NASA’s DART spacecraft impacts the asteroid Dimorphos (200 m in diameter), a satellite of the larger asteroid Didymos (750 m in diameter). The impact is photographed by the Italian cubesat Licia Cube (Light Italian Cubesat for Imaging of Asteroids). The DART demonstration was carefully planned. Didymos’s orbit does not intersect Earth’s at any time, and the energy boost DART provides to Dimorphos is low and cannot destroy the asteroid. The mass of the DART spacecraft at the time of its kinetic impact with Dimorphos is 570 kilograms. The mass of Dimorphos has not been directly measured, but using assumptions for the asteroid’s density and size, Dimorphos’s mass is estimated at approximately 5 billion kilograms. Furthermore, the change in Dimorphos’s orbit from DART’s kinetic impact is projected to bring its orbit slightly closer to Didymos. The DART mission is a demonstration of the ability to respond to a potential asteroid impact threat, should one ever be discovered. DART’s target asteroid is NOT a threat to Earth. This asteroid system is a perfect testbed to see whether intentionally crashing a spacecraft into an asteroid is an effective way to change its course, should an Earth-threatening asteroid be discovered in the future. Although no known asteroid larger than 140 meters has a significant chance of impacting Earth for the next 100 years, only about 40 percent of those asteroids have been found as of October 2021.
