How life arose uniquely in our solar system on Earth depends critically on our understanding of the history of water in the solar system. Despite several studies, understanding the origin of water on planetary bodies remains unknown.
Scientists from the CNRS, Paris-Saclay University, the French Alternative Energies and Atomic Energy Commission (CEA), and the University of Pau and the Pays de l’Adour (UPPA), with support from the Muséum National d’Histoire Naturelle (MNHN), have followed the trail of the isotopic composition of water back to the start of the solar system. They especially tracked the inner regions where Earth and the other terrestrial planets were formed.
They used a newly developed method to analyze one of the oldest meteorites of our solar system. Their data show the existence of two gas reservoirs during the first 200,000 years of our solar system, even before forming the earliest planetary embryos. One of these reservoirs consisted of the solar gas in which all the matter of our solar system originated.
Scientists also measured the meteorite record directly for the first time. They found that the second gas reservoir was enriched in water vapor and already had the isotopic signature of terrestrial water. It was created by a massive influx of interstellar water in the hot internal regions of the solar system upon the collapse of the interstellar envelope and the formation of the protoplanetary disc.
The early presence of this gas with Earth-like isotopic composition infers that Earth’s water was there before the accretion of the first constituent blocks of our planet.
- Aléon, J., Lévy, D., Aléon-Toppani, A. et al. Determination of the initial hydrogen isotopic composition of the solar system. Nat Astron (2022). DOI: 10.1038/s41550-021-01595-7