degradation estimated to be 10⁻⁴ m/Myr. Basalt rock shapes at InSight are likely similar to basalt rock shapes on Earth, but appear more platy, bladed, and elongate in a triangular form factor plot and more discoidal and bladed in an axes ratio plot. Nevertheless, addition of 10 cm to near rim rock heights to account for continued partial embedding in ejecta would result in rock shapes quite similar to terrestrial rocks. Consistency between degradation estimates based on current rock relief and rock shape after accounting for partial embedding in ejecta indicates up to ~30-40 cm early (~0.1 Ga) near-rim deflation was followed by much lesser long-term degradation.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper
Grant, J. A.0000-0001-8276-1281
Wilson, S. A.0000-0001-8872-8546
Golombek, M.0000-0002-1928-2293
Warner, N. H.0000-0002-7615-2524
Williams, N.0000-0003-0602-484X
Weitz, C. M.0000-0002-4646-0825
Gengl, H.0000-0001-7224-2437
Deen, R.0000-0002-5693-641X
Additional Information:The copyright holder for this preprint is the author/funder. Published Online: Tue, 3 Aug 2021. We thank the Jet Propulsion Laboratory, Lockheed Martin Space Systems, CNES, and other partner institutions that built and operate the InSight lander. A portion of the work was supported by the InSight Project at the Jet Propulsion Laboratory, California Institute of Technology, and under grants 80NSSC18K1625 to J. Grant (includes S. Wilson and C. Weitz) and 80NSSC18K1624 to N. Warner from the National Aeronautics and Space Administration. The data used are listed in the figures and (or) repository at Smithsonian. website (doi:10.25573/data.14924253) and can be viewed at: This is InSight Contribution Number 229.
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Subject Keywords:Geology
Record Number:CaltechAUTHORS:20210823-182645874
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:110384
Deposited By: Tony Diaz
Deposited On:24 Aug 2021 18:49
Last Modified:16 Nov 2021 19:40

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