For the first time in several years, NASA has detected Earth's hidden electric field that plays a key role in driving “polar wind” that launches charged particles to space at supersonic speeds. In an article published in the journal Nature on Wednesday, the space agency used observations from a suborbital rocket gathered by a group of international scientists to measure an ambipolar electric field.
NASA discovers Earth's ambipolar electric field
The planet-wide electric field, first hypothesised 60 years ago, has finally been detected, thanks to NASA's Endurance Mission. Using the rocket's measurements, scientists have quantified the ambipolar field's strength, providing an understanding of how it affects the ionosphere, a layer of the upper atmosphere.
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Though weak, the electric field plays a key role in driving a stream of particles into outer space. NASA notes that many of these particles travelling outwards from the Earth's atmosphere “were cold, with no signs they had been heated — yet they were travelling at supersonic speeds.”
“Something had to be drawing these particles out of the atmosphere,” said Glyn Collinson, principal investigator of Endurance at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and lead author of the paper.
{{/usCountry}}“Something had to be drawing these particles out of the atmosphere,” said Glyn Collinson, principal investigator of Endurance at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and lead author of the paper.
{{/usCountry}}In 2016, a team of scientists led by Collison embarked on the task of inventing an instrument that could measure Earth’s ambipolar field.
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The ambipolar field is “bidirectional” as it works in both directions, the space agency explained. While the ions pull the electrons down as they sink with gravity, the electrons lift ions to greater heights as they attempt to escape to space.
“The net effect of the ambipolar field is to extend the height of the atmosphere, lifting some ions high enough to escape with the polar wind,” NASA said.
“It’s like this conveyor belt, lifting the atmosphere up into space,” Collinson continued, adding, “Any planet with an atmosphere should have an ambipolar field. Now that we’ve finally measured it, we can begin learning how it’s shaped our planet as well as others over time.”