Prior to DART’s impact, Dimorphos took 11 hours and 55 minutes to complete an orbit around its larger companion asteroid, Didymos. Following the intentional collision on September 26, 2022, astronomers measured a remarkable reduction in Dimorphos’ orbital period to 11 hours and 23 minutes, representing a 32-minute decrease with a margin of uncertainty of approximately ±2 minutes. This accomplishment far exceeded NASA’s minimum successful benchmark of a 73-second change, making it clear that DART surpassed expectations and demonstrated the feasibility of asteroid deflection techniques.
Reshaping the Asteroid
New studies led by NASA reveal that the DART mission’s impact not only affected Dimorphos’ orbit but also transformed its shape. Initially resembling a relatively symmetrical object, Dimorphos has morphed into a triaxial ellipsoid—something closer to an oblong watermelon. This transformation is attributed to the impact of DART traveling at 5 kilometers per second (3 miles per second), sending shockwaves through the asteroid and causing it to become more elongated while shifting its axis of rotation off-center.