Session B4b: Future of Space, Lunar, and Extraterrestrial Navigation 2

Preliminary Assessment of Lunar GBAS Positioning Performance
Euiho Kim, Danim Jung, and Donguk Kim, Hongik University
Location: Holiday 4-5 (Second Floor)
Alternate Number 1

This paper evaluates the user positioning accuracy of a proposed Lunar Ground-Based Augmentation System (L-GBAS) designed for Lunar Navigation Satellite Systems (LNSS). The L-GBAS utilizes a swarm of lunar rovers equipped with LNSS receivers and UWB inter-ranging transceivers, functioning as reference stations similar to terrestrial GBAS. By integrating LNSS and UWB measurements through cooperative positioning and dedicated communication links, previous research has demonstrated that users within the L-GBAS network can achieve absolute positioning accuracies of a few meters using differential corrections.
This study further investigates the achievable positioning performance of the L-GBAS network from three key perspectives. First, while L-GBAS provides absolute positioning accuracy at the meter level, its relative positioning accuracy is significantly higher—often by an order of magnitude—making it a crucial enabler for challenging lunar applications such as autonomous navigation and robotic operations for in-situ resource utilization (ISRU). To quantify this, we assess the performance of an integrated IMU/L-GBAS system using a Kalman filter. Second, although the expected position bias of the GBAS reference rovers is on the order of a few meters, actual biases may vary depending on the quality of ephemeris data from future LNSS systems. Since cooperative positioning introduces a common bias across all reference receivers, a significant portion of this bias is mitigated through user receiver clock error cancellation in differential corrections. This study analyzes the impact of reference rover position biases on user positioning performance across the L-GBAS coverage area. Third, due to the Moon’s near-absence of an atmosphere, atmospheric effects contribute minimally to the decorrelation of differential corrections, leaving ephemeris errors as the dominant factor. Consequently, the effective coverage area of L-GBAS corrections is expected to be significantly larger than that of terrestrial GBAS systems. This paper examines the impact of ephemeris decorrelation on L-GBAS performance and assesses achievable user positioning accuracy across different lunar regions.
The insights gained from this research will contribute to a better understanding of L-GBAS positioning capabilities and inform strategies for optimal network deployment to meet the stringent accuracy requirements of future lunar exploration and critical mission operations.