Patches of Snow

In early Martian summer, at the time NASA's Mars Reconnaissance Orbiter (MRO) acquired this image, the dunes are almost free of their seasonal ice cover. Only pockets of ice protected in the shade most of the day remain.

The North Pole of Mars is surrounded by a vast sea of sand dunes. In this dune field, the dunes are covered by a seasonal cap of dry ice in the winter.

https://photojournal.jpl.nasa.gov/catalog/PIA22463