Optimal Three-Impulse Lunar Transfers in High Fidelity Models

The study explores the possibility of reducing the fuel costs for two-impulse lunar transfers in a four-body model with the Earth, Moon, and Sun. Lawden’s primer vector theory is applied to derive conditions for impulsive fuel-optimal trajectories. These criteria identify trajectories that could benefit from an additional impulse. A semi-analytical optimization technique computes three-impulse transfers, showing notable improvements in trajectories with an initial lunar gravity assist. The transfers are then adapted to an ephemeris-based solar system model using a multiple shooting technique. The methodology successfully adjusts the trajectories designed in the four-body model to fit the real solar system.