Hera, the European Space Agency's first mission for planetary defence, is due to arrive at its target in November, according to an ESA publication dated 2 November 2026. The small-car-sized spacecraft is headed for Dimorphos, a 151-m-diameter asteroid that orbits its 780-m parent body, Didymos.

Dimorphos is already historic as the first object in the Solar System whose orbit was changed by human action, when NASA's DART spacecraft struck it on 26 September 2022. According to ESA, the impact produced a brightening visible from telescopes on Earth, but what happened to Dimorphos itself is unknown. Hera's task is a close-up survey of the crash site, intended to help turn DART's kinetic impact experiment into a well understood deflection technique.

Scientists also hope the mission yields bonus science. ESA notes that past spacecraft encounters have shown asteroids to be dynamic environments with complex histories, and says many outstanding questions remain, which Hera will explore. The source does not detail the ten mysteries beyond its headline.