[meteorite-list] Stardust Analysis Update - May 12, 2006

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Mon May 15 16:04:43 2006
Message-ID: <200605152002.NAA15053_at_zagami.jpl.nasa.gov>

http://stardust.jpl.nasa.gov/news/status/060512.html

Stardust Analysis Update
Dr. Donald Brownlee
Stardust Principal Investigator
May 12, 2006

[Group photo of Stardust science team at Timber Grove Inn
 near San Francisco, California]

The Stardust Preliminary Examination Team (PET) is now in the second
half of the six month period to complete the initial characterization of
the returned comet samples. The PET consists of about 200 people around
the world organized into sub-teams working on the bulk composition,
organics, mineralogy, isotopes, spectroscopy and craters in the aluminum
holding frame. During the first week in May, representatives of each of
the six sub-teams met to discuss the state of their findings and began
outlining the research papers that they will submit for publication this
summer. The three day workshop was held at the Timber Cove Inn, a remote
seaside location north of San Francisco. The meeting was funded by the
University of California's Institute of Geophysics and Planetary Physics
(IGPP) and organized by John Bradley, Trish Dobson, Andrew Westphal and
Gary Zank. In addition to the comet research, one of the joys of the
meeting was strolling out on the deck to watch grey whales and their
newborns migrate up the coast.

The workshop was an opportunity to compare results, dig though the data
to see the "big picture" issues that will go into the final research
papers and plan out future work. The analysis results came from a
diverse set of instruments ranging from optical microscopes to
synchrotrons larger than shopping centers. In addition to presentations
of data, numerous discussions focused on what had been learned about the
comet. Everyone was elated to work on ancient materials from the edge of
the solar system and there was great anticipation that this work will
provide fundamental insights into the origin of the solar system.

There was a general consensus that many of comet particles are built
like loose dirt-clods composed both of "large strong rocks" as well as
very fine powdery materials. The fine and coarse materials are only
loosely held together and they separated during collection in
low-density aerogel to form tracks shaped like ginseng, turnips or
carrots. The larger components form root-like holes that lead to the
bottoms of the tracks, and the smaller components stopped closer to the
tops of the tracks, forming bulbous turnip-like cavities. The longest
tracks are about two centimeters long and up half a centimeter wide.
Analysis of material in the bulbs has provided the first information on
organic materials in the samples.

[Comet particle tracks in aerogel]

Analysis of the large particles that traveled all the way to the button
of the tracks has revealed a remarkable range of minerals. Some of these
particles contain minerals the form only at extremely high temperatures
- temperatures that could not have existed where the comets formed. Some
of these minerals are similar to "refractory" materials that formed in
the hottest, innermost regions of the disk of gas and dust that formed
the Sun and planets. If these minerals in the comet are from our solar
system then they probably formed close to the young Sun and were
transported all the way from inside the orbit of Mercury past the orbit
of Neptune. Another option is that these "hottest minerals found in the
coldest place" actually formed around other stars. The distinction
between solar system and extra-solar origin of these minerals will be
determined by measuring their isotopic compositions. The abundances of
the isotopes of elements like oxygen is quite different in true stardust
grains, formed around other stars, than it is for materials formed in
our solar system. One of the most exciting outcomes of the workshop was
preliminary data suggesting that the comet is a mix of both stardust
grains from other stars as well as materials formed in the solar system.
As expected, there appears to be true stardust in Stardust.

In addition to Stardust, the sponsors of the workshop also included
sessions on past and future missions. Don Burnett (Caltech) presented
the latest results from the Genesis solar wind mission (a sister mission
to Stardust), Laurie Leshin (Goddard) talked about her work on a Martian
sample return mission, using Stardust technology, and Mike Zolensky
(NASA JSC) and Scott Sandford (NASA Ames) showed images from the
Japanese Hayabusa asteroid sample return mission. Casey Lisse (U.
Maryland) presented his latest results from the Deep Impact comet
mission. One of the most interesting findings of Deep Impact was
evidence for carbonate minerals and silicate minerals that contain bound
water. To date, these materials do not seem to exist or at least be
common in comet Wild 2 sampled by Stardust. Review talks on comet
mineralogy, Calcium Aluminum Inclusions and the formation of the solar
system were given respectively by Diane Wooden (NASA Ames), Glen
McPherson (Smithsonian) and Doug Lin (UC Santa Cruz). A highlight of the
entire meeting was a panel discussion by several of the above speakers
plus Dave Lindstrom (NASA HQ) and Jerry Wasserburg (Caltech). Together
they advised the PET to take care to see the forest through the trees
and write meaningful final reports that will be widely read. Jerry gave
great advice and talked about Stardust and its work on the first comet
samples in comparison with Apollo 11 and his first look at samples from
the Moon, 35 years before.

[Another group photo of Stardust science team]

It was a wonderful meeting and the team left fully charged to complete
the rest of its 6 month initial examination of the comet samples. The
looks on the faces in the above picture express the wonder and
excitement of the meeting. All of the people in the picture played major
roles in Stardust. Jerry Wasserburg is on the right holding up the
banner and Peter Tsou Deputy PI is on his right. Peter and Ben Clark,
just behind Jerrry, have been with Stardust since its beginnings over a
decade ago.
Received on Mon 15 May 2006 04:02:38 PM PDT