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Mars Rover Discovers Evidence of Moisture ; New Findings From Spirit Mission Point to Groundwater

Posted on: Saturday, 6 November 2004, 06:00 CST

NASA's older Martian robotic rover, Spirit, has found evidence that underground water changed a major rock formation called the Columbia Hills, scientists said yesterday.

The evidence includes signature changes in the chemistry and mineralogy of the now arid, elevated terrain as well as a characteristic pattern of internal layering within some of the rocks, called cross-bedding.

Spirit and its six-wheeled robotic twin, Opportunity, landed in January as part of an $835 million search for evidence that frigid and desertlike Mars was once wet and warm enough to sustain some form of life.

"We see evidence for water flowing through these rocks and changing their chemistry," Steve Squyres, a Cornell University astronomer and the mission's principal investigator, said yesterday. "The key thing to realize is that the water evidence we have now in the Columbia Hills points primarily toward groundwater instead of surface water. It's the distinction between water you can draw from a well and water you can swim in."

Spirit descended Jan. 3 into Gusev Crater, a 100-mile-wide equatorial depression that formed billions of years ago from the impact of a comet or asteroid. Some Martian experts believe it was once filled with water.

Opportunity, which descended onto Mars three weeks later, has been more fortunate in its search for a watery past at Meridiani Planum, a site halfway around the planet. In late March, scientists announced Opportunity had found chemical and mineral evidence for a salty sea in a bedrock formation close to its landing site.

Since its arrival, Spirit has rolled more than two miles to the Columbia Hills, a 3- to 41/2-mile- long rise named for the astronauts who perished aboard the space shuttle last year.

Despite mechanical problems affecting two of its wheels, Spirit climbed more than halfway up the 300-foot rise since it reached the hills in mid-May.

The robotic geologist is headed higher, where scientists have spotted a formation that may hold evidence that water once pooled at Gusev.

"I would not be surprised as we move up the hills that we find a section of rock that has been modified in a shallow, open-water environment," said Ray Arvidson, a Washington University planetary geologist and the mission's deputy principal investigator.

Source: Seattle Post - Intelligencer

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