- MADISON, Wisconsin -- Warning: This is not the script of a Hollywood
movie.
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- A massive asteroid 24 miles long by 9
miles wide known as "433 Eros" is on a collision course with
Earth.
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- When it hits, it most certainly will
wipe out all life.
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- The United States sent out a spacecraft
more than two years ago to intercept it, but the craft only is equipped
to observe the menace. It can't deflect or destroy it.
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- That said, don't head for the basement
just yet.
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- Although it is probably twice the size
of the asteroid that killed off the dinosaurs 65 million years ago, Eros
won't arrive here for at least several million years, according to Andrew
Cheng, a scientist with the Near Earth Asteroid Rendezvous project. Cheng
spoke during a briefing at the 30th annual meeting of the Division of Planetary
Sciences of the American Astronomical Society, a gathering of more than
600 scientists from the U.S. and around the world.
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- For the foreseeable future, Eros' greatest
impact will be the wealth of pictures and data it will supply once the
NEAR spacecraft begins orbiting it in January.
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- During a mission update Monday, Cheng
said NEAR was working well.
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- "So far we have had very good luck
with the spacecraft," he said.
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- The 1-ton, equipment-laden craft is on
a mission to boldly go where no space vehicle has gone before: first to
orbit and then, possibly, to land on the surface of a large asteroid whose
orbital path occasionally flies into Earth's path.
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- In recent years, Eros has never gotten
any closer than about 9 million miles from Earth. However, its orbit is
constantly changing and eventually, millions of years from now, it will
collide with our planet, Cheng said.
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- The most critical event in the mission
will be Dec. 20, when NEAR's rockets will begin the burn that will put
it in orbit around Eros, Cheng said.
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- "We are not nervous," he said.
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- By Jan. 20, it will be orbiting the giant
potato-shaped rock, a process that will last a year and bring the craft
to within 20 miles of the surface.
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- One minor concern is whether there is
any debris near Eros that could damage NEAR. NEAR scientists plan to scan
the asteroid as NEAR approaches to make sure there is nothing in the way,
he said.
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- Eros is about 24 miles long and 9 miles
wide.
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- In addition to sending back the most
detailed pictures of an asteroid ever seen, NEAR will collect a large amount
of data about the composition of the asteroid.
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- Discovering the nature of asteroids is
important. The rocky bodies are remnants of the birth of our solar system
4.6 billion years ago, and might hold clues to the materials that formed
Earth and the other planets.
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- NEAR already has sent back pictures of
a 33-mile-long asteroid known as Mathilde during a "fly by" from
a distance of about 750 miles in June 1997. Those pictures revealed one
of the darkest, most battered bodies in the solar system. Mathilde is twice
as dark as a piece of charcoal and reflects only about 3% of the sun's
light, suggesting its surface is rich in carbon.
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- After completing its mission, NEAR could
land on Eros or could be allowed to just drift off into space, Cheng said.
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- In a related matter, two universities
announced at the meeting this week that new programs to find so-called
near-Earth asteroids have discovered several new bodies.
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- An average of 11 near-Earth asteroids
have been discovered each month by the Lincoln Near Earth Asteroid Research
(LINEAR) program of the Massachusetts Institute of Technology, Grant Stokes
of MIT's Lincoln Laboratory said in a statement.
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- "None of the currently known asteroids
are a threat to the Earth in our lifetime," Stokes said.
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- The LINEAR program uses a U.S. Air Force
telescope in Socorro, N.M.
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- Each week for the last year, the California
Institute of Technology's Near-Earth Asteroid Tracking (NEAT) program has
discovered about three, Earth-approaching asteroids with a diameter of
at least 1 kilometer, according to paper released at the conference Sunday.
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- NEAT also uses an Air Force telescope,
one located on the summit of Mount Haleakala in Maui, Hawaii.
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- NEAT scientists say a full-scale network
of three NEAT systems operating 18 nights a month would detect 90% of the
hazardous asteroids, those larger than 1 kilometer in diameter, in the
next 10 to 40 years.
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