[meteorite-list] Scars Left By A Space Rock (Meteor Crater)

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 09:53:35 2004
Message-ID: <200212181651.IAA02795_at_zagami.jpl.nasa.gov>

Scars Left By A Space Rock
Baltimore Sun
16 December 2002

METEOR CRATER, Ariz. -- About 50,000 years ago, a fireball streaked across
the sky at 11 miles per second and crashed into the desert here, triggering
a blast 1,000 times more powerful than the atomic bomb that devastated
Hiroshima.

The meteorite was 150 feet wide and weighed 300,000 tons. In less than 10
seconds, it sent 175 million tons of material flying miles in all
directions. The blast killed all the animal life -- mastodons, mammoths,
giant ground sloths and bison -- within several miles. It created a crater 2
1/2 miles in circumference, 750 feet deep and 4,100 feet wide.

Today, scientists consider this gigantic hole, known as the Barringer
Meteorite Crater, to be the world's youngest and best-preserved impact
crater.

About 300,000 visitors view the crater annually. It's located on privately
owned land in northern Arizona's high desert, about 35 miles east of
Flagstaff and 20 miles west of Winslow.

A dark gray meteorite about 3 feet long and weighing a whopping 1,400 pounds
is on display in the crater's museum. This chunk of dense metal -- 92
percent iron, 7 percent nickel and 1 percent trace metal -- was found in
Diablo Canyon, about 2 miles from the crater. It is believed to have broken
off from the larger meteorite before it hit the ground and exploded.

Clifford Mark, a tour guide, urges visitors to rub the meteorite for good
luck.

"Lightning never strikes twice in the same place, and if you touch this
metallic meteorite, your chances of getting hit by one are cut in half,"
Mark explains in jest.

Actually, the odds of a person getting hit by a chunk of celestial matter
are about 1 in 10 billion. But it has happened. In 1954, Hewlett Hodges was
lying on the sofa of her home in Sylacauga, Ala., when a meteorite crashed
through the roof. The hot rock bounced off a table and grazed her leg. She
was lucky. In 1650, an Italian monk was killed by a piece of a meteorite,
according to legend.

Standing on the crater's 150-foot-tall rim, Mark points to a piece of
wreckage that has been on the crater's floor since the late 1960s. He tells
a story that suggests that the world has more to fear from people flying
small planes than rocks falling from outer space.

"Two guys in a single-engine Cessna decided to fly into the crater to get a
closer look," he explains. "But when they got in, they couldn't get out.
There's a layer of wind spins over the crater like an invisible force field.
Two and a half hours later, they ran out of gas and tried to land, but the
plane cartwheeled and crashed. They were lucky, they lived."

Today, earth and rock have settled in the crater and decreased its depth to
about 570 feet -- deep enough to swallow the Washington Monument in the
nation's capital. Mark says that if the crater was turned into a makeshift
stadium, 20 football games could be played on its floor simultaneously
before an audience of 2 million spectators seated on its sloping sides.

"We're talking about the world's biggest Super Bowl party," he says.

The crater is named after Daniel Moreau Barringer, a Philadelphia lawyer and
mining engineer. Barringer, a member of Princeton University's Class of 1879
and a graduate of the University of Pennsylvania Law School, abandoned his
law practice to pursue a career in mining. After attending the Colorado
School of Mines, he headed to Arizona and struck it rich with a silver mine.

In 1902, Barringer became fascinated with the crater. Many scientists
believed it had been formed by a volcanic steam explosion beneath the earth.
But Barringer was convinced that an extraterrestrial body formed the hole
and beneath it lay $500 million worth of high-grade nickel-iron.

After discovering that the land belonged to the federal government,
Barringer obtained a patent that gave him the mining rights. From 1903 until
shortly before his death in 1929, Barringer squandered a small fortune
mining the site. He gave up after a respected astronomer concluded that the
meteorite had vaporized on impact. A short while later, Barringer suffered a
fatal heart attack.

While Barringer's quest for personal wealth was a dismal failure, his
contribution to science was significant. In 1905, he published a paper
stating that the crater had been formed by an object from outer space,
possibly a small asteroid. He based his idea on meteorite fragments he found
in finely powdered sand. Eventually, geologists came to accept his idea that
rocks can fall from the sky and create gigantic craters.

In the late 1950s, Gene Shoemaker, a planetary scientist specializing in
meteor impacts, made a major discovery on the floor of the Barringer Crater.
He found a mineral called coesite, which is created only by the high
pressure and heat of impact. Scientists have used his findings to identify
other craters around the world.

Shoemaker, along with his wife, Carolyn, and another researcher, David Levy,
identified the comet Shoemaker-Levy 9 that crashed into Jupiter in 1994.
Shoemaker died in a car crash five years ago while searching for craters in
Australia.

An estimated 25,000 meteorites hit the Earth annually, and most cause little
or no damage. The shooting stars that flash across the nighttime sky are
pin-size dust specks burning in the atmosphere.

Craters are formed by very large objects that are not slowed downed or
cushioned as they hurtle through the Earth's atmosphere. Worldwide, there
are at least 170 impact craters, and the Barringer Meteorite Crater is far
from the largest.

In 1991, a huge crater called Chicxulub was discovered on the Yucatan
Peninsula. This hole is about 110 miles wide, and it is believed to be about
65 million years old, hitting about the time when the dinosaurs died off. It
is believed that the explosion kicked up a dust cloud that blocked out
sunlight, causing the Earth's temperature to drop.

The theory linking the extinction of the dinosaurs to an explosion caused by
a body from outer space is about 20 years old. It is the brainchild of Luis
W. Alvarez and his son, Walter Alvarez. But their theory is being challenged
by new scientific research suggesting that the Earth might have been hit by
a swarm of smaller objects instead of a single large one.

Scientists have discovered 1,000 to 1,500 near-Earth asteroids that are less
than a mile in diameter, as well as many smaller ones. It is likely that one
day, one will be on a collision course with Earth, but that potential
catastrophe is likely to happen tens, hundreds or thousands of years from
now, they say.

But during the summer, an asteroid the size of a football field missed the
Earth by a mere 75,000 miles and was not detected until three days after it
passed. In March, a 165-foot- wide chunk of rock passed within 288,000 miles
of Earth.

A collision with either object would have caused a blast equal to millions
of tons of TNT.
Received on Wed 18 Dec 2002 11:51:43 AM PST