(AP) — NASA has launched a spacecraft on a mission to smash into an asteroid and test whether it would be possible to knock a speeding space rock off course if one were to threaten Earth. The spacecraft is called DART, for Double Asteroid Redirection Test. It lifted off from California’s Vandenberg Space Force Base. If all goes well, in September 2022 it will slam head-on into Dimorphos, an asteroid 525 feet (160 meters) across, at 15,000 mph (24,139 kph). The asteroid is no danger to Earth, just a good target for testing out the potentially planet-saving technology.