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Mining for Meteorites - Part 11 of 12

KRAJICK KEVIN (1999) Mining for Meteorites
(Smithsonian, March 1999, pp. 90 -100):

Even the fabulously funded NSF has only one main instrument for finding
meteorites: the human eye. "Still the most powerful tool we have," says
Ralph Harvey, head of the NSF collecting team. Now, NASA is developing a
robot that can be equipped with cameras, infrared sensors, a metal
detector, a magnetometer and a spectrometer for finding samples buried
under ice or in the dark. The robot might be used in Antarctica, where
it would plant little flags next to finds for humans to pick up later.
Simpler technology may solve the problem of finding the oldest
meteorites. Even most Antarctic specimens landed no more than a few
million years ago; older falls have disappeared under ice or rock,
washed into the sea or disintegrated, leaving falls from most of the
earth's history unprospected, except for a handful of "fossil"
meteorites accidentally found in mines and quarries. So Andrew Sicree, a
researcher at Pennsylvania State University, got an idea. Coal mines
routinely run powerful electromagnets over the coal to cull "tramp iron"
- lunch boxes, wrenches and other junk that falls in and could wreck
processing equipment. It might be possible, he believes, that some culls
are iron-rich meteorites that fell when the coal was plant matter
growing on the surface. He has made a deal with 13 mines to save what
they pull out, and is sorting through his first batch of  100,000
pieces.
Searches for the newest meteorites are becoming more imaginative, too.
When thousands of people saw a fireball explode in the sky somewhere
around El Paso, Texas, on October 9, 1997, U.S. and Canadian scientists
assembled to calculate its trajectory, speed and mass so they could
target possible fragments. Alan Hildebrand, a prominent planetary
scientist with the Geological Survey of Canada, went door-to-door with
colleagues to interview witnesses and examine photographs and videos of
the phenomenon. They triangulated seismographs that had recorded the
blast. Then they called in the heavy artillery: a U.S. military network
of low-frequency microphones and light-sensing satellites designed for
detecting nuclear explosions and missile launches. Recently declassified
documents reveal that the devices also record big meteors; scientists
from Los Alamos National Laboratory in New Mexico got the data released.
After collating this information, scientists searched on foot for weeks
in the designated area and found ... nothing.

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