Investigation Into Geometry and Behavior of Cislunar GEO-Grazer Orbits

This thesis investigates a class of cislunar trajectories referred to as GEO-grazers: orbits that traverse the Earth–Moon system while grazing or passing below geosynchronous Earth orbit (GEO). These trajectories are of interest for cislunar space domain awareness (SDA) because they provide natural dynamical pathways by which spacecraft or debris originating far beyond GEO can approach critical orbital infrastructure. The analysis is conducted primarily within the planar circular restricted three-body problem (PCR3BP), using the Jacobi constant to characterize different geometries and timescales of GEO-grazers. Case studies of real cislunar objects are first examined to demonstrate that GEO-grazing behavior has already occurred, both as a result of deliberate mission design and chaotic dynamics. A generalized modeling approach is then used to generate GEO-grazers by time-reversing trajectories that originate at GEO and reach the exterior realm of cislunar space. Across ranges of Jacobi constants, GEO-grazers are shown to exhibit structured behavior, including clustering of lunar realm entry and exit locations, non-monotonic trends in time of flight to GEO, and consistent grouping of GEO impact or grazing regions relative to the position of the Moon. Finally, the practical implementation of GEO-grazers is explored through the identification of cislunar parking orbits via the simulation of impulsive maneuvers that transfer these orbits onto GEO-grazing trajectories. The results demonstrate that maneuvers on the order of tens of meters per second can be sufficient to induce GEO-grazing behavior, particularly when executed within the lunar realm. Collectively, these findings indicate that the existence of GEO-grazers has important implications for the detection, classification, and intent assessment of objects operating in the Earth–Moon environment.