Mars’ Inner Core Found to Be Solid Like Earth’s

• New seismic data from NASA’s InSight mission suggests Mars has a solid inner core, reshaping theories about its internal structure and magnetic history.

Seismic Clues Reveal Core Composition

A recent study published in Nature indicates that Mars possesses a solid inner core, similar in composition to Earth’s. The findings are based on seismic data collected by NASA’s InSight lander, which operated from 2018 until its shutdown in 2022. Over its mission, InSight recorded more than 1,300 marsquakes, with researchers focusing on 23 relatively weak events located between 1,200 and 2,360 kilometers from the lander. These readings allowed scientists to model the planet’s internal layers with greater precision.

Earlier research had suggested that Mars’ core was entirely liquid. The new data points to a solid inner core surrounded by a molten outer layer. This inner core likely consists of iron and nickel, possibly mixed with lighter elements such as oxygen. Its radius is estimated at around 613 kilometers, making up roughly one-fifth of the planet’s total radius.

Implications for Planetary Evolution

Lead investigator Daoyuan Sun from the University of Science and Technology of China noted that crystallization of the inner core may have occurred in the past and could still be ongoing. Mars’ outer core extends to approximately 1,800 kilometers from the center, and its boundary with the inner core may contain a transitional “mushy zone.” The planet’s core was likely fully liquid in its early history, evolving over time into its current layered state. Understanding this transformation could shed light on Mars’ geological and thermal evolution.

The absence of a magnetic field on Mars today may be linked to the slow crystallization of its solid core. Earth’s magnetic field is generated by dynamic movements in its liquid outer core, but Mars lacks such activity. Sun emphasized that further modeling is needed to clarify how the inner core formed and what it reveals about the planet’s magnetic past. These insights could help explain why Mars lost its protective magnetic shield, which once may have supported a more Earth-like environment.

Future Research and Limitations

With the InSight mission concluded, new seismic data from Mars is no longer being collected. University of Maryland geophysicist Nicholas Schmerr, who was not involved in the study, praised the findings but cautioned that many questions remain. He highlighted the need for a network of seismometers to better understand the shape and composition of Mars’ core. Without additional instruments, refining current models will be challenging.

Despite the limitations, the study marks a significant step in planetary science. It demonstrates that even weak seismic signals can yield valuable information about a planet’s interior. The similarity in core structure between Mars and Earth may be coincidental, but it opens new avenues for comparative research. As future missions are planned, deploying advanced seismology tools could be key to unlocking deeper knowledge of Mars’ internal dynamics.