Mars Reconnaissance Orbiter: Features


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Spotlight On Mars - Image

Seasonal Freezing and Thawing on Mars

November 25, 2008

This color mosaic of images shows six vertical, rectangular views of Martian polar terrain as viewed from orbit. The six rectangles are lined up side by side from left to right. The first image on the left shows reddish dust clouds billowing upward from blocks of debris tumbling down the sheer cliffs of the north polar ice cap. The second image from the left shows dark streaks crisscrossing frost-covered dunes. The third image from the left shows circular and scalloped bands of terrain rising above lower-lying, flat surfaces, all covered with a blanket of reddish-brown dust. The fourth image from the left shows a jumble of dark, reddish-brown, irregularly shaped dunes partially coated with white frost. The fifth image from the left shows frosty, white starburst-like formations on top of the red Martian surface. The far right image shows many parallel, reddish-brown streaks fanning downward diagonally across a white, frosty surface (toward the lower right corner of the frame).

On Mars, the stuff we know as "dry ice," or frozen carbon dioxide, is a powerful agent for change. In winter, it forms a polar ice cap. In spring, it becomes an expanding gas that carves channels in the surface and sends loose debris into landslides.

Shown here is some of the spectacular scenery created by carbon dioxide as it freezes and thaws on Mars. From left to right, sun-warmed blocks of icy debris tumble down the cliffs of the north polar ice cap. Dust devils leave tracks on defrosting dune surfaces in the southern hemisphere. Receding south polar ice erodes the surface into scalloped ridges. During northern spring, sun-facing dunes emerge from a blanket of frost. As sunlight penetrates translucent ice near the south pole, the ice turns to gas that expands and erodes radiating channels. Where there's a break in the ice, the gas bursts forth, lofting surface materials downwind.

High Resolution Imaging Science Experiment, Mars Reconnaissance Orbiter

Image credits: NASA/JPL-Caltech/University of Arizona

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