The project aimed to qualify HAUT-S as a satellite subsystem for autonomous onboard Precise Orbit Determination (POD) and Time Synchronization (TS) in low Earth orbit. Integrated as a self contained navigation payload, HAUT-S processed dual-frequency GPS and Galileo pseudorange and carrier-phase observations together with Galileo High Accuracy Service corrections. Its navigation processor combined an extended Kalman filter with a reduced-dynamic orbit model to determine the satellite’s orbit and clock offset continuously in real time, targeting centimetre-level positioning and one-nanosecond timing accuracy. The COTS-based prototype underwent functional, performance, mechanical, environmental, and production verification. Simulator campaigns assessed orbital, signal, correction-outage, and antenna conditions, while vibration and thermal-vacuum tests demonstrated suitability for launch and LEO operation. Production testing confirmed consistent behaviour across all units.