NASA's Double Asteroid Redirection Test (DART) mission achieved more than expected when it collided with asteroid Dimorphos in September 2022. While the immediate result was a 33-minute reduction in Dimorphos' orbital period around its parent body Didymos, new research reveals the impact altered the entire binary system's trajectory around the Sun.

Tracking this change required analyzing 22 stellar occultations between October 2022 and March 2025, combined with nearly 6,000 ground-based measurements spanning 29 years. The University of Illinois Urbana-Champaign team led by Rahil Makadia calculated that DART decreased the Didymos system's along-track velocity by just 11.7 micrometers per second. This tiny nudge, equivalent to a vending-machine-sized spacecraft hitting at over 22,000 kilometers per hour, demonstrated that even small impulses can accumulate over time.

Surprisingly, the DART impact ejected debris that contributed momentum equal to the spacecraft itself, with a momentum enhancement factor of around two. The mission also revealed that Dimorphos is a porous rubble pile with a density of 1.51 tons per cubic meter, compared to Didymos' 2.6 tons per cubic meter. These findings confirm kinetic impact as a viable planetary defense method and will be further verified when ESA's Hera spacecraft arrives at the Didymos system in late 2026.