Mars' Core Looks Bigger than It Is Because of a Layer of Molten Rock

Scientists have found evidence of a hidden layer of radioactive magma surrounding the red planet's core. This revelation may finally explain why Mars lacks an active magnetic field, as reported in a pair of studies.

For years, scientists had been puzzled by the apparent discrepancy in the size and composition of Mars' core based on seismic data collected by NASA's InSight lander. Initial estimates suggested a core much larger and lighter than expected, raising questions about the abundance of lighter elements within it.

However, a game-changing event occurred in September 2021 when a meteorite impact on Mars generated seismic waves that allowed scientists to gain new insights into the planet's interior. This impact provided crucial data that illuminated the core's true nature.

The two separate studies revealed that Mars' core is significantly smaller and denser than previously believed. This way, the Martian core is about 30% smaller in volume than previous estimates. This smaller core is also more dense, resolving the mystery of the unexpected abundance of lighter elements within it.

What makes this discovery even more intriguing is the finding that Mars' core is enveloped by a layer of molten silicates about 90 miles thick, a feature entirely unique to the Red Planet. This molten layer acts as a "heating blanket," concentrating radioactive elements, according to one of the co-authors of the second study.

The presence of this molten silicate layer helps explain why Mars lacks an active magnetic field. Earth's magnetic field results from the interaction between its solidifying inner core and outer liquid core, generating powerful electric currents. The layer of molten rock on Mars serves as an insulator, preventing the core from cooling and solidifying, which, in turn, hinders the development of a magnetic field.