Spaceborne Fourier Transform Spectrometers can be used to obtain IR limb emission spectra from which profiles of temperature and minor constituents can be derived simultaneously in the middle atmosphere. A corresponding experiment, called MIPAS (Michelson Interferometer for Passive Atmospheric SoundiTig) is und-6- development in Winich. MTPAS utilize? a novel type of interfero-meter which uses two double passed triple mirrors both being fixed to a rotating structure to produce optical path difference (P. Burkert, F. Fergg and H. Fischer, IEEE Transact. on Geosc. and Remote Sens. Vol GE-21, 345, 1983). A He-cooled version of MIPAS for broadband emission measurements was described previously (H. Fischer, F. Fergg, H. Oelhaf, D. Rabus, W. Volker and P. Burkert, Beitr. Phys. Atm. Vol. 56, 260, 1983).