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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