Risks from Spacecraft Breakup Events in Near Rectilinear Halo Orbits
Abstract
This study simulates debris-generating spacecraft breakup events in the vicinity of the Lunar Gateway space station's planned Near Rectilinear Halo Orbit (NRHO) with the aim of determining the collision risks that would be posed by the debris. Breakup events near NRHOs could be particularly concerning both due to the current lack of Space Situational Awareness (SSA) capabilities in cislunar space, which would limit the ability to track close approaches between spacecraft and debris objects, and potential risks to humans due to the planned use of NRHOs for crewed exploration through the Artemis program. Therefore, this study seeks to identify the behavior of space debris following breakup events near NRHOs, providing insight into the possible collision risks to the Lunar Gateway resulting from this scenario. Few prior studies have investigated the risk that could be posed by breakup events in cislunar space, although some have begun to raise concerns over artificial debris in cislunar space as interest in this environment has grown. The White House Cislunar Strategy, released in November 2022, specifically mentions the need to understand debris in cislunar space, stating that the United States government will "...aim to understand the long-term effects of growing human activities on the Cislunar environment, and to preserve a safe and sustainable environment in Cislunar space..." Like the near-Earth environment, where debris from spacecraft breakup events comprises the majority of the debris population, breakup events could also become a significant source of debris in cislunar space, necessitating study of their consequences. This research focuses on the simulation of breakup events suffered by objects deployed from the Lunar Gateway's NRHO. The Lunar Gateway will serve as a staging point for future lunar exploration through the Artemis program when it becomes operational in the late 2020s, with many spacecraft arriving and departing. These spacecraft could include small satellites released from the station and resupply modules. In this research, hundreds of random breakup events are simulated using a Monte Carlo approach and High Performance Computing resources. The properties of debris fragments released from spacecraft breakup events are determined by applying the NASA Standard Breakup Model, and the debris is then propagated for up to one year using a high-fidelity cislunar trajectory model. A primary goal of this study is to evaluate the risk to the Lunar Gateway from a nearby debris event. The observed miss distances between the Lunar Gateway and the nearest debris object for each simulated breakup event are calculated and analyzed. NASA has released a 15-year reference trajectory for the Lunar Gateway spanning from 2020 to 2035, so this trajectory can be used to determine the expected location of the space station at any date and time. The miss distances observed in the debris simulation are used to determine the likelihood of collision and the likelihood of close approaches with the station. This evaluation of the risk to the Lunar Gateway could have implications for cislunar space traffic management strategies to mitigate debris risks. In addition, the final locations of all debris objects in cislunar space are identified to determine how many objects remained near the original NRHO or entered other regions of Earth-Moon space. An understanding of the motion of debris following a breakup event and the regions traversed by the debris may help inform the development of cislunar SSA capabilities for debris tracking. This research builds on work presented at the 2022 AMOS Conference in "Long-Term Evolution of Debris Clouds in Low Lunar Orbit." The 2022 paper conducted Monte Carlo simulation of breakup events in low lunar orbits and calculated the risk to other lunar spacecraft. The present research applies similar methods to study breakup events in a different cislunar environment: the region near the Lunar Gateway's NRHO. The dynamics of objects differ greatly between low lunar orbits and NRHOs, so it is important to study the consequences of debris events in both environments, especially with their planned applications for future crewed lunar exploration.
- Publication:
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Proceedings of the Advanced Maui Optical and Space Surveillance (AMOS) Technologies Conference
- Pub Date:
- September 2023
- Bibcode:
- 2023amos.conf...79B
- Keywords:
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- cislunar debris;
- lunar debris;
- space debris;
- NRHO;
- Lunar Gateway;
- cislunar space traffic;
- cislunar breakup events