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NASA Mars rover finds strong evidence of water

NASAs Opportunity Mars rover, which landed on the red planet nearly eight years ago, has discovered a mineral vein that was almost certainly deposited by water billions of years ago.

By Mike WallSPACE.com / December 8, 2011

This image provided by NASA shows a fragment along the rim of Endeavour Crater where the Mars rover Opportunity has been exploring since August. With Martian winter approaching, Opportunity has been in search of a spot to spend the winter.

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A well-traveled NASA Mars rover has found some of the best evidence yet that water flowed on the Red Planet's surface long ago, researchers announced today (Dec. 7).

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The Opportunity rover, which landed on Mars nearly eight years ago, has discovered a thin, bright mineral vein along the rim of a huge crater called Endeavour. This mineral is almost certainly gypsum that was deposited by liquid water billions of years ago, researchers said.

"This is the single most powerful piece of evidence for liquid water at Mars that has been discovered by the Opportunity rover," Steve Squyres of Cornell University, Opportunity's principal investigator, told reporters here today during the 2011 winter meeting of the American Geophysical Union.

Exploring Endeavour Crater

The golf-cart-size Opportunity and its twin, Spirit, landed on Mars in January 2004 to search for signs of past water activity on the Red Planet. [Mars Photos by Spirit and Opportunity]

The two rovers' prime missions were slated to last just three months, but both far outlived their warranties. NASA declared Spirit dead just this year, and Opportunity is still going strong.

After a three-year trek, Opportunity reached the 14-mile-wide (22-kilometer) Endeavour Crater this past August. While poking around Endeavour's rim recently, it found the mineral vein, which is about 20 inches (51 centimeters) long and about the width of a human thumb.

After analyzing the vein with Opportunity's cameras and X-ray spectrometer last month, researchers concluded that it is gypsum, a hydrated calcium sulfate that on Earth is used to make drywall and plaster of Paris. The vein likely formed right where Opportunity found it, researchers said.

"There was a fracture in the rock, water flowed through it, gypsum was precipitated from the water. End of story," Squyres said. "There's no ambiguity about this, and this is what makes it so cool."

Strong evidence

Both Spirit and Opportunity have found other good evidence of water activity on ancient Mars, including signs of hydrothermal systems. But the new discovery at Endeavour Crater is particularly convincing and compelling, researchers said.

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