London: Scientists have discovered the first definitive evidence that the Moon inherited the indigenous noble gases of helium and neon from Earth’s mantle.
The discovery, published in the journal Science Advances, adds to already strong constraints on the currently favored “giant impact” theory that hypothesizes that the Moon was formed by a massive collision between Earth and another celestial body.
It also represents an important piece of the puzzle toward understanding how the Moon and, potentially, Earth and other celestial bodies formed.
For the study, team ETH Zurich analyzed six samples of lunar meteorites from the Antarctic Collection obtained from NASA. Meteorites consist of basalt rock that forms when magma rises above the Moon’s interior and cools quickly.
They remained covered with additional basalt layers after their formation, which protected the rock from cosmic rays and especially the solar wind. The cooling process resulted in the formation of lunar glass particles, among other minerals found in magma.
The team found that the glass particles retain the chemical fingerprints (isotopic signatures) of solar gases: helium and neon from the Moon’s interior. Their findings strongly support that the Moon may have inherited gases indigenous to Earth.
“The detection of solar gases for the first time in basaltic materials from the Moon, which are not related to any exposure to the lunar surface, was such an exciting result,” said Patrizia Will from ETH Zurich.
Without the protection of the atmosphere, asteroids continue to collide with the surface of the Moon. The high-energy impact probably took the meteorites out of the middle layers of the lava flow, similar to the vast plains known as the Lunar Mare.
Eventually the rock fragments came to Earth in the form of meteorites. Many of these meteorite samples have been raised in the deserts of North Africa or, in this case, the “cold deserts” of Antarctica, where they are easy to spot in the landscape.
Knowing where to look inside NASA’s vast collection of 70,000 approved meteorites represents a big step forward.
“I am strongly convinced that there will be a race to study the heavy noble gases and isotopes in meteorite material,” said Professor Heiner Bussmann from ETH Zurich.
He predicts that soon researchers will be looking for noble gases such as xenon and krypton, which are more challenging to detect. They will also search for other volatile elements such as hydrogen or halogens in lunar meteorites.
“While such gases are not essential to life, it will be interesting to learn how some of these noble gases survived the brutal and violent formation of the Moon. Such knowledge could help scientists in geochemistry and geophysics build new models.” that usually show how the most volatile elements of this kind can survive planet formation in our solar system and beyond,” Bussmann said.