In the winter, these dunes in an unnamed crater east of Proctor Crater are covered with seasonal carbon dioxide frost (dry ice). In the spring, the frost gradually evaporates but lingers in protected regions. In this color image bright ice deposits in sheltered areas highlight the ripples on the dunes.
These dunes were imaged during the first year of MRO’s mission. Images taken now in the second Martian spring can be compared to the previous year to study interannual variability.
Written by: Candy Hansen (18 February 2009)
More info and image formats at http://hirise.lpl.arizona.edu/PSP_010854_1325
Image: NASA/JPL/University of Arizona