Surface topographic impact of subglacial water beneath Mars' south polar ice cap

• Published in: Nature Astronomy
• Main Authors: Arnold, N., Butcher, F., Conway, S., Gallagher, C., Balme, M.
• Other Authors: Scott Polar Research Institute, University of Cambridge UK (CAM), Department of Geography Sheffield, University of Sheffield Sheffield, Laboratoire de Planétologie et Géosciences UMR_C 6112 (LPG), Le Mans Université (UM)-Université d'Angers (UA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Nantes université - UFR des Sciences et des Techniques (Nantes univ - UFR ST), Nantes Université - pôle Sciences et technologie, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)-Nantes Université - pôle Sciences et technologie, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ), University College Dublin Dublin (UCD), The Open University Milton Keynes (OU)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2022
• Subjects: [SDU.STU.PL]Sciences of the Universe [physics]/Earth Sciences/Planetology; Ice cap
• Online Access: https://insu.hal.science/insu-03813438; https://insu.hal.science/insu-03813438/document; https://insu.hal.science/insu-03813438/file/Arnold_etal_NatAstro_2022_HAL.pdf; https://doi.org/10.1038/s41550-022-01782-0

International audience Bright radar reflections observed in the Ultimi Scopuli region of Mars’ south polar layered deposits1,2,3 by the Mars Advanced Radar for Subsurface and Ionosphere Sounding instrument have been interpreted as the signature of areas of subglacial water beneath it. However, other studies put forward alternative explanations, which do not imply the presence of liquid water4,5,6. Here we shed light on the issue by looking at the surface topography of the region. On Earth, reduced or absent basal friction, and consequent ice velocity changes, cause a distinct topographic signature over subglacial lakes7. Using Mars Orbiter Laser Altimeter data8, we identify and characterize an anomaly in the surface topography of the south polar layered deposits overlying the area of the putative lakes, similar to those found above terrestrial subglacial lakes of similar size. Ice flow model results suggest that comparable topographic anomalies form within 0.5–1.5 Myr with locally elevated geothermal heating9 or 2–5 Myr without elevated geothermal heating2. These findings offer independent support for the presence of basal water beneath Ultimi Scopuli and suggest that surface topography could supplement radar returns to help identify other potential subglacial water bodies