re: Meanwhile out on Titan geology rules
But once you postulate all this water around at various temperatures, then certainly the conditions to support life abound. This would be especially true on Mars where material has been exchanged between Earth and Mars through impact events. It has already been shown that impacts can produce surprisingly intact and unshocked fragments that could sustain life in spore form for the journey between planets. At this point I would be almost surprised if there was not some common linkage between some subsurface life forms present on Mars as well as Earth.