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Japanese and Taiwanese scientists have for the first time discovered the ability of helium, a normally inert gas, to form compounds with iron under ultra-high pressure, which could radically change our understanding of the composition of the Earth's core and the history of planet formation.
Destruction of chemical dogmas
Helium was traditionally considered a chemically inert gas. New research shows that under extreme pressure, helium can form compounds with iron, containing up to 3,3% helium, which is 5000 times higher than previous measurements.
The researchers used a laser-heated diamond anvil cell to create ultrahigh-pressure conditions. They subjected a mixture of iron and helium to pressures ranging from 5 to 55 gigapascals (50 to 000 times atmospheric pressure) at temperatures ranging from 550 to nearly 000 Kelvin.
Professor Kei Hirose from the University of Tokyo explains the innovative approach:
Rethinking Earth's history
The discovery of iron-helium compounds has far-reaching implications for understanding the origin and evolution of our planet. The presence of helium in the Earth's core indicates that the young Earth may have captured significant amounts of gas from the solar nebula surrounding the early Solar System.
The discovery could also help explain the origin of primordial helium, which is found in volcanic rocks, especially in Hawaii. Unlike regular helium, which contains two protons and two neutrons and is constantly produced by radioactive decay, primordial helium contains two protons and only one neutron and is not produced on Earth.
High ratios of primordial to ordinary helium in volcanic rocks have long led scientists to believe that primordial materials made of primordial helium exist deep in the Earth's mantle. A new study offers an alternative explanation for this phenomenon.
Prospects for planetary science
The discovery could also reimagine the origin of water on our planet. If Earth captured significant amounts of gases from the solar nebula, some of the hydrogen from this ancient gas could have contributed to the formation of Earth's water.
The study, published in the journal Physical Review Letters, opens new perspectives for understanding not only the internal structure of the Earth, but also the processes of formation of other planets in our Solar System and beyond.
The experiment, carried out by graduate student Haruki Takezawa and Professor Hirose's team, demonstrates how new methods for studying extreme conditions can lead to a rethinking of fundamental aspects of geology and planetary science.
