A project funded by the European Space Agency (ESA) and led by StatSat AS, in collaboration with Fugro Norway AS, has successfully completed a demonstration of precise point positioning (PPP) onboard the NorSat-TD satellite.
The initiative tested in space Fugro’s PPP technology, confirming its ability to deliver sub-decimeter precision in low Earth orbit (LEO), without relying on ground-based infrastructure.
Highly accurate positioning of space platforms in LEO is becoming increasingly important for Earth observation applications, safe constellation management, and space debris collision avoidance.
The new system, called SpaceStar, adapts Fugro’s well-known marine PPP solution for space-based applications. The specific goals of the project included testing of SpaceStar’s L-band demodulator and PPP software in orbit, and validation of the resulting performance against external references.
SpaceStar leverages Fugro’s global network of more than 100 reference receivers. The system generates precise orbit and clock corrections for GPS, GLONASS, Galileo, and BeiDou satellites, broadcasting them over L-band to users in real time. Onboard NorSat-TD, SpaceStar was implemented on a software-defined radio (SDR) based on a Xilinx Zynq 7000 series system-on-chip, combining FPGA firmware for L-band demodulation with an ARM-based PPP engine.
The final results, presented at a recent ESA-hosted event, show SpaceStar delivering position errors around 10 cm, velocity accuracies between 5 and 11 mm/s, and time errors below 1 ns RMS.
In-space demonstration
Despite several in-orbit challenges, including an embedded multimedia card (eMMC) storage failure and early orbital decay caused by a propulsion anomaly, the payload operated successfully in RAM-only mode, collecting telemetry and performance data until de-orbiting in May 2025. Through successive reconfigurations and firmware updates, SpaceStar achieved remarkable stability and accuracy across its mission.
Compared with standalone GNSS receiver outputs, SpaceStar improved consistency by more than an order of magnitude. The system also demonstrated robust behavior under signal outages and even rejected spoofed GNSS data during an October 2024 spoofing incident that affected other receivers in LEO. ESA independently validated the onboard solutions using externally computed reference orbits, confirming centimeter-level results.
With these outcomes, the project establishes a solid foundation for operational deployment of SpaceStar-based precise navigation services for future small-satellite missions. StatSat and Fugro plan further collaboration with commercial hardware partners, including Javad, SpacePNT, and GomSpace, to enhance integrity and extend high-precision positioning across new space applications.
The project, entitled ‘In-orbit demonstration of PPP on-board NorSat-TD’, was funded under ESA’s NAVISP program, which fosters European innovation and collaboration in positioning, navigation and timing (PNT).
