Station-Keeping on a Synodic Resonant Orbit Using Solar Sails

In recent years, deep space exploration missions beyond the Moon have become increasingly active, and minimizing fuel consumption has become a critical requirement for long-duration operation. Solar sails, which generate thrust solely from solar radiation pressure (SRP), offer a promising means of achieving propellant-free navigation. This study focuses on station-keeping in the Bicircular Restricted Four-Body Problem (BCR4BP) using SRP as the primary force. The thrust generated by a solar sail depends strongly on spacecraft attitude, resulting in intrinsic coupling between orbital and rotational motion. Under multi-body gravitational environments, this coupling leads to nonlinear behavior and significant instability, necessitating a unified treatment of orbit–attitude dynamics. To address this, a 12-dimensional Floquet-mode-based control approach is formulated, in which unstable modal components in both orbital and attitude dynamics are actively monitored and suppressed. Rather than developing an attitude controller in isolation, the system is stabilized by regulating unstable Floquet modes associated with the coupled orbit–attitude monodromy matrix. Numerical simulations demonstrate that long-term station-keeping near a synodic resonant orbit around the Moon can be maintained using SRP, confirming the feasibility of propellant-free orbit maintenance through unified modal regulation.