Alternative Hybrid Propulsion Transfers for Marco Polo NEOs Sample Return Mission

In this paper the new concept of hybrid propulsion transfers is applied to the trajectory design for the ESA Marco Polo mission, a NEO sample return mission. The concept of hybrid propulsion transfers combine the features of low-energy transfer, which implies impulsive maneuver accomplished using chemical propulsion, and low-thrust transfer. The optimization is performed with a direct transcription procedure. The problem is formulated as a nonlinear programming problem and solved for a finite set of variables, maximizing the final spacecraft mass. The designed hybrid propulsion transfers have been in-depth compared with the baseline trajectories obtained for Marco Polo mission.