[meteorite-list] Crystals on Meteorite Reveal Clues to Early SolarSystem Evolution

From: Jerry <grf2_at_meteoritecentral.com>
Date: Fri, 24 Aug 2007 20:31:03 -0400
Message-ID: <A965475C71CB4005A584E38F737D8574_at_Notebook>

For anyone interested in viewing the parent body referred to in this
article, Aug 29 and 30 provide a splendid backdrop with the bright Jupiter
at center stage.Larry Lebofsky[many of you know that Larry's first "Love"
was astroids before being stung by the "ite virus"] sent me a picture from
S&T depicting this relatively easy viewing[given two consecutive clear skied
night, iffy for New England] which I forwarded to the list. If anyone missed
it, I'd be more than happy to provide that picture again.
Jerry Flaherty
----- Original Message -----
From: "Darren Garrison" <cynapse at charter.net>
To: <Meteorite-list at meteoritecentral.com>
Sent: Wednesday, August 01, 2007 11:08 PM
Subject: [meteorite-list] Crystals on Meteorite Reveal Clues to Early
SolarSystem Evolution


http://www.newswise.com/articles/view/532104/

Newswise - A University of Toronto-led study has uncovered tiny zircon
crystals
in a meteorite originating from Vesta (a large asteroid between Mars and
Jupiter) shedding light on the formation of planetesimals, small
astronomical
objects that form the basis of planets.

To date, studying zircons in eucrites - meteorites formed by volcanic
activity -
has been difficult due to impact- induced fracturing and their small size,
typically less than five microns. Most eucrites are formed within the
asteroid
belt that orbits Mars and Jupiter, a heap of astronomical debris from the
earliest epoch of the solar system. In a study published in the recent issue
of
Science, researchers collected samples from eucrites found in Antarctica
believed to have originated from Vesta. The researchers used new technology
to
reveal that asteroid's boiling rock turned solid and crystallized within
less
than 10 million years of solar system formation.

"Until now we have not been able to determine this time frame
unambiguously,"
says lead author Professor Gopalan Srinivasan of U of T's Department of
Geology.
"By pinpointing the timeframe we're able to add one more piece to the
geological
and historical map of our solar system."

Scientists believe that at some point Vesta was quickly heated and then
melted
into a metallic and silicate core, a similar process that happened on the
Earth.
The energy for this process was released from the radioactive decay that was
present in abundance in the early solar system. What has been unclear is
when
this process occurred. Equipped with the ion microprobe at the Swedish
National
Museum, Srinivasan and colleagues from four institutions set to analyze the
zircons in the eucrites, which formed when a radioactive element -
hafnium-182 -
was still alive. Radioactive hafnium-182 decays to another element -
tungsten-182 - with a nearly 9 million year half-life span. By studying
zircons
for their 182 tungsten abundance, the researchers were able to determine the
crystallization ages of eucrites occurred within that timeframe.

"Zircons on Earth and in space have basically the same characteristics,"
Srinivasan says. "They occur when boiling rock crystallizes and turns into
solid
form primary crystallization products or they could be secondary products
caused
by heating from impacts. We know Vesta became inactive within first 10
million
years of solar system formation which is nearly 4.5 billion years ago. This
provides a snapshot of the early solar system and clues to the early
evolution
of Earth's mantle and core."
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Received on Fri 24 Aug 2007 08:31:03 PM PDT