Daiki Mori, NEC Corporation; Katsuaki Taya, NEC Corporation; Taichiro Sano, NEC Corporation; Yuichi Furukawa, NEC Aerospace Systems; Shizuka Komatsu, NEC Aerospace Systems; Takahito Sakaue, NEC Aerospace Systems; Takayuki Seo, NEC Aerospace Systems
https://doi.org/10.64861/EWOR6958
Keywords: orbital debris, fragmentation events, CDM trends, TLE analysis, low Earth orbit, debris descent prediction, collision risk assessment
Abstract:
The rapid increase in artificial satellites in low Earth orbit has led to a rise in fragmentation events that generate large amounts of debris. When such an event occurs, its effects extend beyond the orbital plane of the parent object and gradually propagate downward to satellites at lower altitudes. As the debris cloud descends, it imposes significant operational burdens on satellite operators. These burdens include more frequent orbit determination, increased collision risk assessments, and higher demand for sensor resources to track debris. In practical operations, once a debris cloud approaches the altitude of active satellites, the number of issued Conjunction Data Messages (CDMs) typically rises sharply. This surge increases the workload on both computational systems and human analysts responsible for evaluating conjunction risks. Anticipating these changes is essential for maintaining safe and efficient satellite operations under increasingly congested conditions in low Earth orbit. Historical fragmentation cases show a consistent pattern: satellites located below the altitude of a debris‑generating event experience noticeable increases in CDM issuance. Each close‑approach alert requires a conjunction analysis, which often depends on computationally intensive orbit propagation. When a fragmentation event produces thousands of debris objects, the number of potential conjunctions grows rapidly, making it difficult for operators to evaluate all cases in a timely manner. Additionally, after the first peak in CDM issuance subsides for satellites near the fragmentation altitude, a secondary rise is often observed for satellites at even lower altitudes. This cascading pattern reflects the gradual downward migration of the debris cloud and highlights the need for methods that can anticipate these shifts before they occur. To better understand this behavior, we analyzed the descending trends of debris generated by several past fragmentation events. Using the Two‑Line Element sets (TLEs) published on Space‑Track, we conducted continuous monitoring of debris altitude changes. This allowed us to examine whether the timing and duration of increased CDM issuance for operational satellites could be inferred from changes in debris orbital elements. The analysis revealed a strong correlation between the downward trend in TLE altitudes and the frequency of CDM issuance. In particular, we found that the CDM issuance trend for satellites positioned at higher altitudes than the operational satellites could be used as a predictor of future CDM activity at lower altitudes. This means that operators do not necessarily need to rely on large‑scale orbit propagation to anticipate debris‑related workload. One important finding from this study is that monitoring TLE data alone can provide early indicators of future conjunction activity. Even before any CDMs are issued for operational satellites, changes in the altitude of the debris cloud can signal when close approaches are likely to occur. When debris begins crossing the orbital region of a reference satellite population, an increase in CDM issuance for those satellites is typically observed. This early indication can then be extrapolated to estimate when satellites at lower altitudes will experience similar increases in conjunction activity. With this approach, operators can forecast medium‑ to long‑term impacts with minimal computational effort. This forecasting capability offers several practical benefits. First, operators can better plan for periods of high CDM frequency by allocating staff and computational resources in advance. Second, sensor resources used to track debris can be scheduled more strategically. Since sensor time is limited, anticipating the optimal periods for increased tracking allows for more efficient monitoring of debris clouds. Third, by reducing the need for frequent orbit propagation of large debris populations, the overall computational load on operational systems can be significantly reduced. This becomes especially valuable during large fragmentation events, where traditional methods may be overwhelmed by the volume of debris. In summary, the study shows that CDM issuance trends and TLE‑based descent patterns can be used as an effective method for forecasting the operational impacts of debris clouds on satellites. This approach provides operators with the ability to anticipate workload increases, plan sensor usage, and maintain safe satellite operations with reduced computational demands. As the orbital environment becomes increasingly crowded due to the rapid deployment of satellites, such predictive methods will play a critical role in ensuring sustainable and efficient operations in low Earth orbit.
Date of Conference: September 15-18, 2026
Track: Space Debris