In the engineering sector, for some years now, it has been common to look for the best shape of a structure in terms of high mechanical performance. To do this, it is used what is commonly called optimization, that is a process through which a certain analysis software implements certain parameters set by the user and calculates, with regard to these constraints, the optimal shape of the structure considered, reorganizing the distribution of the material. Aim of this thesis is to apply the optimization criteria to the mechanical frame of a space telescope. The initial geometry of PLATiNO Space Telescope, used for a preliminary feasibility study, has been used as case study with the objective to identify an optimized design solution in term of minimum mass and maximum stiffness (i.e.: maximize resonant frequencies).