NASA Develops a Nugget to Search for Life in Space

http://www.nasa.gov/vision/earth/tec...s/nuggets.html

NASA Develops a Nugget to Search for Life in Space
NASA
July 27, 2005

Astrobiologists, who search for evidence of life on other planets, may
find a proposed Neutron/Gamma ray Geologic Tomography (NUGGET)
instrument to be one of the most useful tools in their toolbelt.

As conceived by scientists at the Goddard Space Flight Center (GSFC) in
Greenbelt, Md., NUGGET would be able to generate three-dimensional
images of fossils embedded in an outcrop of rock or beneath the soil of
Mars or another planet. Tomography uses radiation or sound waves to
look
inside objects. NUGGET could help determine if primitive forms of life
took root on Mars when the planet was awash in water eons ago.

Similar to seismic tomography used by the oil industry to locate oil
reserves beneath Earth?s surface, NUGGET would look instead for
evidence
of primitive algae and bacteria that fossilized along the edges of
extinct rivers or oceans. As on Earth, these remains could lie just a
few centimeters beneath the surface, compressed between layers of silt.
If a mechanical rover that explores planet surfaces were equipped with
an instrument like NUGGET - capable of peering beneath the surface -
then it might be able to reveal evidence of life beyond Earth.

"This is a brand new idea," said Sam Floyd, the principal investigator
on the project, funded this year by Goddard's Director's Discretionary
Fund. If developed, NUGGET would be able to investigate important
biological indicators of life, and quickly and precisely identify areas
where scientists might want to take samples of soil or conduct more
intensive studies. "It would allow us to do a much faster survey of an
area," Floyd said.

The proposed instrument, which could be carried on a rover or a robot
lander, is made up of three fundamentally distinct technologies - a
neutron generator, a neutron lens, and a gamma-ray detector.

At the heart of NUGGET is a three-dimensional scanning instrument that
beams neutrons into a rock or other object under study. When the
nucleus
of an atom inside the rock captures the neutrons, it produces a
characteristic gamma-ray signal for that element, which the gamma-ray
detector then analyzes. It's also possible to plot the location of the
elements.

After this process, information can then be turned into an image of the
elements within the rock. By seeing images of certain existing
elements,
scientists could tell whether a certain type of bacteria had become
fossilized inside the rock.

Although the concept of focusing neutrons is not new, the ability to
focus them is. Thanks to a Russian scientist who devised the method in
the 1980s, scientists today can direct a beam of neutrons through a
neutron lens made up of the thousands of long, slender, hair-size glass
tubes. The bundle of tubes is shaped so that the neutrons flowing down
them can converge at a central point. Since the method's invention in
the 1980s, manufacturing practices have made this type of optical
system
feasible for space exploration.

The advantage of this technology is that it can create a higher
intensity of neutrons at a central point on the object. This increased
intensity allows a higher-resolution image to be produced.

Floyd and his co-investigators, Jason Dworkin, John Keller, and Scott
Owens, all from NASA GSFC, plan to conduct experiments this summer at
the National Institute of Standards and Technology (NIST) using one of
NIST's neutron-beam lines. By focusing neutrons into various samples
(one of which is a meteorite), they hope to make a three-dimensional
image of the meteorite's internal structure.

"If we're successful, we'll be in position to say whether a space
flight
instrument is feasible," Floyd said, adding that his research should
give Goddard the lead role in developing a new class of instruments to
support missions for NASA's search of life in the future.