[meteorite-list] New Australian fall

From: Darren Garrison <cynapse_at_meteoritecentral.com>
Date: Fri, 18 Sep 2009 12:51:04 -0500
Message-ID: <43i7b5d7ifjdp9iupd1jlrd1o62hkdjp5r_at_4ax.com>

http://www.smh.com.au/technology/sci-tech/rare-snapshot-of-solar-systems-dawn-20090918-fvcl.html

Rare snapshot of solar system's dawn
DEBORAH SMITH SCIENCE EDITOR
September 19, 2009

CAMERAS set up in outback Australia to track fireballs across the night sky have
led scientists to a rare meteorite formed at the dawn of the solar system.

The fiery streak it made on descent allowed them not only to pinpoint where it
would fall on the vast Nullarbor Plain, but also work out where it had come
from.

Three fragments of the meteorite, the biggest the size of a cricket ball, were
found within 100 metres of the predicted landing site, Alex Bevan, head of earth
and planetary science at the Western Australian Museum, said. ''That is
incredible accuracy.''

Dr Bevan said the Nullarbor desert was chosen for a new fireball observatory
because of its pale limestone colour. ''Most meteorites are dark so they
contrast well with the local rock.''

Dubbed Bunburra Rockhole after a nearby landmark, the meteorite was found on the
first day of searching by the international team, which includes researchers
from the Perth museum and CSIRO.

Meteorites are among the most studied rocks on Earth, the team leader, Philip
Bland, of the Imperial College in London, said. ''But it's really rare for us to
be able to tell where they came from.''

Based on its unusual basalt composition and trajectory, the researchers believe
the Nullarbor meteorite was once part of an asteroid in the innermost side of
the asteroid belt between Mars and Jupiter, until a collision chipped it off
millions of years ago.

It then moved into an orbit around the sun similar to that of Earth, before
plummeting to the ground on July 20, 2007.

Weighing about 22 kilograms when it began its fiery descent at an altitude of 60
kilometres, only fragments of less than 200 grams were left when it hit.

''We're cautiously optimistic that this find could be the first of many, and if
that happens, each find may give us more clues about how the solar system
began,'' Dr Bland, whose team's study was published yesterday in the journal
Science, said.

Asteroids in the innermost belt are thought to have formed near the sun and
consist of the same material from which the earth was made.

The fireball observatory consists of a network of four cameras that take a
single time-lapse picture every night to track any shooting stars, and complex
mathematics is required to determine a meteorite's original orbit.
Received on Fri 18 Sep 2009 01:51:04 PM PDT