A Look at a Steep North Polar Scarp

This very steep (more than 60 degrees) scarp shows mass wasting activity every year in the early northern spring, when it is first illuminated after the period of winter darkness. This observation was an attempt to image in late northern winter, in spite of poor illumination.

The solar incidence angle is 91.3 degrees, meaning that the Sun is just below the horizon and there was no direct lighting when this image was acquired. However, the atmosphere scatters light to create some diffuse lighting, and the surface is very bright from winter frost deposition, so a useful image of the surface was obtained.

The image reveals relatively dark streaks down the steep slope, so mass wasting activity has already started. There is some direct illumination here close to noontime at this time of year, which may be sufficient to initiate some activity.

The map is projected here at a scale of 50 centimeters (19.7 inches) per pixel. (The original image scale is 63.3 centimeters [24.9 inches] per pixel [with 2 x 2 binning]; objects on the order of 190 centimeters [74.8 inches] across are resolved.) North is up.

The University of Arizona, in Tucson, operates HiRISE, which was built by Ball Aerospace & Technologies Corp., in Boulder, Colorado. NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, manages the Mars Reconnaissance Orbiter Project for NASA's Science Mission Directorate, Washington.