Concerned
scientists to discuss protecting Earth from
asteroids
GARDEN GROVE, Calif. (AP) -- If only the
dinosaurs had been armed with nuclear weapons.
The
asteroid believed to have ended the reign
of the terrible lizards 65 million years
ago was rare but hardly unique, said scientists
who gathered this week to discuss ways of
aggressively defending our planet from another
such space rock, including by detonating
nukes in space.
Asteroids
capable of inflicting damage on a global
scale hit the Earth roughly every million
years. But that doesn't mean we should dawdle
in developing a method of deflecting such
an Earthbound asteroid, scientists said.
"Just
because it happens on average every 1 million
years doesn't mean we have to wait 1 million
years for it to happen," said David
Morrison, of NASA's Ames Research Center,
one of the 120 scientists attending the
four-day planetary defense conference in
suburban Orange County.
Scientists
in the group have proposed a variety of
strategies to nudge an asteroid off course.
The list is the stuff of science fiction
and includes using lasers, mirrors or atomic
weapons launched from Earth.
Unlike
any other type of natural hazard, an asteroid
impact can kill billions of people in one
fell swoop. But it's also the only natural
hazard that can be prevented, at least in
principle, scientists said.
"The
probabilities are low but the consequences
are high. It's a thing we know will happen
sometime in our future so the responsible
thing is for people to do something about
it," said William Ailor, of The Aerospace
Corp., which sponsored the conference with
the American Institute of Aeronautics and
Astronautics.
Astronomers
estimate there are between 900 and 1,100
near-Earth asteroids 1 kilometer -- about
six-tenths of a mile -- or larger in diameter.
Of those, nearly 700 already have been discovered
and cataloged.
It's
not clear what sort of damage one of those
rocks could cause were it to strike Earth,
although destruction on a global scale is
likely.
"We
don't know what they would do and we don't
want to conduct a science experiment to
find out," said NASA's Morrison, for
whom asteroid 2410 Morrison was named.
U.S.
Rep. Dana Rohrabacher, R-Calif., told the
conference he likened the threat to that
posed in the past by Japanese militarism,
Nazism, Communism or, in the wake of the
Sept. 11, 2001, attacks, terrorism.
"I
hope it won't take that kind of catastrophe
before we start paying attention to the
threat of near-Earth objects," said
Rohrabacher, who introduced a bill this
month to bolster National Aeronautics and
Space Administration spending on the search
for near-Earth asteroids 100 yards and more
across.
Even
something of that size, were it to strike,
say, the Pacific Ocean, could generate a
tsunami capable of destroying all the major
cities along the West Coast, Ailor said.
Early
detection of an inbound asteroid could provide
years to decades of advance warning -- enough
to scramble a mission to push it off course,
Ailor said. Slowing an asteroid down by
even a few inches a second could change
its trajectory enough to prevent its ever
crossing paths with the Earth.
The
Earth moves in space the equivalent of its
own diameter in just six minutes. To move
an Earth-bound asteroid off target then,
it would be enough to delay its arrival
time by six minutes -- enough to allow it
to harmlessly sweep past, Morrison said.
Scientists
also planned to discuss how to publicly
announce the possibility of a catastrophic
impact. They had a dry run last month, when
astronomers spied what they thought was
a 100-foot rock just days from hitting Earth.
An
asteroid that size could create a sizable
blast or, worse, trigger a nuclear reprisal
by a country that wrongfully believed it
was under attack.
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