Data from InSight indicate that Mars has an all-liquid core and an internal mass anomaly

A team of planetary scientists from Belgium, the United States, France and Germany has found evidence from the InSight lander that Mars has an all-liquid core and internal mass anomalies. In their paper published in the journal naturethe group describes their analysis of data sent back to Earth from the probe.

As the research team notes, determining the internal properties of the planets of the solar system is hampered by their inaccessibility. In this case, they were referring to the work of research teams trying to determine the internal makeup of Mars. Until now, no one had been able to prove whether its core was solid or liquid, for example—a characteristic that could influence work in probing whether the planet harbored life at all.

In this new effort, the researchers focused their efforts on data from the InSight lander, which landed on Mars in 2018. It transmitted data from the day it landed until December 2022, when dust covered its solar panels, preventing it from recharging. The researchers note that InSight has two main sensors, one that uses a seismometer to measure earthquakes and another, called RISE, that sends radio signals from the probe back to Earth. And because they were able to pinpoint the probe’s position so precisely, RISES signals can be used to monitor the Red Planet’s rotation and oscillations, both of which provide clues about the planet’s interior.

The researchers found evidence in RISE data of what they describe as a “mass anomaly” beneath the planet’s surface. Anomalies are found to extend from the top of the shelf to the bottom. They further noted that Mars’ gravitational field and likely general shape is determined primarily by the planet’s rotation rate. But they suggest that anomalies may also have an effect. Importantly, by studying and characterizing data about the core separately from data about the mantle, the team found what they believe is evidence that the Martian core is a molten liquid — and they also found a slight increase in the planet’s rotation.