Since its inception, mankind has always been fascinated with Luna. However, it was not until the time of Galileo when scientists began to ask questions about it and began to study it. Over nearly five centuries, researchers have proposed numerous hotly debated theories about how our satellite came to be; Moreover, the hypotheses on which the Apollo program was built, for example, did not have much to do with the current ones. And we still don’t know for sure what happened at the beginning. Now geochemists, cosmochemists and petrologists at ETH Zurich shed new light on the puzzle, reporting evidence showing that the Moon inherited the indigenous noble gases helium and neon from the Earth’s mantle. The conclusions have just been published in the journal ‘Science Advances’.
During his doctoral research at ETH Zurich, Patrizia Will analyzed six samples of lunar meteorites from an Antarctic collection, obtained from NASA. Meteorites are made of basalt rock that formed when magma erupted from the interior of the Moon and then cooled rapidly. This process gave rise to lunar glass particles, among other minerals, which are found in the magma, something like chemical ‘fingerprints’ (the isotopic signatures) of the solar gases: helium and neon. In addition, its surface was covered with basalt, which protected the rock from cosmic rays and the solar wind.
The authors point out that a high-energy impact was necessary to ‘pluck’ these rocks from the depths of the Moon that ended up reaching Earth in the form of meteorites (many of them are found in the deserts of North Africa or, in this case, in the ‘cold desert’ of the antarcticawhere they are easier to spot in the landscape).
Using a highly sensitive mass spectrometer from the Noble Gas Laboratory at ETH Zurich, the research team was able to measure submillimeter glass particles from the meteorites and rule out the solar wind as the source of the detected gases. And they observed that helium and neon were in much higher abundance than expected.
‘Researching’ inside meteorites
Knowing where to look within NASA’s vast collection of some 70,000 meteorites represents a huge step forward. “I am firmly convinced that there will be a race to study heavy noble gases and isotopes in meteoritic materials,” he says. Henner Busemann from ETH Zurich, one of the world’s leading scientists in the field of extraterrestrial noble gas geochemistry. He anticipates that researchers will soon be looking for noble gases like 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 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 could help scientists in geochemistry and geophysics create new models that show more generally how more volatile elements can survive planet formation, in our solar system and beyond.”