This HiRISE observation shows an albedo change associated with an impact crater at the northeast edge of the image. (Albedo measures how much light is reflected by a surface. An albedo of 0 means that no light is reflected). A streak of light material extends away from the crater. This is a wind streak, so called since it results from the interaction of wind and topography.
Wind streaks are common in the area of this image as well as other areas on Mars. They form when dust is preferentially eroded or deposited downwind of a crater or other feature due to its effect on the wind. As such, they are useful indications of wind directions on the Martian surface, an important constraint on modeling the weather of the planet.
Some striations in the image are artifacts due to slight differences between the camera detectors.Written by: Colin Dundas (25 September 2007)
More info and image formats at http://hirise.lpl.arizona.edu/PSP_005109_1770
Image: NASA/JPL/University of Arizona