Crusted Soil on Mars (IMAGE) Washington University in St. Louis Caption An image from the panoramic camera on the Spirit rover shows the terrain around Troy, where Spirit became embedded in soft soil during the spring of 2009. When the rover’s wheels cut through the darker top layer of soil, much lighter soils (white smear toward the bottom of the image) were revealed. Investigation showed that the soils had been sorted according to their solubility in water, evidence that a water cycle persists on Mars to this day. Credit NASA/JPL/Cornell Usage Restrictions Credit required 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.