By ROXANA HEGEMAN
Associated Press Writer
GREENSBURG, Kan. (AP) - Scientists were excited when they pulled a
154-pound meteorite from deep below a Kansas wheat field, but what got
them most electrified was the way they unearthed it.
The team Monday uncovered the find 4 feet under a meteorite-strewn
field using new ground-penetrating radar technology that someday might be
used on Mars.
It was that technology which pinpointed the site and proved for the
first time that it could be used to find objects buried deep in the ground
and to make an accurate three-dimensional image of them.
``It validates the technique so we can use something similar to that
instrument when we go to Mars,'' said Patricia Reiff, director of the Rice
Space Institute.
Such GPR systems had been used in the past to locate smaller meteorites
in Antarctica where ice allows easier penetration of the sonar. But until
the Kansas dig, the technology had not been successfully used for ground
detection in heavy soils - like on Mars - to find meteorites or water
there.
The dig was likely the most documented excavation yet of a meteorite
find, with researchers painstakingly using brushes and hand tools to
preserve evidence of the impact trail and to date the event of the
meteorite strike. Soil samples also were bagged and tagged and organic
material preserved for dating purposes.
``When we find a piece of meteorite, each one is a new sentence we add
to the book to understand the evolution of the solar system,'' Essam
Heggy, planetary scientist at the Johnson Space Center's Lunar and
Planetary Institute in Houston.
Even before they had the pallasite meteorite out of the ground, the
scientific experts at the site were able to debunk prevailing wisdom that
the spectacular Brenham meteorite fall occurred 20,000 years ago. Its
location in the Pleistocene epoch soil layer puts that date closer to
10,000 years ago.
``We know it is recent,'' said Carolyn Sumners, director of Astronomy
at the Houston Museum of Natural Science, as she surveyed progress on the
dig. ``Native Americans could have seen it.''
The expedition was put together by the Houston Museum of Natural
Science and led by meteorite hunters Steve Arnold and Philip Mani. Johnson
Space Center's Lunar and Planetary Institute, the Rice Space Institute at
Rice University and George Observatory in Houston also sent researchers.
Fewer than 1 percent of the meteorites discovered on earth are
pallasite meteorites, known for their crystals embedded in iron, Mani
said.
Sophisticated metal detectors at the site initially detected what had
been thought to be the largest pallasite meteorite ever discovered. But
ground-penetrating radar showed that the object was only a steel cable.
The Brenham field was discovered in 1882. Scientists have since traced
pieces of the shower as far away as Indian mounds in Ohio, indicating the
meteorites were traded as pieces of jewelry and ceremonial artifacts.
The site was largely forgotten in recent decades until Arnold and Mani
leased eight square miles of it and began looking deep below the surface.
More than 15,000 pounds of meteorites have been recovered from the area.
This week's find will end up as part of a new exhibit on comets,
meteors and asteroids at the Houston Museum of Natural Science. The museum
will pay about $50,000 for it, Sumners said. It is valued at more than
$100,000, she said.
Landowner Alan Binford watched with interest as the scientists freed
the meteorite, bagging clumps of his rich Kansas farmland around it.
``I didn't figure there would be that much scientific value,'' he said.
``I never thought about them going to this extent. It is interesting
history.''
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On the Net:
Houston Museum of Natural Science: http://www.hmns.org
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