The global magnetic field of Mars and implications for crustal evolution

Abstract

The Mars Global Surveyor spacecraft obtained globally‐distributed vector magnetic field measurements approximately 400 km above the surface of Mars. These have been compiled to produce the first complete global magnetic field maps of Mars. Crustal magnetization appears dichotomized, with intense magnetization mainly confined to the ancient, heavily cratered highlands in the south. The global distribution of sources is consistent with a reversing dynamo that halted early in Mars evolution. Intense crustal magnetization requires an increased oxidation state relative to mantle‐derived rock, consistent with assimilation of an aqueous component at crustal depths.