During the Martian winter, carbon dioxide ice (dry ice) blankets various landforms, including dunes, in the northern high latitudes. As spring arrives, the ice sublimates, causing unique changes on the surface.

This HiRISE image captures a site featuring a North Polar scarp and nearby dune field, showing the early to mid-stages of defrosting during northern spring. In areas without dunes, the ice remains a continuous layer, while on the dunes, dark defrosting spots appear as the surface material beneath the ice is mobilized and deposited on top.

In some cases, this mobile material also cascades down the steep dune faces, leading to the formation of dark streaks that can be easily identified in our enhanced color cutout. This dynamic interaction between the sublimating ice and the underlying surface provides us a unique glimpse at the seasonal processes that shape the landscape on present-day Mars.

Written by: Vidhya Ganesh Rangarajan  (15 June 2026)