Research on GNSS Navigation Method of Lunar Orbiting Spacecraft Based on Ground Enhancement

With the continuous development of the lunar exploration mission, it is very important to obtain the real-time and accurate position, speed, and time information of the spacecraft near the moon. However, with the increase of distance, the GNSS signal becomes weaker and weaker, and it becomes very difficult to use GNSS to realize navigation and positioning near the moon. In this paper, the GNSS signal power, the number of visible satellites, and the geometric distribution near the lunar orbit are analyzed. This paper proposes a method of using ground station for GNSS navigation enhancement to realize lunar GNSS navigation and positioning. By setting up a ground station on the earth, the navigation enhancement signal pointing to the moon is broadcast. This can enhance the information of lunar orbit GNSS receiver and improve the signal acquisition sensitivity of lunar orbit GNSS receiver. It can also provide its own ephemeris information, improve the visible navigation satellite geometry, and improve positioning accuracy. Simulation results show that this method can realize GNSS navigation and positioning near the moon.