NASA's Opportunity rover has found strong evidence that a rock outcrop in Mars' Meridiani Planum region once was a wet and habitable environment, rover science team members announced at a 2 March news briefing at NASA headquarters in Washington, D.C. We have concluded that the rocks here were once soaked in liquid water, said Steven Squyres, Mars Exploration Rover principal investigator and astronomy professor at Cornell University. He said it was not yet possible to indicate how long ago or for how long the rocks were wet.