Arsia Mons is the third tallest volcano on Mars and one of the largest mountains in the solar system.Even in the frigid conditions of Mars, that much ice-covered water would have remained liquid for a substantial period of time. Scanlon's back-of-the-envelope calculation suggests the lakes could have persisted or hundreds or even a few thousand years. That may have been long enough for the lakes to becolonised by microbial life forms, if in fact such creatures ever inhabited Mars, researchers said.