Panel: NASA needs to do more to spot killer asteroids

— -- NASA is falling well short in its goal to spot huge asteroids that could threaten Earth, and it needs more money and skywatchers to do the job, a science panel said Wednesday.

In 2005, Congress asked the space agency to find 90% of all "potentially hazardous" near-Earth asteroids and comets, ones more than 460 feet wide (farther than home plate to deep centerfield in Yankee Stadium), by 2020. Instead, the three current survey efforts dedicated to the problem, supported at current levels, will likely find only about 15%, suggests the National Research Council panel.

"For the first time, humanity has the capacity and the audacity to avoid a natural disaster," says Irwin Shapiro of the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass., who headed the panel. "It really is a question of how much to invest in an insurance policy for the planet."

Astronomers rate the odds of a civilization-threatening space impact at once every 2 million years. The chances of a smaller impact, such as the 1909 Siberian event that leveled nearly 800 square miles of forest, are rated at once every two centuries, according to a 2008 estimate by space scientist David Morrison of NASA's Ames Research Center in Moffett Field, Calif.

The CfA lists 1,060 "potentially hazardous" asteroids or comets on its registry, those that pass within about 4.5 million miles of Earth as they orbit the sun and measure at least 245 feet across. That's big enough to cause a 3-megaton explosion, more than 100 times more powerful than the Hiroshima bomb .

Despite the 90% detection mandate, "the administration has not requested and Congress has not appropriated new funds to meet this objective," the report notes. Says Laurence Young of MIT, who reviewed a draft of the report: "The sky is falling, but we don't know how fast, and we don't know where and when. We should be improving our abilities to detect these objects."

The NRC report is an interim one, ahead of a final report later this year recommending further options for more asteroid observatories, including spacecraft. At least five new observatories, as well as German and Canadian spacecraft, are under consideration for Earth's asteroid-detecting capabilities. In July, NASA's Jet Propulsion Laboratory started an "Asteroid Watch" website to update the public on near-Earth asteroids and comets.