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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 Abarca, H. and Deen, R. (2022) Degradation at the InSight Landing Site, Homestead Hollow, Mars: Constraints From Rock Heights and Shapes. Earth and Space Science, 9 (2). Art. No. e2021EA001953. ISSN 2333-5084. doi:10.1029/2021EA001953.

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Rock shapes and heights around the InSight lander are examined to refine the degradation history of the 27 m-diameter Homestead hollow. Results document decreasing average exposed rock height and increasing percentage of rocks where height comprises the short axis from outside to within the hollow and support prior models of ejecta deflation accompanied by hollow infilling. We estimate 0.3 m of deflation at the current rim that is realistic compared to rock relief, original ejecta thickness, and predicted aeolian contributions to infilling. We also find that shapes of embayed basalt rocks outside the hollow appear platy, bladed, and elongate in a triangular form factor plot, and more discoidal and bladed in an axes ratio plot. By contrast, expected shapes based on terrestrial studies of basalt rocks are mostly compact, compact platy, compact bladed, compact elongated, platy, bladed, and elongate in triangular form factor plots, and equant with lesser, but significant disc- and blade-shaped rocks in axes ratio plots. We find addition of 10 cm to the heights of rocks near the hollow rim, to account for continued partial embedding in ejecta, yields the best match between observed and expected rock shapes. Exposure of small ejecta rocks in the hollow supports degradation rates of 10⁻⁴ m/Myr during most of hollow history. Results indicate that deflation from ejecta accompanied by downwind deposition in the hollow can account for the current degraded form of the crater. Our approach is a new tool for characterizing small crater degradation on regolith-covered lava plains on Mars.

Item Type:Article
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
Trussell, A.0000-0002-7113-8782
Warner, N. H.0000-0002-7615-2524
Williams, N.0000-0003-0602-484X
Weitz, C. M.0000-0002-4646-0825
Deen, R.0000-0002-5693-641X
Additional Information:© 2022 Smithsonian Institution and Jet Propulsion Laboratory. California Institute of Technology. Government sponsorship acknowledged. This article has been contributed to by US Government employees and their work is in the public domain in the USA. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes. Issue Online: 02 February 2022; Version of Record online: 02 February 2022; Accepted manuscript online: 05 January 2022; Manuscript accepted: 24 December 2021; Manuscript revised: 10 December 2021; Manuscript received: 07 August 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. This is InSight Contribution Number 229. Data Availability Statement: All data used in the paper is freely accessible at the link provided below in the data availability statement that follows. This is InSight Contribution Number 229. Data used in analyses of rocks at the InSight lander and described in the paper are included in three Microsoft 365 Excel files (and associated readme explanation Word file) and ArcGIS shape files (and associated readme explanation Word file, and orthophoto and DEM) that can be freely accessed and downloaded for viewing at Smithsonian. figshare:
Funding AgencyGrant Number
Subject Keywords:InSight; Degradation; Rock Height; Rock Shape; Geomorphic Processes; Geomorphic History
Issue or Number:2
Record Number:CaltechAUTHORS:20210823-182645874
Persistent URL:
Official Citation:Grant, J. A., Wilson, S. A., Golombek, M., Trussell, A., Warner, N. H., Williams, N., et al. (2022). Degradation at the InSight landing site, Homestead hollow, Mars: Constraints from rock heights and shapes. Earth and Space Science, 9, e2021EA001953.
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:08 Feb 2022 17:26

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