In 2022, NASA deliberately crashed the DART spacecraft into Dimorphos, a harmless asteroid moonlet. The goal was not to blow it apart. It was to see whether one well-aimed shove could change an asteroid’s motion.
It worked. Dimorphos began circling its larger partner about 33 minutes faster than before. Debris spraying from the impact acted like extra thrust, adding to the spacecraft’s push.
YR4’s close passage made DART an irresistible comparison while its impact probabilities were still evolving. The experiment matters because tiny changes add up over long distances. Nudge an asteroid years before a possible encounter and, by the time it reaches Earth’s neighborhood, our planet may be nowhere near its crossing point. The winning strategy is less dramatic than an explosion—and much smarter.