Fast-low energy transfer to Earth-Moon Lagrange point L2

A spacecraft comprising;

• a spacecraft bus;
• a hybrid propulsion system connected to the spacecraft bus, the hybrid propulsion system including a high thrust (HT) engine portion, and a low thrust high specific impulse (LT-HI) engine portion;
• and
• a control system connected to the bus and controllably coupled to hybrid propulsion system to effect spacecraft transfer between low earth parking orbit (LEO) and a Lissajous L2 orbit (L2O), the control system being configured for generating an optimal LEO to L2O transfer trajectory employing both the HT engine portion and the LT-HI engine portion of the hybrid propulsion system;
• wherein the optimal LEO to L2O trajectory includes an optimal LT-HI trajectory portion, selected from a stable manifold trajectory, and an optimal HT trajectory portion, and wherein the LT-HI trajectory portion and HT trajectory portion are configured for providing a combined optimal trajectory along the LEO to L2O transfer trajectory, and are optimized substantially simultaneously.

A method for generating a thrusting profile for a hybrid propulsion spacecraft for transfer between low earth orbit (LEO) and a Lissajous L2 orbit (L2O), the method comprising the steps of:

• computing a stable manifold (SM) of trajectories leading to L2O based on thrust generated with a low thrust high specific impulse (LT-HI) engine of the hybrid propulsion spacecraft;
• generating a high thrust (HT) trajectory between LEO and at least one trajectory of the SM, wherein the HT trajectory is generated based at least in part with an impulse change provided by an HT engine of the hybrid propulsion spacecraft, and wherein the HT trajectory and the at least one SM trajectory form a combined trajectory from LEO to L2O;
• and
• optimizing the combined trajectory over both the HT trajectory and the at least one trajectory of the SM in combination and generating a combined optimal trajectory from LEO to L2O.