Charles J. Wetterer, KBR; Christopher Craft, KBR; Jason Baldwin, Complex Futures LLC; Micah Dilley, KBR; Paul Billings, KBR; John Gaebler, KBR; Jill Bruer, AFRL
Keywords: Cislunar, Debris, Sustainability
Abstract:
The increase in the utilization of cislunar space necessitates a better understanding of sustainability and the evolution and distribution of debris from cislunar orbits, whether from collisions, breakups or satellite disposal. Possibilities include sublunar orbits (Earth-centered semi-major axes less than that of the Moon and eccentricities less than some specified limit), superlunar orbits (semi-major axes greater than that of the Moon and eccentricities less than the same limit), highly eccentric orbits (eccentricities greater than the specified limit but less than one), hyperbolic orbits (eccentricities greater than one), lunar orbits, Earth impacts, and Moon impacts. The proportions of debris in these categories will, in many cases, vary over the course of time due to further interactions with the Moon. Current debris models, such as NASA’s Orbital Debris Engineering Model (ORDEM), are designed for low-Earth orbit (LEO) and geosynchronous Earth orbit (GEO) and do not account for this type of debris nor model the debris environment in cislunar space. The added complexity of the orbital dynamics due to the influence of the Moon’s gravity not only makes cislunar orbit determination and tracking of objects more difficult, but it also makes the potential debris environment more dynamic. To start investigating this dynamic environment, breakups in two different cislunar orbit families (the northern halo families about the L1 and L2 Lagrange points, termed “HN1” and “HN2”) were simulated using NASA’s General Mission Analysis Tool (GMAT) as the dynamics model and propagated forward in time for six months, and the resulting debris field distribution was examined as a function of time. Isotropic breakups with a characteristic breakup speed were simulated (while conserving total momentum) to provide insight into the envelope of possibilities that more sophisticated models might yield (e.g., NASA’s Standard Satellite Breakup Model (SSBM)). We compared the resulting fragment distributions from these generic breakup events, both between orbit families and within each orbit family, and examined variations due to the timing of the breakup in each orbit and intensity of the breakup (as quantified by the average relative velocities between debris particles at the time of breakup). For example, the relative synodic phase of the object within the halo orbit greatly influenced the fraction of particles that move into each of the defined orbit classes for the same progenitor orbit (e.g., for HN1 family orbits, more sublunar fragment orbits are produced when the progenitor is leading the Moon at time of breakup). Debris distribution variations as a function of the orbit’s Jacobi Energy, proximity to Moon, Lyapunov stability characteristics, and proximity to Lagrange points were examined. The goal is to use these orbital characteristics to determine a measure of volatility related to a cislunar orbit’s debris-creating potential.
Date of Conference: September 19-22, 2023
Track: Cislunar SDA