Feasibility of a magma ocean dynamo on Mars

Abstract

Crustal magnetization of rocks in regions of Mars surface testifies to an era of dynamo activity. I examine the possibility that the dynamo that operated then, in the first 400-600 Ma after Mars formed, was powered by a crystallizing subsurface magma ocean. Of the ways that a magma ocean dynamo could operate, on Mars only turbulent and magnetostrophic dynamos seem feasible; geostrophic dynamos do not seem so unless very high heat flows, 100-1000 times present, are invoked. Given the anticipated information from the future InSight lander mission, it will be difficult to assess where the dynamo originated unless an inner core is discovered, rendering the dynamo likely to have operated in the core.

Equation of State of Liquid Iron under Extreme Conditions

“…Iron is the sixth most abundant element in the universe and the main component of dense metallic cores of planets. This is not only true for the Earth, but also for Mercury and Mars, which are expected to have partially molten cores [1,2]. Density (ρ) and longitudinal sound velocity (VP) (equivalent to bulk sound velocity, VΦ, in a liquid) are the primary observables of the Earth's liquid outer core [3].…”