A recent study of seismic waves from the inner layers of Mars seems to contradict the widespread opinion about its core. The planet’s center is probably solid, like Earth, rather than partially liquid, as some data so far suggest. If this hypothesis is confirmed, the history of Mars could undergo momentous changes.
Studying the center of the Earth with all the tools available is a complex task, to say the least. There is no heavy machinery capable of digging more than 10 kilometers below the surface without succumbing to the immense heat of the crust. Investigating the inner layers of another planet at an average distance of 54.6 million kilometers, without operators or complex tools, is a challenge that few have ventured to explore. Fortunately, in recent years a reliable way to explore the interior of a planet has been developed: monitoring the behavior of its seismic waves.
In the last decade, NASA managed to place a seismometer on the surface of Mars. The InSight module confirmed in a short time that the red planet was geologically active. Up to 1,300 Martian earthquakes or “marsquakes” have been recorded just in the area where the module is located. With each passing year, InSight continues to gather Martian seismic data that geologists on Earth can leverage.
A team of scientists from the University of Science and Technology of China took that seismometer database to conduct their own analysis of the inner layers of Mars. Their goal was to locate activity that crossed the nucleus to measure its transfer rate. The data set amplified weak signals that usually go unnoticed by other researchers.
According to their report, they found two seismic phases in the record. One was the deep core transit phase and the other was the inner core boundary reflection phase. The waves had a slight change in speed as they passed through a supposedly liquid center. That difference is best explained when you think about a solid core, at least partially.
“Here we show, from the analysis of seismic data acquired by the InSight mission, that Mars has a solid inner core,” points out the article published in the journal Nature. The article notes that the solid region must be approximately 600 kilometers in diameter.
While previous studies point to a liquid Martian core, scientists accept that it is not impossible for it to be solid either. In any case, the ambiguity of the results is a product of the very adverse conditions of studying marsquakes, with only one device that little by little fills with Martian dust. It is also likely that these new signals are just the result of the new way of analyzing information. More testing needs to be done from the solid core angle, the researchers say.
The answer will define the origin of Mars. A liquid core suggests that the planet formed from elements lighter than Earth, which would also explain why it does not have a magnetic field. However, a large, solid core implies that Mars was created from the same materials as its neighbor.
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