Two images of the surface of Mars from the Opportunity rover, left, and the Curiosity rover. Scientists are studying Martian rocks for evidence of past life.
By KENNETH CHANG
Published: March 12, 2013 74 Comments

Several billion years ago, Mars may well have been a pleasant place for tiny microbes to live, with plenty of water as well as minerals that could have served as food, NASA scientists said Tuesday at a news conference on the latest findings from their Mars rover. But they have yet to find signs that actual microbes did live in that oasis.

“We have found a habitable environment that is so benign and supportive of life that probably if this water was around and you had been on the planet, you would have been able to drink it,” said John P. Grotzinger, the California Institute of Technology geology professor who is the principal investigator for the NASA mission.