Peering deeper below the surface of Earth can tell us a lot about its history and geological make-up, and it's the same for any other planet.

The seismometer on board InSight – called SEIS or the Seismic Experiment for Interior Structure – points to a shallow sedimentary layer sandwiched between hardened rocks resulting from lava flows, going down to a depth of around 200 meters or about 650 feet.

From what we know about Mars' history from the craters still visible on the planet today, the researchers suggest the uppermost layer of hardened lava is around 1.7 billion years old, formed during the cold, arid Amazonian period on Mars when there were relatively few meteorite and asteroid impacts.

The deeper layer looks to be some 3.6 billion years old, created during the Hesperian period when there was much more volcanic activity on the Red Planet.