Earth observations of Namibia taken during the STS-97 mission STS097-717-089 (December 2000) --- Sossus Vlei, Namibia, was photographed by one the STS-97 astronauts using a handheld 70mm camera. The long, parallel, deep red dunes at Sossus Vlei ("vlei" is Dutch for marsh), central Namibia, are constructed by the prevailing winds moving northward up the coast, according to NASA scientists studying the STS-97 photo collection. Along the course of the ephemeral stream (white strands at center), the ground-water table is at or near the land surface, and the damp sand disrupts or prevents dune formation. Where winds are deflected around bedrock outliers, smaller and less continuous dunes result. Similar aeolian features can be seen in images of the floor of Hebes Chasma, Herschel impact basin, and the north polar region of Mars, taken with the Mars Orbital Camera.
