Dimorphos’s response is “completely outside of the realm of physics as we understand it” in our day-to-day lives, said Cristina Thomas, the lead of the mission’s observations working group at Northern Arizona University who was not involved with the study. And “this has overarching implications for planetary defense.”
DART showed that a tiny spacecraft can deflect an asteroid. But the study indicates that crashing a similarly disjointed space rock too forcefully risks fragmenting it, which, in a real asteroid emergency, could create multiple Earthbound asteroids.