Graphical Method for Gravity-Assist Trajectory Design

A new analytical technique directly related to Tisserand's criterion that permits the quick identification of all viable ballistic gravity-assist sequences to a given destination is introduced. The method is best presented by a simple graphical technique. The graphical technique readily demonstrates that gravity assists via Venus, Earth, and Jupiter are tremendously effective in sequences such as Venus-Earth-Earth-Jupiter and Venus-Earth-Mars-Earth. Estimates are made for the shortest flight times for a given launch energy to each planet. This graphical technique should provide mission designers with a potent tool for finding economical gravity-assist trajectories to many targets of high scientific interest in the solar system.