[meteorite-list] Tagish Lake Meteorite 'A Gem'

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:00:08 2004
Message-ID: <200207221655.JAA19333_at_zagami.jpl.nasa.gov>

http://news.bbc.co.uk/hi/english/sci/tech/newsid_2144000/2144150.stm

Rare space rock 'a gem'
By Helen Briggs
BBC News
July 22, 2002

British scientists have confirmed that one of the rarest meteorites ever to
fall to Earth is from a time when the Solar System was born.

It provides a glimpse of a period, 4.5 billion years ago, when the planets
were beginning to form.

The chunk of space rock is higher in extra-terrestrial material than any
other meteorite and may belong in a class of its own, say researchers at
London's Natural History Museum.

A team led by Dr Sara Russell is one of a handful around the world that is
analysing slivers of the rock.

It came down over Tagish Lake, a remote area of northern Canada, on 18
January, 2000.

Fragments landed on a frozen lake and were preserved in ice almost
immediately.

By a stroke of luck, they were found by someone who knew to keep them cold
and not to touch them.

"It turns out that this meteorite is a really unique sample," says Dr
Russell. "It's higher in extra-terrestrial organic material than any other
meteorite."

Building blocks

Research at the museum has confirmed that the Tagish meteorite is "extremely
primitive" in its chemical composition.

It has changed little since it first arose "in the very earliest stages of
the Solar System," says Dr Russell.

Tiny grains in the rock should reveal new information about the dust and
gases that came together to make the planets.

"Our work on Tagish lake is very much work in progress at the moment," Dr
Russell told BBC News Online. "What we think we've found is that this is a
sample of the very earliest building blocks of the materials that went on to
make up the planets in our Solar System."

The sample gives scientists a chance to learn more about how the planets
formed.

It could also reveal whether or not other Earth-like planets are likely to
be found around other young stars.

Space gems

The meteorite is from a class known as the carbonaceous chondrites.

These primitive, carbon-rich space rocks contain organic compounds such as
amino acids.

They also contain tiny jewels in the form of pre-solar diamonds and
sapphires.

These would have been made around the stars that were the ancestors of the
Sun, and can tell scientists about the processes that occur inside stars.

Emma Bullock, a postgraduate student in the department, is working on the
composition of the meteorite for her thesis.

"It's unlike any other meteorite we've ever seen so it possibly belongs in a
group all of its own," she says.

"There are [compounds containing the element sulphur] in this meteorite that
aren't found on Earth and there are also some very unusual shapes of
sulphide.

"It's got some other very interesting features," she adds. "It's been
altered by water but not really by heat so that's affected some of the
minerals."
Received on Mon 22 Jul 2002 12:55:07 PM PDT