Mineralogy of the Martian surface from Mariner 6/7 infrared spectrometer data

摘要

The Mariner 6/7 Infrared Spectrometer (IRS) experiment data from the 1969 Mars flyby encounters represent a valuable source of information about the IR reflection/emission spectrum of Mars in the 1.9 and 14.4 micron region. During 1990, the wavelength calibration of the IRS data was completely redone, using information from inflight spectra of Mars taken through a polystyrene film and from the locations of Martian CO2 bands. The response functions of the two instruments were then rederived using laboratory black body spectra. Also, a particular approach was taken to study the IRS data in which the effects of uncertain wavelength and intensity calibration can be minimized. This involves doing ratios of spectra. These are of particular value when applied to study contrasts between various albedo domains on the Mars surface and between spectra with differing emission angle. The latter provide a means of assessing the contribution of the atmosphere and airborne dust to the spectra. Given here are graphs showing two near infrared radiance spectra for very different albedo regions and a ratio of two spectra obtained at very different total solar pathlength (airmass).