The Basal Detectability of an Ice-Covered Mars by MARSIS

The detection of anomalously strong relative basal reflectivity beneath the Martian South Polar Layered Deposits (SPLD) from the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) has led to hypotheses suggesting the presence of basal materials such as liquid water. Here, we propose a forward approach to assess whether such a high signal could be produced by a Martian terrain currently exposed at the surface without liquid water. We convert existing MARSIS surface reflectivity measurements into a basal reflectivity as if it were overlaid by an SPLD-like ice deposit. 0.3%-2% of the surface could produce basal reflections of magnitude similar to the SPLD measurements in the assumption of a 10% impure ice. An ice loss tangent > $ > $0.01 is required to prevent any of the current Martian surface from producing a bright SPLD-like basal reflection. The detected bright terrains are gathered within volcanic constructs of diverse geologic epoch.