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Stardust to Begin Sweep of Interstellar Particles
By Andrew Bridges
Chief Pasadena Correspondent
posted: 06:50 pm ET
19 February 2000
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PASADENA, Calif PASADENA, Calif. Stardust will begin collecting particles of interstellar dust on Tuesday, sweeping up and capturing microscopic specks of material that stream into our solar system from faraway stars. The $165 million NASA spacecraft will keep its dust collector, a waffle iron-shaped instrument, extended until May and then again during much of 2002. During that time, scientists hope the yard- (meter-) square collector will sweep up as many as 100 of the particles. Along with bits of comet dust the flip side of the collector will trap in 2004, Stardust will then return the samples to Earth in 2006, jettisoning them to a soft landing in Utah. "This will be the first sample return mission ever beyond the moon," said Don Brownlee, the missions principal investigator. During the two interstellar dust collecting periods which play second fiddle to the main task of gathering comet samples the spacecraft will fly downwind of the particle stream. That will allow the zippy grains to strike the dust collector. There the micron-sized particles will be trapped in any one of 130 blocks of glass foam, like bugs on a windshield."Except you want to catch the bugs very softly," said Kenneth Atkins, Stardusts project manager at NASAs Jet Propulsion Laboratory. "This is our butterfly net, if you will." The mission makes a novel use of a glass foam called aerogel to grab, slow and trap the diminutive particles, which will traveling at a relative speed of anywhere from 6 to 16 miles (10 to 26 kilometers) a second when they strike the spacecraft.The dust particles are literally samples of stars elsewhere in the galaxy, where they are formed by condensation around those other suns. The Milky Way is awash with the stuff just peer upward on a clear night, Brownlee said. "You see this dark band running along the middle of it?" Brownlee said. "That is interstellar dust, blocking the light of some stars." Their presence inside our solar system was discovered by Ulysses in 1993 and later confirmed by the Galileo spacecraft. Throughout Stardusts flight, its Dust Flux Monitor Instrument (DFMI) will monitor the dust particle impacts and transmit data back to Earth. Furthermore, Stardusts Cometary and Interstellar Dust Analyzer instrument (CIDA) will carry out real-time compositional analysis of the dust as it is strikes the spacecraft. "We want to know what they are," said Brownlee, who gained renown for the discovery of cosmic particles in the stratosphere known as "Brownlee particles." Once the sample capsule is safely back on Earth, scientists will avail themselves of an arsenal of instruments including electron microscopes, ion microprobes, atomic force microscopes, synchrotron microprobes and laser probe mass spectrometers to study the miniature interstellar grains.
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