1. Associate Professor, Dept. of Aerospace Engineering, School of Astronautics, Beihang Univ., Beijing 100191, China (corresponding author).
2. Senior Engineer, DFH Satellite Co., Ltd., 104 Youyi Rd., Beijing 100096, China.
3. Professor, Dept. of Aerospace Engineering, School of Astronautics, Beihang Univ., Beijing 100191, China.