On-line entry trajectory planning and combined prediction guidance for lunar return

For the lunar return mission, a concern of the entry guidance requirement is the full flight envelope applicability and landing accuracy control. The NPC method is not limited by the validity of the approximations, simplifications and empirical assumptions necessary for any analytical treatment, thus it holds greater potential to be more accurate and adaptive. However, the NPC algorithms in the literature which merely predict based on the terminal condition cannot guarantee to meet the g-load constraint. To solve this problem, we combine NPC methods with an analytical constant drag acceleration method, and propose a simple and effective integrated guidance strategy.