Helium isotopes in the lunar regolith - Measuring helium isotope diffusivity in lunar analogs

Abstract

Introduction: The purpose of the present chapter is to provide information about the diffusivities and activation energies of 4He and 3He in analogs of lunar ilmenite, which has been theorized to retain helium isotopes better than other lunar minerals. The presence of noble gases in the surfaces of lunar fines was discovered in early Apollo samples by several investigations (Bauer et al. 1972, Ebergart et al. 1970, Hintenberger et al. 1970). The correlation between lunar helium and the mineral ilmenite was discovered by Eberhart et al. (1970) and subsequently others (Muller et al. 1976, Signer et al. 1977). This correlation was rediscovered by researchers at the University of Wisconsin in the early 1980's while researching sources of 3He for fuel for future fusion reactors (Cameron 1988). The data presented here raise questions about the diffusivities of helium in other lunar minerals and will be useful in the design of future lunar miners. This chapter also provides insight into the mechanisms of space weathering on airless bodies.