These new results provide definitive evidence that Mars has a metallic core. This finding puts into context an enduring mystery about the planet’s interior structure. This interesting discovery serves as an example of how similar Mars is to Earth. Most importantly, it confirms that Mars has both a solid inner core and a liquid outer core. The consequences of these discoveries reach beyond teasing apart the planet’s nascent atmosphere to the possibility of habitability.
The InSight lander provided a wealth of data resulting in a trove of new research. This study supports previous work indicating that Mars has a well-defined inner core of roughly 610 km radius. This new understanding adds to the scientific community’s knowledge of the Martian geology. It begs some fascinating larger questions about the planet’s atmospheric history and magnetic field.
The Structure of Mars’ Core
If that’s the case, then Mars’ core structure may be almost identical to Earth’s. It consists of a faintly solid inner core surrounded by a fluid outer core. All of these similarities point to a remarkable potential. Mars may have been able to produce a magnetic field in the past, like Earth’s dynamo effect. But today, Mars has virtually no dynamic magnetic field, key to understanding its atmospheric loss throughout history.
InSight touched down on the Martian surface in November of 2018. It was instrumental in this discovery by tracking seismic waves produced by Marsquakes. These seismic waves gave scientists the tool to understand the layers inside our planet, ultimately surfacing the discovery that our core was liquid. The extensive period of data collection being conducted, set to run through December 2022, has created an abundance of material for researchers.
Last year, Simon Stähler changed the game with a very influential paper. Following up on preliminary discoveries from the InSight mission, he offered new hypotheses on the structure of Mars’ core. In 2023, Henri Samuel further developed Stähler’s model to update its parameters. His new findings expand our understanding of Mars’ core structure and its geological history.
Impacts on Mars’ Atmospheric Conditions
These new glimpses into Mars’ core paint a much different picture of the planet’s atmospheric history. This insinuates that Mars at some point featured a much denser atmosphere, conducive for the presence of liquid water across the surface. This is a big deal. All that liquid water points to environments that could have been much more conducive to life than those existing on the planet today.
The existence of a solid inner core, paired with a prior generation of magnetic field, probably helped protect the atmosphere. The disappearance of Mars’ magnetic field must have been a key factor in the slow-motion decimation of that planet’s atmosphere to space. Those processes led the planet to the cold, dry, inhospitable world we know today. Knowing how this process works will be key for scientists as they work to unravel whether or not life ever existed on Mars.
The loss of atmospheric pressure over the past billions of years would have gradually made Earth less able to hold onto water. Ancient riverbeds and minerals associated with water offer powerful proof. These findings buttress the claim that Mars may have been habitable in some way during its earlier history.
The Role of Planetary Size and Magnetic Fields
These are all major factors in a planet’s ability to sustain a protective magnetic field, researchers say, with size and density taking the lead. This, in turn, is critical not only for sustaining livable climates. Mars, for its part, given its smaller size and therefore possibly precluded geochemical capacity to maintain such conditions even if they could form over geological timescales.
The solid inner core’s size and density were determined through analysis of seismic data, allowing scientists to draw parallels between Martian and terrestrial planetary structures. These striking similarities suggest that Mars’ geological evolution may have been more Earth-like than previously thought. This is particularly true when it comes to understanding core dynamics and atmospheric interactions.
As scientists continue to explore these findings, they hope to answer critical questions about Mars’ past and future potential for habitability. By piecing together our core structure, we’re helping to unlock some really important clues about our planet’s geologic processes. It helps us to further refine models of planetary evolution across the solar system.