Fresh signs that ancient Mars was life-friendly

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Opportunity rover finds fresh signs that ancient Mars was life-friendly

Ten years after it landed on Mars, NASA's Opportunity rover has hit pay dirt again: This time, the rover's scientists are reporting new evidence that garden-variety life could have thrived on the Red Planet billions of years ago.

Not long after Opportunity bounced to the surface in 2004, the six-wheeled rover came across geological formations that were formed amid standing water, suggesting a sort of habitability on ancient Mars. But back then, the evidence indicated that the water was salty and highly acidic — making for an environment that would have been suitable only for the hardiest organisms on Earth.

Now scientists are fleshing out a scenario that's more in tune with what NASA's Curiosity rover, a more recent arrival, found at a different site thousands of miles away. That suggests that life-friendly conditions could have existed for hundreds of millions of years.

"The punch line here is that the oldest rocks Opportunity has examined were formed under very mild conditions — conditions that would have been a much better niche for life, and also much better for the preservation of organic materials that would have been produced," said Ray Arvidson, a planetary scientist at Washington University in St. Louis.

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