The red planet, one of the most studied bodies in the Solar System, door to door in our cosmic neighborhood, may not always have been our neighbor.
A study published in the journal Earth and Planetary Science Letters posits that Mars actually formed in the Asteroid Belt, about one and a half times farther from the Sun than its current position, before migrating to this location.
About four thousand five hundred million years ago, the Solar System was nothing more than a cloud of dust, and later, rocks, until the fragments were forming the different planets that today make it up. First, the sodas; today we know that Jupiter is the oldest body in the Solar System. And, later, the rocky ones, like Earth and Mars.
The composition of Mars, more similar to that of meteorites
The general belief was that Mars formed near Earth from the very early fragments of the Solar System. But this hypothesis left unanswered questions: why are both planets so different in composition? Mars contains different silicates, lighter than Earth, more similar to those found in meteorites.
Now this question has a possible answer. In an attempt to explain why the elements and isotopes on Mars differ widely from those on Earth, researchers from Japan, the United States, and the United Kingdom conducted simulations to obtain information about the motion of the red planet within the Solar System.
The findings suggest that Mars formed much further from the Sun than it is now and that Jupiter’s gravitational pull pushed Mars to its current position.
The Grand Tack model
The researchers used the so-called Grand Tack model, which suggests that Jupiter played an important role in the formation and final orbital architecture of the inner planets.
The hypothesis holds that an early Jupiter, due to its gravitational force, sent a large concentration of mass toward the Sun, which contributed to the formation of Earth and Venus. Meanwhile, it was pushing material away from Mars, hence the small mass of the planet (it is 11% that of Earth) and the difference between the compositions of the two planets.
One implication that Mars is forming farther from the Sun would have is that the planet was much colder at birth than originally thought , perhaps too cold for liquid water or to sustain life.
This theory seems to challenge the idea that Mars was much warmer and more humid than it is now. Researchers believe, however, that activity on the planet Mars could have occurred later.
According to Stephen Mojzsis, Professor of Geological Sciences at the University of Colorado and co-author of the study: “The formation of Mars in the asteroid belt occurred very early , long before the crust stabilized and the atmosphere established.”
In a paper he co-authored last year, Mojzsis concludes that, at the end of the planetary formation of Mars, it was bombarded by asteroids that formed the myriad craters on the planet. Such large impacts could “have melted the cryosphere and the crust of Mars to densify the atmosphere of Mars and restart the hydrological cycle,” he details.
References: The cool and distant formation of Mars. Mojzsis, Matsumurad. Earth and Planetary Science Letters. (2017) doi.org/10.1016/j.epsl.2017.04.005
Image: NASA
