[meteorite-list] Yet another article on Buzzard Coulee

From: tett <tett_at_meteoritecentral.com>
Date: Mon, 22 Dec 2008 19:01:45 -0500
Message-ID: <49502A69.3080103_at_rogers.com>

http://www.thespec.com/Wire/News_Wire/Science/article/485822

December 22, 2008
Shannon Montgomery, THE CANADIAN PRESS
The Canadian Press, 2008

CALGARY - More than 100 well-preserved meteorites collected after a
heavenly fireball flashed across the prairie sky last month could
provide a glimpse into the very beginnings of our solar system - or even
earlier.

University of Calgary geologist Alan Hildebrand has been studying pieces
that were rapidly collected from the fall site near the
Alberta-Saskatchewan boundary before the season's first snow.

"Most things about these rocks date from 4 1/2 billion years ago, so it
will show us more about the origin of the solar system, I would think,"
he said.

Hildebrand estimated about 10,000 pieces weighing 10 grams or more fell
to the ground when a meteor streaked across Manitoba, Saskatchewan and
Alberta on Nov. 20.

He said there's no doubt that when recovery efforts resume in the
spring, they'll manage to find at least 1,000 of the dark, dimpled
rocks, which would set a Canadian record for the largest number of
pieces found from a single fall.

A sample size that large would allow scientists to figure out a wide
range of things about the original meteorite, which likely weighed 10
tonnes and was about the size of a desk when it slammed into earth's
atmosphere at a speed of about 14 kilometres per second.

They'll be able to extract clues about the meteorite itself, as well as
the parent asteroid that it originally left behind. They will also be
able to study the fireball some witnesses said was as bright as the sun.

"This one obviously made these spectacular, bright bursts that
eyewitnesses were describing, the blue-white flashes," Hildebrand said.
"Each one of those flashes was a fragmentation episode, and with
hundreds of fragments we can better understand that process in the
atmosphere."

The space rocks have been classified as a type called H4. That means
they're high in iron and experienced a lower level of heat than some
other types of meteorites.

This is important because the more heat a meteorite experiences, the
more its components blend together, making it more difficult to figure
out what elements were involved when it was created.

It's possible that the rocks even contain fragments from before our
solar system existed. To check for this, scientists need to churn
through a lot of samples looking for what is essentially a pre-solar
needle in a haystack.

"To find them, you have to destroy a lot of meteorites," Hildebrand said.

"Because we have lots of meteorites here, and probably have hundreds of
kilograms of it, there will be material available for people who want to
do these experiments."

Hildebrand said some of the experiments will focus on whether the
meteorite comes from a known strike between two bodies in an asteroid
belt about eight million years ago.

About half of similar meteorites that fall to earth have been found to
come from that strike, he said.

"In a geologic sense, that's still the blink of an eye. These rocks are
4.5 billion years old, leftover from the start of the solar system, so
what's eight million years compared to 4.5 billion?"

Since they collected the meteorites so quickly after they hit the
ground, many of the elements will still be intact. Hildebrand pointed
out that some well-preserved meteorites have been found to contain salt,
something that suggests the one-time presence of water.

Still, it's only been a month since the first meteorite chunk was
plucked from a pond near Buzzard Coulee, Sask., Hildebrand said, and
it's still hard to hazard a guess about what secrets lie beneath the
rocks' exteriors.

"It may be something we haven't thought of at all, yet."
Received on Mon 22 Dec 2008 07:01:45 PM PST