Modal Survey Test on PRONAOS Telescope.

Abstract

PRONAOS is a balloon-borne astrophysical project of CNES. Among mechanical aspects of the telescope, it must be assured that the servo pointing system operating at a maximum step rate of 10 Hz does not interact with the dynamics of the structure, resulting in adverse vibrations. A modal survey test was performed on the telescope to identify eigenfrequencies in a range up to 50 Hz. Modes were measured up to at least 15 Hz and for some modes, generalized mass and damping were determined by test. The final results are presented in this report. They can serve for direct confirmation of the dynamic properties of the telescope structure and for updating its mathematical model.