Mars' core and magnetism

The detection of strongly magnetized ancient crust on Mars is one of the mo st surprising outcomes of recent Mars exploration, and provides important i nsight about the history and nature of the martian core. The iron-rich core probably formed during the hot accretion of Mars similar to4.5 billion yea rs 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 l imited in duration to several hundred million years. The early demise of th e dynamo could have arisen through a change in the cooling rate of the mant le, or even a switch in convective style that led to mantle heating. Presen tly, Mars probably has a liquid, conductive outer core and might have a sol id inner core like Earth.