Initial measurements of the lunar induced magnetic dipole moment using Lunar Prospector Magnetometer data

Abstract

Twenty‐one orbits of Lunar Prospector magnetometer data obtained during an extended passage of the Moon through a lobe of the geomagnetic tail in April 1998 are applied to estimate the residual lunar induced magnetic dipole moment. Editing and averaging of individual orbit segments yields a negative induced moment with amplitude −2.4 ±1.6 × 10 22 Gauss‐cm³ per Gauss of applied field. Assuming that the induced field is caused entirely by electrical currents near the surface of a highly electrically conducting metallic core, the preferred core radius is 340±90 km. For an iron‐rich composition, such a core would represent 1 to 3% of the lunar mass.