Mars had a magnetosphere much longer than previously thought - what does this mean?

Scientists say that many years ago Mars wasnot at all the way we know it now. The planet contained many rivers and lakes, which we have already talked about many times. The planet's atmosphere retained heat, and the magnetic field reflected cosmic radiation. That is, the conditions were quite favorable for the emergence of life. But everything began to change when the Martian interior cooled and the magnetic field disappeared. Following him, the atmosphere left the red planet, and then the water from the surface of Mars also disappeared. But scientists to this day cannot say exactly when the planet lost its magnetosphere. It would seem, what does it matter now? But in fact, the question is very important, since it depends on it whether life could have originated here at all or there was not enough time for this.

Scientists have found evidence that the magnetic field on Mars has existed for hundreds of millions of years longer than previously thought

The magnetic field of Mars imprinted in the rocks

Is it possible to determine exactly when the planetlost the magnetosphere? The task is quite difficult, but solvable. When iron-bearing minerals crystallize from molten rock, their internal magnetic fields align with the planet's field, resulting in a kind of compass.

When such minerals are subjected to powerful shockloads, and partially melt, they retain the “imprint” of the planet’s magnetosphere of later times. As a result, an ancient “magnetic manuscript” is formed. As a result, scientists can only date the changes that have occurred in the breed in order to decipher this "manuscript".

“They can paint a pretty good picture of what could have happened,” says Jennifer Booz, a paleomagnetist at Northern Arizona University.

It would seem that if everything is so simple, why do scientistsstill can't figure out exactly when Mars lost its magnetic field? The thing is that the data obtained turned out to be very ambiguous. The orbiters have helped map the residual magnetic footprints in the rocks of Mars. However, in the most ancient and largest craters of the planet, left after the fall of the asteroids Hellas, Argyrus and Isis, no magnetized rocks could be found.

Martian rocks contain information about the magnetic field of Mars

This suggests that by the time of the fallasteroids, about 4.1 billion years, Mars no longer had a magnetic field. However, the presence of traces of a magnetic field in the solidified lava, which formed several hundred million years later, contradicts these conclusions. That is, the magnetic field must have existed even millions of years after the formation of the craters. Agree, it is difficult to understand what happened on another planet when the information received contradicts each other.

An asteroid from Mars spoke about the magnetic field

To find out how the magnetic field changedMars over time, scientists decided to carefully study the famous Martian meteorite Allan Hills 84001, which was recovered from Antarctica in 1984. This 2 kg stone is of great interest to scientists because it is 4.1 billion years old. So he was a witness to that critical period for the planet when it was losing its magnetic field. After a strong blow, this stone was torn off from Mars and ended up on Earth.

Allan Hills meteorite 84001 found in Antarctica

For their work, scientists usedstate-of-the-art quantum diamond microscope. The study showed that the planet's magnetic field did persist until 3.9 billion years ago, longer than expected, and existed after the formation of the aforementioned craters.

Did the magnetic field reversal also occur on Mars?

If the magnetic field on Mars existed for another 3.9billion years ago, why weren't traces of it found in ancient craters such as the Hellas Plain? The results of the study suggest that on Mars, as on Earth, the magnetic field sometimes turned upside down. Thanks to the high resolution, the scientists found three types of iron sulfide minerals in the meteorite sample. Two were highly magnetized in different directions, while one did not have a significant magnetic signature.

According to scientists, the stone captured three famousimpact events that, according to radioisotope dating, occurred 4 billion, 3.9 billion, and also 1.1 billion years ago. At the same time, 3.9 billion years ago, the magnetic field was still strong, so its strength was enough to protect life from comic radiation. But the magnetic field of 3.9 billion years ago was directed at an angle of 138° with respect to the magnetic field that was on Mars 4 billion years ago. That is, it is directed almost in the opposite direction.

The rocks in the Hellas Plain were demagnetized

The probability that the stone rotated is extremelysmall. Most likely, the Martian "dynamo" turned its poles over, as it happens on Earth every few hundred million years. This means that layers of alternating magnetic fields could neutralize the magnetic field of the craters. That is, they were, in fact, demagnetized.

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Thus, theoretically, life on Marscould really exist. But according to some scientists, it could also destroy itself, or rather, deprive the red planet of the atmosphere, as we talked about earlier.