NASA’s InSight spacecraft arrived on Mars in 2018 to explore the interior of Mars by monitoring “marsquakes”. The project is now starting to bear fruit. NASA announced that its researchers have mapped the interior of the red planet and discovered some big surprises and big differences from Earth.
Relative to Earth, Mars has a thicker crust, a thinner mantle layer and a larger core, is less dense and more liquid than everyone expected. In turn, NASA suspects that Mars was formed millions of years before our planet, when the Sun itself was not yet fully formed.
“This gives us our first sample of the interior of another rocky planet like Earth, built of the same materials but very, very different,” said Cambridge University seismologist Sanne Cottaar.
Building a map from the limited data provided by InSight was not an easy task. The probe has recorded only one-site earthquakes and has only a single seismometer to begin with. Although Mars is seismically active, it has had no earthquakes greater than 4 on the Richter scale.
Still, by pairing this data with the planet’s magnetism and orbital oscillations, scientists were able to create a detailed map. The planet’s innermost core was found to have a diameter of about 2,275 miles, larger than previously thought.
The crust was very old, thicker in the southern highlands of Mars and thinner in the northern plains, which may have hosted oceans long ago.
The mantle between the crust and the core extends more than 970 miles below the surface. It is thinner than Earth’s and has a different composition, which suggests that the two planets arose from different materials when they formed.
The results gave scientists new insights not just into the interior of Mars, but how rocky planets form in general. This will help them develop new theories about planet formation that could become particularly valuable in the near future.