Marsí northern-most sand dunes are seen as they begin to emerge from their winter cover of seasonal carbon dioxide (dry) ice in this image acquired by the HiRISE camera aboard NASA’s Mars Reconnaissance Orbiter January 16, 2014. The steep lee sides of the dunes are also ice-free along the crest, allowing sand to slide down the dune. Dark splotches are places where ice cracked earlier in spring, releasing sand, according to a NASA news release. REUTERS/NASA/JPL-Caltech/Univ. of Arizona/Handout via Reuters (OUTER SPACE – Tags: SCIENCE TECHNOLOGY) THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. IT IS DISTRIBUTED, EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS – RTR3G4OR

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