The Planetary Fourier Spectrometer: Studies of the Martian Atmosphere and Surface

Abstract

The Planetary Fourier Spectrometer (PFS) is a double-pendulum interferometer designed to fly on the Mars 96 mission. It was recently included in the payload of the upcoming European Mars Express Mission. PFS measures planetary radiation spectra in two spectral regions (1.2-4.5 µm, 6-45 µm). A radiative trasnfer simulation and retrieval technique was developed that will be applied to derive atmospheric models and surface properties of Mars from PFS infrared signatures (Chapter 1). It considers absorption, emission and multiple scattering of thermal and solar radiation by molecular (CO2, H2O, CO) and particulate (palagonite, montmorillonie) species. Synthetic spectra have been calculated in the 2000-8000 cm-1 wavenumber range (1.25-50 µm) for a variety of atmospheric models and surface conditions. Retrieval procedures and results of a simultaneous retrieval of vertical temperature profiles and aerosol optical depths as well as surface temperature, pressure and reflectance are discussed. Real measured spectra obtained by the IRIS instrument on board Mariner 9 are also wxamined. Detailed laboratory investigations have been performed to study reflectance and emittance features of several minerals, which are regarded as possible analog materials of Martian soil (chapter 2). As a result, a spectral database of reference spectra was established. Chapter 3 yields a detailed analysis of Fourier Transform Spectrometers applied to the PFS instrument.