NASA's DART mission altered a binary asteroid system's orbit around the sun.

In 2022 NASA's DART spacecraft struck the small asteroid Dimorphos, shortening its orbit around the larger Didymos; new analysis shows the impact and escaping debris also shifted the binary system's orbit around the sun by about 0.15 seconds and changed its orbital speed by roughly 11.7 microns per second.

NASA's Double Asteroid Redirection Test (DART) intentionally impacted the small asteroid Dimorphos in 2022 to test whether a kinetic hit could alter an asteroid's motion. Scientists report that the impact shortened Dimorphos' orbit around its larger companion, Didymos, and also changed the pair's orbit around the sun. Researchers say the cloud of ejecta created by the collision boosted the overall momentum transfer. The new results were published March 6 in Science Advances. Key facts: - The DART impact occurred on September 26, 2022, when the spacecraft struck Dimorphos at about 6.6 kilometers per second. - Dimorphos' orbital period around Didymos shortened from 11 hours 55 minutes to 11 hours 23 minutes after impact. - The binary system's orbit around the sun was measured to change by about 0.15 seconds, with an orbital speed change of roughly 11.7 microns per second (about 1.7 inches per hour). - Analysis attributes extra push to ejecta; the reported momentum enhancement factor for the event is two, meaning the escaping debris roughly doubled the effective thrust from the initial impact. - Observations supporting the measurement included 22 stellar occultations recorded between October 2022 and March 2025 by 49 amateur astronomers, combined with years of ground-based data. - Density estimates based on the orbital changes put Didymos at about 2,600 kg/m3 and Dimorphos at about 1,540 kg/m3, consistent with Dimorphos being a loosely bound rubble pile and supporting the idea it may have formed from material spun off Didymos. Summary: The DART impact changed both the small moonlet's orbit around its companion and the binary pair's orbit around the sun, demonstrating that a kinetic impact plus ejecta can produce measurable long-term shifts in asteroid motion. NASA plans a Near-Earth Object Surveyor mission after September 2027 to help find more asteroids near Earth's path; further monitoring and analysis will refine understanding of how impact and ejecta affect asteroid orbits.