Halo-Navcam (IMAGE) DOE/Los Alamos National Laboratory Caption This is a mosaic of images from the navigation cameras on the NASA Curiosity rover shows 'halos' of lighter-toned bedrock around fractures. These halos comprise high concentrations of silica and indicate that liquid groundwater flowed through the rocks in Gale crater longer than previously believed. Credit NASA/JPL-Caltech 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.