The Moon is generally depleted in volatile elements and this depletion extends to the
surface where the most abundant mineral, anorthite, features< 6 ppm H 2 O. Presumably the
other nominally anhydrous minerals that dominate the mineral composition of the global
surface—olivine and pyroxene—are similarly depleted in water and other volatiles. Thus the
Moon is tabula rasa for the study of volatiles introduced in the wake of its origin. Since the
formation of the last major basin (Orientale), volatiles from the solar wind, from impactors of …