[meteorite-list] NASA Scientists Find Primordial Organic Matter in Tagish Lake Meteorite

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Fri, 1 Dec 2006 09:17:13 -0800 (PST)
Message-ID: <200612011717.JAA28392_at_zagami.jpl.nasa.gov>

http://www.nasa.gov/centers/johnson/news/releases/2006/J06-103.html

William Jeffs
Johnson Space Center, Houston
281-483-5111

RELEASE: J06-103

NASA Scientists Find Primordial Organic Matter in Meteorite
November 30, 2006

NASA researchers at Johnson Space Center, Houston have found organic
materials that formed in the most distant reaches of the early Solar
System preserved in a unique meteorite. The study was performed on the
Tagish Lake carbonaceous chondrite, a rare type of meteorite that is
rich in organic (carbon-bearing) compounds.

Organic matter in meteorites is a subject of intense interest because
this material formed at the dawn of the Solar System and may have seeded
the early Earth with the building blocks of life. The Tagish Lake
meteorite is especially valuable for this work because much of it was
collected immediately after its fall over Canada in 2000 and has been
maintained in a frozen state, minimizing terrestrial contamination. The
collection and curation of the meteorite samples preserved its pristine
state.

In a paper published in the Dec. 1 issue of the journal Science, the
team, headed by NASA space scientist Keiko Nakamura-Messenger, reports
that the Tagish Lake meteorite contains numerous submicrometer hollow
organic globules.

"Similar objects have been reported from several meteorites since the
60's. Some scientists believed these were space organisms, but others
thought they were just terrestrial contamination," said
Nakamura-Messenger. The same bubble-like organic globules appeared in
this freshest meteorite ever received from space. "But in the past,
there was no way to determine for sure where these organic globules came
from because they were simply too small. They are only 1/10,000 inch in
size or less."

In 2005, two powerful new nano-technology instruments were installed in
the scientists' laboratory at Johnson Space Center. The organic globules
were first found in ultrathin slices of the meteorite with a new JEOL
transmission electron microscope. It provided detailed structural and
chemical information about the globules. The organic globules were then
analyzed for their isotopic compositions with a new mass spectrometer,
the Cameca NanoSIMS, the first instrument of its kind capable of making
this key measurement on such small objects.

The organic globules in the Tagish Lake meteorites were found to have
very unusual hydrogen and nitrogen isotopic compositions, proving that
the globules did not come from Earth.

"The isotopic ratios in these globules show that they formed at
temperatures of about -260?? C, near absolute zero," said Scott
Messenger, NASA space scientist and co-author of the paper. "The organic
globules most likely originated in the cold molecular cloud that gave
birth to our Solar System, or at the outermost reaches of the early
Solar System."

The type of meteorite in which the globules were found is also so
fragile that it generally breaks up into dust during its entry into
Earth's atmosphere, scattering its organic contents across a wide swath.
"If, as we suspect, this type of meteorite has been falling onto Earth
throughout its entire history, then the Earth was seeded with these
organic globules at the same time life was first forming here." said
Mike Zolensky, NASA cosmic mineralogist and co-author of the paper.

The origin of life is one of the fundamental unsolved problems in
natural sciences. Some biologists think that making a bubble-shape is
the first step on the path to biotic life. "We may be a step closer to
knowing where our ancestors came from," Nakamura-Messenger said.

- end -
Received on Fri 01 Dec 2006 12:17:13 PM PST