Autonomous navigation for navigation satellite constellations using X-ray pulsars

This paper investigates a method of autonomous navigation for navigation satellite constellations based on X-ray pulsars. When the X-ray photons from the pulsars are detected with the onboard detector, pulsars' pulse profiles are folded and the image can be obtained. From the detection, the time of arrival (TOA) of the pulsar's signal is recorded with the onboard atomic clocks. Moreover, the navigation parameters for the satellites, including the position, velocity and time, can be resolved accurately by the data processing of TOAs. All of the processes can be implemented by onboard computers. Therefore, getting rid of the transmitting with monitor stations on the Earth can be truly independent to get faster processing rate and reduce the burdens of the ground stations. In order to assess the feasibility and accuracy of the approach and the algorithm, a simulation for navigation of GPS constellation utilizing X-ray pulsars is carried out, which finally shows that it is a potential and effected way to realize autonomous navigation for satellite navigation constellations.