Denvir Higgins, Lawrence Livermore National Laboratory; Travis Yeager, Lawrence Livermore National Laboratory; Peter McGill, Lawrence Livermore National Laboratory
https://doi.org/10.64861/SBXA7376
Keywords: cislunar space, N body dynamics, trajectory families, orbital stability, stretched exponential decay, chaotic dynamics, large scale propagation, simulation
Abstract:
Cislunar space, the volume of space encompassing the Earth and Moon, exhibits chaotic orbital dynamics due to the complex interaction of gravitational bodies. Traditional three body models do not fully capture this environment; their trajectory families cannot be directly applied under realistic N-body dynamics. As a result, the structure and boundaries of trajectory families in cislunar space are less clearly separated, and many semi stable trajectories occupy transitional regions between classical family definitions.
We use the open source SSAPy framework [1], a full-physics propagator optimized for high performance computing, to propagate and analyze one million unaided cislunar trajectories under full N-body dynamics, including perturbations from additional gravitational bodies and radiation pressure. We identify trajectory families based on orbital morphology and location, then quantify their stability using exponential and stretched exponential decay models to derive half-life metrics. The resulting cislunar trajectory catalog and underlying simulation dataset [2] are released for use by other analysts and mission designers.
Trajectories that remain primarily between the Earth and Moon form the most stable family, while nominally circular and periodic trajectories are unexpectedly short lived once full perturbations are included. Stretched exponential models provide better fits for 92.3 percent of families, indicating broad distributions of escape times consistent with chaotic dynamics and cumulative perturbative effects. We also observe regular, periodic deviations within equatorial and polar inclination families that reveal repeatable patterns in their long-term evolution, linked to the timing of gravitational and radiative perturbations.
These results demonstrate that unaided long duration stability in cislunar space is sparse and highly structured, and they highlight large scale N-body propagation using SSAPy as an effective approach for mapping and characterizing this regime. The identified families and their decay metrics provide actionable guidance for mission design and satellite deployment. As future work, we will develop an intelligent query system that uses natural language to retrieve dynamically similar trajectories from this dataset.
This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and was supported by the LLNL LDRD Program under Project Number 22-ERD-054. The document number is LLNL-ABS-2016100.
Date of Conference: September 15-18, 2026
Track: Cislunar SDA