Optimal Continuous-Thrust Responsive Theater Maneuvers

Abstract

This research investigates a continuous-thrust implementation of the responsive theater maneuver, which is designed to alter a spacecraft’s entry conditions as it overflies a specified geographic region, called the exclusion zone. A particle swarm optimization algorithm employing shape-based continuous-thrust trajectory approximation is used to seed a direct orthogonal collocation routine employing a nonlinear programming problem solver. This approach is used to generate optimal continuous-thrust responsive theater maneuver trajectories. The combination of particle swarm optimization, shape-based continuous-thrust trajectory approximation, and direct orthogonal collocation is shown to generate fuel-optimal trajectories for single-, double-, and triple-pass cases of the responsive theater maneuver problem. Further, these continuous-thrust trajectories are shown to satisfy the analytical necessary conditions for an optimal control and require delta velocities only slightly larger than those required for impulsive responsive theater maneuvers delivering the same effects. As continuous-thrust propulsion technology improves, the continuous-thrust responsive theater maneuvers can provide propellant mass expenditure savings over their impulsive counterparts despite requiring more delta velocity.