On 18 October 2026, the European Space Agency’s Hera spacecraft captured its first clear image of Didymos and Dimorphos as separate objects. It used its black-and-white Asteroid Framing Camera from about 1,280 kilometres away; the asteroid pair was then about 197 million kilometres from Earth.
Hera’s approach and investigation
Two thruster manoeuvres earlier in October reduced Hera’s speed relative to the asteroids to 20 metres per second. Didymos is about 780 metres in diameter, while its smaller companion Dimorphos measures about 151 metres across. Launched in October 2024, Hera carries 12 scientific instruments and is set to deploy two CubeSats, Milani and Juventas, for closer observations and possible landing operations.
Hera will examine the site of NASA’s Double Asteroid Redirection Test (DART), which deliberately struck Dimorphos on 26 September 2022. The impact changed Dimorphos’s orbit around Didymos by about 33 minutes—more than initial predictions. Hera will investigate the impact crater, the asteroid’s internal structure, mass and composition to improve planetary-defence strategies. The European Space Agency plans to unveil the first detailed images of Dimorphos on 25 November 2026.
Important Facts for Exams
- Impact-efficiency measurements: Hera will assess kinetic-impact efficiency by measuring crater size and morphology, transferred momentum and the expanding debris cloud.
- CubeSat task split: Hera’s Milani CubeSat studies surface spectra and nearby dust, while Juventas investigates subsurface and internal structure.
- Juventas subsurface radar: Juventas’s JuRa radar operates at 50–70 MHz and is designed to probe an asteroid’s inner layers, with 10–15-metre spatial resolution.
- Autonomous guidance: Hera’s guidance software uses multiple sensors to reconstruct nearby space and independently define a safe trajectory around the asteroid.
