This paper investigates the application of theKoopman Operator theory to the motion of a satellite about a libration point in the Circular Restricted Three-Body Problem. Recently, the Koopman Operator has emerged as a promising alternative to the geometric perspective for dynamical systems, where the Koopman Operator formulates the analysis and dynamical systems in terms of observables. This paper explores the use of the Koopman Operator for computing both 2D and 3D periodic orbits near libration points. Further, simulation results show that the Koopman Operator provides analytical solutions with high accuracy for both Lyapunov and Halo orbits, which are then applied to a station-keeping application.Periodic orbits in the circular Restricted Three-Body Problem (RTBP), such as Lissajous and Halo type trajectories, are of high interest for space mission design applications. In particular, many missions, such as the cislunar space gateway concept, have been proposed that utilize these orbits. The proposed orbit for the gateway is a Near-Rectilinear Halo Orbit (NRHO), which is a non-Keplerian trajectory with the favorable properties of a continuous line of sight coverage for communications with Earth and fuel-efficient access to the lunar surface [1]. Although operating in the RTBP region while utilizing non-Keplerian trajectories has its benefits, it remains challenging to develop, analyze, and perform guidance, navigation, and control for these missions due to the nonlinearities of the RTBP region. Therefore, new approaches for the analytical analysis of these missions are needed.Analytical approaches exist for analyzing the RTBP and developing solutions for their trajectories. In particular, Richardson [2] developed a Lindstedt-Poincaré procedure for computing the Halo orbits through matching the 𝑥-𝑦 periodic frequency with that of the 𝑧 direction motion. Lindstedt-Poincaré methods are powerful perturbation approaches, but they require extensive algebraic computation and can be difficult to derive for higher-order solutions. In addition