Achieving GNSS Compatibility and Interoperability to Support Space Users

The development of GPS and other GNSSs, such as the Russian GLONASS, the European Galileo, and China’s BeiDou, has resulted in new capabilities available for PNT in space. This paper reviews on-going efforts at NASA to implement U.S. PNT policy and engage international partners in the pursuit of compatibility and interoperability among these systems. The objective is to develop a multi-GNSS SSV to support space users between Low Earth Orbit (LEO) and Geosynchronous Orbit (GEO), and eventually into Cislunar space. Key international engagements include bilateral discussions, such as those that led to the 2004 U.S.-European Union Agreement on GPS-Galileo Cooperation, and on-going multilateral discussions at venues such the United Nations (UN) International Committee on GNSS (ICG) and the GNSS Provider’s Forum. Benefits to space users will include improved capabilities for on-board autonomous PNT, and better resilience to potential disruptions to GNSS signals.