PFS: The "Planetary Fourier Spectrometer" (PFS) operates in the infrared between the 0.9 µm and 45 µm wavelength range and is designed to perform vertical optical sounding of the Venus atmosphere. It performed global, long-term monitoring of the three-dimensional temperature field in the lower atmosphere (cloud level up to 100 kilometers). Furthermore, it searched for minor atmospheric constituents that may be present, but had not yet been detected, analyzed atmospheric aerosols, and investigated surface to atmosphere exchange processes. The design is based on a spectrometer on "Mars Express", but modified for optimal performance for the "Venus Express" mission.