http://www.newsweek.com/asteroid-impact-space-dimorphos-didymos-nasa-dart-1746153 > NASA is crashing a spacecraft into an asteroid, in order to test how much a collision would deflect space rocks. > On September 26, the Double Asteroid Redirection Test (DART) spacecraft is due to crash into the side of Dimorphos, a small asteroid orbiting the larger near-Earth asteroid Didymos, at a speed of four miles per second [around 14,400 mph].