[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

New Mitigation Strategy Minimizes Risk Of Asteroid Collisions

News Bureau
University of Illinois at Urbana-Champaign
807 S. Wright St., Suite 520 East
Champaign, IL 61820-6219
(217) 333-1085   fax (217) 244-0161
e-mail: uinews@uiuc.edu

CONTACT: James E. Kloeppel, Physical Sciences Editor (217) 244-1073
E-mail: kloeppel@uiuc.edu

April 1998

New mitigation strategy minimizes risk of asteroid collisions

CHAMPAIGN, Ill. -- The spectacular plunge of Comet Shoemaker-Levy 9 into
Jupiter in July 1994 and recent concern about the projected "near miss" of
Asteroid 1997 XF11 with Earth in October 2028 brought renewed awareness that
collision events do occur within our solar system -- and the next one could
involve our planet. In fact, such a collision may be long overdue, and steps
should be taken to alleviate the risk, a University of Illinois researcher
says.

"If faced with this kind of danger, we would want to send a spacecraft to
intercept the object as far from Earth as possible," said Bruce Conway, a
professor of aeronautical and astronautical engineering. "This would allow
whatever mitigation strategy we use to have the longest time to act."

There are two practical problems that must be solved, however, Conway said.
"The first is simply getting a sizable payload to the object in the shortest
amount of time, and the second is deciding what to do when we get it there."

In a paper published in the September-October (1997) issue of the Journal of
Guidance, Control, and Dynamics, Conway described the optimal low-thrust
interception of a potential collider. The proposed mission scenario would
combine the speed of conventional chemical rockets with the increased
payload capability of continuous-thrust electric propulsion. Having arrived
at the destination, however, what should be done to prevent the impending
collision?

"For years, we assumed that the best mitigation strategy was to blow up the
object with a nuclear warhead," Conway said. "But that may not be such a
good idea. If we blow it up, instead of having just one large mass hurtling
toward the Earth, we could end up with a multitude of smaller -- but equally
lethal -- objects coming at us. A better alternative would be to deflect the
object."

One possible mechanism to accomplish this would involve detonating a nuclear
warhead above the asteroid surface, Conway said. "That would create a
crater, and a large portion of the jet of vaporized material would shoot off
in one direction -- like a rocket -- and push the object in the opposite
direction."

But which direction should the object be pushed to ensure that it will miss
the Earth? And would it make more sense to speed the object up or slow it
down?

Conway's latest research has focused on answering these questions. He
developed an analytical method that, given the orbital parameters of the
object and the interval between interception and close approach, determines
the proper direction in which to push the object to maximize the deflection
in the required time.

Such calculations may never be needed, but they're nice to have just in
case.

"While the probability of a large asteroid or comet colliding with the Earth
is low, the potential for destruction is immense," Conway said. "It's
probably not something we should lose sleep over; but, on the other hand, it
would be really silly not to do anything."
Follow-Ups: