W. D. Smythe R. M. C. Lopes-Gautier A. G. Davies L.W. Kamp J. A. Mosher L.A. Soderblom F.E. Leader R. Mehlman Roger N. Clark F. P. Fanale R. W. Carlson 1997 <p><span>The&nbsp;</span><i>Galileo</i><span>&nbsp;Near Infrared Mapping Spectrometer was used to investigate the distribution and properties of sulfur dioxide over the surface of Io, and qualitative results for the anti‐Jove hemisphere are presented here. SO</span>₂<span>, existing as a frost, is found almost everywhere, but with spatially variable concentration. The exceptions are volcanic hot spots, where high surface temperatures promote rapid vaporization and can produce SO</span>₂<span>‐free areas. The pervasive frost, if fully covering the cold surface, has characteristic grain sizes of 30 to 100 µm, or greater. Regions of greater sulfur dioxide concentrations are found. The equatorial Colchis Regio area exhibits extensive snowfields with large particles (250 to 500 µm diameter, or greater) beneath smaller particles. A weak feature at 3.15 µm is observed and is perhaps due to hydroxides, hydrates, or water. A broad absorption in the 1 µm region, which could be caused by iron‐containing minerals, shows a concentration in Io's southern polar region, with an absence in the Pele plume deposition ring.</span></p> application/pdf 10.1029/97GL02609 en American Geophysical Union The distribution of sulfur dioxide and other infrared absorbers on the surface of Io article