Orbital Blocking Game Near Earth–Moon L₁ Libration Point

This paper explores the blocking capabilities of a spacecraft deployed near Earth–Moon L₁ libration point against another spacecraft attempting lunar gravity assist, based on the ΔV required for interception. The study demonstrates that a pursuer at L₁ libration point can effectively block low-energy evaders with minimal ΔV expenditure, creating a blockade against their use of gravity assists. However, blocking against high-energy evaders is relatively weaker. Pursuers on Lyapunov orbits can execute blockades that L₁ pursuers cannot, albeit with lower mission-capable rates. The paper discusses mission-capable rates for different Lyapunov orbits and evader energies, revealing that each Lyapunov orbit has its unique optimal blocking energy, decreasing as the Lyapunov orbit size expands. In addition, the paper proposes a strategy for evaders to bypass blockades by sacrificing a portion of their ΔV and verifies it numerically. The analysis covers the cost and benefits of the L₁ libration point-related blockade, the importance of the mission-capable rate, and the possibility of lunar-orbit blocking. These findings provide insights for future research on orbital games in the Earth–Moon system and orbital blockade.