Rocknest (IMAGE) American Geophysical Union Caption The Curiosity Rover took this composite self-portrait in the Rocknest sand patch on Mars. Tests of soil at the site suggest that troublesome chemicals called perchlorates are common on the Red Planet. Credit 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.