Nathan R. Boone, Air Force Institute of Technology; Robert A. Bettinger, Air Force Institute of Technology
Keywords: space debris, cislunar, debris risk, lunar debris, moon
Abstract:
This research seeks to determine the longevity of artificial debris clouds in low lunar orbit by simulating a large number of spacecraft breakups in lunar orbit, propagating the resulting debris for at least a year after the breakup, and determining the proportion of particles that decay to the lunar surface in that time. Debris in low lunar orbit can be remarkably stable, as demonstrated by Meador in his paper Long-term orbit stability of the Apollo 11 Eagle Lunar Module Ascent Stage (2021), which showed that the Apollo 11 lunar ascent stage could remain in lunar orbit to this day. This stability could be problematic for future lunar spacecraft if it leads to a long-term accumulation of artificial debris. Therefore, this research effort examines the likelihood of debris accumulation in lunar orbit by determining the time required for debris generated by a spacecraft breakup to decay to the lunar surface for a variety of breakup scenarios.
While debris near Earth has garnered increasing attention in recent years, few studies have examined debris in orbital environments beyond Earth. The recent acceleration in international activity in the lunar environment brings more opportunities for space debris generation, increasing the need to understand the long-term behavior of debris in lunar orbit. Planned crewed lunar operations through the Artemis program make it especially important to evaluate the collision risks posed by a spacecraft breakup event in lunar orbit. An improved understanding of the long-term evolution of debris in lunar orbit could aid in developing policies for the sustainable use of the lunar orbital environment.
In this research, debris is generated by applying the NASA Standard Breakup Model. The debris is then propagated with a high-fidelity lunar trajectory model that incorporates the non-spherical lunar gravity field, the gravitational perturbations of the Earth and Sun, and the force due to solar radiation pressure. The trajectories are propagated until a substantial portion of the debris has decayed to the lunar surface. The time required for debris to decay is analyzed for each breakup scenario. In addition, the probability of collision is used to determine the risk probability to other notional spacecraft operating elsewhere in lunar orbit. Finally, the locations of debris impacts on lunar surface will also be determined to understand the potential risk to future lunar surface infrastructure from an orbital debris event. For each mishap scenario considered in this research, the main results include the proportion of debris that decayed to the lunar surface during the simulation, the total risk probability to other notional lunar spacecraft during the simulation, and a map of the locations of lunar surface impacts.
This research builds on work presented at the 2021 AMOS Conference in Artificial Debris Collision Risk Following a Catastrophic Spacecraft Mishap in Lunar Orbit. The 2021 paper simulated debris from a spacecraft breakup in a polar low lunar orbit for one month and determined the risk posed to one notional spacecraft in an equatorial lunar orbit. The study found that the debris was stable in lunar orbit for one month, with no noticeable change in risk to the notional spacecraft during the simulation, likely due to the short time period considered. The present research determines how the risk changes over the months or years following the breakup event. Furthermore, a variety of new mishap scenarios are considered to evaluate the behavior of debris in lunar orbits orbits other than the polar orbit considered in the 2021 paper. Risks to a variety of other notional spacecraft are also considered to generate a robust analysis of the risks posed by debris in low lunar orbit.
Date of Conference: September 27-20, 2022
Track: Space Debris