Asteroids have been hitting the Earth for billions of years. Now, Earth hits back with the Double Asteroid Redirection Test, or DART. NASA’s first space mission to demonstrate a potential method of planetary defense will target a small moonlet in the binary asteroid system Didymos (which poses no threat to Earth). DART scientists and engineers from the Johns Hopkins Applied Physics Lab and NASA will discuss how to autonomously direct a spacecraft at an asteroid and smash into it, measuring the orbit change from the ground. The first mission to come out of NASA’s Planetary Defense Coordination Office, DART will launch in 2021 from Vandenberg Air Force Base, California, aboard a SpaceX Falcon 9 rocket.