Why this obsession with water? Water is not a pre-requisite for life to exist anywhere in the universe. It is true that most of the species on earth require water for their existence. This need not always be true. In fact, as per scientific research, the first protein cells were formed at a time when earth was mainly abundant in hydrogen. An important corollary to this is that you can't reject possibility on any of the planets just because there is no water/oxygen or the temparature is too high or too low. Maybe there exist some microbes for whom water is as poisonous as cyanide is for us!
