The consequences of an icy porous layer on the thermal state and radar attenuation of Enceladus' ice shell

Abstract

Saturn's moon, Enceladus is considered a priority target for future planetary missions due to its high astrobiological potential. Water jets presumably originating from a subsurface ocean have been observed at the south pole of Enceladus by NASA’s Cassini mission, and their analysis provides a direct window into the ocean composition that, in turn, can help to understand the nature and amount of impurities that may exist within the ice shell. Enceladus’ jet activity generates a highly porous material that affects the thermal state of the ice shell. The thickness of that layer and its distribution are poorly constrained, but local thicknesses of up to 700 m have been reported from the analysis of pit chains on the surface of Enceladus. Such a thick porous layer can strongly attenuate the signal of radar sounders that have been proposed to investigate the Enceladus’ subsurface.