Saturn moon 'once had ocean'

One of Saturn's moons may once have harboured a liquid ocean beneath its icy surface, scientists have told a major conference in Houston, Texas.

Tethys is a mid-sized satellite with a density close to that of pure ice. But a large valley system visible today must have formed when the crust was being heated and under great strain. The team thinks that tidal heating, followed by cooling which froze Tethys' ocean, could have formed the giant Ithaca Chasma rift. Details were presented here at the 39th Lunar and Planetary Science Conference. Moon mix Calculations by Erinna Chen and Francis Nimmo, from the University of California, Santa Cruz, show that tidal interactions were the only viable way of providing the amount of heat associated with the formation of Ithaca Chasma. ......

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But at some point, the orbital interaction between Tethys and Dione was broken, and Tethys fell back into a less eccentric orbit. As it did so, it began to cool.

out of the entire article i found this the most interesting. How a once eccentric orbit which allowed for a warmer planet suddenly changed somehow which caused cooling.

Makes one appreciate how fragile the conditions for the existence for such a basic ingredient in known life is.