Design and analysis of an extended mission of CE-2: From lunar orbit to Sun-Earth L2 region

Chang'E-2 (CE-2) has firstly successfully achieved the exploring mission from lunar orbit to Sun-Earth L2 region. In this paper, we discuss the design problem of transfer trajectory and at the same time analyze the visible segment of Tracking, Telemetry & Control (TT&C) system for this mission. Firstly, the four-body problem of Sun-Earth-Moon and Spacecraft can be decoupled in two different three-body problems (Sun-Earth + Moon Restricted Three-Body Problems (RTBPs) and Earth-Moon ephemeris model). Then, the transfer trajectory segments in different model are computed, respectively, and patched by Poincaré sections. The full-flight trajectory including transfer trajectory from lunar orbit to Sun-Earth L2 region and target Lissajous orbit is obtained by the differential correction method. Finally, the visibility of TT&C system at the key time is analyzed. Actual execution of CE-2 extended mission shows that the trajectory design of CE-2 mission is feasible.