Integrated navigation based on X-ray pulsars and asteroids during interplanetary cruise

To improve the autonomous navigation ability during interplanetary cruise, we designed an autonomous navigation system based on observing pulsars and asteroids. The X-ray pulsars were observed by an X-ray detector, and the images of asteroids were taken by the navigation camera. Thus the times of pulsars' pulse arrival and the pixels of asteroids were obtained through signal processing. The centralized Kalman filter was used to estimate the system's state. The onboard atomic clock error was corrected. The orbit in the Deep Space I mission was adopted to validate this navigation method. The numerical simulation results show that this method is very feasible in the interplanetary cruise phase. Moreover, this integrated navigation system can solve the problem of atomic clock error divergence when the optical navigation based on asteroids is applied independently. This method can improve the orbit determination accuracy by 57.18%.