RESUMO
The Double Asteroid Redirection Test (DART) spacecraft successfully performed the first test of a kinetic impactor for asteroid deflection by impacting Dimorphos, the secondary of near-Earth binary asteroid (65803) Didymos, and changing the orbital period of Dimorphos. A change in orbital period of approximately 7 min was expected if the incident momentum from the DART spacecraft was directly transferred to the asteroid target in a perfectly inelastic collision1, but studies of the probable impact conditions and asteroid properties indicated that a considerable momentum enhancement (ß) was possible2,3. In the years before impact, we used lightcurve observations to accurately determine the pre-impact orbit parameters of Dimorphos with respect to Didymos4-6. Here we report the change in the orbital period of Dimorphos as a result of the DART kinetic impact to be -33.0 ± 1.0 (3σ) min. Using new Earth-based lightcurve and radar observations, two independent approaches determined identical values for the change in the orbital period. This large orbit period change suggests that ejecta contributed a substantial amount of momentum to the asteroid beyond what the DART spacecraft carried.
RESUMO
Analysis of CCD photometric observations of near-Earth asteroid (154244) 2002 KL6 indicate that it may be a binary system. The presumed primary has a synodic rotation period of 4.60869 ± 0.00005 h and lightcurve amplitude of 0.65 ± 0.03 mag. The presumed satellite has an orbital period of 24.05 ± 0.02 h and maximum lightcurve amplitude of 0.07 mag. The secondary lightcurve showed no mutual events and seems to indicate that the satellite's rotation is tidally locked to its orbital period.
