Some requirements to simulate soil/environment parameters for composition analysis by mid-infrared spectrometry.

Abstract

The potential of the mid-infrared region for the mineralogical compostition analysisof planetary surfaces is - unfortunately - constrained by the in this region strong influence of morpholo- gical parameters (as particel size and porosity) on the spectral contrast and on the shape of spectral features. Partly this handicap can be evaded by the "Usefulness of weak bands in mid- infrared remote sensing of particulate planetary surfaces" (Salisbury et al. (1987)).Usage of the weak overtone and combination tone bands instead of the strong fundamental vibration bands is advantageous because the contrast of these bands does not decrease with decreasing particle size, but typically increases. To get unambiguousresults, however, weak bands should be inter- preted with caution.Small variations of the spectral features can be caused not only by the interesting variations of sample composition and by morphology, but also by "experimental" parameters controlling the thermal gradient within the sample (LOGAN et al., (1973)). In consideration of LOGAN's results it is recommended to measure emittance spectra of Mars analog material - at least for comparison with the common laboratory data - by using an experimental configura-tion camparable to the remote sensing situation. A sketch of a suitable equipment is proposed.