A Far-Infrared Spectro-Spatial Space InterferometerThis thesis describes the physics and computational aspects of an end to end simulator to predict the performance of a Space based Far Infrared Interferometer. The present thesis also includes, the science capabilities and instrumental state of the art. The latter is the ambitious next step which the Far Infrared Astrophysical community needs to take to improve in anyway on the results of the most recent and current space telescopes in this wavelength