A Method of X-ray Pulsar-Based Navigation for Constellation in Libration Points

A method of X-ray pulsar-based navigation for satellites constellation in Halo orbit is given in this article. The dynamics of libration point orbits offer many opportunities for flexible, low-energy trajectories, and missions around libration points are arising. Autonomous navigation is necessary for spacecraft autonomy in libration point, as well as significantly benefits China's deep space missions. In this paper, the state equation is established according to the dynamic characteristic in the libration point orbit. The difference of pulse arrival time to different satellites can be regarded as the measurements in the measurement equation. Unscented Kalman filter is applied to estimate the state of the system. Simulations demonstrate that this method is feasible for autonomous navigation for satellites constellation in the Sun-Earth libration point orbit. Comparing X-ray pulsar-based method with the traditional inter-satellite links navigation principle, satellites constellation rotation can be solved. Combining inter-satellite links and pulsar measurements in the UKF filter, the state of the system can be estimated more precisely and in a more quick way.