Simultaneous Explorer 35 and Apollo 15 orbital magnetometer observations: Implications for lunar electrical conductivity inversions

Comparisons of simultaneous Explorer 35 and Apollo 15 subsatellite magnetometer measurements indicate that the inductive response of the moon to solar wind transients is not detectable at subsatellite altitude (100 km) on the day side of the moon. Thus, within the limitations of the present study, it appears that day side confinement of the induced fields by a thin (≤ 100 km) current layer just above the lunar surface adequately describes global electromagnetic induction in the moon. This result is a direct experimental justification of a hitherto questioned assumption in the inversion of magnetic field data to lunar electrical conductivity profiles.