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CCNet 75/2001 - 4 June 2001
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"The real threat from the sky is from small-scale objects, said Air
Force Brig. Gen. Simon Worden, deputy director for operations at the U.S.
Space Command, Peterson Air Force Base, Colorado. A small asteroid
just 80 feet (24 meters) across created Meteor Crater in Arizona
20,000 to 50,000 years ago."
--Leonard David, Space.com, 31 May 2001


"We need to improve our response time. Right now, there is no quick
response capability. If we had an emergency today, it would take at
least two years to put a system together. We'd like to see that reduced to
a few weeks."
--Andy Smith, International Planetary Protection Alliance


"This is the first time a species can do something about their
supposedly inevitable extinction. It's a great time to be living," Schmitt
said."
--Apollo 17 Moonwalker, Harrison "Jack" Schmitt


ASTEROID BUSTING: WE HAVE THE TECHNOLOGY

From Space,com, 31 May 2001
http://www.space.com/scienceastronomy/astronomy/defending_earth_010601-1.html

By Leonard David
Senior Space Writer
 
ALBUQUERQUE, NEW MEXICO -- When Earth is on the receiving end of a comet or
an asteroid, things get messy. Fire, explosions, tidal waves, suffocation,
climate change, crop failures and starvation can occur from regional to
global scale.

While dinosaur-killing impacts and mass extinction are now acknowledged to
be doomsday events over long stretches of time, little is being done about
preparing today for smaller, yet troublesome impactors.

A growing choir of experts are calling for an increased ability to detect,
inspect and deflect "rock bombs" from space that prove threatening to Earth.

ACE in the hole

The good news is that most impacts can be prevented, and putting that
capability in place need not be expensive. Most hardware to thwart incoming
objects is already available, said Andy Smith of the Safety Research
Institute in Albuquerque.

The Tunguska event, which took place in June 1908, was an massive aerial
explosion, which flattened thousands of acres of forest near the Tunguska
River, Siberia, Russia. The explosion created energy equal to 14 megatons of
dynamite. According to research, the cause of the explosion was likely a
section of a comet, which crashed into Earth.

"The biggest need we have is for information to be put in the hands of the
technical community and the policy makers," Smith told SPACE.com. "We have
the technology to prevent almost all impacts," he said.

Smith has formed the International Planetary Protection Alliance (IPPA) to
take on the most important technical challenge in history: Asteroid/Comet
Emergency (ACE) Prevention/Preparedness Plan.

The IPPA is pulling together a diversity of disciplines, such as
paleontologists, astronomers, archeologists, physicists and chemists, to
tackle the job, Smith said. "Each of these groups is a culture, so we have
the problem associated with culture clash. If we can overcome that, then
these people can work together to solve the problem," he said.

Smith was one of several experts, including former astronauts, raising the
issue of close encounters of the impact kind at the National Space Society's
20th annual International Space Development Conference, held here May 24-28.

Astronaut John Young, famed for his Gemini, Apollo, and shuttle exploits,
said that the greatest achievement of the human race for the 21st century is
ahead -- learning to live and work in other places in the solar system. The
long-term benefit of that quest is the preservation of our species, he said.

"From what I know about impacts, sooner or later we're going to get taken
out," Young said. "The problem right now is that we don't know when that
'sooner or later' is. It could be tomorrow...it could be 10,000, or a
hundred thousand years from now," he said.

Young said that Earth is likely to take a hit from a nearly mile
(1.6-kilometer) wide or larger diameter asteroid in the next 50 years. A
giant wallop would set civilization back 10,000 years, he said.

"The human exploration of space is what it's all about, as far as I'm
concerned. I say let's get on with it because we may not have a lot of
time," Young said.

Big shot for small stuff

The real threat from the sky is from small-scale objects, said Air Force
Brig. Gen. Simon Worden, deputy director for operations at the U.S. Space
Command, Peterson Air Force Base, Colorado.

A small asteroid just 80 feet (24 meters) across created Meteor Crater in
Arizona 20,000 to 50,000 years ago.

Noting that his views are his own and do not necessarily reflect Air Force
or government positions, Worden said that planetary defense against
asteroids is a step-by-step process. "First, find them. Second, go study
them up-close-and-personal. And then, and only then, try and move
something," he said.

Worden said that objects measuring from 33 feet (10 meters) to 1,640 feet
(500 meters) in diameter can deliver a surprising and powerful punch. For
example, about two years ago a meteor blew itself apart over Greenland,
unleashing enough energy to produce "significant effects" on the ground, he
said.

Similarly, in January of last year and high over the Yukon, a meteor roughly
16 feet (5 meters) across plowed through the atmosphere and released as much
energy as the atomic bomb dropped on Hiroshima. The super-bright fireball
lasted about 10 seconds, fostered loud booms and was detected by U.S. Air
Force spacecraft.

"My personal message is that there are a lot of meteor strikes every year.
Virtually all of them burn up in the upper atmosphere. But about once a
decade there is something that is big enough, and gets deep enough, so that
it does cause noticeable effects on the ground," Worden said.

March of the microsatellites

"So it's a big job," Worden said.

Making the point, on May 25 double asteroid 1999 KW4 flashed by Earth at a
distance of a little over 3 million miles (5 million kilometers). Classified
as a potentially hazardous pair, 1999 KW4 is flittering through space on a
path that may smack Earth, but not for at least a thousand years. The larger
of the two space rocks is around three-quarters of a mile (1.2 kilometers)
in average diameter.

It is estimated that there is a near miss of Earth's orbit by an object
every half-hour.

A major new development for planetary defense is the evolution of
microsatellites. These small and inexpensive spacecraft are being built here
in the United States, as well as in Canada and the United Kingdom, Worden
said.

Not only can faster, better, cheaper microsatellites help snoop for
asteroids, they are ideal for up-close inspection, as well as for pushing
space rocks out of harm's way.

On one hand, to move giant Asteroid Eros off track would mean using a
nuclear knockout blast, or, as Worden deemed it, utilizing "a physics
package" as the means for deflection. But at ramming speed, a microsatellite
could slap a smaller asteroid onto a different course. "You get a lot of
energy out of just running something into something," he said.

Bad news

There's no good news in the event that Earth gets a calling card from the
cosmos anytime soon.

Mark Boslough, principal member of the technical staff in the computational
physics department of Sandia National Laboratories in Albuquerque, said
supercomputer simulations paint a less-than-rosy picture.

"Once you get into a kilometer-size range of impactor, it is going to be bad
news," Boslough said. "Those happen, on average, once every 300,000 years."

Computer work at Sandia demonstrates how impacts can induce climate change.
At hypervelocity speeds, an object basically changes the chemistry of the
atmosphere. "A lot of greenhouse gases are created, adding to dust and soot
from global firestorms. You end up having something equivalent of a nuclear
winter," a sun-blocking event that, over time, runs from very cold to high
heating of Earth's surface, Boslough said.

Boslough said that computer modeling of impactors show how a ring of debris
would be formed around Earth. This band of particles would persist, blocking
sunlight and also playing havoc with global temperatures.

If that's not bad enough, debris shot high above Earth would surely impact
low-orbiting satellites, Boslough said.

Tsunami conditions

Plunking down in ocean waters, an asteroid measuring several miles
(kilometers) across would churn up frightening tsunami conditions, said Jack
Hills, a researcher at neighboring Los Alamos National Laboratory.

For example, given an impact far out in the Pacific Ocean, those along the
California coastline might have several hours of time for fleeing to higher
ground. But on the Atlantic coast, with high mountains far from shore, the
situation is perilous.

"Long Island would be totally hosed," Hills said. "I'm not sure people
should have been allowed to build there, not just because of any asteroid
impact threat but even from storm surges. If something occurred today, it
would cause over $100 billion in damage on Long Island," he said.

Be it a city buster, tsunami killer, civilization destroyer or
mass-extinction impactor, challenging work is ahead to fend off future
terror falling from space.

"We need to improve our response time," said Smith of the International
Planetary Protection Alliance. "Right now, there is no quick response
capability. If we had an emergency today, it would take at least two years
to put a system together. We'd like to see that reduced to a few weeks," he
said.

It is time to come to grips with the issue of planetary defense, said Apollo
17 Moonwalker, Harrison "Jack" Schmitt.

"How do you deal with a discovery of an Earth-crossing asteroid that
actually is Earth-crossing? It's one thing to chart asteroids and analyze
their trajectories, Schmitt said. "We have the technology base. We just
haven't implemented it from an engineering point of view to do something
about it," he said.

"This is the first time a species can do something about their supposedly
inevitable extinction. It's a great time to be living," Schmitt said.

Copyright 2001, Space.com

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