The early Earth was bombarded by material that sank to its core or was splashed, requiring the planet to receive more impacts to deposit some of the elements present in his mantle.
Credit: Southwest Research Institute
The earth may have been bruised by the impact of more than one object the size of the moon at the beginning of its life.
New simulations suggest that much of the material that crashed on our young planet may have been absorbed by the Earth's core or bounced off space, which required more collisions to leave the elementary signatures scientists see today in the cortex.
the young solar system was a violent place. Planetesimals, massive objects that failed to grow on planets, ended up destroying themselves by crashing into other objects during a period known as late accretion. These collisions left traces of highly siderophile elements, metals have an affinity for iron, such as gold, platinum and iridium, within the mantle of our planet. [How the Moon Formed: 5 Wild Theories]
By measuring how much of these metals were mixed with the mantle, scientists estimated that about half of the percent of Earth's present mass came from colliding planetasimals. But these estimates assumed that the mantle clung to all highly siderophile elements.
New simulations suggest that, on the other hand, part of the material could have been transported to the nucleus, where it would have been mixed or expelled from the system altogether. Both results would have reduced the amount of metals that would have mixed in the mantle. That means that Earth could have absorbed two to five times more impacts than previously thought.
"We modeled massive collisions and how metals and silicates were integrated into the Earth during this 'late accretion phase', which lasted hundreds of millions of years after The formation of the Moon, "Simone Marchi, a researcher at the Southwest Research Institute (SwRI) in Colorado and lead author of a Nature Geoscience document that describes these results, said in a statement. Marchi worked with Robin Canup, also at SwRI, and Richard Walker, a geologist at the University of Maryland.
"According to our simulations, the late accretion mass delivered to Earth may be significantly greater than previously thought, with important consequences for the earliest evolution of our planet," Marchi said.