First Multi-Constellation Observations of Navigation Satellite Signals in the Lunar Domain by Post-Processing L1/L5 IQ Snapshots

2025-12-30

AI Summary

This study investigates the effective reception and utilization of multi-system, multi-frequency GNSS signals in cislunar space and on the lunar surface to enhance spacecraft autonomous orbit determination. By post-processing short-duration L1/L5 IQ snapshots collected by the LuGRE receiver, a hybrid coherent/incoherent acquisition method is employed to compensate for code Doppler, while low sampling rates and 4-bit quantization enable efficient signal processing. The work presents the first experimental confirmation at lunar distances that signals from BeiDou, RNSS, and SBAS can be detected, thereby overcoming the conventional reliance solely on GPS and Galileo. Simulations demonstrate that incorporating these additional constellations increases the percentage of epochs with at least four visible satellites above a 26 dB-Hz carrier-to-noise ratio threshold from 11% to 46%, significantly improving GNSS-based autonomous navigation capabilities for lunar missions.

Technology Category

• Intelligent Robots: Multimodal Perception & Sensor Fusion
• Natural Language Processing: Language Grounding & Multi-modal NLP
• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Experiences and lessons learnt from Web-based algorithms and system deployments
• Semantics and Knowledge: Methods to enhance, augment, integrate or synergize semantic models such as knowledge graphs and LLMs
• Search and Retrieval-Augmented AI: Multilingual and cross-lingual Web search

Abstract

The use of Global Navigation Satellite Systems (GNSS) to increase spacecraft autonomy for orbit determination has gained renewed momentum following the Lunar GNSS Receiver Experiment (LuGRE), which demonstrated feasible onboard GPS and Galileo signal reception and tracking at lunar distances. This work processes in-phase and quadrature (IQ) snapshots collected by the LuGRE receiver in cis-lunar space and on the lunar surface to assess multi-frequency, multi-constellation signal availability. Signals from additional systems beyond GPS and Galileo, including RNSS and SBAS constellations, are observable and successfully acquired exclusively in the recorded IQ snapshots. These observations provide the first experimental evidence that signals from multiple constellations, including systems not supported by LuGRE realtime operations, are detectable at unprecedented distances from Earth. Useful observables can be extracted from the IQ snapshots, despite minimal sampling rates, 4-bit quantization, and short durations (200 ms-2 s), through a hybrid coherent/non-coherent acquisition stage compensating for code Doppler. These observations are exploited to tune simulation tools and to perform extended simulation campaigns, showing that the inclusion of additional constellations significantly improves availability; for a 26 dB-Hz acquisition threshold, the fraction of epochs with at least four visible satellites increases from 11% to 46% of the total epoch count. These findings indicate that BeiDou, RNSS, and SBAS signals can substantially enhance GNSS-based autonomy for lunar and cislunar missions.

Problem

• GNSS
• lunar navigation
• multi-constellation
• signal availability
• spacecraft autonomy

Innovation

• multi-constellation GNSS
• lunar navigation
• IQ snapshot processing
• code Doppler compensation
• extended signal availability