Infrared Spectrometer PFS for the Mars 94 orbiter

PFS (the Planetary Fourier Spectrometer) covers the range 1.25-45 μm with spectral resolution about 2 cm-1 and angular resolution 0.035 - 0.070 rad (10 - 20 km on the Martian surface working at the periapsis). The instrument has two spectral channels: shortwavelength (SW) and longwavelength (LW) with a boundary near 5 μm. The photoconductive detector (PbSe) is used in the SW channel and the pyroelectric in LW channel. The main optical units of both channels are rotating interferometers with cubic mirror comer reflectors. The infrared radiation from Mars is directed to the interferometers by the pointing system that allows to observe selected points on the Martian surface. A 'dichroic' plate splits the beam between LW and SW channels. Several hundred spectra will be obtained during one periapsis passage. These spectra will be used for investigation of Martian atmosphere (temperature and pressure vertical profiles, variations of small constituents such as H2O and CO, pressure near the surface, aerosol distribution, composition and optical depth) and some of surface properties (thermal, compositional, textural). Scientific facilities of six countries (Italy, Russia, Germany, Poland, France and Spain) cooperate in the work on this experiment.