Kaiser Crater Dunes

This VIS image is located in Kaiser Crater and shows many individual dunes. This sand dune field is one of several regions of sand dunes located on the southern part of the crater floor. The crater floor is visible between the dunes, indicating that there is a limited sand supply creating the dunes. These dunes are composed of basaltic sand that has collected in the bottom of the crater. The topographic depression of the crater forms a sand trap that prevents the sand from escaping. Dune fields are common in the bottoms of craters on Mars and appear as dark splotches that often lean up against the downwind walls of the craters. Dunes are useful for studying both the geology and meteorology of Mars. The sand forms by erosion of larger rocks, but it is unclear when and where this erosion took place on Mars or how such large volumes of sand could be formed. Local winds continue to move the sand dunes across the crater floor. There are two sides to a dune, the low angle slope of the windward face and the high angle slope of the leeward side. The steep side is called the slip face. Wind blows sand grains up the low angle slope of the dunes which then "fall down" the slip face. In this way the whole dune moves towards the slip face. The winds blow from the windward to the leeward side of the dunes. In this image the slip faces are on the left side of the dune, so the dunes are slowly moving to the left side of this image. Kaiser Crater is 207km in diameter (129 miles) and is located in Noachis Terra west of Hellas Planitia.