Game-theoretic maneuvering strategies for orbital inspection of non-cooperative spacecraft in cislunar space

The problem of maneuvering for a servicing spacecraft (inspector) to inspect a non-cooperative spacecraft (evader) in cislunar space is investigated in this paper. The evader, which may be a malfunctioning or uncontrolled satellite, introduces uncertainties due to its potential maneuvering capabilities. To address this challenge, the scenario is modeled as a special orbital game, incorporating the unique complexities of the cislunar environment. A variable-duration, turn-based inspection and anti-inspection game model is designed. The model defines both players’ rules, constraints, and victory conditions, providing a framework for non-cooperative inspection. Strategies for both players are developed and validated based on their dynamical properties. The inspector’s strategy integrates two-body Lambert transfers with shooting methods, while the evader’s strategy aims to maximize the inspector’s fuel consumption. Simulation results show that the evader’s optimal strategy involves deliberate fluctuations in its lunar periapsis altitude, with the inspector’s required ΔV up to eight times greater than the evader’s. The impact of game constraints is evaluated, and the effectiveness of deploying the inspector in low lunar orbit is compared with the inspector at the Earth-Moon Lagrange point L₁. The strengths and weaknesses of both are shown. These findings provide valuable insights for future orbital servicing and orbital games.