Our Solar System's Other Water World?

Although some potential evidence of extra-terrestrial life has made its way here to Earth there has never been a suggestion that another world was currently in any condition to support life. The exsistance of water has been detected on the moon, but the building blocks of life are clearly lacking. The topography of Mars indicates that its ecosystem may have once supported water - a requirement for life - but as far as we can see none remains. At least not on Mars.

These photos depict Antarctica's Ross Ice Shelf and the Jovian moon Europa. The similarity in color has led us to entertain the possiblity a liquid ocean exists underneath Europa's icy crust. How can this be? Earth has a very habitable surface, but internal pressure keeps its rocky innards in a molten state. This same force of internal pressure could be responsible for keeping Europa's subsurface temperature warm enough to maintain a liquid ocean despite the frigid cold of space. And where there is water there is the possiblity of life.