"It doesn't take a genius to recognize there is a potential threat to our planet that could well cause ... the loss of millions and millions of people," he told the scientists gathered in Baltimore. "We are not prepared, and it's not something that would cost a gazillion dollars to be prepared for."
Vital observatory
He urged the scientists to lobby Congress for funds to help international efforts in the field and to prevent proposed budget cuts in NASA's own search programs.
In particular, he argued for a rescue of the Arecibo Observatory in Puerto Rico. Radar astronomy from Arecibo enhances the accuracy of optical tracking of asteroids. But the National Science Foundation has recommended cuts that could lead to its closure.
"We know what can happen if we just sit by and wait, and pray," Rohrabacher said.
So far, scientists haven't found any dangerous space objects on a path toward Earth. But they are closely watching an asteroid called 99942 Apophis, a rock with a diameter of 700 to 1,000 feet, discovered in 2004.
Apophis caused a brief sensation when initial orbit calculations gave it a 2.7 percent chance of smashing into Earth in 2029 - by far the most serious threat ever identified. Subsequent observations of its orbit eliminated the possibility of a 2029 collision, but scientists still rate the chances of an impact at 1 in 45,000 when the asteroid returns in 2036.
At this week's conference in Baltimore, Jon D. Giorgini, a senior analyst with the Solar System Dynamics group at NASA's Jet Propulsion Lab, said 1 in 45,000 is still regarded as a "historically high" risk, a once-in-800-years event.
The problem, he said, is that precise measurements of the threat from Apophis won't be possible for years. Too many factors have to be understood and evaluated for a precise fix on the asteroid's path.
Solar wind alone can deflect the asteroid by up to 18.6 million miles between now and 2036, Giorgini said. And the tiny gravitational influence of other asteroids could move it by twice the width of Earth, according to a paper Giorgini published this year in the journal Icarus.
Scientists will need new optical observations in 2011 and radar observations from Arecibo in 2012 and 2013 to refine their Apophis calculations.
The Jet Propulsion Lab's Paul W. Chodas reported on work he has done to estimate how much warning we can expect of an asteroid headed for a collision with Earth. The majority of objects miss Earth entirely, of course.
