Scientists have proven the existence of a molten silicate layer covering the metallic core of Mars. This explains why the Red Planet has no magnetic field. The discovery is reported in a paper published in the journal Nature.
The researchers analyzed seismic data collected by NASA's InSight lander. They were able to identify a thin layer of molten silicates located between the Martian mantle and core. They also found that the core is both denser and smaller than previously thought. The size of the core is 1,650 kilometers, not 1,830, which implies a density of 6.5 grams per cubic centimeter. That's 5 to 8 percent more than previous seismic estimates.
Molten silicates form an insulating layer that prevents the convective movement of the magma. This explains why Mars has no active magnetic field to protect its surface from the solar wind.
However, during the first 500-800 million years of the planet's evolution, there were other sources of the magnetic field, such as collisions with large celestial bodies and core vibrations caused by interactions with ancient satellites, which are now absent. The results confirm that Mars was once a molten ocean of magma that later crystallized to form a layer of molten silicate enriched with iron and radioactive elements at the base of the Martian mantle. This dramatically changed the thermal evolution and cooling history of the Red Planet. /BGNES