Aitken mare ridge (IMAGE) University of Maryland Caption Close up of a mare ridge near the Aitken impact crater. Credit Smithsonian Institution, University of Maryland Usage Restrictions Credit must be given to the creator. Only noncommercial uses of the work are permitted. No derivatives or adaptations of the work are permitted. License CC BY-NC-ND 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.