A Rock Named Chester Lake (IMAGE) Washington University in St. Louis Caption This is a Pancam false color mosaic of the rock target Chester Lake, acquired on sol 2709 (the 2,709th day of Opportunity’s mission). This rock, located on Cape York, on the edge of the Endeavour crater, is a breccia in which various rock fragments have been cemented together in a finer-grained matrix, probably during formation of the Endeavour crater billions of years ago. Opportunity is about to make in-situ measurements of this rock which will determine whether it contains clay minerals formed in the presence of water. 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.