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Helium-3 is an isotope, or version, of helium that has only one neutron instead of two. It is considered to be a promising fuel for nuclear fusion reactions, a speculative energy source based on the same processes that power the Sun and other stars. Helium-3 is also a primordial ingredient of our planet that could illuminate key processes in the core, such as the generation of Earth’s protective magnetic field, which has played a major role in the emergence of life on Earth. Most helium-3 in the universe dates nearly all the way back to the Big Bang 13.8 billion years ago, distinguishing it as an incredibly ancient gas that often hangs around in nebulas. When Earth began to form some 4.6 billion years ago, helium-3 from the solar nebula became trapped in its core, where it remains with other primordial elements to this day. Previous research has suggested that trace amounts of this rare element may leech out of the core and travel up to Earth’s surface, but the finer details of this hypothesis are still a mystery.Now, scientists led by Forrest Horton, a geochemist at Woods Hole Oceanographic Institution, have discovered that ancient lava flows from Baffin Island, a huge landmass in Canada’s Arctic Archipelago, contain the highest ratios of helium-3 (3He) to helium-4 (4He), another isotope, ever seen in any terrestrial volcanic rocks. The team suggests that “the extremely high 3He/4He helium in these lavas might derive from Earth’s core,” a finding that may rewrite the history of ancient elements in the center of our world, according to a study published on Wednesday in Nature.
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“3He is exceptionally rare in Earth because helium that is released from the solid Earth escapes to space, and because little 3He is produced within our planet (unlike 4He, which is the product of radioactive decay of naturally occurring isotopes),” Horton said. “Our study may contribute to our understanding of the origins of terrestrial 3He but does not guide efforts to extract 3He from rocks or produce energy from 3He.” “Note that cosmic ray bombardment enriches 3He in the top few meters of rocky bodies in the Solar System, so ancient surfaces like those on the Moon and meteorites can have much higher 3He/4He than observed in the Baffin Island lavas,” he added.Perhaps one day, helium-3 will become valuable enough as a potential resource to motivate prospectors to mine it on other worlds, a scenario that has been explored in many science fiction stories, such as the film Moon. In the meantime, scientists like Horton are eager to understand the origin and implications of Earth’s ultra-scarce helium-3 reserves, which could offer an entirely new view of the mysterious core 1,800 miles under our feet.
“In many ways, our study raises more questions than it answers, so there is a lot of work to do,” Horton said. “One important question is, assuming helium is leaking out of the core, whether any other elements also escape from the core? And when did these elements migrate into the rocky part of the planet?” “I am especially excited to explore potential links between helium and other elements, including hydrogen and carbon (essential building blocks of life),” he concluded. “Another implication of our study is that mantle plumes that deliver material from the deep Earth evolve over time; a systematic study of mantle plume evolution may provide a clearer picture of processes near the core-mantle boundary.”Update: A previous version of this article had the headline “Earth’s Core Is Leaking In the Arctic and Scientists Don’t Know Why.” Lead author Forrest Horton expressed to Motherboard that the leak occurred far below the surface of the Earth and ended up in surface lava via mantle plumes. Motherboard has updated the headline to reflect this.