ESA clears Hera to begin Didymos arrival operations this week after Tuesday review
Isabelle Voss ·
The European Space Agency said Tuesday that its Hera spacecraft is set to start proximity operations at the Didymos and Dimorphos system later this week, following a final readiness review at ESOC in Darmstadt. Hera will close in to a few kilometers, characterize the DART impact site, and eventually deploy two CubeSats to investigate the moonlet’s surface and interior.
This milestone matters because it turns DART’s 2022 impact from a successful demonstration into a calibrated technique. By measuring the mass, structure, and momentum transfer at Dimorphos, Hera will give agencies the data needed to design and time any future kinetic deflection with less uncertainty.
Why Hera’s arrival matters DART shortened Dimorphos’s orbital period around Didymos by about 33 minutes. That change confirmed the concept, but the momentum enhancement factor and the role of ejecta are still model dependent. Hera will refine these numbers by mapping the crater, weighing the bodies through radio science, and linking surface geology to the dynamical change.
ESA plans to release the 6U CubeSats Milani and Juventas after initial survey orbits. Milani will map composition and dust through multispectral imaging. Juventas carries a low frequency radar to sound the interior, a first for a small body mission.
How the approach will work Hera will approach on a sequence of hyperbolic arcs, then enter loosely bound terminator orbits measured in kilometers, not meters, because gravity at Didymos is extremely weak. The spacecraft will navigate autonomously using optical landmarks and laser ranging, since one way light time will be several minutes and rules out real time joystick control.
Operations will proceed in phases. Teams will first secure navigation around the primary, then lower the altitude to image the impact site on Dimorphos at higher resolution. CubeSat deployments will follow, with relay through Hera to return radar and spectral data.
ESA officials said the navigation challenge is driven less by propellant limits and more by solar radiation pressure and the irregular gravity field. The flight plan uses natural motion trajectories to reduce thruster use and to keep safe distances if optical tracking is lost.
For the broader technology landscape, Hera advances European autonomy in precision deep space navigation, proximity operations, and miniaturized sensing. Those capabilities feed directly into commercial in orbit servicing, debris removal, and small body prospecting, where autonomous guidance and low gravity flight dynamics translate into new service markets.