How to deflect asteroids and save the Earth
Thursday, April 16, 2009
You may want to thank David French in advance. Because, in the
event that a comet or asteroid comes hurtling toward Earth, he may
be the guy responsible for saving the entire planet.
French, a doctoral candidate in aerospace engineering at North
Carolina State University, has determined a way to effectively
divert asteroids and other threatening objects from impacting Earth
by attaching a long tether and ballast to the incoming object. By
attaching the ballast, French explains, "you change the object's
center of mass, effectively changing the object's orbit and
allowing it to pass by the Earth, rather than impacting it."
Sound far-fetched? NASA's Near Earth Object Program has identified
more than 1,000 "potentially hazardous asteroids" and they are
finding more all the time. "While none of these objects is
currently projected to hit Earth in the near future, slight changes
in the orbits of these bodies, which could be caused by the
gravitational pull of other objects, push from the solar wind, or
some other effect could cause an intersection," French
explains.
So French, and NC State Associate Professor of Mechanical and
Aerospace Engineering Andre Mazzoleni, studied whether an
asteroid-tether-ballast system could effectively alter the motion
of an asteroid to ensure it missed hitting Earth. The answer?
Yes.
"It's hard to imagine the scale of both the problem and the
potential solutions," French says. "The Earth has been hit by
objects from space many times before, so we know how bad the
effects could be. For example, about 65 million years ago, a very
large asteroid is thought to have hit the Earth in the southern
Gulf of Mexico, wiping out the dinosaurs, and, in 1907, a very
small airburst of a comet over Siberia flattened a forest over an
area equal in size to New York City. The scale of our solution is
similarly hard to imagine.
"Using a tether somewhere between 1,000 kilometers (roughly the
distance from Raleigh to Miami) to 100,000 kilometers (you could
wrap this around the Earth two and a half times) to divert an
asteroid sounds extreme. But compare it to other schemes," French
says, "They are all pretty far out. Other schemes include: a call
for painting the asteroids in order to alter how light may
influence their orbit; a plan that would guide a second asteroid
into the threatening one; and of course, there are nukes. Nuclear
weapons are an intriguing possibility, but have considerable
political and technical obstacles. Would the rest of the world
trust us to nuke an asteroid? Would we trust anyone else? And would
the asteroid break into multiple asteroids, giving us more problems
to solve?"
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North Carolina State University
Thanks to North Carolina State University for this article.
