载人登月探测时，由于各种资源的限制，返回舱月面起飞后1至2圈内就必须与轨道舱进行短交会对接，此时的精密测定轨最为关键，必须对返回舱进行快速精密测定轨。针对于此，本项目将首次研究高精度的三探测器（着陆器、轨道舱、返回舱）间的S频段同波束VLBI技术，即用地面射电望远镜同时观测三探测器，利用轨道舱、着陆器、返回舱间的高精度同波束VLBI数据并结合测速测距数据，以轨道舱的精密绕月轨道和着陆器的月面基准位置为参考，快速且精确地测出返回舱从月面上升的轨迹和轨道及二者之间的相对位置和速度，为返回舱与轨道舱的快速交会对接提供强有力地面测控支持。本项目将主要针对三探测器同波束VLBI设计方案、三探测器同波束VLBI实时处理技术和软件研发以及三探测器精密测定轨技术及其应用进行研究。刘庆会作为同波束VLBI技术的倡导者并已将之应用于月球车相对定位和采样返回多目标测定轨中，需对此技术持续研究以用于载人登月任务。

In a human lunar mission, due to a variety of resource constraints, the return-cabin must dock with the orbital module within 1 to 2 circles after it uplifts from the lunar surface, the precise orbit determination must be performed quickly. In this study, we will use the S-band same-beam VLBI technique among three spacecrafts (return-cabin, orbital module, and lander), and obtain high-accuracy differential phase delay data. Using the differential phase delay and Doppler/range data, we can determinate the orbit of the return-cabin and the relative position between the return-cabin and the orbital module, based on the precise orbit of the orbital module and the precise position of the lander. This project will focus on three study fields: design of the on-board radio sources, study of the real-time processing technology for obtaining the differential phase delay data and developmemnt of the processing software, and study the precise orbit determination technology for three spacecrafts.