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Mining for Meteorites - Part 2 of 12

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

Don't feel undereducated if you didn't know that; for ages, humans
misunderstood or ignored meteorites. In the 19th century, some
scientists dismissed them as wild superstition or explained them as
terrestrial rocks hurled by rogue winds or conglomerates formed by
thunderstorms. After one split up and fell over Weston, Connecticut, in
1807, a myth grew up that Thomas Jefferson had commented: "I would more
easily believe that two Yankee professors would lie than that stones
would fall from heaven."
Since then, modern astronomy and scores of well-documented falls have
shown that earth's atmosphere is bombarded with perhaps 50,000 tons of
interplanetary debris each year. Probably most comes out of the asteroid
belt, a collection of sub-planet-size junk floating between Mars and
Jupiter. Some may be pieces of comets. By the 1980s, scientists had
accepted the once far-out idea that a few rare ones are pieces of Mars
and the moon, blasted into space by asteroid or comet impacts. When
those chunks intersect our orbit, they plummet to earth. Fortunately for
us, most celestial debris consists of dust-size particles, not proper
rocks. Even spectacular shooting stars are usually pea-size; most are
consumed far above earth's surface. Long-term photographic records of
meteors suggest perhaps 6,800 meteorites, each weighing at least a
pound, touch down annually. No one knows for sure how many, because
almost none are found. There are good reasons. Three-quarters of the
planet is ocean; most of the rest is uninhabited. Most meteorites are
far smaller than the ones that fell on Portales, and set down without
fireworks - just a golf-ball thud on the ground. There, they can easily
be obscured by plants, dirt or similar-looking rocks.
Explosions of the big ones are seen for hundreds of miles, but optical
illusions often send searchers to the wrong spots. Until recently,
fragments of only 2,600 meteorites had ever been identified, most of
them chance finds of corroded old pieces. Even now, pieces of only five
or six witnessed falls are retrieved worldwide each year. On the bright
side, no human-meteorite fatality is known, though a 1911 fall did kill
a dog in Egypt.

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