Abstract:The time delay based on solar oscillation is a new type of celestial navigation measurement, which can provide the distance information of the spacecraft relative to the reflected celestial body. Combined with the star angle measurement, it can improve the navigation performance. However, both the measurement model of star angle and the measurement model of time delay contain the position vector of Phobos relative to Mars. The ephemeris error of Phobos will affect the navigation accuracy. To solve this problem, a celestial star angle/ time delay measurement integrated navigation method based on online estimation is proposed, and a state model including Phobos position and velocity is established. The star angle and time delay measurement are used to simultaneously estimate the position and velocity of Phobos. The simulation results show that the proposed method can effectively suppress the influence of the ephemeris error of Phobos on the integrated navigation accuracy, and provide high-precision autonomous navigation information for the spacecraft.