Thermal calculation and structure analysis of space Main Optical Telescope

Primary mirror with Φ 1m and f 3.5m is the most important optical part in the space Main Optical Telescope (MOT). Since its required surface error is less than λ/40(rms.), where λ is about 0.6μm, the mirror deformation induced by space heat and gravity must be within 0.015μm, it's necessary to make thermal calculation and structural analysis to improve its structure. In this paper, the MOT structure and its finite element model is described. The mechanical properties are then analyzed in order to verify whether this structure can meet the optical requirements of sufficient strength, stiffness, and thermal stability. Mechanical analysis is carried out with MSC.Nastran software under 3 different load cases: gravity influence on-ground, dynamic impact during launching, weightlessness and heat environment in-orbit. Space thermal analyses are also done to simulate the space environment. The coupled deformation of heat and structure is finally analyzed. Calculation results show that different support ways and support forces will be the keys to determine the surface precision of primary mirror. The structure can meet the optical demands, but the thermal deformation can not, especially in an asymmetric temperature distribution, which should be tested and controlled by some strict methods.