X-ray pulsar/starlight Doppler integrated navigation for formation flight with ephemerides errors

Currently, the deep space explorer formation fight is a novel area of aerospace technique [15]. The formation fight can increase redundancy backup, decentralize the cost, and provide a multi-platform for the deep space exploration [17]. For the deep space explorer formation fight, both absolute and relative navigation accuracies are crucial, especially the relative one. Orbit determination of a spacecraft is primarily performed at a ground station [4]. Unfortunately, subject to the long distance between the explorer and the earth, traditional ground station-based navigation methods cannot provide high-accuracy and real-time navigation information. Consequently, the autonomous navigation systems [12], [13], which observe the celestial bodies to obtain the navigation information, are highly attractive.