That's what science is about surely. The hypothesis comes first, which is then modified as further evidence comes to light. The fact that there is water present on this planet and the temperature range appears to be "earth-like" (0 - 35C IIRC) then there is the possibility of carbon based lifeforms similar to those on earth also being there. To my mind it does not preclude the possibility of different life forms on other planets where there is no water.
I'm surprised that no-one has started the usual "this proves there is no God" sub-thread. Oops. Just saying like.