An international team of scientists at NASA and other institutions say they’ve discovered a weak, planet-wide electric field wrapping the Earth that was first hypothesized by researchers decades ago.
As detailed in a new paper published in the journal Nature, the team made its discovery using observations from NASA’s Endurance mission. The suborbital rocket launched in May 2022, reaching an altitude of 477 miles while measuring minute changes in the electric charge.
The discovery of the Earth’s “ambipolar electric field” may have played an essential role in our planet’s evolution and could help us search for remote and potentially hospitable planets beyond our star system.
Researchers first hypothesized the energy field in the late 1960s. At the time, spacecraft crossing our planet’s poles detected an outflow of charged particles, a phenomenon scientists later called the “polar wind.” These particles were cold despite traveling at supersonic speeds, puzzling scientists at the time.
“Something had to be drawing these particles out of the atmosphere,” said lead author and Endurance principal investigator Glyn Collinson in a NASA statement.
It turns out, our planet’s been giving charged particles the cold shoulder for quite a while.
But, thanks to technical limitations, detecting the hypothesized electric field has remained impossible until now.
NASA’s Endurance rocket launched a few hundred miles from the North Pole in an archipelago called Svalbard to give the team the best chance of finding proof of this field. “Svalbard is the only rocket range in the world where you can fly through the polar wind and make the measurements we needed,” said co-author and University of Leicester space physicist Suzie Imber in a statement.
The rocket’s instrument needed to be extremely sensitive to changes in the electric potential. “A half a volt is almost nothing — it’s only about as strong as a watch battery,” Collinson explained. “But that’s just the right amount to explain the polar wind.”
The team found that particles launched into space at supersonic speeds experienced an outward force over ten times the pull of gravity. The scientists suggest that the ambipolar field enhances the far edge of the Earth’s ionosphere, a protective barrier of electrons that ward off much of the Sun’s radiation in the upper atmosphere. The findings also hint at similar electric fields wrapped around planets like Venus and Mars.
“Any planet with an atmosphere should have an ambipolar field,” Collinson said. “Now that we’ve finally measured it, we can begin learning how it’s shaped our planet as well as others over time.”
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