The HiRISE camera aboard the Mars Reconnaissance Orbiter spacecraft spotted these changing seasonal frost patterns inside the Louth Crater on Mars. The crater, located at 70 north latitude, contains a mound covered by water frost that lasts throughout the year, unusual for this northern latitude.

Seasonal frost composed of carbon dioxide instead of water, deposited during northern winter, can also reach this latitude. At the time this image was acquired in northern spring, the carbon dioxide frost was in the process of sublimating back into the atmosphere (i.e., changing directly from ice to gas).

Sand dunes near the edge of the mound (not visible here) appear clear of frost in the summer.

• Video Player: Mars Reconnaissance Orbiter
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— NASA/JPL/University of Arizona and SPACE.com Staff

Credit: NASA/JPL/University of Arizona