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Multiple subglacial water bodies below the south pole of Mars unveiled by new MARSIS data


The detection of liquid water by the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) at the base of the south polar layered deposits in Ultimi Scopuli has reinvigorated the debate about the origin and stability of liquid water under present-day Martian conditions. To establish the extent of subglacial water in this region, we acquired new data, achieving extended radar coverage over the study area. Here, we present and discuss the results obtained by a new method of analysis of the complete MARSIS dataset, based on signal processing procedures usually applied to terrestrial polar ice sheets. Our results strengthen the claim of the detection of a liquid water body at Ultimi Scopuli and indicate the presence of other wet areas nearby. We suggest that the waters are hypersaline perchlorate brines, known to form at Martian polar regions and thought to survive for an extended period of time on a geological scale at below-eutectic temperatures.

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Fig. 1: Ultimi Scopuli Mars Orbiter Laser Altimeter topographic map and location of MARSIS profiles collected in the region.
Fig. 2: SPLD thickness.
Fig. 3: Data collected outside and inside the bright area.
Fig. 4: Spatial distribution of normalized basal reflectivity and acuity.
Fig. 5: Relative dielectric permittivity map computed by inverting the radar data considering all regions where the number of samples is larger than 100.

Data availability

Data reported in this paper are available through the Zenodo research data repository (

Code availability

The code used to produce the figures and numerical results stated in the text is available from the corresponding author on reasonable request.


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This work was supported by the Italian Space Agency (ASI) through contract ASI-INAF 2019–21-HH.0 and, in part, by EU H2020 agreement 776276 Planmap. MARSIS is operating onboard the European Space Agency spacecraft Mars Express. We would like to thank S. E. Beaubien for careful proofreading of the manuscript and improvement of the English.

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S.E.L. and E.P. designed the research, developed the methodology, performed data analysis and wrote the manuscript. G.C., L.G. and A.P.R. developed the geological context and contributed to writing relevant sections of the manuscript. G.C. and E.P. developed and wrote the geochemical discussion. E.M. and B.C. performed data analysis, contributed text and figures, and co-wrote the manuscript. A.C. conducted data pre-processing. F.S. contributed to inverse electromagnetic modelling, to the interpretation of the geophysical data and to writing of the manuscript. M.C. contributed to data acquisition and analysis and discussed ideas. F.D.P. contributed text and figures and discussed ideas. R.N. contributed to data acquisition and analysis. R.O. discussed ideas and co-wrote the manuscript. S.E.L., E.P., G.C., L.G., A.P.R., E.M., B.C., F.S. and R.O. edited and revised the manuscript.

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Correspondence to Elena Pettinelli.

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Lauro, S.E., Pettinelli, E., Caprarelli, G. et al. Multiple subglacial water bodies below the south pole of Mars unveiled by new MARSIS data. Nat Astron 5, 63–70 (2021).

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