Number of Undetected 'City Killer' Asteroids 'Very Large,' House Panel Told

A House panel heard today that the country is ill-prepared to even detect a 100-meter-diameter asteroid that could wipe out a city or cause other catastrophic effects such as a smothering dust cloud or towering tsunami waves.

Lawmakers have been on edge about America's ability to react to or even notice in time space rocks coming through the atmosphere since the Feb. 15 flyby of asteroid 2012DA14 coupled with the explosion of a meteor above Chelyabinsk, Siberia.

As scientists predicted, 2012DA14 was harmless but the shock wave from the Russian meteor blew out windows and injured 1,200 people.

That rock caught NASA as off-guard as the Siberian residents.

"It came out of the sun," John Holdren, director of the White House office of science and technology policy, told the House Science, Space and Technology Committee today. "It came from a direction where our telescopes could not look. We cannot look into the sun."

"We had no insight in that at all," said Gen. William Shelton, commander of U.S. Air Force Space Command. "We were aware of the event when it occurred."

Holdren said dozens of asteroids a meter or more in size, with the biggest usually four meters across, enter and burn up high in the Earth's atmosphere each year. A larger event like the 1908 asteroid explosion over Siberia that leveled trees for 850 square miles could cause "hundreds of thousands of casualties" if the 15-megaton explosion happened over an urban area.

But the probability of this once-in-1,000-years event is further lessened by taking into account that land only covers 30 percent of the Earth and urban areas make up 2-3 percent of that land area.

"But the potential consequences of such an event are so large that it makes sense to take the risk seriously," Holdren said.

In 1998, Congress told NASA to find and track at least 90 percent of near-Earth objects greater than one kilometer in diameter within the next decade; that was finished by 2011. In 2005, Congress wanted all such objects with diameters of more than 140 meters catalogued by 2020.

"About 80 tons of material in the form of dust grains and small meteoroids enter the Earth's atmosphere every single day. Objects the size of a basketball arrive once a day, and objects as large as a car arrive about once per week," NASA administrator Gen. Charles Bolden testified, adding his agency is trying to work toward the goal of sending a manned mission to an asteroid by 2025.

To better protect the Earth, though, an agency that already canned the space shuttle will have to have deep pockets.

"I do not believe that NASA is somehow going to defy budget gravity and get an increase when everyone else is getting cuts," said Chairman Lamar Smith (R-Texas). "But we need to find ways to prioritize NASA's projects and squeeze as much productivity as we can out of the funds we have."

"Examining and exploring ways to protect the Earth from asteroids and meteors is a priority for the American people and should be a priority for NASA," he added.

Under questioning from Smith, Holdren said current capabilities have detected less than 10 percent of 100-meter asteroids -- an estimated 13,000 to 20,000 "city destroyers."

"The number of undetected potential city killers is -- is very large. It's in the range of 10,000 or more," Holdren said.