NASA records Martian environmental history

PASADENA, Calif., May 21 (UPI) -- The U.S. space agency says its Mars rover Opportunity has recorded environmental changes that occurred during billions of years at a Martian crater.

Opportunity surveyed Victoria Crater September 2006 through August 2008. The National Aeronautics and Space Administration said findings from that work reinforce and expand what researchers learned from Opportunity's exploration of two smaller craters after landing on Mars in 2004.

"The rover revealed the effects of wind and water," NASA said, with the data showing water repeatedly came and left billions of years ago, with wind persisting much longer, heaping sand into dunes between ancient water episodes.

Those activities, the space agency said, still shape the landscape today.

"What drew us to Victoria Crater is the thick cross-section of rock layers exposed there," said Steve Squyres of Cornell University, the principal investigator for the science payloads on Opportunity and its twin rover Spirit. "The impact that excavated the crater millions of years ago provided a golden opportunity, and the durability of the rover enabled us to take advantage of it."

The findings are reported in the journal Science.