A key element of ESA’s Hera mission for planetary defence has left the facilities of its manufacturer OHB in Bremen – a major step in preparation for its eventual odyssey to the Didymos asteroid system.

The mission’s Propulsion Module, seen here, has been delivered to Avio, southeast of Rome, where propellant tanks, thrusters and associated pipes and valves will be integrated with it. The fully equipped Propulsion Module is what will take Hera on its 26-month trek through deep space to the main Didymos asteroid and its smaller Dimorphos companion.

On 26 September this year Dimorphos will become the very first Solar System body to have its orbit altered by human action in a measurable way, when NASA’s DART spacecraft impacts with it. When Hera arrives at the asteroid in December 2026 the spacecraft will perform a detailed post-crash investigation, assessing the mass and make-up of Dimorphos and measuring the crater left by DART’s impact, helping to validate kinetic impact as a workable planetary defence method.

Meanwhile Hera’s other half, the Core Module, is also taking shape at OHB in Bremen. The Core Module will carry all the mission’s scientific instruments as well as on-board computer and other subsystems. The spacecraft will be completed when these two halves are eventually joined together, ahead of Hera’s planned launch in October 2024.