Earth’s water existed before planet Earth

To understand how life came about, scientists study the chemistry of carbon and water. In the case of water, they track the various forms, or isotopes, of its constituent hydrogen and oxygen atoms through the history of the universe, like a giant treasure hunt.

Researchers from the CNRS, the University of Paris-Saclay, the Commissariat for Atomic Energy and Alternative Energies (CEA) and the University of Pau and Pays de l’Adour (UPPA), with the support of the Muséum National d’Histoire Naturelle (MNHN), followed the trace of the isotopic composition of water until the beginning of the solar system, in the interior regions where the Earth and the other telluric planets were formed. They did this by analyzing one of the oldest meteorites in our solar system, using an innovative method developed specifically for their study.

Their data show that two reservoirs of gas existed during the first 200,000 years of our solar system, even before the formation of the first planetary embryos. One of these reservoirs was the solar gas from which all the matter in our solar system originated.

With the meteorite, scientists were able to measure its recording directly for the first time. The second gas reservoir was enriched with water vapor and already possessed the isotopic signature of terrestrial water. It was created by a massive influx of interstellar water into the hot inner regions of the solar system, during the collapse of the interstellar envelope and the formation of the protoplanetary disk.

The early existence of this gas with an isotopic composition similar to that of Earth implies that the water of the Earth was there before the accretion of the first building blocks of our planet. These findings are published in natural astronomy.

Reference: “Determination of the initial isotopic composition of hydrogen in the solar system” by J. Aléon, D. Lévy, A. Aléon-Toppani, H. Bureau, H. Khodja and F. Brisset, February 3, 2022, natural astronomy.
DOI: 10.1038/s41550-021-01595-7

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