Comanche Outcrop on Mars Indicates Hospitable Past . ... Credit Copyright: Mars Exploration Rover Mission , JPL , NASA Explanation: Could life once have survived on Mars? ... Although evidence from the martian rovers indicates that long ago Mars might once have had liquid water on its surface, that water might also have been too acidic for familiar life forms to thrive. ... NASA Web Site Statements, Warnings, and Disclaimers . NASA Official: Jay Norris. ... A service of: LHEA at NASA / GSFC . ...