According to a study published Monday in the scientific journal Nature Astronomy, the analysis of the composition of samples of matter brought back from the asteroid Ryugu by a Japanese space mission accredits the theory of an extraterrestrial origin of water.
Thus, C-type asteroids like Ryugu, "rich in volatile substances (able to pass easily from the solid state to the gaseous state) and organic (or carbonaceous) substances, could have been one of the main sources of the water on Earth", according to this study which involved Japanese and foreign researchers.
"The contribution to the Earth of volatile substances, that is to say organic matter and water, is still the subject of an important debate", explains the study, which nevertheless recalls that organic substances identified on Ryugu "probably represent an important source of volatile substances", in addition to other potential sources such as solar winds.
The particles reported from Ryugu "are undoubtedly among the least contaminated solar system materials available for laboratory study."
An asteroid located 300 million kilometers away
"Ongoing research on these precious samples will certainly expand our understanding of early processes in the solar system," they said.
Discovered in 1999, Ryugu (“Dragon Palace” in Japanese) is located more than 300 million kilometers from our planet and is less than 900 meters in diameter.
According to many scientists, some of the material from this asteroid was created about five million years after the birth of our solar system and was not heated above 100 degrees Celsius.
In 2019, the Japanese probe Hayabusa-2 managed to collect 5.4 grams of rock and black dust from Ryugu, and a capsule containing this exceptional cargo returned to Earth at the end of 2020, with the promise of provide new clues about the origin of life on Earth.
In June, another Japanese scientific study had revealed the presence in these samples of amino acids, molecules at the base of life because capable of forming proteins by combining with each other.