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  • Dick writes about Earth and planetary science for Science magazine.
 

Video: Huge Dust Devil Prowling Mars

5 April 2012 2:06 pm
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Credit: NASA/JPL/University of Arizona

Earth may have terrifying tornadoes, but when it comes to dust devils, Mars has us beat. A camera onboard the Mars Reconnaissance Orbiter has captured a stunning example of a swirling funnel of dust spinning up to an altitude of 20 kilometers. (The animation above provides a side view.) On Earth, tornadoes often reach such heights, but dust devils seldom reach up more than a few hundred meters. That's because dust devils only draw their energy from the solar heating of the surface; tornadoes also tap the heat energy from the condensation of water vapor in a tornadic storm. Mars is too dry for that, but the thinness of its air allows dust devils to soar, even on their restricted energy diet. Astronauts wouldn't be knocked off of their feet if caught in one, but martian dust devils are strong enough to play many roles. They loft dust high into the atmosphere between major dust storms. Some Mars scientists suspect dust devils generate enough static electricity to produce bleach-like chemicals that consume any organic matter—and any living thing—in martian soil. And dust devils have certainly lent NASA a hand; they occasionally blow the dust off a rover's solar cells, letting it power back up and keep on truckin'.

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