Automated Design of the Europa Orbiter Tour

Before the Europa Orbiter can be placed in orbit about Europa, it will be placed into a 200-day Jovian orbit and targeted for Ganymede. After a series of gravity-assist flybys of the Galilean satellites, the orbital energy is reduced to lower the arrival hyperbolic excess velocity at Europa. These energy-saving techniques reduce the propellant cost for Europa orbit insertion to a minimum. Key constraints during the tour include total time of flight and radiation dosage. Tours may employ 10 or more encounters with the Jovian satellites; hence, there is an enormous number of possible sequences of these satellites. A graphical method based on Tisserand's criterion is presented that greatly aids the design process. The Tisserand graph method facilitates the study of a wide range of arrival conditions, arrival dates, and satellite tours.