Near Infrared Spectral Reflectance of Simulated Martian Frosts

Citation

Kieffer, Hugh Hartman (1968) Near Infrared Spectral Reflectance of Simulated Martian Frosts. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/BHED-BJ17. https://resolver.caltech.edu/CaltechETD:etd-07172006-093716

Abstract

In view of the apparent conflict between spectral observations and recent theories of the Martian polar caps, comparison spectra were obtained for frosts of relevant composition and grain size. The spectral reflectances of frosts formed from pure CO2, and pure H2O and mixtures of these gases have been measured from 0.8 to 3.2 [microns]. Low-weight fractions or small surface concentrations of H2O resulted in spectra similar to pure H2O frost spectra. The concentration of the condensable gas and the radiation balance effect the frost textural scale and the contrast of the reflection spectrum. The emissivity of the polar caps may be small, in contrast to previous assumptions. Probable processes of frost formation and sublimation on Mars and seasonal variations of frost composition suggest that reflection spectra obtained in the Martian spring may be misleading. In light of the laboratory results and probable Martian conditions, previous suggestions that the Martian polar caps are H2O are not valid. Future diagnostic observations in the near and thermal infrared are suggested. Figures 10, 11 and 12 are photographs of frost samples and will not reproduce well. Photographic copies may be ordered.

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