Ryan Mitch, Gregory Weaver, Jonathan Bruzzi, Wesley Millard, Bob Summers, Justin Bradfield, Johns Hopkins University - Applied Physics Lab

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This paper presents an extensible and passive Cislunar Position, Navigation, and Timing (PNT) service architecture called Lighthouses. The architecture is independent of the Global Positioning System (GPS) and provides useful performance at a size, weight and power level that is acceptable for most spacecraft. This architecture was developed under a low-cost strategy. The architecture’s candidate hardware realization and several key trades are presented. The first key trade considers the dilution of precision that a user spacecraft will experience in Cislunar space, and analyzes several options for a space-based augmentation to the ground transmitter system. The second trade considers the volume of Cislunar space that must be serviced by the architecture, as well as ways for servicing the volume around each ground transmitter. The third trade considers the way that each ground transmitter in the network is coordinated to optimize user performance. These trades motivate a baseline set of parameters that define the architecture. The baseline Lighthouses design is used to evaluate the PNT performance of three major mission classes: Low Earth Orbit (LEO), Geostationary Earth Orbit (GEO), and L-point missions. The PNT performance of these satellites are evaluated against the expected requirements of a space domain awareness-type mission and Lighthouses is shown to perform satisfactorily. Other missions with more stringent PNT requirements are considered, and the inclusion of even one satellite augmenting the architecture is shown to address these use cases.