An altitude-normalized magnetic map of Mars and its interpretation

Techniques developed for the reduction and analysis of terrestrial satellite magnetic field data are used to better understand the magnetic field observations made by Mars Global Surveyor. A global distribution of radial (B_r) magnetic field observations and associated uncertainties is inverted for an equivalent source magnetization distribution and then used to generate an altitude- normalized map of Br at 200 km. The observations are well-represented by a potential function of crustal origin, consistent with a remanent origin for the Martian magnetic features. The correlation between the 40546 B_r observations and B_r calculated from the magnetization solution at observation locations is 0.978. For a magnetization distribution confined to a 50 km layer, calculated magnetizations range from -22 to +17 A/m. We see correlations with tectonics that were only hinted at in earlier maps. Magnetic features appear to be truncated against Valles Marineris and Ganges Chasma, suggestive of a major change in crustal properties associated with faulting.