The modal analysis of a rotating elastic space vehicle composed of a central rigid body connected to two solar arrays is the subject of this investigation. The global modes differential equations of the whole mechanical system are defined by means of Hamilton variational principle. By application of the spectral decomposition continuum approach of Rayleigh-Ritz, it is shown that the distributed flexibility of the mechanical system subjected to external torques can be described by a linear combination of these global modes different from the usual ordinary modes. The spectral decomposition continuum approach of Rayleigh-Ritz is the mathematical tool used to perform the modal analysis. It derives from this study, the fundamental transfer functions of the space vehicle in terms of the global modes of the whole system. The numerical simulation of these global modes of great interest in this study is performed by means of the fundamental transfer functions relating the external torques to the rotating space vehicle attitudes motions.

vibration, global mode, spectral decomposition, transfer function.