Data on the chemical and isotopic composition of Mars indicate that it was not born in the company of Earth, Mercury and Venus, but on the site of the modern main asteroid belt, astronomers say in an article published in the journal Earth and Planetary Science Letters.
“We tried to understand how Mars could be born in that part of the protoplanetary disk, whose matter the Earth did not have time to“eat”during its birth. We concluded that this was not possible, and that Mars should have formed at a great distance from the Sun, in the inner part of the asteroid belt. Subsequently, Mars migrated to its current orbit, wasting energy by ejecting its old 'neighbors' towards Jupiter,”says Ramon Brasser of the Tokyo Institute of Technology (Japan).
Secrets of the fourth planet
Scientists today believe that 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 matter went to the formation of the star - the Sun, and from the rest of the matter that did not fall into the center, a rotating protoplanetary disk was formed, from which the planets, their satellites, asteroids and other small bodies of the solar system later arose.
Previously, it was believed that all planets formed in approximately the same orbits where they are now. Astronomers today believe that Jupiter and other giant planets were "sculptors" whose migrations towards the Sun and the outskirts of the Solar System orchestrated the formation of the "embryos" of the Earth and other rocky planets and their interactions with each other.
Brasseur and his colleagues suggest that another space "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 form at such a close distance from the Earth, in fact, in the first days of the existence of the solar system. The matter of the protoplanetary disk, according to planetary scientists today, simply should not have been enough to provide both the Earth and Mars with all the necessary "building materials".
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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 interior of our planet or its satellite.
Son of the Sun
After analyzing these chemical differences, Brasseur's team tried to find the source of the matter from which Mars was "molded", if it was born not in the inner part of the protoplanetary disk, together with the Earth and its "neighbors", but in some other place. It, as the first data on the proportions of silicon-30, vanadium-51 and other rare isotopes showed, was in the colder and more distant part of the solar system.
Using this data, astronomers 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 born not in its current orbit, but where the mythical planet Phaethon was supposed to exist.
It, as astronomers of the 18th and 19th centuries believed, existed between the modern orbits of Mars and Jupiter and was destroyed in the distant past, turning into the modern main asteroid belt. In fact, according to Brasseur and his colleagues, she escaped from there.
Mars, as these calculations show, did indeed form quite early - about 10 million years ago, and left the asteroid belt about 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 caused the red planet to lose energy, which it wasted on "catapulting" its smaller counterparts outside the solar system.
The scientist hopes that it will be possible to check this idea after the appearance of new data on the chemical composition of the most ancient rocks of Mars, as well as 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.
