“Once we had that model, we could move towards implementation, planning orbital trajectories to minimise radiation doses, setting rad-hard requirements for payloads and subsystems, and plan the testing of candidate components.”

Sensitive electronics are protected inside a pair of lead-lined vaults within the body of the Juice spacecraft, whose mission trajectory has been set out with survivability in mind. So for example, Juice will fly past 21 Callisto times, and end up in orbit around Ganymede, but will only fly past Europa twice, because this icy moon orbits closest to Jupiter and its halo of radiation. Even so, these two flybys will cause Juice to sustain around a third of its overall radiation exposure in one go.