NASA’s Lunar Communications Relay and Navigation Systems (LCRNS)

In early 2020, NASA's Space Communication and Navigation (SCaN) program recognized the need for lunar orbiting relays to enable Artemis mission flexibility to land at the lunar South Pole or the lunar far side, in areas with limited or no direct Earth communication, and to reduce strain on NASA's ground systems especially the Deep Space Network (DSN). The lunar relays would not only improve the landing site availability but would also contribute to astronaut safety by providing communications and navigation services independent of Earth’s line of sight. At the end of 2020, the NASA Goddard Space Flight Center (GSFC) created a concept design to evolve lunar relay capabilities and lay the foundation for the Lunar Communications Relay and Navigation Systems (LCRNS) project. Since its inception in April 2021, LCRNS has worked with SCaN’s stakeholders, including the Moon-to-Mars and the Artemis program, to identify and represent NASA’s requirements for communications and navigation in lunar orbit. The project’s charter is to enable an interoperable commercial lunar communications and navigation orbiting service infrastructure that meets NASA's needs, represents a sustainable approach to long-term human and robotic exploration, and embodies an extensible solution for Moon –to –Mars missions. This paper will: (1) describe NASA’s vision for LCRNS; (2) introduce the early concept for a lunar communications relay and navigation satellite, and the corresponding evolution of performance and interoperability requirements; (3) describe the important differences in communications approaches between LCRNS and NASA’s existing Tracking and Data Relay Satellite System (TDRS); (4) explain how LCRNS plans to validate commercial services capabilities; and (5) introduce LCRNS Position, Navigation, and Timing Instrument (LPI).