Hazardous Devils
 Four "dust devils" swirl across Mars in this 2005 image from the Spirit rover. Although these are relatively small, some Martian dust devils seen from orbit can be miles tall and thousands of feet in diameter. [Credit: NASA/JPL/Texas A&M]
Dust devils are twisting columns of air that look like small tornadoes. They're found in dry, sunny spots on both Earth and Mars.
The ones on Earth can be nuisances, but they're seldom dangerous. But the ones on Mars could be trouble. They're a lot bigger -- as big as several city blocks, and thousands of feet tall. That means they carry a lot more sand, so they could give a manned lander a good sandblasting. And the fine-grained sand is caustic, so it could eat away at hoses, seals, joints, and other equipment.
As dust particles in the devils rub together, they generate static electricity -- just like rubbing a balloon against a wool sweater. On Earth, the electrical fields are fairly mild. But scientists and engineers are concerned that those on Mars could be stronger. If so, they could short out computers, interfere with radio transmissions, and make it harder to clean dust off of spacesuits.
Since dust devils are common on Mars, scientists are studying the little twisters here on Earth to learn more about their potential hazards to Mars explorers.
Script by Damond Benningfield, Copyright 2006
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