Use of weak stability boundary trajectories for planetary capture

The consideration of transfers to the Weak Stability Boundary region represents one of the most advanced concepts when trying to reduce the propellant requirements to obtain an interplanetary goal. Deimos Space, under ESA contract, has developed a tool to simulate such transfers to inner planets, giant planets and natural moons of giant planets. The method is based on a three-step approach consisting on: selection of strategy, generation of initial solutions and numerical optimisation. The feasibility of building WSB transfer trajectories to Mercury, Venus and Mars has been proven. Instead of ∆V saving, the greatest advantage results from the increased flexibility in the selection of the final orbit with no ∆V penalty in most cases. The use of the Sun/Planet WSB region for the problem of giant planets capture does not introduce significant profit since the penalty in transfer time makes the mission unrealistic. Feasible missions to Jupiter and Saturn are obtained when using a double flyby strategy in Ganymede and Titan respectively. The capture by a natural moon of a giant planet incorporates a phase of energy reduction by moon flybys using resonant orbits linking at the end with the WSB region of the moon to achieve a ballistic capture.