Enlarge / Riding atop a SpaceX Falcon 9 rocket, NASA’s Double Asteroid Redirection Test, or DART, spacecraft sets off to collide with an asteroid in the world’s first full-scale planetary defense test mission in November 2021. (credit: NASA/Bill Ingalls) On a fall evening in 2022, scientists at the Johns Hopkins University Applied Physics Laboratory were busy with the final stages of a planetary defense mission.