Minimum-Fuel Low-Earth-Orbit Aeroglide and Aerothrust Aeroassisted Orbital Transfer Subject to Heating Constraints

Abstract

A numerical optimization study of minimum-fuel low-Earth-orbit aeroglide and aerothrust aeroassisted orbital transfer of a small spacecraft subject to constraints on heating rate and heating load with a required inclination change is considered. The aeroassisted orbital transfer is formulated as a three-phase optimal control problem consisting of an exoatmospheric deorbit phase, an atmospheric flight phase that may or may not include thrust, and a second exoatmospheric flight phase. The two different variations of the three-phase optimal control problem that arise from the trajectory design are solved using a high-accuracy adaptive Gaussian quadrature collocation method. The fuel consumption of both the aeroglide and aerothrust aeroassisted maneuvers are assessed as functions of the maximum allowable heating rate, the maximum allowable integrated heat load, the maximum lift-to-drag ratio of the vehicle, and the initial mass of the vehicle. Finally, the key features of the optimal aeroglide and aerothrust maneuvers are identified.