By Mike Deliman
As recently as even 2004, it was believed that possibly in the past, but certainly now, Mars was, or is, a bone-dry planet. Water could not have existed in any sufficient amount to sustain life, at least not in any recent times.
Various mapping missions though, showed significant traces of water-ice beneath the surface. As early as 2002, Mars Odyssey showed traces of ice underground, perhaps even a large amount. But we still hadn't detected anything at the surface to confirm these traces.