Preliminary Contingency Trajectory Design for Multi-Moon Tours: Application to Europa Clipper

Moon tours are multiflyby strategies that enable science missions in outer-planet many-moon systems while keeping propellant cost tractable. Although nominal tour design accounts for navigation and maneuver-execution uncertainty, discrete contingencies such as missed burns or loss of science capability can require a dedicated escape trajectory to a mission-dependent safe orbit set. This paper formulates contingency escape route design as a deterministic problem that transfers a spacecraft from a nominal moon tour to a safe orbit set using arbitrary flyby sequences and impulsive maneuvers. Motivated by Europa Clipper, where escape from the Jovian radiation environment can require perijove raising and avoidance of unintended Galilean moon encounters, the proposed framework combines energy-based safe orbit identification, full-ephemeris patched-conic broad search, and high-fidelity refinement. Representative cases from Europa Clipper’s Galilean moon tour demonstrate feasible escape trajectories and provide a systematic approach to contingency mitigation for multi-moon tours.