Satellite Constellation Design for a Lunar Navigation and Communication System

There has been a growing interest in using small satellites (SmallSats) for a future lunar navigation and communication satellite system (LNCSS). We conceptualize the design of a SmallSat-based LNCSS with Earth-global positioning system (GPS) time transfer that provides navigation and communication services near the lunar south pole. A hybrid constellation design is formulated, wherein all satellites provide navigation services while only a fraction are communication-enabled. Using Systems Tool Kit software, we examine various LNCSS case studies based on an elliptical lunar frozen orbit with a lower-grade chip-scale atomic clock. Case studies are evaluated in terms of (1) navigation considerations, including position and timing accuracy, lunar user equivalent ranging error, and dilution of precision, (2) communication considerations, including data volume, availability, and data rate, and (3) SmallSat factors, including cost, size, weight, and power. We performed a trade-off analysis for satisfying the criteria outlined by international space agencies while designing low-cost, low-SWaP lunar constellations.