Assembly and Testing of a Thermal Control Component Developed in Brazil

ABSTRACT: The optical solar reflector is basically a mirror of second surface with low absorptivity/emissivity ratio and negligible degradation in the space environment, which makes it an excellent coating for thermal control of satellites. It works as a radiator and is used in particular parts of the external surfaces of the satellites in order to reject the undesirable heat to the deep space. In the Brazilian Space Programs, the radiators of the satellites are generally painted with special white paints in order to reject heat instead of the use of optical solar reflector. The problem of white-ink radiators is the high degradation of the thermo-optical properties that happen over the useful lives. Thus, a process of manufacturing and assembly of optical solar reflector was developed in Brazil. To validate this process in terms of mechanical and thermal properties, 3 types of optical solar reflector radiators were manufactured, and their absorptivity and emissivity properties at the temperature of 23 ºC were measured. Optical solar reflector coupons were mounted on aluminum plates to perform vibration, thermal vacuum and thermal-shock tests. A study was also done to optimize the thickness of the glue to fix the structure of the satellite on the optical solar reflector. It showed an excellent environmental stability and maintained its thermo-optical characteristics after the tests.

摘要：光学太阳反射镜（Optical Solar Reflector）本质为一种第二表面反射镜，具备极低的吸收率与发射率比值，且在空间环境中性能退化可忽略不计，是卫星热控涂层的优异选择。其作为辐射器，被安装于卫星外表面的特定区域，用于将多余热量排放至深空。在巴西航天计划中，卫星辐射器通常采用专用白色涂料实现排热功能，而非光学太阳反射镜。白色涂料辐射器的痛点在于其热光性能会在服役周期内发生显著退化。为此，巴西开发了一套光学太阳反射镜的制造与装配工艺。为验证该工艺的力学与热学性能，研究人员制备了3种光学太阳反射镜辐射器，并测试了其在23℃环境下的吸收率与发射率性能。将光学太阳反射镜试片安装于铝板上，开展了振动、热真空及热冲击试验。同时，研究还针对卫星结构与光学太阳反射镜连接所用胶粘剂的厚度进行了优化。试验结果表明，该光学太阳反射镜具备优异的环境稳定性，经上述试验后仍保持了原有的热光特性。