NASA's InSight mission finally looked into the interior of Mars and found the planet's crust could consist of three layers, according to a prerecorded talk later replayed during the virtual American Geophysical Union meeting on Dec. 15, and initially reported in Nature.
This marks the first time scientists directly probe the interior of a planet besides the Earth, and will also help researchers come to know how the Red Planet initially formed and evolved through the ages.
NASA's InSight mission reveals 'cake-like' layers of Mars
Before the InSight mission, researchers had only studied the interior structures of Earth and the moon. "This information was missing, until now, from Mars," said a seismologist from the University of Cologne in Germany, Brigitte Knapmeyer-Endrun, the virtual meeting.
This represents a major discovery for InSight — which made its landing on Mars in November 2018, with aims to probe the Red Planet's interior structure.
Mars less seismically active than Earth, more so than moon
As of writing, InSight lander is sitting near the martian equator, resting on a smooth plain called the Elysium Planitia. The lander uses a highly-sensitive seismometer to tune-in to geological energy thrumming away inside the planet, and so far the mission has picked up the vibrations of 480 'marsquakes,' said Principal Investigator Bruce Banerdt, who is also a scientist at NASA's Jet Propulsion Laboratory.
Mars isn't as seismically active as Earth, but it thrums more than the moon.
InSight's data shows Mars consists of two, three layers
Just like they do on Earth with earthquakes, seismologists use marsquakes to map the interior structure of the Red Planet. Since seismic energy reverberates through the ground in two types of waves, they can measure the subtle differences in how they move, and calculate where the planet's core, mantle, and crust begin and terminate, in addition to learning the make-up of each layer.
These basic geological layers help scientists study the way Mars initially cooled and formed billions of years ago — when the solar system was young. According to Banerdt, "we have enough data to start answering some of these big questions."
The Earth's continental crust is generally separated into sublayers of varying types of rock. Researchers had hypothesized the martian crust was similarly layered, said a planetary geologist of the Lunar and Planetary Institute in Houston, Texas, Justin Filiberto, to Nature. But InSight's new data shows the Red Planet consists of either two or three layers.
Mars' crust likely 12 to 23 miles thick, depending on layers
The three-layer model best fits with geochemical models, in addition to martian meteorites, said Julia Semprich, a planetary scientist at the Open University in the U.K., to Nature.
The crust is either 12.4 or 23 miles (20 or 37 km) thick, depending on whether it consists of two or three layers, respectively, said Knapmeyer-Endrun during her talk. This thickness likely varies at different locations around the Red Planet, but it's unlikely to be more than 43.5 miles (70 km) on average, she added.
InSight could reveal information about Mars' core, mantle
Here on Earth, our crust thickness vacillates between 3 to 6.2 miles (5 to 10 km) under the oceans, and roughly 24.85 to 31 miles (40 to 50 km) under the continents.
In the next several months, InSight scientists aim to report measurements from even deeper inside Mars, said Banerdt. And this could eventually turn up new information about the Red Planet's core and mantle — opening the door to a new horizon of questions surrounding the life of both the planet and the early solar system.