By ANDREW BRIDGES AP Science Writer
LOS ANGELES
(AP) - A group of scientists is seeking a standardized protocol
for dealing with the possibility of an asteroid or comet striking
the Earth, saying humans can do more than the dinosaurs ever could
before a colossal impact precipitated their extinction 65 millions
years ago.
The call comes
as interest grows in the swarm of asteroids and comets that orbit
the sun in the Earth's immediate neighborhood. The concerns were
sparked in part by several recent false alarms about impending
impacts.
``In some
sense, it's something we know we need to worry about, but we need
to decide at what level we need to worry about it _ and that's
a question for everybody,'' said Daniel D. Durda, a research scientist
in the department of space studies of the Southwest Research Institute
in Boulder, Colo.
In recent
weeks, a paper written by Durda and fellow scientists Clark R.
Chapman and Robert E. Gold has been making the rounds among experts
who study impact hazards. The goal, they write in the 19-page
paper, is to encourage discussion of how to replace the ``haphazard
and unbalanced'' way the world now addresses any potential impact.
``They are
spot-on that this is a problem. They are also right on time in
terms of this just now being recognized as serious enough a topic
so as to go to the next step in terms of 'what if,''' said Richard
Binzel, a professor of planetary science at the Massachusetts
Institute of Technology who developed a scale to rank the potential
danger of an impact. ``We have now overcome the giggle factor.''
How serious
the potential threat could be is underscored by an effort sponsored
by the National Aeronautics and Space Administration to catalog
90 percent of all near-Earth objects, or NEOs, that are 0.6 miles
or larger in diameter. The objects are a mix of comets, frozen
balls of ice and dust that formed in the far reaches of the solar
system, and asteroids, which were formed in the inner solar system
between the orbits of Mars and Jupiter.
Occasionally,
those objects are pushed closer to the sun, either through collisions
or by the tug of gravity, and cross the orbit of the Earth.
So far, the
search effort has turned up about half of an estimated population
of 1,100 NEOs.
``It is really
in the last few years the search effort has begun to bear fruit
and bear it massively,'' said Thomas Morgan, discipline scientist
for NASA's NEO observation program. If an Earth-bound asteroid
or comet were spotted, scientists have proposed either attaching
a rocket engine to it to nudge it out of the way, or smashing
it to pieces with an atomic bomb. But even if a warning about
a potential impact comes years or decades in advance, the feasibility
and expense of such a deterrent is unknown.
If an attempt
to destroy or deflect an NEO should fail, and an object just a
half-mile in diameter struck the Earth, it would unleash an amount
of energy equivalent to 10 million times the power of the atomic
bomb dropped on Hiroshima. The event could do for many humans
what a larger object is widely believed to have done for the dinosaurs.
``The public
has all heard of the extinction of the dinosaurs, and they expect
something to be done about (any potential impact), so therefore
something should be done,'' said Bill Cooke, a NASA contractor
and space environment expert who has penned his own paper on the
subject.
The Federal
Emergency Management Agency, for one, would respond in a way similar
to how it does now with hurricanes _ or the recent return to Earth
of the Russian Mir space station.
``If we were
dealing with a larger object, like an asteroid that could have
a much more severe impact on the United States, as we have more
advance knowledge of where it might hit, we would immediately
start alerting states that something was coming,'' said Marc Wolfson,
a FEMA spokesman.
For now, word
of a potential threat comes by way of a casual bulletin posted
on the Internet that is invariably redistributed by the media.
``There's
nothing set in stone yet as far as procedures go. That's what
we want to get people talking about: Who should be notified? Who
shouldn't? There's no desire to be secretive, but you don't want
to cry wolf too often,'' Durda said.
Such a cry
has come once in each of the past three years, most recently in
November when astronomers announced an object known as 2000 SG344
had a 1-in-500 chance of hitting the Earth in 2030. According
to a then-new International Astronomical Union policy, astronomers
made that announcement within 72 hours of reaching a consensus
that a risk to the planet existed.
With SG344,
however, the alarm was retracted almost immediately as other astronomers
better calculated the object's orbit. ``It was a very normal scientific
process, but in the public's eye it looked like a mistake,'' Binzel
said. ``It's a trade-off between being very open and honest about
what we have and waiting and waiting until we have every last
piece of data in hand.'' One expert said the flaps, while embarrassing,
were an issue of public relations, and not science.
``These are
problems in communication. They are not problems in the basics
of what we're doing,'' said David Morrison, chairman of the International
Astronomical Union's working group on NEOs. ``The issue is really
one of how do we communicate with the media and the public.''
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