Les scientifiques sont à un pas de découvrir l’origine de la lune

Preuve supplémentaire de l’origine de la Lune.

La lune a toujours été un sujet d’intérêt humain. Mais ce n’est qu’à l’époque de Galilée que les chercheurs ont commencé à l’étudier sérieusement. Au cours de près de cinq cents ans, les chercheurs ont proposé une variété d’idées très controversées sur la formation de la Lune. Géochimistes, cosmologistes et scientifiques du pétrole de ETH Zurich Il a maintenant jeté un nouvel éclairage sur l’histoire de l’origine de la lune.

Les conclusions de l’équipe de recherche, qui ont été récemment publiées dans la revue progrès scientifique, prouve que la Lune a obtenu les gaz nobles originaux hélium et néon du manteau terrestre. Cette découverte renforce les limites déjà strictes de la théorie largement acceptée de « l’impact géant », qui stipule que la Terre et un autre corps céleste sont violemment entrés en collision pour former la Lune.

Section mince de l’échantillon de la NASA, LAP 02436, Lunar Mare Basalt contenant des gaz nobles d’origine. Type d’image : microscopie optique, lumière polarisée. Crédit : ETH Zurich/Patrizia Will

Météorites de la Lune à l’Antarctique

Patrizia a examiné six échantillons de météorites lunaires du groupe antarctique[{ » attribute= » »>NASA provided for her doctoral work at ETH Zurich. The meteorites are made of basalt rock, which was created when magma welled up from the Moon’s interior and quickly cooled. After they formed, additional layers of basalt proceeded to cover them, shielding the rock from cosmic rays and, in particular, the solar wind. The cooling process resulted in the creation of lunar glass particles amongst the other minerals found in magma.

Will and the team found that the glass particles still had helium and neon chemical fingerprints (isotopic signatures) from the Moon’s interior. Their results provide compelling evidence that the Moon inherited the gases indigenous to the Earth. “Finding solar gases, for the first time, in basaltic materials from the Moon that are unrelated to any exposure on the lunar surface was such an exciting result,” says Will.

Thin section of the Lunar Mare Basalt containing the indigenous noble gases (sample LAP 02436). This picture was taken by applying plane and cross-polarized light. Credit: ETH Zurich / Patrizia Will

Without the protection of an atmosphere, asteroids constantly pelted the Moon’s surface. It likely took a high-energy impact to eject the meteorites from the middle layers of the lava flow similar to the vast plains known as the Lunar Mare. Eventually, the rock fragments made their way to Earth in the form of meteorites. Many of these meteorite samples were picked up in the deserts of North Africa or in, in this case, the “cold desert” of Antarctica where they are easier to spot in the landscape.

Grateful Dead lyrics inspire lab instrument

In the Noble Gas Laboratory at ETH Zurich resides a state-of-the-art noble gas mass spectrometer named, “Tom Dooley” – sung about in the Grateful Dead tune by the same name. The instrument got its name, when previous researchers, at one point, suspended the highly sensitive equipment from the ceiling of the lab to avoid interference from the vibrations of everyday life.

Using the Tom Dooley instrument, the research team was able to measure sub-millimeter glass particles from the meteorites and rule out solar wind as the source of the detected gases. The helium and neon that they detected were in a much higher abundance than expected.

The Tom Dooley is so sensitive that it is, in fact, the only instrument on Earth capable of detecting such minimal concentrations of helium and neon. It was used to detect these noble gases in the 7 billion years old grains in the Murchison meteorite – the oldest known solid matter to date.

Searching for the origins of life

Knowing where to look inside NASA’s vast collection of some 70,000 approved meteorites represents a major step forward. “I am strongly convinced that there will be a race to study heavy noble gases and isotopes in meteoritic materials,” states ETH Zurich Professor Henner Busemann, one of the world’s leading scientists in the field of extra-terrestrial noble gas geochemistry. He anticipates that soon researchers will be looking for noble gases such as xenon and krypton which are more challenging to identify. They will also be searching for other volatile elements such as hydrogen or halogens in the lunar meteorites.

Busemann comments, “While such gases are not necessary for life, it would be interesting to know how some of these noble gases survived the brutal and violent formation of the moon. Such knowledge might help scientists in geochemistry and geophysics to create new models that show more generally how such most volatile elements can survive planet formation, in our solar system and beyond.”

Reference: “Indigenous noble gases in the Moon’s interior” by Patrizia Will, Henner Busemann, My E. I. Riebe and Colin Maden, 10 August 2022, Science Advances. 
DOI: 10.1126/sciadv.abl4920