It’s always exciting to catch geologic surface events in action on Mars, reminding us that the red planet isn’t just a museum piece but a very active place! The image above is from the HiRISE camera on the Reconnaissance Orbiter showing dust clouds billowing up nearly 200 feet at the base of an ice cliff in Mars’ north polar region. The left side shows the top of the cliff, covered in carbon dioxide frost…on Earth we call it “dry ice” and often use it to keep food cold during shipping (and to make neat fog effects at Halloween parties.)

The entire cliff is about 2000 feet high and is made up of layers of dust and water ice. During the spring months on Mars’ northern hemisphere the increased sunlight warms up the surface and causes the carbon dioxide ice to sublimate – turn directly to gas – and may be the cause of these dust avalanches, which have happened before along the same scarp. This is most likely a regular event during the Martian spring.

Researchers at the University of Arizona have been studying these images closely, trying to learn more about the mechanics of the avalanches and the effects of seasonal changes on Mars. Click the image to read more on the HiRISE website, and see the full image scan here.

Image: NASA/JPL/University of Arizona