[meteorite-list] The Impire strikes dust

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Mon, 1 Sep 2008 12:12:21 -0500
Message-ID: <027801c90c55$e5747d60$2d42e146_at_ATARIENGINE>

Hi, List

    The age of the Karin cluster of the Koronis
family is 5.75 ? 0.05 million years. This is very
young for an asteroidal breakup. The age was
determined in 2002, as described in this press
release from SwRI:
http://www.swri.org/9what/releases/2002/15asteroid.htm

    There's a good discussion here:
http://www.geotimes.org/june02/WebExtra0613.html

    The asteroid 832 Karin is less than 12 miles in
diameter, but was originally more than 20 miles
(33 kilometers). 832 Karin contains less than 20%
of the mass of the 40-to-90-member cluster:
http://en.wikipedia.org/wiki/Karin_Cluster

    There is an ongoing argument about the spectral
characteristics of the surface of Karin. It is claimed
(by some and denied by others) that the surface shows
spectral variations with rotation, which would mean
that "space weathering" has not re-processed the
surface damaged by the impact. Here's one side:
http://apollo.cnuce.cnr.it/rossi/publications/Vernazza_etal_832Karin.pdf
And here's the other side:
http://sasakitakanori.com/wp-content/uploads/2006/08/karin_antarcticmeteorites_2004.pdf
(For every expert, there is an equal and opposite expert.)

    The Karin cluster is no longer the youngest asteroid
family. A small one derived from 1270 Datura is dated
to only 425,000 years old, and the 11-member Iannini
family is younger than 5 million years although the
exact age has not yet been determined. Cluster families
once thought to be much older -- the Veritas family was
dated at 80 million years old -- have been found to be
much younger (Veritas at 8.3 to 8.9 million years).

    One improvement in dating clusters has been the
ability to include the Yarkovsky and YORP effects
in the calculations. Here's a nice paper on Yarkovsky
and YORP effects on the dynamics of asteroid families:
http://journals.cambridge.org/download.php?file=%2FIAU%2FIAU2004_IAUC197%2FS1743921304008609a.pdf&code=a0c52e6d39bb0e22d298f403f4d38dc7

    The implication is that breakups are much more
frequent than formerly believed, that breakups continue
to happen and will happen in the (relatively) near
future, and that the solar system is not the quiet
orderly place we want to think it is. (It's the natural
inclination to say "Nothing happening here. Move
along. Nothing to see. Keep moving. Move along,
please...")

    We've had this argument right here on The List,
about whether the dust particles so easy to collect
are actually cosmic dust or industrial dust. Genge's
analysis bears directly on this. He is saying that the
particle size is so small that individual particles do
not constitute a valid sample of the source, but by
combining a full analyses of 600 particles into one
high-mass "sample," the cosmic origin becomes
clear and even precise as to asteroidal source type
(a methodologically appealing argument).

    I'm going to go sweep some asteroid dust off
my porch now, while I wait for the next big asteroid
breakup...


Sterling K. Webb
-------------------------------------------------------------------
----- Original Message -----
From: "Darren Garrison" <cynapse at charter.net>
To: <meteorite-list at meteoritecentral.com>
Sent: Monday, September 01, 2008 10:25 AM
Subject: [meteorite-list] The Impire strikes dust


http://www3.imperial.ac.uk/newsandeventspggrp/imperialcollege/newssummary/news_1-9-2008-9-1-49?newsid=43054

Cosmic connections: Imperial scientist locates the origin of cosmic dust

Monday 1 September 2008

The origin of the microscopic meteorites that make up cosmic dust has been
revealed for the first time in new research out today (1 September 2008).

The research, published in the journal Geology, shows that some of the
cosmic
dust falling to Earth comes from an ancient asteroid belt between Jupiter
and
Mars. This research improves our knowledge of the solar system, and could
provide a new and inexpensive method for understanding space.

Cosmic dust particles, originally from asteroids and comets, are minute
pieces
of pulverised rock. They measure up to a tenth of a millimetre in size and
shroud the solar system in a thin cloud. Studying them is important because
their mineral content records the conditions under which asteroids and
comets
were formed over four and a half billion years ago and provides an insight
into
the earliest history of our solar system.

The study's author, Dr Mathew Genge, from Imperial College London's
Department
of Earth Science and Engineering, has trekked across the globe collecting
cosmic
dust. He says:

"There are hundreds of billions of extraterrestrial dust particles falling
though our skies. This abundant resource is important since these tiny
pieces of
rock allow us to study distant objects in our solar system without the
multi-billion dollar price tag of expensive missions."

The origin of the cosmic dust that lands on Earth has always been unclear.
Scientists previously thought that analysing the chemical and mineral
content of
individual dust particles was the key to tracing their origin. But this
study
suggests that a comparison of multiple particles gives better results.

To pinpoint the cosmic dust's origin, Dr Genge analysed more than 600
particles,
painstakingly cataloguing their chemical and mineral content and
reassembling
them like a complex jigsaw. Dr Genge comments:

Dr Genge's work locates the origin of some cosmic dust

"I've been studying these particles for quite a while and had all the pieces
of
the puzzle, but had been trying to figure out the particles one by one. It
was
only when I took a step back and looked at the minerals and properties of
hundreds of particles that it was obvious where they came from. It was like
turning over the envelope and finding the return address on the back."

Dr Genge found that the cosmic dust comes from a family of ancient space
rocks
called Koronis asteroids, which includes 243 Ida, widely photographed by the
NASA Galileo probe. The rocks are located in an asteroid belt between Mars
and
Jupiter and were formed around two billion years ago when a much larger
asteroid
broke into pieces. Further analysis shows that the dust originates from a
smaller grouping of 20 space rocks within the Koronis family called Karin
asteroids. It comes from an ancient chondrite rock, common in Karin
asteroids,
which was formed in space at the birth of the solar system.

Chondrite meteorites often fall to Earth and Dr Genge was able to match the
mineralogy and chemistry of the dust particles with chondrite meteorite
samples
previously collected. He backed up the cosmic dust's origin with infrared
astronomical satellite data which showed Karin asteroids grinding and
smashing
against one another to create cosmic dust.

Dr Genge says his research holds exciting possibilities for a deeper
understanding of our early solar system. He concedes that analysing space
dust
will never entirely replace space missions, but adds that we may not have to
visit so many different places. He concludes:

"This research is the first time we have successfully demonstrated a way to
locate the home of these important little particles. The answer to so many
important questions, such as why we are here and are we alone in the
universe,
may well lie inside a cosmic dust particle. Since they are everywhere, even
inside our homes, we don't necessarily have to blast off the Earth to find
those
answers. Perhaps they are already next to you, right here and right now."
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Received on Mon 01 Sep 2008 01:12:21 PM PDT