Space operation system for Chang’E program and its capability evaluation

Abstract

Space operation for China’s first lunar exploration program, Chang’E will be provided by the S-band aerospace Telemetry, Tracking and Command (TT&C) network designed for China’s manned space program. This is undoubtedly a great challenge to the ground TT&C system. The largest antennas of China’s S-band aerospace TT&C network has an aperture of only 12 m. A series of technical measures have been taken into the designing of the spacecraft-ground TT&C system to ensure that such antennas can communicate with Chang’E-1 lunar probe 400,000 km away. These include installation of high-gain directional antennae and medium-gain omni-directional antennae for the probe, adding channel encoding to the downlink channel, using both high and low data rates for information transmission and upgrade and design of ground equipment terminals. Among them, the omni-directional antenna will operate in the earth-ground transfer orbit phase and the directional antenna will operate in the lunar orbit phase. These measures satisfy the spacecraft-ground link and program design requirements.

To provide accurate navigation for the probe during its Earth-Moon flight and initial lunar orbiting flight, China’s VLBI system designed for astronomical observations, will also be used besides the ranging and range rate measurement capabilities of the S-band TT&C network. The purpose is to provide 100 m accuracy in position determination during lunar orbit. This paper describes the system design, technical challenges, solutions and capability evaluation of space operation for Chang’E-1.