The distribution of trace gases in earth's atmosphere will be analysed in a long term German-Russian space mission for more than three years, beginning in 1994. The FTIR-spectrometer, designed for this mission, has been tested with sun occultation measurements from the ground. The column contents of CH₄, CO₂, N₂O, CO, H₂, and O₃ could be retrieved. Spectral intervals for 25 different trace gases for the space mission have been identified and their retrieval accuracies were computed. The analysis shows, that with "MIRIAM" the lateral and vertical distribution of many trace gases can be analyzed as well as their long term variations.