Yet another Saturnian moon may be hiding liquid

New Scientist : Titan has ethane and methane rivers and lakes. Enceladus has eruptions of water at its southern pole. Now it appears that Mimas may have a subsurface liquid layer. The moon was considered unlikely to have any liquids because it isn’t geologically active and has a nonmolten core. Nevertheless, Radwan Tajeddine of Cornell University and his colleagues believe otherwise. Examining pictures of the moon taken by Cassini, they observed an irregularity in the rotation of the moon’s surface, which could be explained by the presence of a layer of liquid lying beneath it. The more likely explanation for the wobble, however, may be the possibility that Mimas’s silicate core is not spherical, as it is unlikely that a subsurface water layer could remain liquid for so long without any core heating. Another Cassini flyby could provide evidence for either option. If the core is irregularly shaped, it would have an uneven gravitational effect on the spacecraft.