A meteor like the one in Russia occurs every 30 to 50 years, Binzel said.
On Tuesday, in the wake of the Russia meteor, the House Science, Space and Technology Committee held a hearing on what the United States is doing to track and monitor "near-Earth objects" that pose a threat to the planet. The meteor in Russia was estimated to be 50 to 60 feet across, and scientists generally don't track objects that size.
"We look for bigger ones, ones that could really screw up our planet," said David Morrison, senior scientist at the NASA Ames Research Center in California.
If a meteor half a mile to a mile wide were to hit land, it could form a crater and blow enough dust into the stratosphere to block out the sun and affect crops worldwide for a year, he said.
Should such an object be detected by telescopes, all hope would not be lost. "If we had enough warning, then we could build a spacecraft that would go out and change its course," he said.
But if scientists learned only a few weeks in advance that a large object was heading toward a particular spot on Earth, he said, "all we could do is evacuate."