Reaching and Navigating in Geostationary Orbit with a GNSS Receiver: Challenges and In-flight Results

Utilization of GNSS receivers on-board a Geostationary platform is becoming an attractive alternative for position and timing determination for ground operations and cost minimization. To increase competitiveness, the use electric propulsion to perform or complement the transfer manoeuvres to GEO orbit is nowadays employed. This imposes long duration orbits that intersect several times the “GNSS sphere” (the sphere of center the Earth’s center and radius equal to the semi-major axis of the GPS orbits - approx. 26500 km – or GALILEO orbits at ~ 29300 km), where GNSS performances are strongly influenced by the availability of measurements to the GNSS Receiver. In this paper we will review the first results and the return of experience of the first commercial GNSS receiver embarked on the NEOSAT Platform made by Thales Alenia Space, which, according to the authors, is the first European multi-constellation (GPS+GALILEO) operational receiver that was experiencing a fully electric Orbit Rising to GEO orbit (of a duration of about 6 months), geostationary positioning and, according to the authors knowledge, first-in-the-world to provide tracking of GALILEO signals in Geostationary orbit (i.e. above the GALILEO sphere), enabling the use of the full Space Service Volume up to GEO stationary altitude and more for commercial applications.