seven rail cars. The tail of ejecta from Dimorphos created by the DART impact is at least long with a mass of at least , and possibly up to 10 times that much. The DART impact on the center of Dimorphos decreased the orbital period, previously 11.92 hours, by roughly 32 minutes. While the orbital change was small, the change is in the velocity and over the course of years will accumulate to a large change in position. For a hypothetical Earth-threatening body, even such a tiny change could be sufficient to mitigate or prevent an impact, if applied early enough. As the diameter of Earth is around 13,000 kilometers, a hypothetical asteroid impact could be avoided with as little of a shift as half of that (6,500 kilometers). A velocity change accumulates to that distance in approximately 10 years. Sequence of operations for impact Gallery See also Notes References External links Double Asteroid Redirection Test (DART) Mission – NASA's Planetary Defense page on DART DART’s Mission to Bump an Asteroid – NASA Blog NASA's DART Mission Launch, 2021-11-24 – Official Broadcast/Stream DART's Impact with Asteroid Dimorphos (Official NASA Broadcast) 2021 in California 2022 in spaceflight Articles containing video clips Impactor spacecraft Missions to asteroids NASA space probes Planetary defense Solar System Exploration program Spacecraft launched in 2021 SpaceX commercial payloads SpaceX payloads contracted by NASA Spacecraft decommissioned in 2022