Minimum-Fuel Low-Earth Orbit Aeroassisted Orbital Transfer of Small Spacecraft

The problem of small spacecraft minimum-fuel heat-rate-constrained aeroassisted orbital transfer between two low Earth orbits with inclination change is considered. Assuming impulsive thrust, the trajectory design is described in detail and the aeroassisted orbital transfer is posed as a nonlinear optimal control problem. The optimal control problem is solved using an ftp-adaptive pseudospectral method, and the key features of the optimal trajectories are identified. It was found that the minimum impulse solutions are obtained when the vehicle enters the atmosphere exactly twice. Furthermore, even for highly heat-rate-constrained cases, the final mass fraction of the vehicle was fairly large. Finally, the structural loads on the vehicle were quite reasonable, even in the cases where the heating rate was unconstrained.