| Recent discoveries regarding Saturn's moon, Enceladus, have transformed the small icy moon into one of the most desirable solar system destinations for future robotic reconnaissance. In designing a mission to Enceladus, the insignificant size of Enceladus and its close proximity to Saturn combine to create a remarkably challenging multi-body problem. This investigation offers an overview of three key aspects of the Enceladus transfer problem including: the design of an Enceladus science orbit, the design of Saturnian orbits that permit periodic encounters with Enceladus and additional Saturnian moons, and the design of gravity-assist flyby sequences in the Saturnian system involving five of Saturn's most massive moons: Enceladus, Tethys, Dione, Rhea, and Titan. Although focused specifically on the design problem associated with supporting a mission in the Saturnian system, the Enceladus transfer problem is analyzed from a multi-body perspective. A substantial portion of this investigation involves the application of the Circular Restricted Three-Body Problem (CR3BP) to the Saturnian system, though the dynamics of the Saturnian system are also investigated using a six-body dynamical model. A technique is introduced to design a sequence of gravity-assist flybys by incorporating multiple gravity fields and applying a scheme that adjusts only one initial variable to yield a trajectory with multiple flybys. The capabilities of the trajectory design algorithm are demonstrated through the design of specific gravity-assist flyby sequences that are used to reduce the orbital energy of a spacecraft in a large Saturnian orbit to an energy level that is closer to the level of Enceladus' Saturnian orbit. |
