Tuesday, November 14, 2006

Defending the Planet

Continued from page 2

By Gigi Marino

Schweickart has launched a campaign to save life as we know it. "No one is looking at how to prevent an asteroid impact, which could wipe out millions of people and affect the global economy," he says. To help prevent such a catastrophe, he founded the B612 Foundation, whose goal is "to significantly alter the orbit of an asteroid, in a controlled manner, by 2015." (B612 is the asteroid home of the Little Prince in St. Exupéry's children's story.)

Working with several organizations, including the ASE, NASA, and the European Space Agency, Schweickart has raised awareness about near-Earth asteroids (NEAs). He is leading the ASE effort to draft an international treaty on the deflection of near-Earth objects, including asteroids, to be presented to the United Nations in 2009. And he was a guest on a recent episode of Nova ScienceNow that focused on NEAs. "We have probably been hit by objects as big as 100 kilometers, which boils off most of the water in the oceans," says Schweickart. "The whole evolution of life has been shaped by asteroids and comets hitting the earth."

NASA's Spaceguard Survey has already identified nearly 850 asteroids one kilometer in diameter or larger. "But we realized that the problem would be with smaller, far more numerous objects that are more likely to hit Earth," ­Schweickart says. Schweickart estimates that there is about a 2 percent chance of such a destructive collision happening in this century. "We began working with Congress to bring the discovery size down to 140 meters," he says. "We anticipate finding 100 times more objects." Although several NASA-supported research groups, including the Jet Propulsion Laboratory at Caltech, now track close approaches of near-Earth objects (neo.jpl.nasa.gov/ca), B612 advocates not just tracking NEAs but also devising a plan--tested beforehand--to prevent a devastating hit.

Blowing up asteroids with nuclear weapons, Schweickart­ says, is "Hollywood" and the worst thing one could do: "You'll only compound the problem and aggravate your grandchildren's lives." (He has 11 grandchildren and seven children of his own.) B612 has developed two deflection techniques, the newest of which is a gravitational tractor. Ed Lu and Stan Love, who invented the gravitational tractor, are NASA astronauts at the Johnson Space Center and founding members of B612. Their method employs the basic principle of gravity: any two masses attract each other.

"We've proposed flying an unmanned spacecraft out to an asteroid and parking it in front of the asteroid. It's pulling you, and you pull it," says Schweickart. "Gravitational pull acts on both bodies. We would use a very small pair of ion engines with little thrust [so] that [the vehicle would] hover in front of the asteroid and not fall to the surface. [Park] it long enough, and you get the velocity change you need--even if it's weeks, months, or years."

Schweickart is undaunted by the immensity of the task he's tackling. And although no agency in any nation has yet been assigned responsibility for preventing asteroids from hitting Earth, he's not daunted by the politics, either. "For the first time, humankind, in conjunction with the machines we've built, has the capability to assume responsibility for the continuation of our own future," he says. "That's what I'm dedicating my time to--getting our cosmic act together."

For more information on Schweickart's B612 Foundation, visit www.B612Foundation.org.

For more photos of Schweickart in space, visit www.technologyreview.com/media/rusty.