The volatile substances of the meteorites contributed to the formation of the Earth's protective atmosphere in its beginnings. And, thanks to new measurements, It is estimated that about 60 percent of the water on Earth today comes from this source.
This created the conditions for life on Earth to develop in its current form, according to this new study carried out by the University of Tübingen, in which the isotopes of selenium in rocks derived from the Earth's mantle have been measured.
In several places, the research team took samples of mantle rocks, which have been brought to the surface by plate tectonic processes and have not changed with respect to their composition of selenium isotopes since the formation of the Earth. The researchers determined the isotopic signature of selenium in these rocks. Isotopes are atoms of the same chemical element with different weights.
The selenium found in the Earth's mantle today must have been added after the formation of the Earth's core, so that it has to come from space. Geologically speaking, at the last moment of Earth's formation, after our moon also formed, between 4,500 and 3,900 million years ago, as explained by María Isabel Varas-Reus, co-author of the study and member of the Isotopos Geochemistry Group in Tübingen:
It has long been possible to measure selenium isotopes in high concentrations, for example, in river samples. However, the concentration of selenium in high temperature rocks is very low. The samples must dissolve at high temperatures and selenium is volatile. This makes measurements difficult. "But recently it became possible to measure selenium isotopes in high temperature rocks.
This finding is not so shocking considering that, every day, lEarth receives about 100 tons of extraterrestrial matter in the form of dust grains. 99% of these grains have an approximate size of between 0.05 and 0.5 millimeters.