Application of Positioning Reduction in the Orbital Transfer Stage of the Chang'E-4 Relay Satellite

The successful launch of Chang'E-4 relay satellite in June 2018 has laid a good foundation for the mission of landing on the back of moon at the end of the year. Very long baseline interferometry (VLBI) system plays an important role in satellite positioning and orbital transfer. In this paper, the data accuracy of delay, delay rate and positioning of VLBI observations during the real-time phase of the Chang'E-4 relay satellite mission are calculated, and the application of positioning reduction in the real-time track monitoring of the orbit control arcs of the Chang'E-4 relay satellite is presented. In the process of the relay satellite entering Halo orbit, we show the real-time change of the orbit elements converted by our positioning method and compare the real-time positioning results with the post-time orbit determination results to further verify the validity and accuracy of our real-time positioning results. We provide a new Halo real-time track monitoring method.