Autonomous Navigation Based on the Earth-Shadow Observation near the Sun–Earth L2 Point

This paper is devoted to a novel autonomous navigation method for spacecraft around the Sun–Earth L2 point. In contrast to the previous navigation methods, which rely on ground-based or inter-spacecraft measurements, the proposed method determines the orbit based on Earth-shadow measurements. First, the navigation framework using the Earth-shadow measurement is proposed. Second, the geometric analysis is used to derive the mathematical model of the Earth-shadow measurements. Then, the fifth-degree Cubature Kalman filter (CKF) is designed to estimate the states of the spacecraft. Numerical simulations are implemented to validate the performance of the proposed navigation method. Finally, the simulation results show that the navigation system is observable and that the proposed method could be potentially useful for an autonomous navigation mission near the Sun–Earth L2 point in the future.