NASA's DART mission changed Didymos asteroid pair's orbit around the Sun.

New research reports that DART's 2022 impact on the moonlet Dimorphos shortened its orbit around Didymos and also shifted the binary system's 770-day orbit around the Sun by about 0.15 seconds.

NASA's DART spacecraft intentionally struck the small asteroid Dimorphos in September 2022. The impact shortened Dimorphos's orbit around its larger companion, Didymos, and blasted a cloud of debris into space. A study published in Science Advances reports the collision also produced a measurable change to the Didymos–Dimorphos system's 770-day orbit around the Sun. Researchers combined radar, long-term ground observations and 22 stellar occultations recorded between October 2022 and March 2025 to reach these results. Key findings: - DART's impact shortened Dimorphos's roughly 12-hour orbit around Didymos by about 33 minutes. - The binary system's 770-day heliocentric orbital period changed by about 0.15 seconds after the impact. - The system's orbital speed altered by about 11.7 micrometers per second (roughly 1.7 inches per hour). - Ejecta from the collision produced a momentum enhancement factor near two, meaning debris roughly doubled the momentum change compared with the spacecraft alone. - The team used 22 stellar occultations, thousands of ground-based position measurements, and spacecraft navigation data to measure the system's motion with high precision. - Analysis indicates Dimorphos is slightly less dense than earlier estimates, consistent with a rubble-pile origin. Summary: This result is the first reported instance of a human-made impact producing a measurable change in a natural object's orbit around the Sun. The change is tiny but, over years or decades, such a shift can accumulate in ways relevant to planetary defense planning. Further study is expected when the European Space Agency's Hera spacecraft arrives to examine the system later this decade, and NASA is developing the NEO Surveyor mission to improve detection of hard-to-find near-Earth objects.