NASA Builds Six-Foot Crossbow to Harpoon Comets
By Mark Brown, Wired UK
What’s the best way to take a sample from a violently speeding comet? One that’s doing cartwheels through the cosmos, spewing out chunks of rock and speeding through the solar system at 150,000 miles an hour?
Landing on its surface sounds like risky business, so engineers at NASA’s Goddard Space Flight Center are working on a harpoon gun that can spear the heart of the comet, collect a sample of subsurface dirt in its tip and reel it back into the hovering craft.
To that end, the Goddard lab now houses a monstrous six-foot-long crossbow, with a bow made from a pair of truck carriage springs, and a string made from a half-inch-thick steel cable. This industrial-strength ballista can generate a level of force up to 1,000 pounds.
The engineers only point the bow towards the floor, for safety reasons. “It could potentially launch test harpoon tips about a mile if it was angled upwards,” said NASA’s Bill Steigerwald in a press release.
The engineers are also building a special arrow, with a collection chamber secreted away inside a hollow tip. “It has to remain reliably open as the tip penetrates the comet’s surface, but then it has to close tightly and detach from the tip so the sample can be pulled back into the spacecraft,” explains Donald Wegel, lead engineer on the project.
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http://www.wired.com/wiredscience/2011/12/nasa-comet-harpoon/
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