22 December 2004
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a group of north polar dunes in late spring, just before the final patches of wintertime frost sublimed away. The dunes beneath the frost are dark because they contain minerals rich in reduced (unoxidized) iron. The dune slip faces (the steepest slopes on the dunes) point toward the upper right (northeast), indicating that the dominant winds involved in sand transport in this region blow from the lower left (southwest). These dunes are located near 76.3°N, 261.1°W. The image covers an area about 3 km (1.9 mi) wide and sunlight illuminates the scene from the lower left.