We’re told to never judge a book by its cover, but it’s apparently fine to judge what lies inside Mars by listening to the echoes of meteorite impacts.

We know very little about the interior of the Red Planet. We know that once it had a global magnetic field and active volcanoes, but it’s unclear if the core is still molten or not. If it is, plate tectonics and earthquakes (which are called marsquakes on Mars) are a possibility.

To find out, the next spacecraft to arrive on Mars will come equipped with precise seismometers to detect tremors. The InSight Lander will listen carefully for seismic waves caused by meteorites, and use the data to make some educated guesses at what materials it passed through along the way.