Craft poised to collect comet dust
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Artist's view of Stardust
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PASADENA, California (AP) -- A spacecraft is on track to catch a comet by its tail later this week, capturing hundreds of specks of dust from the shimmering cloud that envelops the dirty ball of ice and rock, according to NASA.
The Stardust spacecraft is expected to fly within 186 miles (300 kilometers) of comet Wild 2 on Friday, collecting samples and snapping photographs. At the time, the comet and probe will be 242 million miles (390 million kilometers) from Earth.
During the flyby, Stardust should capture roughly 1,000 particles of dust ripped from Wild 2 (pronounced vilt-two) by streams of gases boiled from the comet's surface by the warming rays of the sun. Scientists are eager to study the dust since it represents pristine examples of the building blocks of our solar system, preserved for billions of years by the cold of space.
They also believe the dust contains many of the organic compounds necessary for life. Comets that pelted the Earth long ago could have delivered those molecules to our planet.
"This could prove to be a pivotal time for science, a remarkable opportunity to gather evidence that might actually tell us how the planets formed and give us clues about how life on Earth began," said Donald Brownlee, a University of Washington astronomer and the main scientist for the $200 million mission.
The spacecraft also should take multiple images of the comet's tiny nucleus, believed to be just 3.4 miles (5.5 kilometers) across. If successful, Stardust will become only the third spacecraft to capture such a close view of the dark heart of a comet, normally obscured by a bright veil of dust and gas.
Protective bumpers will shield the unmanned spacecraft as it plows through that veil at 13,650 mph. A tennis racket-shaped canister packed with a material called aerogel will capture the particles during the flyby. Aerogel is 99.8 percent air, making it the world's lightest solid.
The canister already has swept up bits of interstellar dust since the spacecraft's 1999 launch.
In 2006, Stardust will jettison the canister during a flyby of Earth. The canister and its extraterrestrial cargo should fall over Utah.
There, southwest of Salt Lake City, the National Aeronautics and Space Administration plans for a helicopter to pluck the parachuting package from the sky. Scientists hope to analyze the particles for their chemical, elemental, isotopic and mineralogical composition.
Copyright 2004 The
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