How does the partially molten layer form above Mars’s core?

A team from the CNRS, the National Museum of Natural History, and Sorbonne Université has demonstrated how a layer of partially molten rock forms approximately 1,550 km beneath Mars’s surface, and remains right above its core. At such depths, the rocks in the mantle begin to melt at temperatures approximately 100°C lower than previously thought, producing an iron-rich liquid that is denser than the surrounding mantle, and migrates down towards the depths. These experimental results provide a physical explanation for some of the seismic data gathered during the InSight mission (NASA-CNES). This research will be published in the journal Nature Geoscience on September 18th, 2026.