Insight is a Mars lander that successfully touched down on Nov 26, 2018. Insight is going to study the interior (core) of Mars

NASA and Jet Propulsion Laboratories created the Insight Lander Program to determine what the Martian Core is like

InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is a Mars lander designed to give the Red Planet its first thorough checkup since it formed 4.5 billion years ago. It is the first outer space robotic explorer to study in-depth the "inner space" of Mars: its crust, mantle, and core.