[meteorite-list] Comet Dust Has Hints of Organic Matter (Stardust)
From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Fri Feb 24 13:34:51 2006
Comet Dust Has Hints of Organic Matter
By Irene Mona Klotz
February 24, 2006
Feb. 24, 2006 - Specks of comet dust carried to Earth inside a NASA
science probe show tantalizing hints of organic compounds, bolstering
suspicions that comets delivered key ingredients for the development of
life on Earth.
Analysis of the samples brought back last month aboard the Stardust
capsule is in the very early stages, but lead scientist Donald Brownlee
said this week that he is encouraged by what researchers have found so far.
"We're seeing a variety of things that we know absolutely come from a
comet," Brownlee, an astronomer with the University of Washington, said
at the annual meeting of the American Association for the Advancement of
Though analysis has just begun, the samples so far have revealed iron,
sulfides, glassy materials and traces of olivine.
The samples are from Comet Wild-2, which flew just 149 miles (240
kilometers) past the Stardust spacecraft on Jan. 2, 2004.
During the encounter, the spacecraft extended a collection tray filled
with 132 tiles of lightweight, heat-resistant gel that captured
individual particles streaming off the comet's body.
As they bored into the gel, the particles created carrot-shaped trails,
many of which were visible to the naked eye when scientists opened the
canister upon its return to Earth a year later.
"When you have the samples in hand, it's a whole different universe,"
Early indications show Stardust collected at least 2,300 comet particles
measuring 15 micrometers - one-third the diameter of a human hair - or
larger, according to University of Chicago researchers who built one of
the spacecraft science instruments.
Scientists are particularly keen to learn if any of the comet samples
contain traces of matter from the original dust cloud that provided the
raw materials for the creation of the solar system some 4.8 billion
Comets are believed to be relatively unchanged since their formation
because they primarily dwell far from the sun's heat in a perpetual
deep-freeze beyond Neptune's orbit.
After dropping off its return capsule for a parachute landing on Earth,
the Stardust spacecraft was placed into a solar orbit while NASA weighs
options for a second comet encounter. No more samples can be returned,
but the probe has cameras and other instruments for close-up studies.
The first scientific results from the Stardust mission are expected to
be released next month.
Received on Fri 24 Feb 2006 01:33:01 PM PST