Life could have existed on Mars, but the planet "committed suicide": what NASA's InSight spacecraft saw
Mars was probably once a habitable planet with a magnetic field similar to that of Earth due to the planet's solid core. However, over time, the core evolved, causing it to become liquid and depriving the planet of protection from the solar wind, which is destructive for living organisms.
The new discovery was made by scientists who studied the data obtained by NASA's InSight Martian module, whose mission was officially terminated in December 2022. The research was published in the journal Proceedings of the National Academy of Sciences.
An international team of researchers studied seismic data obtained by the InSight spacecraft, which recorded waves passing through the core of the red planet. This can be an indication of only one thing: the Martian "core" is in a completely liquid state, unlike the Earth's core, which has a solid inner and liquid outer part.
"In 1906, scientists first discovered the Earth's core by observing how seismic waves from earthquakes affect its passage. More than a hundred years later, we are applying our knowledge of seismic waves to Mars. With InSight, we are finally discovering what is at the centre of Mars and what makes Mars so similar and different from Earth," said Vedran Lekic, associate professor of geology at the University of Maryland (UMD), who is one of the study's authors.
To understand what Mars' core is like, the researchers studied data from two seismic events on the red planet. One of them was caused by a Mars rover, and the other by a strong impact from a meteorite fall. Subsequently, they studied the time it took for seismic waves to pass through Mars and compared them with the waves remaining in the mantle.
The data were then combined with other seismic and geophysical measurements to estimate the density of the core and its compressibility.
When the final data were obtained, the scientists said that they indicated that Mars most likely has a liquid core.
In addition, they managed to find out its composition. It turned out that a significant part of the core is made up of light elements (with low atomic numbers), namely sulphur and oxygen. Scientists assume that these two elements make up a fifth of the nucleus' mass.
This is in sharp contrast to the Earth's core, which has much less light elements.
Thus, it has been established that the Martian core is much less dense and more compressible than the Earth's core.
"The properties of the planet's core can serve as a summary of how the planet was formed and how it has dynamically evolved over time. The uniqueness of the Earth's core allows it to generate a magnetic field that protects us from the solar winds, allowing us to store water. The core of Mars does not generate this shield, and therefore the conditions on the planet's surface are hostile to life," said Nicholas Schmerr, associate professor of geology at UMD, another co-author of the paper.
Both Lekic and Schmerr agree that it is highly likely that Mars' core was not always like this. The traces of magnetism that have been repeatedly detected in the Martian crust may indicate that the red planet's core used to be more similar to the Earth's and generated a protective magnetic field.
Over time, Mars evolved to its current conditions, turning from a planet with a potentially habitable environment to an incredibly hostile one.
Lekic also said that the data indicate that the Martian core contains hydrogen and scientists have yet to figure out how it was formed there.
Further research will allow scientists to better understand how planets form and their further evolution. It is possible that this will give them clues about what will happen to the Earth in the future.
Earlier, OBOZREVATEL also reported that astronomers managed to pick up a strange radio signal from the rocky exoplanet YZ Ceti b, which orbits its star 12 light-years from Earth. Scientists suggest that the signal may indicate the existence of a magnetic field on the planet, which is essential for life.