from americanlivewire.com: The global network that listens for nuclear weapons detonations detected 26 asteroids exploded in Earth’s atmosphere from 2000 to 2013, data collected by the Comprehensive Nuclear Test Ban Treaty Organization shows. These explosions include the Feb. 15, 2013, impact over Chelyabinsk, Russia, which left more than 1,000 people injured by flying debris. City-killer asteroids are forecast to strike about once every 100 years, but the prediction is not based on hard evidence. B612 intends to address that issue with a privately funded, infrared space telescope called Sentinel that will be tasked to find potentially dangerous asteroids near Earth. The telescope, which will cost about $250 million, is targeted for launch in 2018.