Studies of Martian Atmosphere and Surface by the Planetary Fourier Spectrometer on Board the Mars-94 Mission

Abstract

FTIR spectrometry is a powerful tool to investigate the atmosphere and surface composition of planetary bodies. Studies of Mars will be provided by the Planetary Fourier Spectrometer (PFS) on board the Russian Mars-94 mission. The PFS mainly focuses on problems of the Martian atmosphere but will give some information of the surface composition as well. Especially for atmospheric observations a high spectral resolution must be required. For analysis of the Martian ground the signal-to-noise ratio is the most important parameter to be optimised. These conditions define the optical layout of the instrument. The presented work discusses the solution of the optical instrument as well as the expected results of PFS remote sensing. The spectrometer consists of a dual Rotational Reflector Interferometer (RRI) covering two spectral ranges 220 - 1670 cm-1 and2080 - 8000 cm-1. In the RRI two pairs of retroreflectors connected by L-shaped arms with a common axle are driven in parallel on a circular path. Partial deadjustment due to tolerances as well as tolerance effects of the optical elements are taken into account in the estimation of the spectral responsivity in comparison with the radiation of the Martian surface and atmosphere.