NASA/JPL/Malin Space Science Systems
The edges of the retreating seasonal polar caps of Mars are sites of frequent dust storms. The temperature contrast between the cold polar cap surfaces and the adjacent, warmer, frost-free surfaces set up the conditions for cold air to come streaming off the polar cap, picking up dust as soon as it hits the frost-free terrain. Dust storms are the result. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a dust storm in southeast Noachis Terra near 55°S, 316°W, on 21 June 2001. This was one of several precursor storms that led up to the global dust events of 2001. The frosted surface of the seasonal south polar cap is the lighter-toned terrain in the lower half of the image; the darker upper half is frost-free. Winds are blowing the dust storm (located at left-center) toward the north (top/upper right). The large crater just below the center of the picture is Peneus Patera. It is approximately 120 km (~75 mi) across. This MOC red wide angle picture is illuminated by sunlight from the upper left.
Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, California. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, California and Denver, Colorado.