Optimization of Aero-gravity assisted maneuvers for spaceplanes at high atmospheric flight on Earth

Gravity assists are impulse maneuversthat save costs for interplanetary missions, resulting from close approaches to celestial bodies. Aero-Gravity Assist maneuvers offer another solution to reduce mission cost by taking advantage of aerodynamic forces through cruise flights over the atmospheres of minor planets, like the Earth, which is selected because has been used on multiple gravity assist maneuvers. Despite their theoretical feasibility, the technological requirements make them impossible at low altitudes. Therefore, this work focuses on a spaceplane aeromaneuvering at high atmospheric altitudes and in continuum hypersonic flow, with Knudsen Numbers between 10-3 and 10-2. It is formulated as an optimal control problem with the dynamic optimization suite GEKKO, and solved via nonlinear programming. Nine different cost functions are analyzed separately: the maximization of longitude, latitude, and velocity at the end of the atmospheric flight; minimization of heat transfer, dynamic pressure, and load factor along the trajectory; minimization of flight time; and maximization of plane inclination and range angle. The results show a successful outcome in all cases, with a conclusive Monte Carlo analysis further demonstrating the robustness of the controller to support uncertainties in the initial conditions and atmospheric density.