Application of ZEM/ZEV guidance for closed-loop transfer in the earth-moon system

The vision for advanced missions to the lunar far-side brings many challenges to the forefront of the space community. This paper focuses on two subjects pertaining to lunar far-side operations: utilization of a feedback guidance algorithm and the ability to exploit invariant manifolds for reaching desired states in a fuel efficient manner. The performance of the δr/δv form of the ZEM/ZEV (Zero-Effort-Miss/Zero-Effort-Velocity) feedback guidance algorithm is evaluated through scenarios in the Circular Restricted Three-Body Problem. All scenarios include the use of invariant manifolds to complete transfers. A grid search is implemented to find invariant manifolds and δr/δv trajectories that minimize the fuel used during the transfer. Overall, the use of the δr/δv guidance algorithm for targeting manifolds is successful when thrust is not saturated, but becomes problematic when thrust saturation exists. Conclusions were drawn by exploring halo to halo transfers, descending from, and ascending to the lunar far-side.