Man in the Moon has 'Graphite Whiskers'

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Whitney Clavin 818-354-4673
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Tina McDowell 202-939-1120
Carnegie Institution, Washington, D.C.
tmcdowell@ciw.edu

News release: 2010-220 July 1, 2010

Man in the Moon has 'Graphite Whiskers'

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.cfm?release=2010-220&cid=release_2010-220

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.

-end-

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