Hardware-in-the-Loop testing of a GNSS Receiver for Improved Space Situational Awareness: the SARGASSIA project

The growing number of objects in Low Earth Orbit (LEO) poses a significant threat to space infrastructure because of the potential for collisions and the subsequent escalation of space debris. This study explores the possibility of enhancing European Space Surveillance and Tracking capabilities by leveraging GNSS and MEOSAR to efficiently compute and relay spacecraft positioning in the event of a failure. The SARGASSIA system integrates a low-power GNSS receiver on board the LEO satellite and an active beacon to transmit PNT information. This paper focuses on the preliminary implementation of the GNSS module, aiming to enhance robustness against spinning conditions of uncontrolled spacecraft and reduce power consumption. An extensive hardware-in-the-loop testing campaign has been conducted on a COTS solution to test the receiver's performance against the attitude dynamics of a faulty LEO satellite. The primary objective of this study is to characterize the minimum activation time required to provide a meaningful PNT solution, specifically in terms of Time-To-First-Fix, and the corresponding accuracy for a Galileo-only solution. This baseline is then extended to advanced capabilities, including the processing of Galileo I/NAV improvements and access to additional GPS satellites. The results demonstrate the potential to significantly shorten PNT convergence time, thereby extending the operational lifespan of the overall SARGASSIA system.