Achievement of the planetary defense investigations of the double asteroid redirection test (DART) mission

Abstract

NASAʼs Double Asteroid Redirection Test (DART) mission was the first to demonstrate asteroid deflection, and the missionʼs Level 1 requirements guided its planetary defense investigations. Here, we summarize DARTʼs achievement of those requirements. On 2022 September 26, the DART spacecraft impacted Dimorphos, the secondary member of the Didymos near-Earth asteroid binary system, demonstrating an autonomously navigated kinetic impact into an asteroid with limited prior knowledge for planetary defense. Months of subsequent Earthbased observations showed that the binary orbital period was changed by –33.24 minutes, with two independent analysis methods each reporting a 1σ uncertainty of 1.4 s. Dynamical models determined that the momentum enhancement factor, β, resulting from DARTʼs kinetic impact test is between 2.4 and 4.9, depending on the mass of Dimorphos, which remains the largest source of uncertainty. Over five dozen telescopes across the globe and in space, along with the Light Italian CubeSat for Imaging of Asteroids, have contributed to DARTʼs investigations. These combined investigations have addressed topics related to the ejecta, dynamics, impact event, and properties of both asteroids in the binary system. A year following DARTʼs successful impact into Dimorphos, the mission has achieved its planetary defense requirements, although work to further understand DARTʼs kinetic impact test and the Didymos system will continue. In particular, ESAʼs Hera mission is planned to perform extensive measurements in 2027 during its rendezvous with the Didymos–Dimorphos system, building on DART to advance our knowledge and continue the ongoing international collaboration for planetary defense.