Autonomous orbit determination for future GEO and HEO missions

The use of GNSS space receivers for autonomous orbit determination is receiving increasing interest due to the important economical and operational benefits made possible by the reduced on-ground operations and the improved pointing performance when associated to one Star Tracker. However, the exploitation of GNSS for navigating satellites in orbits beyond the GNSS constellations has not yet gained full acceptance among spacecraft designers, manufacturers and operators. With GPS modernization and upcoming Galileo as well as with evolving receiver technologies, the feasibility for the use of GNSS in geostationary and higher orbits must be thoroughly assessed as the number of factors involved and its impact on navigation performance is significant when compared to land user receivers. This paper describes the feasibility of GNSS receiver and Orbital Filter for Autonomous Orbit Determination and the main expected performances under different missions, environment and receiver architectures. The most critical factors affecting navigation performance are presented and studied in detail using a Software Simulation Tool in a dedicated test campaign. Main results of the test campaign are then presented, illustrating the achievable performances for GEO/GTO and HEO orbits under the different GNSS sensor configurations. The presented results show that the usage of GNSS receiver technologies with the advent of Galileo and GPS modernization offer new possibilities and superior performance for autonomous orbit determination, promising important economical and operational benefits for next generation of space users in either GEO or HEO orbits.