Mars may have a bigger core than previously expected. Three studies published in the journal Science reveal the interior structure of Mars could be a massive metallic core based on the seismic waves produced by marsquakes.
According to National Geographic, NASA's InSight lander (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) has uncovered details of the Red Planet's layers, including a less dense mantle and a roughly 2,300-mile-wide metallic core that is larger than previous research thought.
The lander arrived at the Elysium Planitia on Mars in November 2018. It has measured faint marsquakes on the Red Planet since it was first discovered in 2019. The data from the lander will refine models for how Mars was formed and changed for billions of years and reveal how a possibly habitable world became the hostile, rusty desert it is today.
Marsquakes Reveal Mar's Metallic Heart
Since it is impossible to get a sample of Mars' core, scientists have to rely on the seismic waves produced by marsquakes to estimate the Red Planet's layers, The Next Web reported. For instance, Earth's core is estimated by finding the area where the core disrupts incoming seismic waves from distant quakes.
One of the studies, titled "Seismic detection of the martian core," relied on the slow, sideways-traveling waves known as the S-waves that are reflected the surface by the interface between the core and mantle.
Seismologists worldwide analyzed the seismic waves detected near the InSight probe and combined it with information from mineral physics and seismic waves that travel throughout Mars' mantle. They were able to estimate the size and density of the planet's core, which suggests that its size is just over half of Mars' radius.
The study reveals that the Martian core contains a high fraction of sulfur and other light elements. Meanwhile, experiments show that liquid iron compounds with this much sulfur are less likely to solidify like the solid core of Earth due to the pressure and temperature of the core. This finding could help in understanding why Mars has no planet-wide magnetic field like Earth.
Layers of Mars' Crust
Theorists have used data from landers and orbiters to create thick- and thin-crust models of Mars. Some of these models estimate that the Martian crust could be as thick as 68 miles (110 kilometers), while some models show that it could be thicker than Earth's crust.
But InSight uses seismic waves to measure the crust's thickness directly beneath its landing site, Space.com reported. During marsquakes, seismic waves echo through the planet, and the primary or P-waves travel quickly through the layers, similar to how sound waves travel in the air. It is then followed by the secondary or S-waves whose vibrations are perpendicular to the wave's direction.
P-waves and S-waves allow scientists to determine how far away the quake occurred and provide information about the planet's interior. Scientists think that beneath InSight, there are at least two layers in the crust. The top layer is about 6 miles (10 kilometers) thick, probably fractured by repeated meteorite impacts since its formation.
Meanwhile, the second layer extends to roughly 12 miles (20 kilometers) and is likely a pristine surface that is shielded from the impacts. The scientist said that a third layer might also be present, which extends to a depth of approximately 24 miles (30 kilometers). But further studies are required to confirm this.