Lunar Electrical Conductivity Profile

Abstract

RECENT measurements and analysis of magnetic field fluctuations on the surface of the Moon have led Sonett et al.¹ to conclude that the Moon is stratified into an upper mantle, a lower mantle and a core. Using an eight-layer model, their computer analysis of magnetic field fluctuation data led to the conclusion that there is a highly conducting shell about 100 km thick, located about 220 km below the lunar surface. In this article their experimental data are reanalysed in terms of a simple two layer model. I conclude that the field fluctuation spectrum observed accurately follows from a Moon with an inner core which has a uniform conductivity of 6 × 10⁻⁴ mho m⁻¹ and an insulating mantle about 160 km thick. These results coincide more closely with the preliminary conclusions of Sonett et al.² than their more refined calculations which indicate a very non-uniform and non-monotonic conductivity profile.