Observability-Based Navigation Using Optical and Radiometric Measurements for Asteroid Proximity

In this article, to improve navigation performance, observability-based navigation using optical and radiometric measurements for asteroid approach phase is proposed in tandem with the optimization of the configuration of spacecraft formation. By introducing the relative range and range-rate between spacecraft measured by radiometric sensors, the position and velocity of the two spacecraft are estimated, and the estimation performance degradation at the end of asteroid approach phase is reduced. A better observability of the integrated navigation system has been proven based on a novel geometry measurement model. Furthermore, a configuration optimization method is developed based on the lower bound of the Cramer-Rao inequality and the observability degree of the navigation system. By optimizing the configuration of spacecraft formation, the observability and estimation accuracy of the navigation system have been improved. Three cases of different configurations of spacecraft formation are established for numerical simulation, demonstrating the improvement in the accuracy of the navigation method.