Fall in the Hellas Basin
We took this image during the Martian fall in the Southern Hemisphere, in the giant impact crater known as Hellas Basin where small boulders cast long shadows. The long shadows emphasize small scale topographic features. Wind erosion is responsible for much of the morphology in this region.
Frost is condensing, and shows up as bright blue patches in the enhanced color image. This is seasonal carbon dioxide frost. Closer to the pole, carbon dioxide condenses from the atmosphere and forms a seasonal polar cap. At this latitude we do not expect a thick layer to form but rather the frost collects in cold protected areas on poleward-facing slopes.
Images and posts from HiRISE, the high resolution camera onboard the Mars Reconnaissance Orbiter (MRO, NASA).