HiRISE: Icy wonderland

Although the season is late spring, carbon dioxide ice still covers much of the surface at this high latitude site. It is still a chilly –128 degrees Celsius [–198° F]. The weak boundaries of the polygonal structure of the surface have been eroded by spring sublimation of carbon dioxide as energy from the Sun turns ice to gas. The larger troughs in this image accentuate the surface polygonal… [More at link]