for National Geographic News
Scientists say there is no doubt that abundant water once soaked Mars. Now the big question is whether the red planet ever supported life.
The early signs are promising.
"[Mars] had a habitable environment that was suitable for some kind of life as we know it on Earth," said Steve Squyres, an astronomy professor at Cornell University in Ithaca, New York, and the principal investigator for NASA's Mars Exploration Rover Mission.
Eleven papers by 122 researchers connected with the Mars mission were published last week in the journal Science, detailing what scientists say is "the first clear geological and geochemical documentation of water on Mars."
That presence of water suggests a habitable environment.
"Whether or not it was an inhabited environment is a different question and one that we can't answer yet," Squyres said in a telephone interview.
NASA's twin robot geologistsOpportunity and Spiritlanded on Mars in January 2004. Both rovers were expected to operate on the surface of Mars for 90 days, but they are still going strong almost a year later.
Less than two months after Opportunity landed, scientists announced that the rover had found evidence of water on Mars.
The new reports describe Opportunity's initial 90 days on Mars, including documentation of the first close-up look at Martian bedrock at the Eagle Crater landing site.
Scientists have found huge concentrations of sulfur on the planet, thought to have formed as a result of water evaporating. They have also discovered jarosite, a sulfate that contains water and forms under acidic conditions. Textures in rocks further indicate that currents of water flowed in the Martian past.
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