Spaceborne global navigation satellite system (GNSS) has significantly revolutionized the development of autonomous orbit determination techniques for low Earth orbit satellites for decades. Using a state-of-the-art combination of GNSS observations and satellite dynamics, the absolute orbit determination for a single satellite reached a precision of 1 cm. Relative orbit determination (i.e., precise baseline determination) for the dual satellites reached a precision of 1 mm. This paper reviews the recent advancements in GNSS products, observation processing, satellite gravitational and non-gravitational force modeling, and precise orbit determination methods. These key aspects have increased the precision of the orbit determination to fulfill the requirements of various scientific objectives. Finally, recommendations are made to further investigate multi-GNSS combinations, satellite high-fidelity geometric models, geometric offset calibration, and comprehensive orbit determination strategies for satellite constellations.

This study aims to assess the autonomous navigation performance of an asteroid orbiter enhanced using an inter-satellite link to a beacon satellite. Autonomous navigation includes the orbit determination of the orbiter and beacon, and asteroid gravity estimation without any ground station support. Navigation measurements were acquired using satellite-to-satellite tracking (SST) and optical observation of asteroid surface landmarks. This study presents a new orbiter-beacon SST scheme, in which the orbiter circumnavigates the asteroid in a low-altitude strongly-perturbed orbit, and the beacon remains in a high-altitude weakly-perturbed orbit. We used Asteroid 433 Eros as an example, and analyzed and designed low- and high-altitude orbits for the orbiter and beacon. The navigation measurements were precisely modeled, extended Kalman filters were devised, and observation configuration was analyzed using the Cramer-Rao lower bound (CRLB). Monte Carlo simulations were carried out to assess the effects of the orbital inclination and altitudes of the orbiter and beacon as key influencing factors. The simulation results showed that the proposed SST scheme was an effective solution for enhancing the autonomous navigation performance of the orbiter, particularly for improving the accuracy of gravity estimation.