[extropy-chat] stardust discovery

spike spike66 at comcast.net
Wed Mar 15 05:44:37 UTC 2006



Specks of 'fire and ice' in comet dust

Tuesday, March 14, 2006; Posted: 1:13 p.m. EST (18:13 GMT) 

(CNN) -- Scientists with NASA's Stardust mission said they have found "fire
and ice" in dust from the tail of Comet Wild-2, findings they called
surprising on Monday.

"Remarkably enough, we have found fire and ice," said Stardust principal
investigator Don Brownlee of the University of Washington. 

"In the coldest part of the solar system, we have found samples that have
formed at extremely high temperatures. So, the hottest samples in the
coldest place."

Launched in 1999, the Stardust spacecraft orbited the sun on a long
intercept course with Wild-2. 

On January 2, 2004, it flew through the comet's tail, collecting bits of
dust in a tennis racket-shaped collector resembling an ice-cube tray, filled
with a substance called aerogel -- a low-density silica glass, nearly as
light as air. The aerogel cushioned the fast-moving particles for the trip
back to Earth.

On January 15 of this year, the Stardust spacecraft passed by Earth and
jettisoned a 100-pound capsule containing the dust samples. It entered the
atmosphere over the Pacific Ocean traveling almost 29,000 miles per hour,
and streaked across the sky over Oregon and Nevada on its way to its landing
zone at the Air Force Utah Test and Training Range west of Salt Lake City.

The sample canister was soon transported to NASA's Johnson Space Center in
Houston, Texas, where it was opened and where the samples will be housed on
a long-term basis.

Scientists have pored over the samples for a little more than a month. So
far, six of the 132 "cells" containing the aerogel have been removed, and
the some of the larger dust particles have been extracted and analyzed.

Scientists say the minerals found in the samples include magnesium olivine,
and other compounds rich in calcium, aluminum and titanium. 

While none of these minerals are new to the scientists, they do express some
surprise at finding them in a comet. Scientists believe comets are icy,
rocky debris left over from the formation of the solar system 4.5 billion
years ago. While they orbit the sun, comets populate the frigid fringes of
the solar system, and any minerals frozen inside them are preserved in a
deep freeze.

"We found mineral grains that are considered very high-temperature minerals
-- they normally form under extremely high temperature conditions," Brownlee
said. "And yet they were collected in a comet, the Siberia of the solar

So how is it that these high-temperature minerals came to reside deep inside
a comet, far from the blast furnace where they were formed?

"There are two major possibilities," Brownlee said. "One that they formed in
the innermost, hotter-most regions of our solar system when the sun and
planets were forming, and they were thrown out -- all the way out to the
Pluto region of the solar system. The other possibility is they were formed
around other stars, in hot regions around other stars."

The goal of the Stardust mission is to study how the solar system formed and
evolved. This early analysis of the Stardust samples seems to be evidence
that the early solar system was a dynamic, explosive place.

"If these are really from our own sun, they've been ejected out,
ballistically out, all the way across the entire solar system, and landed
out there," said Stardust scientist Mike Zolensky. "These materials where
basically on a big conveyor belt -- being shot out, and then gradually
drifting in, and then being shot out again."

"It's like everything else in science," he said. "You learn something about
one thing, and it raises more questions somewhere else. So we can't write
all the answers right now, it's just great we have new mysteries to worry
about now."

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