Cosmic dust and solar wind – sources of helium in the ocean
Researchers from the Ioffe Physico-Technical Institute RAS believe that solar wind brings helium enriched cosmic dust into oceanic rock.
Studying the isotopic composition of helium in deepwater oceanic ferro-manganous rock, they learned that the correlation of Helium-3 and Helium-4 isotopes is exactly the same as in oceanic basalts. It is interesting that the Helium-3 isotope in basalts is relic, ancient “solar” helium that has entered earth rock and has been retained to date in the Earth’s mantle. Furthermore the Earth’s mantle and basalt rock also contain the heavy Helium-4 isotope, formed as a result of the breakdown of ancient uranium and thorium. The scientists concluded that Helium-3 accumulates in oceanic rock today as well, thanks to the action of cosmic dust and solar wind.
This is evidenced by the results of an experiment conducted by the scientists. Heating basalts, ferro-manganous rock and samples of red-clay deepwater silt, the physicists detected that the lighter Helium-3 isotope is discharged from these substances at a higher temperature than that for the heavier isotope. And what can this provide evidence of? The scientists assume that cosmic helium endures a difficult journey: Helium-3 appears in flows of cosmic dust when exposed to solar corpuscular radiation. The cosmic dust, enriched with the light isotope, first penetrates the Earth’s atmosphere, where it receives a “thermal tempering” (at this point it loses a part of the helium which vaporizes at a comparatively low temperature, while the “high-temperature” helium, which is observed in the experiment, remains). The thermal tempering of particles that have passed through the atmosphere enables these particles to then exist happily in the aggressive oceanic environment.