Semi-Decentralized Multi-Spacecraft Collision Avoidance under Communication Constraints

2026-07-29

AI Summary

This study addresses the challenge of cooperative collision avoidance among multiple spacecraft under intermittent ground station communication constraints. The authors propose a semi-decentralized partially observable Markov decision process (SDec-POMDP) framework that explicitly incorporates ground station visibility into the multi-agent decision-making model for the first time. To solve for joint maneuver strategies, they design an approximate recursive short-horizon semi-decentralized A* algorithm (RS-SDA*). Operating solely within actual communication windows, this approach significantly reduces coordination synchronization events—by 28.5% compared to continuous coordination—while closely approximating the maneuver performance of centralized planning. Moreover, it satisfies safety distance constraints more consistently than heuristic rule-based methods and minimizes unnecessary orbital deviations.

Abstract

Current spacecraft collision-avoidance operations rely on intermittent ground-station contacts, requiring operators to plan with delayed and asynchronously updated information. Consequently, maneuvers must be planned with only intermittent information sharing between operators, raising the question of how much coordination is needed to achieve collision-avoidance performance comparable to centralized planning. Although decision-theoretic approaches such as partially observable Markov decision processes (POMDPs) capture the sequential and uncertain nature of collision avoidance, existing multiagent extensions typically assume either continuous information sharing or communication models that do not reflect operational ground-station constraints. To explicitly model this intermittent information availability, we formulate the spacecraft-to-spacecraft collision avoidance problem as a semi-decentralized POMDP (SDec-POMDP), where we govern information propagation directly by realistic ground-station visibility windows. Joint maneuver policies are computed using approximate Recursive Small-Step Semi-Decentralized A* (RS-SDA*), following the state-of-the-art A*-based lineage for decentralized multiagent planning. Across a representative suite of conjunction scenarios, semi-decentralized planning recovers near-centralized maneuver quality while requiring 28.5% fewer synchronization events than continuous coordination. Comparisons with representative rule-based operator heuristics further show that communication-aware planning more consistently achieves the desired operational miss-distance band while minimizing unnecessary trajectory deviation. Together, these results establish a practical planning framework for autonomous collision avoidance under realistic intermittent communication, bridging the gap between idealized centralized coordination and fully decentralized planning execution.

Problem

• collision avoidance
• multi-spacecraft
• communication constraints
• semi-decentralized planning
• intermittent communication

Innovation

• semi-decentralized planning
• SDec-POMDP
• intermittent communication
• multi-spacecraft collision avoidance
• RS-SDA*