Mars: Mariner 9 Spectroscopic Evidence for H2O Ice Clouds

Science  26 Oct 1973:
Vol. 182, Issue 4110, pp. 381-383
DOI: 10.1126/science.182.4110.381


Spectral features observed with the Mariner 9 interferometer spectrometer are identified as those of H2O ice. The measured spectra are compared with theoretical calculations for the transfer of radiation through clouds of ice particles with variations in size distribution and integrated cloud mass. Comparisons with an observed spectrum from the Tharsis Ridge region indicate H2O ice clouds composed of particles with a mean radius of 2.0 micrometers and an integrated cloud mass of 5 x 10-5 grain per square centimeter.