Planetary Defence Investigation
Hera is ESA's part of the first full-scale test of asteroid deflection. On 26 September 2022 NASA's DART spacecraft deliberately crashed into Dimorphos, a 151-metre moon of the 780-metre asteroid Didymos, and shortened its orbit by about 33 minutes. Hera will measure the crater, the mass of Dimorphos and the exact change to its orbit, turning a one-off experiment into a technique that could one day protect Earth.
Arrival and CubeSat Companions
After a Mars flyby in March 2025, Hera first spotted Didymos on 7 October 2026 and slowed down with braking burns on 15 and 22 October 2026. ESA planned its arrival for November 2026, followed by months of mapping from closer and closer range and the release of two CubeSats in early 2027: Milani, to study the asteroids' surfaces and dust, and Juventas, with a low-frequency radar to probe the inside of Dimorphos.
Its Place on the Map
Around its arrival, until the spacecraft's own path is published, the tracker shows the position of Didymos itself: Hera stays within a few dozen kilometres of it, a tiny distance next to its distance from Earth.