Linking Averaged and Unaveraged Three-Body Dynamics Near Smaller Primaries: Symmetric Periodic Orbits

Abstract

Within a three-body system comprised of two celestial bodies and a spacecraft, the dynamical environment near a smaller primary is significantly perturbed, motivating a balance between global insight and model fidelity. While averaged dynamics offer an integrable model to classify solution landscapes, they inherently lack the accuracy of the unaveraged dynamics, such as the Hill Restricted Three-Body Problem and Circular Restricted Three-Body Problem. This work establishes a systematic bridge between the averaged and unaveraged regimes by explicitly linking averaged equilibria to symmetric periodic orbits in the unaveraged three-body systems. A unified frequency framework is introduced to characterize the mapping of invariant tori across the dynamical models. Leveraging the parity of the resonance ratio, an initialization scheme is developed to identify admissible apse configurations, enabling the a priori prediction of solution multiplicity and symmetry types. Furthermore, the global evolution of families derived from averaged equilibria is traced via bifurcation and frequency analysis. These findings are synthesized into archetypical bifurcation diagrams, providing a comprehensive atlas of the symmetric periodic orbit web within the HR3BP and CR3BP. The resulting framework not only clarifies the topological origins of complex periodic orbit families but also offers a versatile tool for trajectory design in cislunar and multi-body environments.