Constraining the Temperature of Mars’ Deep Interior

Abstract:

InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) is a Mars lander dedicated to the study of the deep interior of the planet. In the context of this collaboration, results from laboratory experiments, calculations, and modeling are used together to infer the interior structure and the thermal history of the planet from geophysical observations.

We recently performed a systematic study of the eutectic melting curves and eutectic point chemical composition of Fe-rich binary alloys by in situ X-ray absorption spectroscopy in laser heated – diamond anvil cell (LH-DAC) and applied electron microscopy analysis of the recovered samples. These new experimental findings are compared with literature in situ X-ray diffraction data and other ex situ diagnostics to constrain the melting temperatures and the eutectic compositions for the Fe-X binary systems (with X = C, O, S and Si) over a pressure range relevant to the conditions of the Martian core.

As geodetic observations suggest the presence of a liquid core, our results directly provide lower bounds to its temperature. We show that tighter constraints can be placed on the temperature at the core mantle boundary once eutectic melting and composition determinations are combined with melting temperatures of end-members and results from core compositional models. Finally, we discuss how the thermal history of Mars is constrained by our experimental data.