Scientists have unveiled that Mars possesses a solid inner core, greatly enhancing our understanding of the planet’s interior structure. Results from NASA’s InSight mission indicate that beneath the Martian surface lies a solid core encased in a liquid outer shell. This discovery potentially resolves a longstanding mystery regarding the red planet’s formation and evolution.
The findings, published in the journal Nature, suggest that Mars may have once supported a thicker atmosphere conducive to liquid water. This atmosphere could have been maintained by a protective magnetic field similar to Earth’s. Today, however, Mars lacks such a magnetic shield, leading to speculation that its loss contributed to the planet’s transition into the cold and arid environment we observe now.
Understanding the core structure of Mars is vital as it mirrors key features of Earth’s geology, particularly the presence of a solid centre surrounded by liquid. On Earth, convection within the liquid core generates a dynamo effect, creating a magnetic field that protects the atmosphere from solar winds and prevents it from eroding. The absence of a similar magnetic field on Mars has raised questions about its past climate and the potential for life.
Longstanding evidence, including dry lake beds and valley systems, indicates that liquid water flowed on Mars millions of years ago. The mineral composition found in these ancient geological formations points to a more hospitable environment that may have existed in the past.
The new study led by Huixing Bi from the University of Science and Technology of China builds upon previous work by scientists like Simon Stähler from ETH Zurich, who, in 2021, first identified the Martian core and its liquid properties. Stähler’s research utilized seismic data from InSight, which landed on Mars in November 2018 and concluded operations in December 2022. His team detected seismic waves originating from Mars quakes, facilitating a pioneering analysis of the core’s dimensions and density.
While Stähler’s team proposed a core entirely composed of liquid, the recent study presents evidence of a solid inner core with a radius of approximately 610 km. This solid core indicates ongoing crystallization and solidification processes as the planet cools, suggesting that Mars may have had a magnetic dynamo at some point in its history, similar to Earth’s.
The implications of these findings are significant. The presence of a solid inner core increases the likelihood that Mars had a magnetic field in the past, which would have been crucial in maintaining its atmosphere and, by extension, conditions suitable for liquid water. The new model reconciles the earlier findings with additional data, allowing for a more nuanced understanding of Mars’ geological history.
This new research is a remarkable example of the evolving nature of scientific inquiry. The discrepancies between the findings of Stähler and Bi highlight the dynamic nature of scientific exploration. Bi’s team employed refined methodologies to analyze specific seismic events, demonstrating the potential for extracting meaningful data from the noise inherent in the seismic readings.
The quest to understand Mars continues to motivate a multitude of high-profile missions. NASA’s rovers, including Spirit, Opportunity, Curiosity, and Perseverance, have focused on the planet’s surface mineralogy, while the European Space Agency’s ExoMars Trace Gas Orbiter examines the Martian water cycle. NASA’s Maven spacecraft studies atmospheric loss, and InSight has been pivotal in seismic research.
As researchers delve deeper into Mars’ history, future investigations will likely focus on the broader geological context and the implications of the newly discovered core structure. Understanding the core’s characteristics is essential for developing theories about planetary formation, growth, and evolution across our Solar System.
The ongoing analysis of InSight’s data will be crucial in either supporting or challenging Bi’s new model. The scientific community eagerly anticipates further insights into the enigmatic geology of Mars and what it reveals about the planet’s capacity to host life in the past.
