[meteorite-list] Man in the Moon has 'Graphite Whiskers'

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu, 1 Jul 2010 14:45:23 -0700 (PDT)
Message-ID: <201007012145.o61LjNOK018801_at_zagami.jpl.nasa.gov>

http://www.jpl.nasa.gov/news/news.cfm?release=2010-220

Man in the Moon has 'Graphite Whiskers'
Jet Propulsion Laboratory
July 01, 2010

PASADENA, Calif. -- In a new analysis of a lunar sample collected by
Apollo 17, researchers have detected and dated carbon on the moon in the
form of graphite -- the sooty stuff of pencil lead -- which survived
from around 3.8 billion years ago, when the moon was heavily bombarded
by meteorites. Up to now, scientists thought the trace amounts of carbon
previously detected on the surface of the moon came from the solar wind.

Some of the graphite revealed by the new study appeared in a rare rolled
form known as "graphite whiskers," which scientists believe formed in
the very high-temperature reactions initiated by a meteorite impact. The
discovery also means that the moon potentially holds a record of the
carbon input by meteors into the Earth-moon system when life was just
beginning to emerge on Earth. The research is published in the July 2
issue of the journal Science.

"The solar system was chaotic, with countless colliding objects 3.9
billion years ago," explained lead author Andrew Steele, based at the
Carnegie Institution for Science in Washington, D.C. "Volatiles --
compounds like water and elements like carbon -- were vaporized under
that heat and shock. These materials were critical to the creation of
life on Earth."

"Materials that fell on the early Earth fell on the moon as well,
because the two bodies basically share the same gravity well," said Marc
Fries, a planetary scientist who conducted the research while working at
NASA's Jet Propulsion Laboratory, Pasadena, Calif., and is now based at
the Planetary Science Institute in Tucson, Ariz. "This sample is like a
pristine page from Earth's past, before plate tectonics and other forces
erased the history of this ancient carbon material on Earth."

While the sample from the Mare Serenitatis area came back to Earth in
1972, the research team, led by scientists at the Geophysical Laboratory
of the Carnegie Institution for Science, used a new technique known as
Raman spectroscopy on the sample. Previous techniques enabled scientists
to get a sense of the composition, but this kind of spectroscopy is more
sensitive and also allows scientists to create an image of the minerals.
The graphite whiskers appeared to be a few micrometers in diameter and
up to about 10 microns long.

Scientists were surprised at the finding of graphite and graphite whiskers.

"It shows that modern spatially resolved techniques could be used to
discover further surprises in the now 40-year-old Apollo collection,"
said co-author Mihaela Glamoclija, based at the Carnegie Institution.

The scientists ruled out the possibility that the graphite was a result
of contamination, because graphite whiskers, in particular, form under
very hot conditions, between 1,830 and 6,500 degrees Fahrenheit (1,273
to 3,900 Kelvin). They also ruled out the solar wind as the source,
because the graphite and graphite whiskers were much larger than carbon
implanted by the solar wind, and while contamination occurred throughout
the sample, the graphite was restricted to a discrete blackened area of
the sample.

"We believe that the carbon we detected either came from the object that
made the impact basin, or it condensed from the carbon-rich gas that was
released during impact," said co-author Francis McCubbin, of the
Carnegie Institution.

The research was partly funded by the NASA Astrobiology, Mars
Fundamental Research, and the Lunar Advanced Science and Exploration
Research programs in NASA's Planetary Division in Washington. The
California Institute of Technology manages JPL for NASA.

Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.
whitney.clavin at jpl.nasa.gov

Tina McDowell 202-939-1120
Carnegie Institution, Washington, D.C.
tmcdowell at ciw.edu

2010-220
Received on Thu 01 Jul 2010 05:45:23 PM PDT