Coupled versus uncoupled optimal solutions for thermal and dynamic problems in spacecraft atmospheric flight

This paper aims to address a significant issue related to the coupled and uncoupled treatment of the thermal and dynamic problems in the optimization of aeroassisted orbital maneuvers and the simultaneous optimal sizing of the associated heat shields. The literature generally focuses on decoupled treatments that reduce the computational load; in this manner, consequently, a decrease in the representativity of the solution manifests. The general operating mode first optimizes the trajectory and subsequently defines the optimal heat shield design based on that trajectory.

This paper analyzes the impact of both treatments on the evaluation of the convenience of an aeroassisted maneuver with respect to an equivalent purely propulsive exoatmospheric maneuver in relation to the achievable total mass savings of the propellant and the heat shield. Two case studies are analyzed via an optimization methodology that references genetic algorithms: the first case study is related to an aerobraking maneuver and the second case study is related to an orbital plane change.

The results demonstrate that the adoption of decoupling produces conservative solutions, i.e. unfavorable estimates, with a lower level of convenience of the aeroassisted technique compared to equivalent purely propulsive exoatmospheric maneuvers.

This type of analysis can provide an appropriate discernment criterion for the selection of the modus operandi based on the available computational power and the desired level of representativity.