Enhancing Space Domain Awareness Using Star Trackers in Satellite Formations

Space Domain Awareness (SDA) represents a critical area of research focused on the comprehensive monitoring of the near-Earth space environment. This includes the detection, tracking, and identification of objects, as well as the estimation of orbital parameters and prediction of conjunction events. Distributed satellite systems, particularly those equipped with inter-satellite links, are recognized as valuable assets for enhancing SDA capabilities. This study presents an algorithm developed to integrate data exchanged between satellites within a formation, allowing for precise realtime determination of the orbital parameters of target Resident Space Objects (RSO). The algorithm utilizes the Global Navigation Satellite System (GNSS) receivers and star trackers operative on each of the spacecraft in the formation. The proposed approach aims to improve the accuracy of RSO identification and orbit determination, and it can serve as a supplementary objective for Earth Observation (EO) satellite formation missions. By leveraging the differential viewpoints of two satellites observing a common RSO, the methodology utilizes the parallax effect to provide realtime positional estimates of the RSO. The coherence of simultaneous observations further enhances the accuracy of orbit determination. Simulation results demonstrate that this approach has the potential to significantly improve the precision of RSO orbit determination.