Nearly two months after the spacecraft's sample-collecting capsule landed safely in the Utah desert, scientists at Johnson Space Center have sent out about 200 particle samples from Comet Wild 2 (pronounced Vild) to research team members around the world.

"Remarkably, we've found fire and ice," said Donald Brownlee of the University of Washington in Seattle, Stardust's principal investigator. "We've found the hottest samples from the coldest place, the 'Siberia' of the solar system" - the Oort Cloud of cometary bodies located far beyond the orbit of Pluto.

Brownlee and colleagues briefed reporters on the latest findings in the study of the cometary particles, which range in size from one to 15 microns in diameter, or smaller than a human hair. Stardust captured the particles in a collection matrix made of a substance called aerogel, which consists of silicon glass but is about 90 percent air.

He said among the minerals found in the particles were olivine, an iron-magnesium-silicate compound that forms only at extreme temperatures - in the neighborhood of 1,100 degrees Celsius (2,000 degrees Fahrenheit). This means the nucleus of Wild 2 must have formed close to the center of the solar system - or perhaps close to some other star about 4.5 billion years ago.

Team member Peter Tsou explained how the team extracted individual particles from the 132 aerogel cells using a technique called keystoning, which requires cutting pie-shaped wedges around the impact zone with a vibrating instrument called a harmonic saw.

Tsou said that before Stardust returned the samples, the team worried about attempting to capture the particles - which hit the collector at a speed of about 6 kilometers per second (nearly 14,000 miles per hour) - without completely destroying the particles or damaging the aerogel grid. The impact zones showed evidence of some miniature explosions, he said, but the technology "does work."

Michael Zolensky, the principal sample curator at said the analytical techniques used to examine the Wild 2 samples have improved so much since ESA's Giotto spacecraft flew past Comet Halley - exactly 20 years ago, on March 13, 1986 - it now is possible to conduct "atomic-level" examinations of the particles. "We can tell their origins, temperature and chemistry, and detect the presence of organics with spectroscopy," he said.

So far, Brownlee said, the biggest revelation is the presence of high-temperature minerals among the particles. This strongly suggests the comet formed near a source of extreme heat. "Comet Wild 2 probably was born close to the Sun, and then expelled," he explained.

All three team members emphasized the value of having captured the samples and returned them to Earth. "The fabulous thing is that we have these samples and we can study them in the lab," Brownlee said.

Zolensky explained that the Stardust team will continue their analyses of the particles for several more months, "then open up access to anyone in the world who's qualified - that stage will go on for the rest of our lives."

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