Planetary defence requires planetary cooperation. Hera is set to rendezvous with the asteroid pair in 2026, by which time NASA’s DART spacecraft will have already impacted Dimorphos, the smaller of the two asteroids. This cosmic shove is expected to slightly shift Dimorphos’ orbit around Didymos.

Hera and its CubeSats will carefully examine the crater left by DART, as well as the surface and interior of the asteroids. Altogether, DART’s impact and Hera’s data will help us understand whether this technique could be used in future to deflect an asteroid on a collision course with Earth.