New high-accuracy spacecraft VLBI tracking using high data-rate signal: A demonstration with Chang’E-3

Abstract

As the scientific data volume in deep-space exploration rapidly grows, spacecraft heavily relies on high data-rate signals that span several megahertz to transmit data back to Earth. Employing high data-rate signals for high-accuracy radiometric interferometry can simultaneously deal with data transmission and spacecraft navigation. We demonstrate very long baseline interferometry (VLBI) tracking of the Chang’E-3 lander and rover to determine their relative lunar-surface position using downlink high data-rate signals. A new method based on the VLBI phase-referencing technique is proposed to obtain the differential phase delay, which is much more accurate than the differential group delay acquired by conventional VLBI approaches. The systemic errors among different signal channels have been well calibrated using the new method. The data from the Chang’E-3 mission were then processed, and meter-level accuracy positions of the rover with respect to the lander have been obtained. This demonstration shows the feasibility of high-accuracy radiometric interferometry using high data-rate signals. The method proposed in this paper can also be applied to future deep-space navigation.