After the 2005 U.S. Congress request that NASA find 90% of the estimated 20,000 potentially-dangerous asteroids and comets, the space agency has reported that they do not have the money to complete the task.

NASA was tasked with locating and tracking all asteroids larger than 140 meters in diameter, which is slightly smaller than most major league football stadiums. While objects of that size are not large enough to cause mass-extinction events like the one that wiped out the dinosaurs 65 million years ago, they are large enough to devastate an area of 32,00 square kilometers, or about the size of the state of Belgium or Taiwan. An impact or mid-air explosion would release the power of 100 million tons of dynamite, equivalent to 10,000 atomic bombs.