The Red Planet may have formed in the Asteroid Belt before finally settling into its home next to Earth.
According to a new study, Mars may have originated approximately 1.5 times further from the Sun as its current position, which would help explain the vastly different compositions between Earth and Mars.
Researchers from Japan, the U.S. and the U.K. ran simulations to gain insights into Mars movement within the solar system.
The researchers paid particular attention to simulations consistent with the so-called Grand Tack model, which suggests that Jupiter played a major role in the formation and final orbital architecture of the inner planets.
The researchers theorized that when Jupiter was first established, a large concentration of mass was plowed towards the Sun, which contributed to the formation of Earth and Venus, while simultaneously pushing material away from Mars.
This theory accounts for the planet’s relatively small mass—roughly about 11 percent of the mass of Earth—and the difference between the two planets’ compositions.
In Grand Tack simulations, the researchers gleaned additional insight into Mars’ formation, where a small percentage of the simulations suggested that Mars formed much farther from the sun than it is now and that Jupiter’s gravitational pull pushed Mars into its current position.
“Low probability means one of two things: that we don’t have a better physical mechanism to explain Mars’ formation or in the enormous panoply of possibilities we ended up with one that is relatively rare,” University of Colorado Geological Sciences professor Stephen Mojzsis, a co-author of the study, said in a statement.
Researchers generally believe that Mars was formed near Earth from the same building blocks. However, it has not been explained why the two planets are so different in composition if they were formed from the same building blocks. Mars contains different, lighter, silicates than Earth, more akin to those found in meteorites.
A implication of Mars forming farther away from the sun is that the planet would have been colder than originally thought—likely too cold for liquid water or sustainable life—challenging the long standing theory that Mars was once far warmer and wetter than it is now.
“Mars’ formation in the Asteroid Belt took place very early in Mars’ history, well before the crust stabilized and the atmosphere was established,” Mojzsis said.
In a paper he co-authored last year, Mojzsis concludes that late in Mars’ planetary formation it was bombarded by asteroids that formed the planet’s countless craters. Such large impacts could “melt the cryosphere and Mars’ crust to densify Mars’ atmosphere and to restart the hydrologic cycle.”
