At 1:21 a.m. EST on November 24, NASA’s Double Asteroid Redirection Test (DART) mission was launched from Vandenberg Space Force Base onboard a SpaceX Falcon 9 rocket. In the ensuing few hours, the spacecraft established communication with mission operators and successfully unfurled its solar arrays. DART will orbit the Sun just outside Earth’s orbit for ten months, waiting for the Didymos asteroid system to approach. Didymos, classified as a near-Earth object, is 780 meters in diameter. It also has a moonlet, the 160-meter-diameter Dimorphos, which is the target of DART.
The DART spacecraft was built by the Johns Hopkins University Applied Physics Laboratory and is the first full mission dedicated to planetary defense against potentially hazardous asteroids and comets. While most spacecraft are not designed to crash onto their targets (at least initially), the DART probe is intended to collide with the moonlet Dimorphos at approximately 6 kilometers per second when the spacecraft intercepts the Didymos system between September 26 and October 1, 2022. The mission will test the kinetic impact method of deflecting an asteroid, in which a spacecraft transfers momentum to a larger object via impact, changing its orbit and potentially deflecting it from its original course. This method could be used to nudge near-Earth bodies off a collision course with Earth.
The impact of DART into Dimorphos is predicted to shorten its orbital period around Didymos by several minutes, which will be tracked by Earth-based telescopes. The moonlet orbits its primary body (Didymos) at a lower velocity than the binary system orbits the Sun, so the effect of DART’s kinetic impact within the system can be gauged more precisely and sensitively than if the target was a single asteroid orbiting the Sun. While the Didymos system is not an immediate threat to Earth, the data from this test will validate modeling of the kinetic impact deflection method and improve our understanding of its effectiveness for planetary defense. READ MORE