Dual-target Signal Simulation of Very Long baseline Interferometry for Chang’E-5

Very long baseline interferometry (VLBI) is an important deep-space tracking technology from radio astronomy. A mission that uses VLBI, China’s lunar sample-return mission Chang’E-5 (CE-5) collects soil samples on the lunar surface, arrives at a rendezvous point, and docks in the lunar orbit through cooperation of the Orbiter and the Ascender. During rendezvous and docking, the Chinese VLBI network (CVN) used same beam VLBI (SBI) to observe two high-velocity probes simultaneously. However, before the launching of the CE-5, CVN lacked the capability to examine dynamic dual-target tracking ability of SBI mode because there were no similar space probes can be used in tests of upgraded VLBI data-processing system. This study proposes a method to simulate VLBI signals and acquire relevant data from the dual-target probe and calibration quasar signals recorded by each station according to the orbits and beacons of probes, station coordinates, etc. The real-time data-processing capability of the system is verified by processing the simulated data during rendezvous and docking. The consistency between simulation and VLBI data-processing was consistent to better than 0.05 ns. This method is universal and can also be used in VLBI simulation and orbital analysis of other deep-space probes.