Watch Out for Flying Moondust
Nov. 23, 2007: At Cape Canaveral, not far from the launch pad where the space shuttle lifts off, there's a ragged hole in a chain link fence. Its message: Watch out for flying boulders.
"The powerful exhaust of the shuttle's solid rocket boosters blasts concrete out of the flame trench below the engines," explains physicist Phil Metzger of the Kennedy Space Center (KSC). "On some launches, boulders of concrete up to a half meter wide are blown out as far as a half a kilometer away, traveling fast enough to shatter concrete light poles and punch through chain link fences."
This is no problem as long as people and equipment are kept at a safe distance, easily done. But, Metzger wonders, what if all this was happening on the Moon?
NASA is returning to the Moon in the next decade with plans to establish a durable outpost. There will be habitats, rovers, supply depots and mining equipment. Ships will be coming and going, landing and blasting off--and kicking up debris that might fly a lot farther than boulders at Cape Canaveral. Metzger is researching this problem as part of his work at KSC's Granular Mechanics and Surface Systems Lab.
"Boulders are no concern," he says. Lunar spacecraft will be far less massive than the space shuttle and they won't need such a powerful kick to escape lunar gravity. Movies made by six Apollo spacecraft of their landings and takeoffs showed nothing larger than gravel being rolled away by exhaust gases from the landing rockets.
Instead, Metzger is sweating the really small stuff--"moondust."
//snip//Now, Metzger is helping other teams of NASA engineers figure out how to mitigate the effects of lunar landings and takeoffs. One strategy might be to locate spaceports in places where mountains and hills serve as natural dust blockers. Artificial berms or other ingenious structures might offer a solution, too.
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