Researchers gather evidence on how Mars formed

Scientists have been studying the Red Planet to try and figure out how the planet formed and if it may have had life in the distant past. The NASA InSight spacecraft landed on Mars about two years ago and this month detected some boundaries in the rock, tens or hundreds of kilometers below the planet's crust. Researchers say that the boundaries are surprisingly thin.

The new discoveries have led to some new theories on how Mars may have formed. Scientists believe that the planet once cooled itself via a type of plate tectonics that follows a pattern of "upwelling mantle rock and subducting crust," which allowed the planet to cool itself efficiently. Some scientists believe the findings offer evidence of more dynamic crust cooling earlier in the planet's life than previously believed.

One of the key instruments aboard InSight that has been deployed on Mars is a seismometer to record seismic activity inside the planet. So far, nothing larger than a magnitude 4.5 has been discovered, indicating seismic waves don't travel as deep under the surface of Mars as some expected. The largest marsquakes recorded so far have been magnitude 3.7 and magnitude 3.3. Those quakes were recorded by the lander, allowing scientists to gather some information on the thickness of the crust and the layers inside.

The data shows that Mars could be made up of two or three layers, with the planet's crust seemingly thinner than Earth's crust. Calculations estimate that the outermost shell of Mars is only 20 to 37 kilometers thick. Mars's core is estimated to be liquid and about 1800 kilometers in diameter, which is more than half the planet's total diameter.

Scientists are continuing to study Mars in an effort to learn more about the geology of the planet. Future missions will also help learn more about Mars and whether it harbored life in the distant past.