Assessing the detectability of Europa’s eutectic zone using radar sounding

Abstract

Radar sounding is a geophysical method capable of directly imaging subsurface interfaces within the ice shell of the icy moons, including Jupiter’s moon, Europa. For this reason, both the European Space Agency’s JUpiter ICy moons Explorer and the National Aeronautics and Space Administration’s Europa Clipper missions have ice penetrating radar sounders in their payloads. In addition to the ice–ocean interface and shallow water lenses, liquid water in the eutectic zone of Europa’s ice shell could also be a target for radar sounding investigations. However, the wide range of possible configurations for eutectic-zone water bodies and the overlying ice make their absolute echo strength difficult to predict. To address this challenge, we employ a suite of simple water configurations and scattering models to bound the eutectic detectability in terms of its effective reflectivity. We find that, for each configuration, a range of physically plausible eutectic parameters exist that could produce detectable echoes, with effective reflectivity values greater than -50 dB at HF or VHF frequencies.