NASA/JPL/Malin Space Science Systems
These four Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) images show north polar sand dunes as they appeared on four different days over the past ten weeks. In summer, the dunes would be darker than the substrate on which they occur. However, it is currently spring in the northern hemisphere, and the dunes are still covered with frost from the previous winter. The MGS MOC has been busy over the past several months, documenting the changes in frost patterns that occur on dunes and interdune substrates all over the north polar region. The site shown here was imaged on 30 March, 23 April, 16 May, and 9 June 2004. The bright frost that covers the dunes progressively changes from one image to the next, as dark spots develop and frost sublimes away. This defrosting dune monitor site is located near 80.0°N, 237.5°W. Each strip is about 1.1 km (0.7 mi) wide and illuminated by sunlight from the lower 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.