Researchers have recreated the expected conditions in the core of Mars billions of years ago and discovered that the activity of the hot metal could generate a short-term magnet set to disappear.
Mars is a barren planet governed by global dust storms, according to Science Alert. It is also an ice world, where winter night temperatures drop to minus 140 degrees Celsius at the poles. But Mars is not always a dry, barren, freezing, harsh world. It used to be a warm, moist place, where liquid water flowed all over the surface, filling lakes, canals and forming islands. Mars then lost its magnet. Without the protection of the magnet, the Sun has stripped the planet's atmosphere. Without atmosphere, water is the next "victim".
The current Mars is the Mars that we have always known: A place where only robots feel the hospitality of the planet. Mars still has a magnet issued from the shell, but it is a weak magnet that has little protection.
The loss of magnetism was a disaster for Mars. How did it happen? A new study published in Nature Communications has answered that question.
The "death" of Mars magnetism
The author of the study, Professor Kei Hirose from the Department of Earth and planets at the University of Tokyo (Japan), said: "The Earth's rotation is driven by the largest unimaginable convection of hot metals in its core. Magnet on other planets is believed to work in the same way. Although the inside composition of Mars is still unknown, evidence from meteorites shows that it is melted iron enriched with sulfur.
In addition, seismic data from NASA's InSight rover on the surface shows us that the core of Mars is larger and less dense than previously thought. These indicate the presence of lighter elements such as hydrogen. With this detail, we prepared the iron alloys that we expected to form the core and put them into the experiment."
According to the website of the University of Tokyo, the experiment involved diamonds, laser rays and a very surprising thing. Scientists have created a sample containing iron, sulfur and hydrogen (Fe-S-H) - something they expect to have formed the Martian core. They placed the sample between two diamonds and compressed it while heating it with infrared laser, to simulate the temperature and estimated pressure at the core.
Observing samples with X-rays and electronic beams allowed the research team to visualize what was happening during the pressure melting process and even map how the sample's composition had changed during that time.
"We were surprised to see that a specific behavior could explain a lot. The unified Fe-S-H initially separated into two separate fluids with unprecedented complexity under these pressures. One is the sulfur-rich iron liquid, the other is the hydrogen-rich liquid, and this is the key to explaining the origin and ultimately the death of Mars- surrounding magnetism," said Professor Kei Hirose.
Loose iron rich in hydrogen and poor in sulfur, with lower density, will float on loose iron rich in sulfur, poor in hydrogen, thicker, causing convection flows. These electric fields, similar to those on Earth, will create a magnet that can maintain hydrogen in the atmosphere around Mars, thereby allowing water to exist in liquid form.
However, it did not last long. Unlike the inner convection lines of the Earth that are extremely long, once two Liquid are completely separated, there will be no more lines to create a magnet. And when that happens, the hydrogen in the atmosphere is blown out of the universe by the solar wind, leading to the breakdown of water vapor and eventually the evaporation of the oceans on Mars. All of this happened about 4 billion years ago.
