[meteorite-list] Real Stardust From NASA Mission Lands at Washington University in St. Louis

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu, 18 Jan 2007 11:00:48 -0800 (PST)
Message-ID: <200701181900.LAA14277_at_zagami.jpl.nasa.gov>

http://record.wustl.edu/news/page/normal/8461.html

'Real' stardust from NASA mission lands on campus

'Real' stardust from NASA mission lands on campus
By Susan Killenberg McGinn
Record (Washington University in St. Louis)
January 18, 2007

Stardust, the NASA spacecraft mission, was given that name in hopes that
the seven-year journey to capture comet samples would bring back to
Earth, well, stardust.

In an article in a special issue of the journal Science, University
researchers are the first to report that a sample they received from the
mission actually does contain stardust - particles that are older than
the sun.

"When the comet samples became available to analyze, one of the key
scientific questions was to see whether this material also contained
'real stardust' particles," said Frank J. Stadermann, Ph.D., senior
research scientist in physics in Arts & Sciences and a co-author of the
article. "As it turned out, the one and only stardust particle in all of
the analyzed comet samples was found right here in the St. Louis lab."

The findings appear in the Dec. 15, 2006, article "Isotopic Compositions
of Cometary Matter Returned by Stardust." Stadermann, who is a sample
adviser for the Stardust mission, also is a co-author on the six other
reports about the mission's initial findings that appear in the special
issue.

Launched Feb. 7, 1999, the Stardust spacecraft sped through the tail of
Comet Wild-2 at 15,000 mph Jan. 2, 2004. For 15 minutes, the spacecraft
extended a honeycomb-like collector, capturing cometary dust grains in
132 ice-cube-sized cells made of aerogel, a silicon-based solid that is
99.8 percent air and resembles frozen pale-blue smoke.

After the sample-return capsule's safe landing on the Utah salt flats
Jan. 15, 2006, particles - each much smaller than a grain of sand - from
several of the collector's cells were extracted, sliced up and disbursed
to 50 labs around the world for analysis. Of those 50 labs, called
"pre-liminary examination groups," two are at the University.

In late February, Stadermann received his team's first cometary
material: three slices of one particle.

Wasting no time, Stadermann and his WUSTL team - Ernst K. Zinner, Ph.D.,
research professor of physics and of earth and planetary sciences in
Arts & Sciences; Christine Floss, Ph.D., research associate professor of
physics; and Kuljeet Kaur Marhas, Ph.D., postdoctoral research associate
in physics - went right to work on it and, eventually, 10 other Stardust
samples. The three researchers also are co-authors on the Science article.

Kevin D. McKeegan, Ph.D., professor of geochemistry at UCLA, is first
author on the article. McKeegan earned a doctorate in physics from WUSTL
in 1987, with Zinner serving as his adviser. In addition to McKeegan,
five other WUSTL alumni are either first or co-authors on some of the
seven Science articles.

Brigitte Wopenka, Ph.D., senior research scientist in earth and
planetary sciences and a member of the McDonnell Center for the Space
Sciences in Arts & Sciences, is a co-author on two of the Science
articles. As the other WUSTL researcher to receive Stardust samples to
study, Wopenka is using a technique called Raman microprobe spectroscopy
to characterize the inorganic composition and carbonaceous organic
make-up of individual cometary dust grains.

>From the 'cosmic freezer'

Using the University's state-of-the-art ion probe, the NanoSIMS
(Secondary Ion Mass Spectrometer), Stadermann's team analyzed the
particles' elemental and isotopic composition.

The NanoSIMS, which Stadermann and Zinner helped design and test, can
resolve objects as small as 50 nanometers - one thousand times smaller
than the diameter of a human hair.

The first NanoSIMS instrument in the world was purchased by WUSTL in
2000 for $2 million, with partial support from NASA, the National
Science Foundation and the McDonnell Center for the Space Sciences.

The measurements at WUSTL yielded a unique result providing a key
component for our understanding of the composition and origin of comets,
Stadermann said.

"When we made the discovery of the stardust grain in the comet sample,
we were very excited, and we immediately knew that this little particle,
although it is only 1/100,000 of an inch in diameter, would be one of
the most important findings of the comet dust analysis," Stadermann said.

"This discovery proves that comets comprise dust grains from outside the
solar system in addition to the many other components that were formed
inside the solar system," he continued. "The fact that these very
different ingredients survived side-by-side in the comet shows how well
the material was preserved in this 'cosmic freezer' for the past 4.5
billion years.

"NASA picked the name 'Stardust' for this mission many years ago,"
Stadermann noted. "Only because of our measurement here at Washington
University we now know that the comet really does contain true stardust."

Scientists hope the Stardust findings will provide answers to
fundamental questions about comets, the origin of the solar system and
possibly even the origin of life itself.

This discovery complements ongoing research in the Laboratory for Space
Sciences, which is part of the departments of Physics and of Earth and
Planetary Sciences and the McDonnell Center for the Space Sciences.

"We certainly have a lot of expertise in analyzing small grains," Zinner
said of the Laboratory for Space Sciences research group. "We have
worked on interplanetary dust particles since the late '70s and have
been involved in the discovery of many types of presolar grains -
'stardust' in the literal sense - since 1987."

In 1987, Zinner and WUSTL colleagues and scientists at the University of
Chicago found the first stardust in a meteorite. Those presolar grains
were specks of diamond and silicon carbide.

Since then, members of WUSTL's space sciences lab have played leading
roles in analyzing these grains in the laboratory and interpreting the
results.

"With the NanoSIMS, we have an instrument that is ideally suited to the
analysis of such grains," Zinner said. "The finding of stardust in
meteorites and now comets gives us information about the early solar
system."

"The parent bodies of primitive meteorites [asteroids] formed in
different places, closer to the sun, than comets, which formed farther
away," Zinner continued. "The preservation of stardust in both types of
solar system bodies tells us something about their formation history.
However, at present we have evidence for only one stardust grain in
cometary material, making it a little early to make far-reaching
conclusions."

Floss added: "The preliminary examination of the comet samples is only
the first step, and it is clear that we will continue to study such
samples for years to come. There are so many questions about the early
solar system for which the answers are still hidden in these tiny dust
particles."
Received on Thu 18 Jan 2007 02:00:48 PM PST