Asteroid defense mission shifted the orbit of more than its target

Italy's LICIACube spacecraft snapped this image of asteroids Didymos (lower left) and Dimorphos (upper right) a few minutes after the impact of DART on September 26, 2022. Credit: ASI/NASA

On September 26, 2022, NASA’s Double Asteroid Redirection Test (DART) spacecraft crashed into a binary asteroid system. By intentionally ramming a probe into the 160-meter-wide moonlet named Dimorphos, the smaller of the two asteroids, humanity demonstrated that the kinetic impact method of planetary defense actually works. The immediate result was that Dimorphos’ orbital period around Didymos, its larger parent body, was slashed by 33 minutes.

Of course, altering a moonlet’s local orbit doesn’t seem like enough to safeguard Earth from civilization-ending impacts. But now, as long-term observational data has come in, it seems we accomplished more than that. DART actually changed the trajectory of the entire Didymos binary system, altering its orbit around the Sun.

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