WASHINGTON – In this lifetime there's a 10 percent chance,not just for snow,sun or sleet,but for a 60-meter asteroid to strike some part of the Earth.
And the 10 megatons of energy generated by the impact could do the damage of 700 Hiroshima-sized bombs blasted simultaneously,said Edward Lu,a NASA astronaut.
Lu is also president of the B612 Foundation,a nonprofit,private organization attempting to “significantly alter the orbit of an asteroid in a controlled manner by 2015,” according to the group's Web site.
Lu and other researchers testified Wednesday before the Senate Subcommittee on Science,Technology and Space,which is considering “whether Congress should pass legislation to do something about this threat from space,” said Sen. Sam Brownback,R-Kan.
Brownback said the chances of being killed by an asteroid striking the Earth are about the same as dying in an airline crash. But he emphasized that exploring NEOs – short for near Earth objects – is part of the government's duty to protect everyone's security.
Lu said technology exists to counteract what Brownback described as a “real or perceived” danger in the public mind.
“We think we now have the potential to change those odds,” said Lu,who proposed a $1 billion test that would deflect an asteroid by using a “nuclear-powered spacecraft” with “high-efficiency propulsion.”
“The first time you attempt to deflect an asteroid should not be on the real day,” Lu said. He said the government should choose a small asteroid with a trajectory not headed toward Earth for such a test.
Lu said the plan would be to “fly to an asteroid,rendezvous and attach to this small asteroid and push on it.”
The continuous thrust would “slowly alter” the asteroid's velocity,putting the rock on a new path,Lu said.
Two asteroids hit the Earth in the last century,blasting the Tunguska region of Siberia in 1908 and an unpopulated part of Brazil in 1947.
Since 1998,Congress has appropriated $4 million annually to detect at least 90 percent of the NEOs measuring at least a kilometer across,and by 2008 to predict these asteroids' future orbits,a project known as “Spaceguard Survey.”
So far,the project has tracked more than 700 of about 1,100 such asteroids. But witnesses warned that smaller asteroids are also dangerous.
“If the U.S. Capitol flew at the U.S. Capitol,it would destroy the Washington metropolitan area totally,” said Rusty Schweickart,chairman of the B612 Foundation board.
Lu and Schweichart said the project might draw private investment because asteroids could be sources of fuel,oxygen,minerals and water. Lu said they could become “space habitats.”
Lindley Johnson,NEO Observation Program manager at NASA,said a large asteroid collision could destroy all life on Earth.
“Of those we've found,none are on impact trajectory,” said Johnson,a native of Wilsey,Kan. “There is a hazard out there still with the small ones.”
The discussion came three weeks after a 100-foot asteroid came within 26,500 miles of Earth,the “closest approach to Earth ever recorded,” according to NASA's NEO program Web site.
“This is equivalent to riding in an airliner and seeing a small plane suddenly pass a few hundred feet off the wing – a pretty scary occurrence,” Brownback said. “Had this asteroid hit the Earth – as a somewhat bigger one did in 1908 – it would have released over a megaton of energy.”
After the hearing,which Brownback described as being primarily “informational,” he said technology should help people to realize that life with NEOs is “not a matter of being powerless.”
He said it was too early to know what congressional response might follow.