The first piece of irrefutable evidence suggesting that the Moon inherited the local noble gases helium and neon from the Earth’s mantle has been discovered by scientists.
The discovery, adds to the already substantial limitations of the currently popular “giant impact” theory. This theory proposes that the Moon formed as a result of a massive collision between the Earth and another celestial body. However, the newly discovered evidence contradicts this hypothesis. It is also an important piece of the puzzle for understanding how the Moon formed, as well as possibly understanding how the Earth and other celestial bodies formed.
For the purpose of the study, the group from ETH Zurich analyzed six samples of lunar meteorites taken from a collection in Antarctica that NASA had sent them. The basalt rock that makes up meteorites was created when magma erupted from the interior of the moon and quickly cooled. This process resulted in the formation of meteorites.
After their formation, they remained covered with additional layers of basalt, which served to shield the rock from the harmful effects of cosmic rays and, in particular, the solar wind. In addition to the formation of other minerals present in the magma, the process of cooling led to the formation of particles of lunar glass.
The research group came to the conclusion that the glass particles retain the chemical fingerprints, also known as isotope signatures, of the solar gases, helium and neon, which come from the interior of the Moon. Their findings provide conclusive evidence that the Moon has acquired some of the noble gases that are characteristic of Earth. According to Patricia Will of ETH Zurich, “Finding solar gases for the first time in lunar basalt materials that are not associated with any impact on the lunar surface was such an exciting result.”
Because the Moon does not have an atmosphere to protect it, the surface of the Moon is constantly being bombarded by asteroids. It is likely that an impact with a high amount of energy was required in order to eject meteorites from the middle layers of the lava flow, such as the expansive plains that are known as the Moonmare.
In the end, pieces of rock fell to Earth as meteorites and landed on their respective locations. Many of these meteorite specimens have been discovered in the deserts of North Africa or, in this case, the “cold desert” of Antarctica, where they are easier to spot in the landscape due to their stark contrast with the surrounding terrain.
A significant advance has been made in the form of the realization that knowing where to look within NASA’s vast collection of approximately 70,000 approved meteorites. According to Henner Busemann, a professor at ETH Zurich, “I have no doubt that there will be a competition to investigate the heavy noble gases and isotopes in meteoritic materials.”
He anticipates that scientists will soon begin searching for noble gases like xenon and krypton, which are more difficult to recognize. In lunar meteorites, they will also search for other volatile elements, like hydrogen and halogens, among other things.
It would be interesting to know how some of these noble gases survived the violent and turbulent formation of the Moon, despite the fact that such gases are not required for life. According to Busemann, having such knowledge could assist geochemists and geophysicists in the creation of new models that more generally show how even the most volatile elements can survive the formation of planets in our solar system and beyond.