NASA's DART impact (2022)
NASA flew a 570-kilogram spacecraft, DART, straight into the small asteroid Dimorphos at about 6 km/s. It was the first test of deflecting an asteroid by hitting it. The craft steered itself into the target using onboard cameras in the final hour.
The impact shortened Dimorphos's orbit around its larger companion by about 32 minutes, more than expected.
DART proved a kinetic impactor can measurably move an asteroid, making it the leading planetary-defense method on the table.
Hayabusa2's close, high-speed pass tests the same precise autonomous guidance a DART-style deflection needs.
