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Explaining Bright Radar Reflections Below The South Pole of Mars Without Liquid Water

Nature Astronomy volume 6, pages 1142–1146 (2022)Cite this article

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Matters Arising to this article was published on 09 January 2023

The Original Article was published on 28 September 2020

arising from: S. E. Lauro et al. Nature Astronomy https://doi.org/10.1038/s41550-020-1200-6 (2021).

The south polar layered deposit (SPLD) is a several-kilometre-thick formation of relatively pure water ice that takes its name from the ubiquitous layering visible in both optical imagery and radar sounding data1. Radar observations collected recently by the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) have revealed strong reflections at the base of the deposit that were initially interpreted as evidence for liquid water2,3,4. Although such a possibility is exciting, here we demonstrate that similar reflections can be generated as the natural result of thin layer interference, without invoking any liquid water or otherwise rare materials. This result, combined with other recent work, calls into question the likelihood of finding liquid water below the SPLD.

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Fig. 1: Schematic diagrams of the three simulated scenarios.
Fig. 2: Comparison between observed and simulated MARSIS echoes.
Fig. 3: Simulated normalized basal echo power as a function of layer thickness.

Data availability

MARSIS data is available through the ESA Planetary Science Archive as well as the NASA Planetary Data System. Superframe data is available through the Orosei et al.2 supplementary material.

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Acknowledgements

This work was funded in part by a NASA Mars Data Analysis grant awarded to D.E.L.

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  1. Cornell Center for Astrophysics and Space Science, Ithaca, NY, USA

    D. E. Lalich, A. G. Hayes & V. Poggiali

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  1. D. E. Lalich
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  2. A. G. Hayes
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  3. V. Poggiali
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Contributions

D.E.L. conceptualized the study, performed simulations, and prepared the manuscript. A.G.H. assisted with conceptualization, interpretation, and manuscript preparation. V.P. assisted with simulations, data analysis, and manuscript preparation.

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Correspondence to D. E. Lalich.

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Lalich, D.E., Hayes, A.G. & Poggiali, V. Explaining Bright Radar Reflections Below The South Pole of Mars Without Liquid Water. Nat Astron 6, 1142–1146 (2022). https://doi.org/10.1038/s41550-022-01775-z

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