Mars was born in the asteroid belt

The data on the chemical and isotope composition of Mars indicate that he was not born in the company of the Earth, Mercury and Venus, but in place of the modern main asteroid belt, astronomers state in an article published in the journal Earth and Planetary Science Letters.

“We were trying to understand how Mars could have been born in the part of the protoplanetary disc whose matter had not been eaten by the Earth at the time of its birth.We came to the conclusion that it was impossible and that Mars had to be formed at a great distance from the Sun, In the interior of the asteroid belt, Mars subsequently migrated to its current orbit, losing energy to throw out its old “neighbors” in the direction of Jupiter, “says Ramon Brasser of the Tokyo Institute of Technology, Japan.

Secrets of the fourth planet

As scientists believe today, the solar system began to form about 4.6 billion years ago as a result of the gravitational collapse of a giant interstellar molecular cloud. Most of the substance went to the formation of the star – the Sun, and from the rest of the matter, not getting into the center, a rotating protoplanetary disk formed, from which subsequently the planets, their satellites, asteroids and other small bodies of the Solar system arose.

Previously it was believed that all the planets were formed approximately in the orbits where they are now. Today, astronomers believe that Jupiter and other giant planets were “sculptors” whose migrations toward the Sun and toward the margins of the Solar System were conducted by the formation of “embryos” of the Earth and other stony planets and their interaction with each other.

Brasser and his colleagues suggest that another cosmic “migrant” could be Mars, whose existence has long been a mystery to astronomers.

The fact is that the mass of Mars is too large for it to be formed at such close distance from the Earth actually in the first days of the existence of the solar system. Matter of the protoplanetary disk, as planetologists now believe, simply did not have to be enough to provide both the Earth and Mars with all the necessary “building materials.”

An additional problem is that Mars is not similar to Venus, Earth and the Moon in its isotopic composition – its matter is much more similar to the primary material of the solar system than the bowels of our planet or its satellite.

Son of the Sun

Analyzing these chemical differences, the Brasser team tried to find the source of matter from which Mars was “molded” if it was not born in the inner part of the protoplanetary disk, together with the Earth and its “neighbors”, but in some other place. He, as shown by the first data on the proportions of silicon-30, vanadium-51 and other rare isotopes, was in the colder and far part of the solar system.

Using this data, astronomers have tried to determine the position of the “newborn” Mars on the map of the solar system, using a computer model of its evolution. As these calculations showed, the red planet was not born on its current orbit, but where the mythical planet Phaethon supposedly was supposed to exist.

It was believed by astronomers of the 18th and 19th centuries to exist between the modern orbits of Mars and Jupiter and was destroyed in the distant past, turning into a modern main belt of asteroids. In fact, according to Brasser and his colleagues, she escaped from there.

Mars, as these calculations show, really formed early enough – about 10 million years ago, and left the asteroid belt approximately 120 million years after the birth of the Sun. The reason for this was the gravitational interactions between Mars, large protoplanetary bodies in the asteroid belt and Jupiter. They forced the red planet to lose the energy that it was spending on “bailing out” its smaller brethren outside the solar system.

To check this idea, as the scientist hopes, it will be possible after the appearance of new data on the chemical composition of the ancient rocks of Mars, and also with the help of more detailed models of the solar system, in which the distribution of different types of primary matter – enstatite and ordinary chondrites – would be completely different.