Frosty Alcoves Viewed On Kaiser Crater Dunes On Mars
ID: ESP_045614_1330 date: 19 April 2016 altitude: 250 km https://uahirise.org/hipod/ESP_045614_1330 NASA/JPL-Caltech/University of Arizona
Kaiser Crater hosts a large field of sand dunes. Every winter the dunes are covered with a layer of seasonal carbon dioxide ice (dry ice). In early spring the ice begins to sublimate (going directly from solid ice to gas).
In this image, the dunes are partially free of seasonal ice, with the contrast making it easy to see the ripples. Deep alcoves have been carved at the crest of the dune.
We hypothesize that this is the result of the gas coming from the dry ice, destabilizing the sand at the crest.
As blocks of ice protected in the cold shadows of the alcove break off they slide downslope, carving the channels we see.
Astrobiology, Astrogeology,
