[meteorite-list] Asteroids and Comets: Deadly Dangers from Above

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue Jun 15 12:55:01 2004
Message-ID: <200406151654.JAA20173_at_zagami.jpl.nasa.gov>

http://www.cbn.com/CBNNews/News/040615a.asp

Asteroids and Comets: Deadly Dangers from Above
By Gailon Totheroh
The Christian Broadcasting Network
June 15, 2004

Comets generally travel faster than asteroids, as fast as 150,000 miles
an hour, meaning they could pack a bigger punch.

(CBN News) - Scientists are concerned
about terrorism like many of us are today, but not from people -- from
outer space.

Asteroids and comets constantly spin near us, threatening death and
destruction. A dead-on hit by the largest of these cosmic cannonballs
could mean the end of life as we know it.

Now is the time for a new age of exploration and discovery, to go seek
out the universe -- but maybe it's the reverse -- the universe may be
coming after us, in the form of comets or asteroids.

Physics and astronomy professors like Gary Copeland at Old Dominion
University are predicting 'an event' could be right around the corner.
"We'll get one to two events per century that will be equal to all the
destructive power of all the weapons in World War II."

That would mean that the event would be equivalent to the total
destructive power of every bullet, every shell, every mortar, every bomb
of WW II hitting at once -- including the atomic ones.

The last space projectile of this magnitude was a mere 200 feet across.
The asteroid struck central Russia in 1908, and the resulting fireball
torched miles and miles of forest. But fortunately, the area was nearly
uninhabited.

Copeland remarked, "If it [the central Russian asteroid] had happened
over New York City, it would have been a different ball game."

CBN News asked him, "Meaning millions killed?" Copeland replied, "Yes,
yes."

Hollywood envisioned this scenario with the movie, "Deep Impact." In the
movie, it is discovered that two comets are on a collision course with
Earth.

But while Hollywood may sensationalize the risk, members of Congress are
seriously concerned. Representative Dana Rohrbacher, who leads the House
Space and Aeronautics Subcommittee, said, "There is a threat to us and
to our lives, of objects coming from space that could hit our planet and
kill millions of people. It's happened in the past and it will happen in
the future. The question is when, and how many people will be affected. "

Not so long ago, science assumed the risk was even smaller for these
extremely rare events. But better technology means we're discovering
more, and finding a higher risk than was first believed.

Any actual strike brings some devastation, and with the planet's surface
two-thirds water, well, that's a big target.

Copeland said, "There's probably evidence that several things like this
happened in previous centuries, but they didn't land on Earth. On water
is where they hit, and of course, they produced the Tsunamis, the tidal
waves."

Copeland says the impact of a space object can generate 900-foot waves,
similar to the impact envisioned in Hollywood films. And if there is
little advance warning, low-lying areas near the strike are more than
vulnerable. "It's not survivable, nor is it escapable," says Copeland.
"You get in your car and try to drive away, meanwhile a wave moving at
600 miles an hour comes in. There's no way."

And how about a sizable mass that hit in the Atlantic? Copeland said
that places like Florida, which is pretty flat, "would be inundated, it
would disappear for a while."

And a medium-sized strike off the California coast? Also deadly.

But even that much devastation doesn't compare with the mother of all
asteroid strikes in the past.

"There's a place in Africa that's a crater over a hundred miles across,"
Copeland explains. "It wasn't recognized as a crater until they had
satellite photographs to see it." The Vredefort crater has a diameter of
185 miles, and was created by an asteroid estimated to be six miles wide.

The damage today from even a much smaller rock could mean long-term
global devastation.

An asteroid or comet impact on land would shoot debris high into the
atmosphere, and could create year-round winter conditions by blocking
sunlight for a year or more. That would lead to unstable weather
patterns with a nearly non-existent growing season. And that could mean
mass starvation and economic ruin for years.

Part of the reason asteroids and comets can pack so much damage is their
velocity. Comets generally travel faster than asteroids, as fast as
150,000 miles an hour, meaning they could pack a bigger punch. Don't get
too comfortable, though, the slowest asteroids travel at a deadly 25,000
miles an hour.

And don't forget that the pull of the planets can alter the course of
asteroids, and especially comets, when Jupiter drags them closer to Earth.

So are we all just doomed if one of these astral assailants strikes
right off our shores? Is there anything we can do to stop an asteroid
from smashing into our neighborhoods? The truth of the matter is, right
now, not much.

But astronomers are getting better at tracking them. Still, with most
observatories in the Northern Hemisphere, objects flying in the Southern
skies could more easily go undetected. So far, astronomers have
discovered 700 or so, out of an estimated 1100 of the largest, most
dangerous asteroids.

And each sighting does boost our potential to protect ourselves. There
is even a global effort to look for asteroids. That is the Spaceguard
Survey, and Congressman Rohrbacher wants to go further, with the Pete
Conrad bill.

"The purpose of the Pete Conrad bill," says Rohrbacher, "is to get
people looking up, and not just looking down. Certainly we have to worry
that we might stumble over things in our path, but we also have to worry
about what might be coming at us from up above."

And already on the drawing boards are plans to launch a rocket with a
bomb, to divert an asteroid headed our way. That could make the rock
speed harmlessly past us. Better science will give us more lead-time on
a threat, enabling the kind of evacuations already used for flooding and
storms, perhaps even with months or years of advance notice.

University scientists are already working on the problem of an asteroid
or comet collision, but they really need more research to accurately
assess the danger. With funding, that could take about 10 years, and by
then government officials could come up with a plan to at least minimize
the potential global impact.

 
Received on Tue 15 Jun 2004 12:54:49 PM PDT