Double Asteroid Redirection Test (DART) is a planned space probe that will visit the double asteroid Didymos and demonstrate the kinetic effects of crashing an impactor spacecraft into an asteroid moon for planetary defense purposes. The mission is intended to test whether a spacecraft impact could successfully deflect an asteroid on a collision course with Earth.

A demonstration of an asteroid deflection is a key test that NASA and other agencies wish to perform before the actual need of planetary defense is present. DART is a joint project between NASA and the Johns Hopkins Applied Physics Laboratory (APL), and it is being developed under the auspices of NASA’s Planetary Defense Coordination Office.

The mission’s target is 65803 Didymos, a binary asteroid system in which one asteroid is orbited by a smaller one. The primary asteroid (Didymos A) is about 780 m (2,560 ft) in diameter; its small satellite Dimorphos (Didymos B) is about 160 m (520 ft) in diameter in an orbit about 1 km from the primary. DART will target the smaller asteroid, Dimorphos.