[meteorite-list] The Best Way to Deflect an Asteroid

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue, 11 Dec 2007 12:28:48 -0800 (PST)
Message-ID: <200712112028.MAA27236_at_zagami.jpl.nasa.gov>


The Best Way to Deflect an Asteroid
New York Times
December 9, 2007

In 1908, an asteroid is thought to have entered the earth's atmosphere
and exploded over a Siberian forest, leveling some 800 square miles of
trees in what is known as the Tunguska Event. If we knew today that
another asteroid were on a path to intersect with our planet, what could
we do?

Massimiliano Vasile, a lecturer in aerospace engineering at the
University of Glasgow, recently concluded a two-year study comparing
nine asteroid-deflection methods, rating them for efficiency, complexity
and launch readiness.

The best method, called "mirror bees," entails sending a group of small
satellites equipped with mirrors 30 to 100 feet wide into space to
'swarm" around an asteroid and trail it, Vasile explains. The mirrors
would be tilted to reflect sunlight onto the asteroid, vaporizing one
spot and releasing a stream of gases that would slowly move it off
course. Vasile says this method is especially appealing because it could
be scaled easily: 25 to 5,000 satellites could be used, depending on the
size of the rock.

The losing ideas - satellites equipped with lasers; detonating a nuclear
explosion; pushing the asteroid with a spacecraft, to name a few - might
still have their place. Vasile says improved technologies could make
others appealing in the future. (In March, NASA released a report on
"near Earth objects" that deemed the nuclear-explosion method the most

Michael Gaffey, professor of space studies at the University of North
Dakota, says the risk of dying from an asteroid strike is about 1 in 2
million. The problem is that the consequences are tremendous; a
half-mile-wide asteroid or larger, of which there are more than 700 that
come close to Earth's orbit, could have an impact equal to 60 billion
tons of TNT. While it is not likely to happen, you still want to be
prepared. "You don't panic, you don't have to run around screaming and
waving your hands," Gaffey says. "But you do need to devote resources to
Received on Tue 11 Dec 2007 03:28:48 PM PST

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