Mars Opportunity Image (IMAGE) University of California - Berkeley Caption Cracks caused by the contraction of sulfate are evident in this image of the surface of Mars' Meridiani Planum site by NASA's Opportunity Rover. Credit Photo courtesy of NASA Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.