Reacción a "The presence of a solid inner core has been detected on Mars"

I find the work very interesting and represents an important step forward in better characterizing the planet and improving our understanding of the internal configuration and evolution of Mars and other planets and moons about which we know relatively little. Its publication in a journal as renowned as Nature suggests that it has undergone an exhaustive peer-review process and is based on data from NASA's InSight mission, which provides reliability.

Because knowledge of the characteristics of the interior of planetary bodies comes from numerical modeling using indirect sources, such as how a body moves in space (orbital dynamics) or how vibrations propagate from one side of the planet to the other (seismic waves), much remains to be determined, even for our own planet. The discovery of Earth's solid inner core took place less than 100 years ago, and very recently it has been suggested that its structure could be even more complex (e.g., this article from last year in this same journal). Therefore, advances in various fields still allow for paradigm shifts in how we understand the elusive interior of planetary bodies.

Until now, the most widely accepted model assumed that Mars' core must be completely liquid. Mars has magnetic anomalies, not a global magnetic field like Earth's, but its crust is highly magnetized. This would mean it must have had a global magnetic field produced by a dynamo that currently does not exist. This dynamo would consist of electrically conductive material (rich in iron, for example) that, when liquid due to the high temperatures and pressures of the planet's interior, would move and generate magnetic forces. These are not only responsible for compasses pointing north and the northern lights, but also have a major impact on the habitability of Earth by protecting us from the solar wind. Based on the data previously available on Mars, the hypothesis that best fit these changes in magnetism (an ancient but currently absent global field) was that the core was completely liquid.

This work presents that, according to the analysis of seismic data from the recent InSight mission, the "inner core" of Mars could be solidified, although it maintains that the outer part of this core should still remain in a liquid state (as is the case on Earth). Until now, the only seismological data on Mars, which are one of the main sources for understanding a planet's interior, came from the Viking missions launched by NASA in the 1970s. But due to their characteristics and configuration (they were not in direct contact with the ground), the results were very limited. InSight's seismometer, SEIS, was the first to obtain direct data from the surface with high sensitivity, and the detailed analysis of these signals has allowed these researchers to make this new interpretation that changes the current paradigm.

One implication would be that Mars is more like Earth than previously thought. Not only does it have a core that differentiates between these two states, but the authors propose that the solid inner core would reach 0.18 of its radius, while on Earth it is 0.19. One possible interpretation is that Mars is older than we thought (it has already begun the crystallization process of its interior and will be able to retain its internal heat for less time), but at the same time, the crystallization process may imply that Mars is "more alive," maintaining more efficient convection and therefore greater geological activity. In any case, it is a further step in understanding what planetary bodies are like and how they evolve.

[Regarding possible limitations] As the study itself states, the seismic analyses come from a single seismometer (InSight's SEIS), which implies some uncertainty. Future, more widely distributed seismological measurements could definitively confirm this interpretation, and in the absence of new data, studying the impact of this new configuration on the most advanced numerical models will allow us to better understand the planet and its evolution.