Hera

Summary

ESA's planetary-defence mission, a "crash-scene investigation" at Dimorphos, the asteroid moonlet that NASA's DART spacecraft hit in 2022, changing its orbit. Hera will measure its mass, structure and crater so that the kinetic-impactor technique can be modelled precisely.

Now as of 3 Nov 2026

The spacecraft is on its final approach. After braking manoeuvres in October its speed relative to the asteroids is about 20 m/s. On 18 October the AFC camera resolved Didymos and Dimorphos as two separate objects for the first time, from 1,280 km away (ESA). According to heise, arrival was due on 4 November, and ESA expects to publish the first detailed images of Dimorphos on 25 November. The approach is stepwise: 25–30 km, then 10, 4 and 1 km; the CubeSats will be released "in the coming months".

Sizes: Didymos is 780 m across, Dimorphos 151 m; on average they are 1.15 km apart.

Key dates

1. 7 Oct 2024Launch (Falcon 9)done
2. 12 Mar 2025Mars gravity assist, images of Deimosdone
3. Mar 2026Deep-space manoeuvre sets course for Didymosdone
4. 7 Oct 2026First detection of the system (a single dot, ~236,500 km)done
5. 18 Oct 2026First image showing Didymos and Dimorphos separately (1,280 km)done
6. ≈ 4 Nov 2026Arrival at the system (per heise; ESA's article gives no date)expected
7. 25 Nov 2026First detailed images of Dimorphos releasedplanned
8. 2026–2027CubeSats Milani and Juventas released; approach to ~1 kmplanned

Timeline

1. 27 Oct 2026"First light": Hera sees the two asteroids separately (image of 18 October, 1,280 km) — ESA
2. 7 Oct 2026Exactly two years after launch, the first image of the target (a single dot, ~236,500 km) — heise
3. Mar 2026Deep-space manoeuvre puts Hera on course for Didymos — ESA
4. 2025ESA announces arrival a month earlier than planned (November instead of December 2026) — ESA