Eclipse Analysis of Periodic Orbit Families at Earth-Moon Libration Points

Due to the Sun-Earth-Moon geometric configuration, spacecraft in orbit experience periods of no illumination. Understanding the shadow distribution characteristics of orbits is crucial for spacecraft power management and mission planning. This study investigates shadow distribution properties of periodic orbits in the Earth-Moon li-bration point system. A lunar periodic orbit database containing 17 orbit families was established based on the Circular Restricted Three-Body Problem (CRTBP), including Distant Retrograde Orbits (DROs), Lyapunov, Halo, and vertical orbits at L1-L5 points. Using a conical shadow model, numerical simulations were conducted over a one-year period to analyze Earth and lunar shadow distributions across different orbit types. Relationships between orbital characteristic parameters (perilune distance for Halo orbits, amplitude for others) and shadow duration were examined. Results indicate superior shadow performance for L3, L4, and L5 orbits compared to L1/L2 orbits, with large-amplitude DROs showing fewer shadows. Among collinear libration point orbits, Halo orbits with moderate perilune distances exhibit better shadow avoidance, while triangular libration point orbits benefit from large am-plitudes. Multiple continuous shadow-free orbital intervals were identified, providing references for mission design in Earth-Moon libration point exploration.