Dust Devil Spotted Whirling Across Mars
Dust devils are a well-known and fairly common atmospheric phenomenon on Mars. The Mars rovers even have an unexpected use for them: dust devils make for great solar panel scrubbers.
They have been photographed by Mars surface missions, and Mars satellites since the 1970′s Viking orbiters have built a formidable collection of dust devil photographs.
Seen here, tumbling across an alluvial fan (sediment deposited by an ancient river), a very obvious dust devil leaves a long shadow across the Martian plain. This photo was captured by NASA’s Mars Reconnaissance Orbiter’s (MRO) awesome High-Resolution Imaging Science Experiment (HiRISE) on Aug. 14. It was orbiting over 300 kilometers above the Martian surface at the time.
Dust devils on Mars develop in the same way they do on Earth. On a warm day, the air just above the ground will heat up, causing the air to rise. Immediately above the heated layer, cooler air falls. If the conditions are right, a stable convection cell will form. All that’s needed then is a small horizontal gust of wind and the convection cell will begin to spin. A dust devil is born.
Although the formation processes are similar, dust devils on Mars are bigger — they can develop 10 times as high and 50 times as wide as their terrestrial counterparts. Considering Earth dust devils can exceed 10 meters wide by 1 kilometer high, the Martian versions can be monstrous in comparison.
Their effects are often seen after they remove the bright upper layers of dust, leaving prominent dark tracks crisscrossing the Marian landscape.
Although they are a common feature shaping the Martian landscape, dust devils could also pose a hazard to future manned missions to the Red Planet. They could interrupt communications, blow-out sensitive electronics — as they generate an electrical charge as they whirl — and cause all kinds of mischief to delicate inflatable habitats.
Image credit: NASA/JPL/University of Arizona