Researchers from ETH Zurich discover first real proof that Moon inherits native noble gases from the Earth’s mantle. This discovery represents an important piece of the puzzle towards understanding how the Moon and, potentially, the Earth and other celestial bodies were formed.
Thin section of Lunar Mare basalt containing native noble gases (sample LAP 02436). Image type: optical microscope, cross-polarized light. Image credit: ETH Zurich / Patrizia Will
Mankind has maintained a long-standing fascination with the Moon. However, it was not until Galileo’s time that scientists really began to study it. Over the course of nearly five centuries, researchers have come up with many controversial theories about how the Moon was formed. Geochemists, space chemists, and petrochemicals at ETH Zurich shed some light on the Moon’s origin story.
In a study just published in the journal Science Advances, the team reports findings that the Moon inherits native noble gases helium and neon from the Earth’s mantle. This discovery adds already strong limitations to the now-popular “Giant Impact” theory, which suggests that the Moon was formed by a massive collision between the Earth and an asteroid. other body.
The thin portion of the NASA sample, LAP 02436, Lunar basalt contains native noble gases. Image type: optical microscope, cross-polarized light. (Image credit: ETH Zurich / Patrizia Will)
Meteors from the Moon to Antarctica
During her doctoral research at ETH Zurich, Patrizia Will analyzed six samples of lunar meteorites from a collection in Antarctica, obtained by NASA. Meteorites consist of basalt that was formed when magma rose from the Moon’s interior and cooled rapidly. They are still covered by additional layers of basalt after formation, which protect the rock from cosmic rays and especially the solar wind.
The cooling process leads to the formation of moon glass beads among other minerals found in magma. Will and his team discovered that glass beads hold chemical fingerprints (isotope symbols) of the solar gases: helium and neon from the Moon’s interior. Their findings strongly support that the Moon inherited noble gases originating from the Earth. “Finding solar gas for the first time in basaltic materials from the Moon that is not associated with any contact on the lunar surface is an exciting result,” said Will.
Without the protection of the atmosphere, asteroids continuously peck at the surface of the Moon. It likely took a high-energy impact to push the meteors out of the middle layers of lava flows similar to the vast plain known as the Moon. 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 this case the “cold deserts” of Antarctica, where they are easier to spot in the landscape.
Grateful Dead lyrics inspire lab instruments
In the Noble Gas Laboratory at ETH Zurich, there is a modern noble gas mass spectrometer called, “Tom Dooley” – sung to the Grateful Dead tune of the same name. The instrument is so named, when previous researchers, at one point, hung the highly sensitive device from the lab ceiling to avoid interference by the vibrations of everyday life.
Using the Tom Dooley instrument, the team was able to measure glass particles smaller than millimeters from meteorites and rule out the solar wind as the source of the detected gases. The helium and neon they detected were much more abundant than expected.
Tom Dooley is so sensitive that it is in fact the only device in the world capable of detecting such minimum concentrations of helium and neon. It was used to detect these noble gases in 7-billion-year-old particles in the Murchison meteorite – the oldest known solid to date.
Searching for the origin of life
Knowing where to look within NASA’s vast collection of some 70,000 approved meteorites is an important step forward. Professor Henner Busemann of ETH Zurich, one of the world’s leading scientists in the field of extraterrestrial noble gas geochemistry, said: “I am convinced that there will be a race to study noble gases and heavy isotopes in meteorite materials. He predicts that soon researchers will be looking for noble gases such as xenon and krypton, which are more difficult to identify. They will also look for other volatile elements such as hydrogen or halogens in lunar meteorites.
Busemann commented: “Although such gases are not essential for life, it will be interesting to see how some of these noble gases survived the brutal and violent formation of the moon. Such knowledge could help geochemists and geophysicists create new models that show more holistically how such volatile elements can persist during formation. planet, in our solar system and beyond. “
Source: ETH Zurich
