Tiny nudge, big consequence: DART subtly shifts binary asteroid's solar orbit
NASA’s Double Asteroid Redirection Test (DART) slammed into the small moon Dimorphos in 2022, shortening its orbit around the larger asteroid Didymos from 11 hours 55 minutes to 11 hours 23 minutes. A new analysis shows ejecta from the cratering boosted the thrust by a momentum-enhancement factor of about two, meaning the ejecta carried away momentum that amplified Dimorphos’ deflection. Because Dimorphos is bound to Didymos, the extra push nudged the whole binary’s orbit around the Sun, changing their heliocentric orbital period by about 0.15 seconds. The result, based on ground-based observations including 22 amateur stellar occultations, supports the feasibility of asteroid deflection and informs future efforts, including NASA’s planned Near-Earth Object Surveyor to find more near-Earth objects after 2027.
