Regolith Activation on the Lunar Surface and its Ground Test Simulation

Activation of the surfaces of lunar regolith particles can occur through interactions with solar electromagnetic radiation, solar and galactic particle radiation and micrometeoroid bombardment. An attempt has been made to quantify the relative importance of each of those effects. The effects of these activated surfaces may be to enhance the adhesion and toxicity of the particles. Also key to the importance of activation is the lifetimes of activated states in various environments which is controlled by their passivation rate as well as their activation rate. Although techniques exist to characterize the extent of activation of particles in biological system, it is important to be able to quantify the activation state on the lunar surface, in ground-test vacuum systems, and in habitat atmospheres as well. Introduction The surface of the Moon is covered by a layer of crushed rock from 8 to 48 m deep known as the lunar regolith (Ref. 1). The composition of the regolith samples returned from the six Apollo sites and the two Luna sites have been studied in great detail. These are summarized in the Lunar Sourcebook, (Ref. 2) and numerous other references. From these studies it is known that 65 to 90 percent of the regolith is composed of silicate minerals, depending on location on the lunar surface. The largest component is made of plagioclase feldspars [(Ca-Na)(AlSi)