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Posted by: dvandorn Jan 31 2006, 04:44 PM

I was watching a special on the National Geographic Channel last night, in which they discussed the Taggish Lake (I think I have that name right) meteor.

Now, in earlier coverage of that event, I had learned that the pieces of that meteor were light and frothy, with more voids than rock. However, last night, an LPI investigator showed one rather solid piece and stated that it was simply a set of clays.

So -- if that's the case, then why in the Solar System was anyone surprised that Deep Impact indicated the presence of clays in Temple II?

Obviously, the Taggish Lake meteor was a fairly decent-sized chunk of a comet. Which means we've been examining cometary clays for some years now.

Anyone have any further details on this?

-the other Doug

Posted by: The Messenger Jan 31 2006, 05:00 PM

Interesting.

There has been obvious downplay on the clay found in Tempel I - Jessica Sunshine did not mention clay in her Planetary Society interview, not even when she was ask if there were any surprises.

I will venture that the emphesis on the 'frothy' is driven by the fact that it does seem to provide a comet with at least a 'shell' that has low density, pockets for water and organics; and allows a comet to have the physical properties that make it a gas-water vapor-dust emitting comet.

One question that remains is, are the clays an intregal relic of the nucleus, or dust and other stuff picked up sweeping through the inner solar system? 

Posted by: ljk4-1 Feb 3 2006, 04:00 PM

UA Scientist and Private Collector Form Center to Save Meteorites

http://www.spaceref.com/news/viewpr.html?pid=18920

"If something isn't done soon, most of Earth's rare space rocks could be gone in
a lifetime. This particularly alarms scientists who want to study meteorites -- rocks from outer space ranging in size from microscopic particles to boulders weighing tons -- because the extraterrestrial rocks can help them unlock the secrets of our solar system's history and, possibly, the origins of life."


-- Dust Found in Earth Sediment Traced to Breakup of the Asteroid Veritas 8.2
Million Years Ago

http://www.spaceref.com/news/viewpr.html?pid=18911

"In a new study that provides a novel way of looking at our solar system's past,
a group of planetary scientists and geochemists announce that they have found evidence on Earth of an asteroid breakup or collision that occurred 8.2 million years ago."

Posted by: RGClark Feb 4 2006, 03:50 PM

Thanks for the info. I hadn't seen that before. Apparently clay has been seen in several carbonaceous meteorites. Note that the term "phyllosilicates" is often used to mean clays:


STRUCTURE AND BONDING OF CARBON IN CLAYS FROM CI CARBONACEOUS CHONDRITES.
Laurence A.J. Garvie1 and Peter R. Buseck1,2, 1Department of Geological Sciences, Arizona State University,
Tempe, Arizona 85287-1404, ****@asu.edu, 2Department of Chemistry and Biochemistry, Arizona State
University, Tempe, Arizona, 85287
http://www.lpi.usra.edu/meetings/lpsc2005/pdf/1515.pdf

ASTEROIDAL WATER: THE EVIDENCE FROM THE AQUEOUS ALTERATION EXHIBITED BY CHONDRITIC METEORITES.
M.E. Zolensky, SN2, NASA Johnson Space Center, Houston, TX 77058 USA
Eleventh Annual V. M. Goldschmidt Conference (2001)
http://www.lpi.usra.edu/meetings/gold2001/pdf/3052.pdf

THE PETROLOGY OF FINE-GRAINED MICROMETEORITES: EVIDENCE FOR THE DIVERSITY OF PRIMITIVE ASTEROIDS.
M. J. Genge1, J. Bradley2, C. Engrand3, M. Gounelle1, R. P. Harvey4and M. M.Grady1, 1Department of Mineralogy, The Natural History Museum, London SW7 5BD,2MVA Inc, Atlanta, USA,3C. S. N. S. M., Orsay, France, 4Case Western Reserve Univ., Ohio, USA
Lunar and Planetary Science XXXII (2001)
http://www.lpi.usra.edu/meetings/lpsc2001/pdf/1546.pdf

Mineralogy of Phyllosilicate-rich Micrometeorites and Comparison with Tagish Lake CI and Sayama CM Chondrite.
Noguchi, T.; Nakamura, T.
32nd Annual Lunar and Planetary Science Conference, March 12-16, 2001, Houston, Texas, abstract no.1541
http://www.lpi.usra.edu/meetings/lpsc2001/pdf/1541.pdf


And this discusses carbon globules in the Tagish lake meteorite:

CARBONACEOUS NANOPARTICLES IN TAGISH LAKE AND IVUNA: WHY DO THEY IN TAGISH LAKE HAVE NITROGEN-ENRICHED RIMS?
T. Noguchi1 and A. Naka-zawa1, E. Okunishi2, H. Naraoka3, T. Nakamura4, and K. Naka-mura5. 1Department of Materials and Biological Sciences, Ibaraki University. E-mail: tngc@mx.ibaraki.ac.jp. 2JEOL Co. Ltd., 3Department of Earth Sciences, Okayama University, 4Department of Earth and Planetary Sciences, Kyushu University, 5JSC, NASA
68th Annual Meteoritical Society Meeting (2005)
http://www.lpi.usra.edu/meetings/metsoc2005/pdf/5155.pdf

The organic compounds in these globules contain 100 atoms of carbon. Perhaps someone with knowledge of organic chemistry can answer this question: does this amount of carbon in organics occur in nature not related to life?

This article may also be interesting:

Microfossils in CI and CO carbonaceous meteorites.
Hoover, Richard B.; Rozanov, Alexei Y.; Jerman, Gregory A.; Costen, James
Instruments, Methods, and Missions for Astrobiology VII. Edited by Hoover, Richard B.; Rozanov, Alexei Y. Proceedings of the SPIE, Volume 5163, pp. 7-22 (2004).
http://adsabs.harvard.edu/cgi-bin/bib_query?2004SPIE.5163....7H [abstract only]

I don't have access to this paper, but perhaps the forms they discuss look like those in fig 1. from here:

NITROGEN AND CARBON ISOTOPIC MEASUREMENTS OF CARBON NANOGLOBULES FROM THE TAGISH LAKE METEORITE BY SECONDARY ION MASS SPECTROMETRY.
J. W. Ashley1,2, G. R. Huss1, L. A. J. Garvie1, Y. Guan1, P. R. Buseck1,3, and L. B. Williams1. 1Department of Geological Sciences, Arizona State University, Box 871404, Tempe, AZ 85287-1404; 2Minor Planet Research, Inc., Box 17131, Fountain Hills, AZ, 85269-7131; 3Department of Chemistry/Biochemistry, Arizona State University, Box 871404, Tempe, AZ 85287-1604.
Lunar and Planetary Science XXXVI (2005)
http://www.lpi.usra.edu/meetings/lpsc2005/pdf/2205.pdf



Bob Clark

Posted by: Rob Pinnegar Feb 4 2006, 06:05 PM

As a sidenote, I know a few of the people who helped hunt for fragments of the Tagish Lake meteorite pretty well. I actually had the chance to go up there myself, but at the time the significance of the discovery wasn't yet known, and I had a conference talk to prepare.

So, I turned it down. Always have regretted that. Anyways, my buddy Phil McCausland went up there instead, and did a better job than I could've done (Phil has a lot more field experience than me).

Some of the video footage from the hunt is fun to watch. The best scene is of Alan Hildebrand (from U of Calgary) sticking a chainsaw into the ice in an attempt to reach a big chunk of the meteorite, and getting his boots covered in pulped meteorite slush. Apparently he overestimated its depth. I gather he wasn't very happy about that.

Posted by: Rob Pinnegar Feb 4 2006, 06:25 PM

From what I remember, the reason the Tagish Lake meteorite caused such a stir was that it turned out to be the first (and so far, only) known member of a class of carbonaceous chondrites -- I think it's called a C2? So it may not be all *that* representative of most comets.

There was an article in Science in October 2000 that described Tagish Lake. I've got a copy somewhat in my apartment, but can't find it right now. However, I'm pretty sure Peter Brown and Alan Hildebrand are the lead authors. (They also included every person from the recovery team in the author list. It is because of this kind of thing that abstract volumes are so bloody thick).

Posted by: The Messenger Feb 5 2006, 06:17 PM

In my own experience - we see the formation of nano-molecules - bucky balls and such, in high temperature, high pressure fuel-rich combustion. They are a real nuisance - they scratch and plug almost any valve type and lead to frequent replacement.

Posted by: ljk4-1 Apr 25 2006, 03:33 PM

This article focuses on how "pristine" the Tagish Lake meteorite is.

But what about other meteorites such as the famous Murchison one
from 1969, where amino acids never seen on Earth before were found
on it?

http://www.ast.cam.ac.uk/AAO/local/www/jab/astrobiology/murchison.html

And what about those meteorites which landed on Antarctica? Sure,
maybe they didn't get picked up right away, but the South Pole tends
to be a really good deep freezer and may have done a good job at
preserving those space rocks from the get-go, making them also
pristine? Any interesting examples that stand out - besides ALH84001?

http://www.spacedaily.com/reports/One_Of_A_Kind_Meteorite_Unveiled.html

Posted by: ljk4-1 May 5 2006, 04:54 PM

Meteorites discovered to carry interstellar carbon

http://www.spaceref.com/news/viewpr.nl.html?pid=19771

Using new techniques, scientists at the Carnegie Institution's Department of
Terrestrial Magnetism have discovered that meteorites can carry other, much
older passengers as well -- primitive, organic particles that originated billions
of years ago either in interstellar space, or in the outer reaches of the solar
system as it was beginning to coalesce from gas and dust.

Posted by: ljk4-1 May 30 2006, 08:17 PM

Announcement from Planetary Science Research Discoveries [PSRD]

New Issue: Carbonaceous chondrites contain organic compounds with high deuterium/hydrogen ratios, suggesting they formed in interstellar space.

Full story and pdf link at:

http://www.psrd.hawaii.edu/May06/meteoriteOrganics.html