Design, analysis and evaluation of titanium antenna reflector for deep space missions

The activities presented under this paper were focused on designing, manufacturing, testing and evaluation of a metallic antenna reflector for space applications. The main challenge was to obtain a low mass, while maintaining the reflector capability to withstand the mechanical loads encountered during the launching phase, as well as the harsh space environment with significant temperature variations, without any detrimental effect over the dimensional stability of the reflective surface. The chosen material was titanium alloy for the reflector and stainless steel for fasteners and mounting supports. Manufacturing parameters have been investigated aiming for low internal stresses during processing and to obtain the best results in terms of dimensional accuracy and surface roughness. One of the five analysed reflector architectures (reflector breadboards) was selected and manufactured using two different finishing operations, milling and turning, the latter being the one presenting the best results. Dimensional accuracy of the reflector breadboard, before and after vibration and environmental tests, was found to be smaller than the imposed requirements, thus validating the reflector proposed design. After the breadboarding activity, an optimized version of the antenna reflector (demonstrator), also validated by structural analysis, was developed. Unfortunately, the measured profile deviation of the demonstrator was higher than the imposed requirements (by 50%), mainly due to internal stresses during mechanical processing of the new geometry. Before the experimental evaluation of the reflector demonstrator, a surface coating was developed and applied to the reflective surface of the demonstrator. Despite the profile deviation, the demonstrator meets the imposed mechanical requirements and offers important lessons to be applied in the future development activities.