Magnetization of the lunar crust

• Published in: Journal of Geophysical Research: Planets Vol. 117; no. E8
• Main Authors: Carley, R. A., Whaler, K. A., Purucker, M. E., Halekas, J. S.
• Format: Journal Article
• Language: English
• Published: Washington, DC Blackwell Publishing Ltd 01-08-2012; American Geophysical Union
• Subjects: Earth sciences; Earth, ocean, space; Exact sciences and technology; global; Lunar Prospector; magnetic anomalies; Magnetic fields; Magnetism; magnetization; Moon; Planetology; Planets; satellites; altitude; Lower bound; models; magnetic field; magnetometers; magnetization; thickness; Moon; Space remote sensing; Satellite observation; global; damping; crust; Earth; Mars; lunar crust; solution; Spherical harmonic; uncertainties; direction
• ISSN: 0148-0227; 2169-9097; 2156-2202; 2169-9100
• DOI: 10.1029/2011JE003944

Magnetic fields measured by the satellite Lunar Prospector show large scale features resulting from remanently magnetized crust. Vector data synthesized at satellite altitude from a spherical harmonic model of the lunar crustal field, and the radial component of the magnetometer data, have been used to produce spatially continuous global magnetization models for the lunar crust. The magnetization is expressed in terms of localized basis functions, with a magnetization solution selected having the smallest root‐mean square magnetization for a given fit to the data, controlled by a damping parameter. Suites of magnetization models for layers with thicknesses between 10 and 50 km are able to reproduce much of the input data, with global misfits of less than 0.5 nT (within the uncertainties of the data), and some surface field estimates. The magnetization distributions show robust magnitudes for a range of model thicknesses and damping parameters, however the magnetization direction is unconstrained. These global models suggest that magnetized sources of the lunar crust can be represented by a 30 km thick magnetized layer. Average magnetization values in magnetized regions are 30–40 mA/m, similar to the measured magnetizations of the Apollo samples and significantly weaker than crustal magnetizations for Mars and the Earth. These are the first global magnetization models for the Moon, providing lower bounds on the magnitude of lunar crustal magnetization in the absence of multiple sample returns, and can be used to predict the crustal contribution to the lunar magnetic field at a particular location.
Key Points
Global crustal magnetization models from Lunar Prospector magnetometer data
Model layers 10‐50 km thick fit the input data and some surface field estimates
These are the first global magnetization models for the Moon