Helium-3: An Enigmatic and Scarce Isotope with Astonishing Potential
Helium-3 is no ordinary isotope. This peculiar gas, predominantly formed during the Big Bang, stands out as the only stable isotope, apart from protium, that boasts more protons than neutrons in its atomic composition.
Not only does Helium-3 captivate scientific curiosity, thanks to its promise in fusion reactors, but it has also emerged as a highly sought-after resource. Surprisingly, we know of an abundant reservoir. Our very own Moon, lacking a protective magnetic field, has been incessantly bombarded by Helium-3 carried by the solar wind, prompting proposals for lunar mining (reminiscent of the captivating film Moon). However, Earth itself houses a substantial supply of Helium-3, hidden beneath its surface.
During the early formation of our planet, Helium-3 from the Sun’s solar nebula infiltrated the Earth’s core, an unproductive location considering our limited exploration of the mantle. However, on rare occasions, minute quantities – approximately 2,000 grams (4.4 pounds) per year – manage to escape to the surface, where they await discovery.
Recent findings shed light on lava rocks on the ocean floor as an unexpected hiding place for Helium-3. Nonetheless, the geological process responsible for transporting this isotope from the core to these volcanic rocks remained a perplexing enigma. A new team of researchers may hold the answer, unraveled through the examination of ancient lava flows from Baffin Island in Canada’s Arctic Archipelago, which boast the highest helium-3 to helium-4 ratios ever recorded.
A groundbreaking study, conducted by a team from Princeton University and the Guangzhou Institute of Geochemistry, revealed that the isotope infiltrates magnesium oxide at the critical boundary between the Earth’s core and mantle, thus facilitating its transfer into the mantle. Prior research indicated that when helium-3 encounters magnesium oxide, it undergoes “exsolution,” transforming from a homogeneous mineral into one with distinct crystalline phases. It appears that “magnesium oxide at core-mantle boundary conditions exhibits an exceptional affinity for helium.”
The team’s exploration of Baffin Island, with its extraordinary helium-3 to helium-4 ratios, yielded evidence that “volatile elements from the solar nebula have withstood the test of time within the mantle since the early stages of planetary accretion,” eventually ascending to the surface via mantle plumes – immense upwellings of molten rock originating from the core-mantle boundary.
This groundbreaking research has been published in the prestigious journal Nature.
[H/T: Vice]
