DART IMPACT-DRIVEN SKEWED EJECTA PLUME

NASA's Double Asteroid Redirection Test (DART) successfully impacted Dimorphos, the satellite of the binary system (65803) Didymos. After the DART impact at 23:14:24.183±0.004 UTC on September 26, 2022, the resulting ejecta plume immediately grew, and was captured in detail by ground- and space-based telescopes and LICIACube, the Italian CubeSat released from DART before the impact. The impact reduced Dimorphos's orbital velocity, leading to an orbital period change of 33.0±1.0 (3?) minutes and thus a momentum enhancement (?) factor of 2.2-4.9, depending on its unknown mass. This ? (>1) factor indicates the critical role of the DART impact-driven ejecta in kinetic deflection. Here, we apply image processing and statistical estimation techniques to show that the ejecta cone has a skewed geometry, stretched along Dimorphos's short axis. Given both Hubble Space Telescope (HST) and LICIACube LUKE images taken at an early stage of the ejecta formation, our preliminary solution prefers a cone opening angle of ~145 deg along the short axis and that of ~95 deg along the equatorial plane.