为了在月球上完成天文观测任务，对月基反射镜二维跟踪转台进行了热力学分析及结构设计。采用航天轻量化法设计反射镜的二维转动机构以减少载荷重量；采用外转子机构实现垂直轴系以大大提高系统沿发射方向的一阶模态。由于水平轴系跨度较大，设计中采用了一端固定另一端游动的精密轴系，并通过合理设计深沟球轴承游隙有效解决了温度变化导致的转动机构卡死的问题，进一步提高了机构的可靠性。为了满足精度要求，系统采用蜗轮蜗杆+步进电机驱动方式，严格控制蜗轮蜗杆的加工及安装工艺。在控制中以光电开关为位置定位元件，使得转台的单轴指向精度优于60″。验证试验显示：系统发射方向的一阶谐振频率达到81 Hz，它可在-25 ℃ ～+60 ℃温度下正常工作，其指向精度(方位及俯仰)≤60″。 结果表明该转台具有精度高、力学性能好、可靠性高、重量轻等特点。

To implement the astronomical observation on the moon, the thermal analysis and structure design of a 2D reflection mirror gimbal for the lunar based astronomy optical telescope were performed. The 2D rotary structure of reflection mirror was designed based on lightweighting method to reduce the load mass. Because an external rotor mechanism was used for the vertical shaft, the first order mode of the system along the emission direction was greatly improved. For a larger span in the horizontal shaft, a shaft system with one fixed end and another free end was adopted. Moreover, the clearance of deep groove ball bearings was designed rationally to eliminate the block of the rotary structure caused by temperature changes on the moon. In order to meet the high accuracy ，the reflection mirror gimbal used a worm gear and a step motor to drive the gimbal and to control the machining in a strict technology. In addition, an optics switch was used to achieve high accuracy position and make the accuracy of gimbal be better than 60″。 Experiments show that the first order resonant frequency of the system can reach 81 Hz along the rocket-firing track, the mechanism works well at -25 ℃ to +60 ℃ without stuck phenomenon and its direction accuracy is less than 60″. These results demonstrate that the system is characterized by high accuracy, high reliability and light weight.