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NASA launches comet-smashing spacecraft
(Agencies)
Updated: 2005-01-13 08:08


The "Deep Impact" spacecraft is launched by a Delta II launch vehicle at 1:47:08 p.m. EST from Space Launch Complex 17B, Cape Canaveral Air Force Station, Florida, January 12, 2005. [Reuters]

Nothing like this has ever been attempted before.

Little is known about Comet Tempel 1, other than that it is an icy, rocky body about nine miles long and three miles wide. Scientists do not even know whether the crust will be as hard as concrete or as flimsy as corn flakes.

"One of the scary things is that we won't actually know the shape and what it looks like until after we do the encounter," said Jay Melosh, a planetary geologist at the University of Arizona.

The comet will be more than 80 million miles from Earth when the collision takes place — on the sunlit side of the comet, NASA hopes, in order to ensure good viewing by spacecraft cameras and observatories. The resulting crater is expected to be two to 14 stories deep, and perhaps 300 feet in diameter.

Scientists stress that Deep Impact will barely alter the comet's orbital path around the sun and will not put either the comet or a chunk of it on a collision course with Earth. In the 1998 movie "Deep Impact," astronauts try to blow up a comet in hopes of saving the Earth, but the comet winds up being split in two and one section slams into the Atlantic, creating a huge tsunami on the East Coast.
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