About 1,000 asteroids big enough to cause catastrophic damage if they hit Earth are orbiting relatively nearby, a NASA survey shows. In a project known as Spaceguard, the U.S. space agency was ordered by Congress in 1998 to find 90 percent of objects near Earth that are 1 km (0.6
About 1,000 asteroids big enough to cause catastrophic damage if they hit Earth are orbiting relatively nearby, a NASA survey shows.
In a project known as Spaceguard, the U.S. space agency was ordered by Congress in 1998 to find 90 percent of objects near Earth that are 1 km (0.62 of a mile) in diameter or larger.