A search for water on the moon at the Reiner Gamma Formation - A possible site of cometary coma impact

Earth-based telescopic measurements of the Reiner Gamma Formation in the 3-micron region were made to search for evidence of water at this proposed site of cometary interaction with the lunar surface. Comparison of the spectra of Reiner Gamma and laboratory measurements of a variety of minerals with adsorbed water or structural OH(-) show that there is no evidence for water at the locations measured. While these measurements rule out the presence of abundant bound H2O at these locations, they do not exclude the presence of OH(-) bearing minerals that have absorptions not detectable through the wet terrestrial atmosphere. The possible effects of high lunar temperatures on the reflectance spectra were examined, and it was concluded that these effects would not obscure a bound water absorption if it were present. Upper limits on the amount of water that could be present at the locations observed and remain undetected are 2.25 average wt pct for a mixture consisting of discrete patches of water-bearing and water-free minerals and 0.01 wt pct for an intimate mixture of these two materials.