Scientists have confirmed that Mars possesses a solid inner core, shedding light on a significant planetary mystery. Findings from NASA’s InSight mission suggest that the red planet has an interior structure resembling that of Earth, with a solid core encased in a liquid outer layer. This discovery has implications for understanding Mars’ evolution and its climatic history.
The research, published in the journal Nature, indicates that billions of years ago, Mars may have supported a thicker atmosphere that allowed liquid water to flow across its surface. This atmosphere could have been sustained by a protective magnetic field, akin to Earth’s, which Mars currently lacks. The disappearance of this magnetic field might have contributed to the gradual loss of atmosphere, transforming Mars into the cold, arid landscape it is today.
Mars’ core structure has long intrigued scientists. On Earth, the solid inner core and liquid outer core work together to create a dynamo effect, generating a magnetic field that shields the atmosphere from solar winds. The presence of residual magnetization in Mars’ crust suggests that a similar magnetic field may have existed in the past, likely resulting from a core structure comparable to Earth’s. However, researchers believe that Mars’ core cooled and ceased its movement at some point in its history.
Evidence of past water flow on Mars is abundant. Features such as dry lake beds and extensive valley networks indicate that the planet once harbored more hospitable conditions. Despite this, Mars today has a thin atmosphere, and the water necessary to support life is largely absent.
Initial findings from the InSight lander had identified Mars’ core as primarily liquid. The latest research led by Huixing Bi from the University of Science and Technology of China introduces the possibility of a solid inner layer within the liquid core. This revelation raises questions about the planet’s capacity to sustain a magnetic field and a habitable climate.
The debate surrounding Mars’ core structure has seen significant developments. In 2021, Simon Stähler from ETH Zurich and colleagues provided groundbreaking analysis of seismic waves from Martian quakes. Their work suggested a larger, less dense liquid core without a solid inner component. They estimated the core’s size to be approximately half of Mars’ radius, or about 900 kilometers, inferring it contained lighter elements that affected its crystallization.
The discovery of a solid inner core, approximately 610 kilometers in radius, by Bi and colleagues provides critical insights. Its presence indicates ongoing crystallization and solidification as Mars cools, suggesting the planet may have experienced a dynamo effect in the past. The thermal changes between the solid inner core and the liquid layer could have driven convection necessary for generating a magnetic field.
While there may appear to be conflicting findings, the scientific community views this as a sign of progress in data collection and analysis. InSight, which landed on Mars in November 2018, communicated with Earth for the final time in December 2022. Stähler’s initial model has been revised to reconcile new data, indicating that a solid inner core cannot be ruled out, as the initial signal strength was not sufficient to confirm or deny its existence.
The latest study employed advanced data analysis techniques, selecting specific seismic events at calculated distances to extract reliable signals from instrument noise. This research is expected to influence future studies and potentially lead to a clearer understanding of Mars’ core structure.
Understanding the interior composition of planets like Mars is vital for exploring their formation, evolution, and current states. Prior to the InSight mission, models suggesting a core structure similar to Earth’s were not widely supported. The ongoing research continues to reshape our understanding of Mars and its geological history, offering insights that may bridge the gap between Earth and its neighbors in the solar system.
