A NASA survey has identified around 1,000 asteroids that are large enough to cause catastrophic damage if they were to collide with Earth. This survey, known as Spaceguard, was mandated by Congress in 1998 with the goal of locating 90 percent of objects near Earth that are 1 km in diameter or larger. The survey has been completed, with 93 percent of the objects accounted for, according to astronomer Amy Mainzer of NASA's Jet Propulsion Laboratory. Using the retired WISE telescope, scientists also discovered approximately 20,500 smaller asteroids near Earth, a significant finding compared to previous estimates of 36,000 to 100,000 objects with a diameter of about 100 meters. Mainzer told Reuters that while asteroids could still cause significant damage, the likelihood of impact is low. However, history has shown that a major asteroid strike is possible, as evidenced by a 5 to 10 km (3.1 to 6.2 miles) asteroid or comet that hit Earth 65 million years ago and led to the extinction of dinosaurs. Mainzer emphasized that an impact of that magnitude could devastate life on Earth. Scientists are currently using archived WISE observations to identify potentially hazardous objects that come within about 4.6 million miles (7.4 million km) of Earth. Up to now, there is no established strategy for addressing the possibility of an asteroid heading towards Earth.