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Cracking May Signal Past Water on Mars

Friday, October 8, 2004; Page A03

NASA's Mars rover Opportunity has found an unusual pattern of cracking on a rock it discovered inside a Martian crater -- evidence, perhaps, that water may once have soaked parts of the crater bed, researchers said yesterday.

The rock displays cracks in the shape of polygons -- like mud cracks in a dry puddle. Opportunity earlier this year found evidence of liquid water long ago on Mars, but the cracks suggest what scientists termed a "second water episode" after the crater was formed.

An image taken by the Mars rover Opportunity shows a polygonally fractured rock located in a Martian crater. (National Aeronautics And Space Administration Via AP)

"There is no evidence of a pond or lake," Cornell University's Steven Squyres, the Mars mission's lead scientist, said yesterday in a telephone news conference. "There may -- may -- have been a brief moistening or a frost" that caused the cracks.

NASA officials said Opportunity and its cousin, Spirit, are operating almost flawlessly more than six months after their primary mission ended. Plans are for Opportunity to investigate a nearby rock for further evidence of water erosion before leaving the crater. Spirit will continue to explore a set of highlands dubbed the Columbia Hills.

-- Guy Gugliotta

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