Stardust Mission Yields Ancient Comet Dust

Closeup view of a cometary impact (center) into aerogel was inspected by scientists at a laboratory at the Johnson Space Center hours after the Stardust Sample Return Canister was delivered to the Johnson Space Center from the spacecraft's landing site in Utah. CREDIT: NASA

ST. LOUIS—After a seven-year wait, scientists have finally been able to analyze the cometary and stellar dust particles captured by the NASA Stardust spacecraft.

Researchers performed preliminary analysis on particles from six of Stardust's 132 collectors. Already, they are finding many of the same materials in samples from the Comet Wild 2 (pronounced "Vilt 2") that they believe formed the early stars, planets, and other objects.

While the samples appear to lack indicators of water, they do contain sulfides, a key component to life.

"When you have the samples in hand, it's a whole different universe," project leader Don Brownlee of the University of Washington said during a press briefing here today at the annual meeting of the American Association for the Advancement of Science.

The early results reveal that the 4.5 billion-year-old comet contains iron, sulfides, glassy materials, olivine, and what the scientists termed potentially interesting isotopic traces. They believe that these materials were also available during the formation of other objects in our solar system.

Stardust also captured contemporary particles as they passed through the solar system.

More than a million particles larger than one micron (a millionth of a meter) in diameter are believed to have been captured in ice-cube-sized aerogel collectors. Many of the impacts left carrot shaped troughs in the aerogel, each with a sample at the bottom.

"The biggest impacts were big enough to put your little finger in," Brownlee said.

NASA's other recent comet mission, Deep Impact, revealed carbonates, hydrated silicates, water ice, clay, iron, and olivine in a different comet.

"That's the big question: Is there a difference?" Brownlee said of the two comets.

Deep Impact hit Comet Tempel 1 in its body, which likely had warmed up from millions of years of impacts with other bodies. Stardust, however, captured particles jetting out from its tail. Many of the bits are thought to be the original, unadulterated materials that formed the comet.

"We're confident that the things coming out [of Comet Wild 2] are the same as those that went in," Brownlee told SPACE.com. "We believe that we collected the most pristine samples of a comet, those that have never been warmed."

While further analysis of Tempel 1 revealed water ice on its surface, so far no evidence of water has been detected in the particles. The other sign of water would be the presence of hydrate silicates, which were present in Tempel 1, Brownlee said, but so far none of these have been found in the Stardust samples.

Stardust was launched on it nearly seven-year flight on Feb. 7, 1999 and is a NASA Discovery-class mission. Its encounter and dust-sample collection at comet Wild 2 occurred Jan. 2, 2004, with the spacecraft flying by the comet at roughly 149 miles (240 kilometers) distance.

NASA's Stardust spacecraft successfully landed on the Utah desert at about 5:12 a.m. EST (1012 GMT) on Jan. 15, 2006. The total cost of the mission was about $212 million.

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