25 August 2006
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows part
of a dune field in Chasma Boreale, the large north polar trough. The
bright material covering the dunes is frozen carbon dioxide. This carbon
dioxide frost accumulates during the northern autumn and winter, and
sublimes away (turns directly from solid to gas) during the spring and
summer. The image was acquired near the end of the northern spring. The
dark areas in this image are places where the frost sublimed away,
revealing the coarse dark sand of the dunes.
Location near: 84.5°N, 19.2°W
Image width: ~3 km (~1.9 mi)
Illumination from: lower left
Season: Northern Spring
