Research On Self-deployable Structure Of Secondary Mirror Of Space Telescope

With the gradual development of micro-satellite technology and the extension ofapplication field of earth observation technology, researchers show more concern andattention on how to obtain high-resolution images with micro-satellite platformequipped with deployable space telescope. Since the deployable space telescope isfolded before it starts to operate in orbit, the distance between primary mirror andsecondary mirror becomes short and the volume of the telescope becomes smallduring launch. The telescope extends to its work configuration after it’s in orbit.Compared with the traditional space telescope, deployable space telescope has smallsize, light weight and costs less for launch. The deployable structure is one of the keytechniques of deployable space telescope, and this paper focuses on the study of aself-deployable structure of the secondary mirror.Firstly, the optical system of the deployable telescope is designed and optimized，and the influence on the imaging quality of the deployment precision of secondarymirror is analyzed.Secondly，based on the design of the optical system, a coilable self-deployablestructure of secondary mirror is proposed. The design of the main components of thedeployable structure, including longerons, batten rings and diagonal stringers, isdiscussed, and the main structural parameters are calculated. The static performanceof the deployable structure is analyzed, and the formulas of the bending stiffness,bending strength, torsion stiffness, shear stiffness, and buckling load of the structureare derived.Thirdly, finite element method is used to analyze the dynamical performance ofthe fully deployed structure: the natural frequencies of the structure and the effects ofdiagonal stringers on vibration modes are analyzed through modal analysis; thedisplacement response of the secondary mirror in micro vibration environment isanalyzed through frequency response analysis. Finally, we fabricate a prototype of the deployable structure and make apreliminary experiment with the model. Based on the problems found in theexperiment we make improvement to the design, a joint adjusting the diagonalstringers and a joint with torsion spring are designed and the details of the two kindsof joint are discussed.At the end of this paper, the research work is summarized, the problems need tobe solved and the future work is discussed.