Mars likely had liquid water early in its past—but it was probably too acidic and oxidizing for life, scientists say.

Anne Minard in Boston, Massachusetts
for National Geographic News

Feb 17, National Geographic

That's the latest news from the longer-than-expected visits to the red planet by NASA's rovers Spirit and Opportunity, said Andrew Knoll, a Harvard University researcher and member of NASA's Mars program.

"That's not a very good place to live, and it's a worse place for the kind of chemistry that we think gave rise to life on Earth," he said.

Knoll and other Mars scientists presented their latest results in Boston Friday at the annual meeting of the American Association for the Advancement of Science.

Related findings will be published in an upcoming issue of the Journal of Geophysical Research—Planets.

Martian Gauntlet

Spirit and Opportunity have been traversing the Martian surface for nearly 1,400 Martian days—well beyond their expected life spans of 90 days apiece.

The machines' most celebrated findings have come in geology, including evidence of water in the planet's past. But they've also shown that the water was high acidic and briny with dissolved minerals.

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photo: A composite image by the Opportunity rover shows bedrock from the inside of Mars's Victoria Crater. Scientists say the latest findings from Opportunity and its sister rover Spirit reveal that Mars likely had a watery past—but was probably too acidic and briny with dissolved minerals for life (Image courtesy NASA/JPL-Caltech/Cornell University)