Rare gas adsorption on solids of the lunar regolith

Abstract

This article analyzes the composition and concentration data on rare gases in the lunar solids taken in the Apollo 11 and 12 missions. The results indicate, among others, the following striking facts: 1. 1. Rare gas retention by the lunar materials is primarily by adsorption rather than absorption. 2. 2. The origin of the rare gases is primarily solar wind rather than indigenous or radiogenic. 3. 3. The accommodation coefficient of the lunar regolith for rare gases seems amazingly high. This is indicated by almost negligible fractionation; the composition of rare gases in the breccia, soil, and type A crystalline rocks is astonishingly close to that in solar wind. 4. 4. “Structural adsorption” potentials of rare gases on lunar solids appear amazingly high on the basis of the adsorption concentrations and a tenuous lunar “atmosphere.” Intense surface activation of the lunar materials is thus indicated.