“Ryugu – visited by Hayabusa2 – and Bennu – visited by NASA’s OSIRIS-REx spacecraft – are carbon rich ‘C-class’ asteroids, very different from the silicate-rich ‘S-class’ Didymos and Dimorphos, but all of them do seem to possess a comparable lack of cohesion. We still need to understand and clarify this behaviour, because we cannot make statistics on only a trio of asteroids, but a general lack of cohesion for all small asteroids is an intriguing suggestion, and would be good news for planetary defence, because if we know in advance how a body will react, this will make it easier to design the appropriate deflection tools!”

Hailing from 24 institutions in all, the team forms part of the larger international Hera Science Working Group. They are looking forward to finding out if their colleagues’ latest observations of the Didymos system validate aspects of their modelling, such as the altered asteroid shape and resulting orbital perturbations, which will eventually be fully made clear by Hera.