Science Highlights - ALMA Observes Ejecta from the Double Asteroid Redirection Test (DART)

The Double Asteroid Redirection Test (DART) is a proof of concert for planetary defense from killer asteroids. The mission was designed to change the orbital period of Dimorphos, the smaller asteroid in the Didymos–Dimorphos binary asteroid system, via a kinetic impactor. In a recent article in the Planetary Science Journal led by Dr. Nathan Roth, ALMA observations of the binary asteroid system were done pre- and post-impact to measure the ejecta. The average ejecta mass observed between 3.5 to 8.6 hours after the impact are 1-6x10⁷ kg match pre-impact simulations, providing confirmation of the DART method.  The ejecta were primarily large particles, thus 0.87mm ALMA observations provide the best sensitivity to the total ejecta mass and ALMA's ability to provide support for such missions.  

Pre- and post-impact (+3.5 hours) continuum flux maps of the Didymos-Dimorphos asteroid binary system. The asteroid illumination phases, the directions to the Sun (S) and the DART spacecraft impact (D), and the heliocentric vector (dr_H/dt), are shown in the lower right corner.