Copy link for Scientists Measure Mars' Core — and It Is Shockingly Big! For the first time, scientists have looked at the heart of Mars — the planet's core. They measured its size by listening to "Marsquakes," which aren't too different from earthquakes. The eavesdropping machine that did the listening: NASA's InSight lander, positioned on the Red Planet's surface. It turns out, Mars' core is much bigger than anyone expected. How to Listen for Marsquakes NASA sent InSight on its Mars mission in 2018. The goal was to collect seismic data from sensors that track the noises produced by Marsquakes. That seismic noise bouncing around inside the planet helps measure the size of Mars' core. (It's also how the cores of Earth and the moon were measured.)