[meteorite-list] Reactor Reveals Hidden Life Of Rocks

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:04:51 2004
Message-ID: <200205232316.QAA06611_at_zagami.jpl.nasa.gov>

http://www.eurekalert.org/pub_releases/2002-05/uoc--rrh052302.php

Contact: Andy Fell
ahfell_at_ucdavis.edu
530-752-4533
University of California - Davis

Reactor reveals hidden life of rocks
May 23, 2002

Geologists at the University of California, Davis, are using neutron beams
from a nuclear reactor to see inside rocks. The method could be used to look
for traces of life in rocks from Mars or very ancient rocks from the Earth.

"Normally, we'd make a three-dimensional image by cutting the rock in
slices. With this method, we can do it without destroying the rock," said UC
Davis geology professor Charles Lesher.

Researcher Martin Wilding, geology assistant professor Dawn Sumner and
Lesher have already used the method, called neutron tomography, to find
bacteria living inside rocks collected in the Mars-like environment of
Antarctica's dry valleys and Israel's Negev desert. They're also using it to
study the structure of volcanic rocks and glasses, and of "black smoker"
chimneys collected from the deep ocean floor.

Neutron tomography could also be used for biology experiments, such as
filming water movement inside plants, Wilding said.

"We're just scratching the surface of what we can do," he said.

Neutrons are very sensitive to water and light elements such as the hydrogen
and carbon, which are major components of living things. But they can pass
right through a steel container. In contrast, water and most living tissue
are fairly transparent to X-rays, but X-rays are stopped by heavier
elements. That means that neutron beams can be used to scan a Martian rock
for traces of life even while it is sealed in a metal container.

The process is comparable to a medical CT (computed tomography) scan with
X-rays. The sample rotates in the neutron beam and a series of pictures are
taken with a digital camera system. These two-dimensional images are
reconstructed, using the same equations used for CT scans, into a series of
"slices" through the sample. These slices can also be made into a
three-dimensional image.

The neutron beam is generated by the research reactor at UC Davis' McClellan
Nuclear Radiation Center. The reactor was built in 1990 by the U.S. Air
Force to check for corrosion in aircraft components. It was transferred to
UC Davis in 2001.

Note: Quicktime movies of bacteria within a rock and of geology samples are
available. Contact Andy Fell for details.

Media contacts:
Martin Wilding, Geology, 530-752-5041, mcwilding_at_ucdavis.edu
Charles Lesher, Geology, 530-752-9779, lesher_at_geology.ucdavis.edu

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Received on Thu 23 May 2002 07:16:02 PM PDT