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Mars' core and magnetism

Abstract

The detection of strongly magnetized ancient crust on Mars is one of the most surprising outcomes of recent Mars exploration, and provides important insight about the history and nature of the martian core. The iron-rich core probably formed during the hot accretion of Mars 4.5 billion years ago and subsequently cooled at a rate dictated by the overlying mantle. A core dynamo operated much like Earth's current dynamo, but was probably limited in duration to several hundred million years. The early demise of the dynamo could have arisen through a change in the cooling rate of the mantle, or even a switch in convective style that led to mantle heating. Presently, Mars probably has a liquid, conductive outer core and might have a solid inner core like Earth.

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Figure 1
Figure 2: Radial magnetic field at 200-km altitude, based on data collected by the Mars Global Surveyor spacecraft.
Figure 3: Possible scenarios of martian core evolution.

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Correspondence to David J. Stevenson.

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Stevenson, D. Mars' core and magnetism. Nature 412, 214–219 (2001). https://doi.org/10.1038/35084155

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