Aeroassisted Orbital Transfer Trajectory Optimization Considering Thermal Protection System Mass

Aeroassisted orbital transfer is recognized as a potential technology to enhance operational responsiveness in space with significant fuel savings. To endure aerodynamic heating resulting from the flight through the atmosphere, however, considerable thermal protection is required, thereby potentially decreasing the mass savings due to lower fuel consumption. In this paper, the relationship between achievable fuel savings and thermal protection system size is investigated by coupling trajectory optimization and thermal protection system design through the single parameter of maximum heating rate constraint. The optimal solution that minimizes the total mass of fuel and the thermal protection system is then determined. A trajectory optimization procedure and a thermal protection system mass estimation model are then applied to the transfer of a vehicle between two low-Earth orbits with a specified inclination change. All trajectory parameters, including deorbit, boost, and recircularization impulses, are optimized and the thermal protection system is sized with ablative and reusable materials. It is found that the minimum overall mass (fuel and thermal protection system) is achieved when no heating rate constraint is imposed, which is also the scenario that minimizes the fuel consumption alone.