A Dark Sand Dune on Mars . ... Credit Copyright: NASA / JPL - Caltech Explanation: What is that dark sand dune doing on Mars? NASA 's robotic rover Curiosity has been studying it to find out, making this the first-ever up-close investigation of an active sane dune on another world. Named Namib Dune , the dark sand mound stands about 4 meters tall and, along with the other Bagnold Dunes, is located on the northwestern flank of Mount Sharp . ... NASA Official: Jay Norris. ...