The hypothesis is far from unanimous. “In our simulations, Theia’s mantle and Earth’s mantle mixed fairly well,” attests a planetary scientist. Miki Nakajima From the University of Rochester in New York. In recent years, his work has focused on the evolution of the internal structure of rocky planets in our solar system.
“I don’t think the impact material would have been completely mixed, but the degree of homogeneity was underestimated in this study,” the geodynamicist adds. Maxim Palmer From University College London. Without being linked to the study recently published in the journal naturePalmer collaborated with Deng on a Related study From a few years.
Scientists realize that these areas of high density have long occupied the Earth’s mantle, but their exact age and origin are still a matter of debate.
“There is an alternative explanation for the formation of these giant columns,” Palmer adds. He particularly mentions A The theory under which The solid mantle we know today was a thick layer of molten magma, before it differentiated to form today’s layers. The top layer quickly solidified, sending its heat into space. The bottom layer hardened more slowly and thus had time to form more or less dense areas, according to some studies.
The next step will be to compare the chemical signatures of the materials in these massive plumes and on the Moon, which is largely composed of Theia. “If they have the same geochemical signature, they must come from the same planet,” Yuan says.
However, taking new samples is easier said than done. It is impossible to dig the earth into giant pillars. However, as Yuan shows us, rocks from the lower mantle sometimes find their way to the surface, and this is particularly the case with basalt from oceanic islands.
The moon’s surface has been exposed to space erosion for billions of years and is at risk of contamination by meteorites; Therefore, the researchers want to analyze samples from the lunar mantle as well. The ones they have so far come mainly from the surface.
To obtain new parts of the Moon, we will have to wait for a future sample return mission to the South Pole, where the mantle is more exposed and accessible. Until then, scientists will continue to improve their models to try to identify Theia’s spectrum.