Preliminary Contingency Trajectory Planning for Europa Clipper’s Galilean Moon Tour

The Europa Clipper, now en route to the Jovian system, will employ highly eccentric orbits around Jupiter to conduct over 50 Europa flybys to investigate the moon’s habitability. This study addresses a novel trajectory design challenge essential for contingency planning during the mission’s intensive phase of visiting the Galilean moons. In the event of a flight system anomaly or instrument failure, the spacecraft must quickly depart its nominal path and execute a transfer to a safe orbit to mitigate further risk; this safe orbit is characterized by reduced radiation exposure and a low probability of untargeted moon encounters. We propose a framework that enables the preliminary design of these critical contingency escape trajectories, which involve multi-flyby transfers among the Galilean moons with arbitrary sequences and impulsive maneuvers. The methodology first uses an ephemeris-free two-body model for orbital energy analysis, then generates initial guesses under a full-ephemeris two-body model, and culminates in optimization within a full-ephemeris N-body model. The results demonstrate the feasibility of the designed escape transfers, validating the method’s viability for a new and critical class of multi-moon tour design problems that are indispensable for mission contingency mitigation.