The Richat Structure

The Richat Structure has attracted attention since the earliest space missions because it forms a conspicuous bull's-eye in the otherwise rather featureless expanse of the desert. The structure, which has a diameter of almost 50 kilometres, has become a landmark for space shuttle crews. Initially interpreted as a meteorite impact structure because of its high degree of circularity, it is now thought to be a symmetrical uplift that has been laid bare by erosion.