First hypothesized over 60 years ago Bipolar electric field Polar winds are the primary driver of a constant outflow of charged particles into space above the Earth’s poles. These electric fields lift charged particles in the upper atmosphere to higher altitudes than usual, and may have shaped the evolution of Earth in ways that are still unknown.
Collinson othersThey report that a potential drop of +0.55 ± 0.09 V exists between 250 km and 768 km due to the planetary electrostatic field, generated solely by the outward pressure of ionospheric electrons. They experimentally demonstrate that the Earth’s ambipolar field controls the structure of the polar ionosphere, increasing its scale height by 271%. Image courtesy of NASA.
Since the 1960s, spacecraft flying over Earth’s poles have detected streams of particles streaming from Earth’s atmosphere into space.
Theorists predicted these outflows, named them polar winds, and stimulated research to understand their causes.
Some outflow from the atmosphere was expected — intense, unobstructed sunlight should send some atmospheric particles escaping into space, like water vapor evaporating from a pot of water — but the observed polar winds were more puzzling.
Many of the particles inside were cold and showed no signs of heating, but they were moving at supersonic speeds.
“Something must be attracting these particles to the outer reaches of the atmosphere,” said Dr. Glynn Collinson, Endurance mission principal investigator and a researcher at NASA’s Goddard Space Flight Center.
The electric fields, hypothesized to be generated at subatomic levels, would be incredibly weak and their effects would be expected to be felt only for distances of hundreds of miles.
For decades, detecting it has been beyond the limits of existing technology.
In 2016, Dr Collinson and his colleagues began inventing a new instrument that they thought would be suitable for measuring Earth’s bipolar magnetic field.
The team’s equipment and ideas were perfectly suited for a suborbital rocket flight launched from the Arctic.
The researchers named the mission “Antarctic Expedition,” in honor of the ship that carried Ernest Shackleton on his famous 1914 Antarctic voyage. Endurance.
They set course for Svalbard, a Norwegian island just a few hundred miles from the North Pole and home to the world’s northernmost rocket launch site.
“Svalbard is the only rocket launch site in the world that can fly through the polar winds and make the measurements we need,” said Dr Susie Ingber, an astrophysicist at the University of Leicester.
Endurance was launched on May 11, 2022, reaching an altitude of 768.03 kilometers (477.23 miles) and splashing down in the Greenland Sea 19 minutes later.
Over the 518.2 kilometres (322 miles) altitude where Endurance collected data, it measured a change in electrical potential of just 0.55 volts (V).
“Half a volt is almost meaningless – it’s about the strength of a watch battery – but it’s just right for describing polar winds,” Dr Collinson said.
Hydrogen ions, the most abundant type of particle in the polar wind, experience an outward force from this field that is 10.6 times stronger than gravity.
“That’s more than enough to counter gravity, in fact to launch you into space at supersonic speeds,” said Dr. Alex Grosser, a research scientist at NASA’s Goddard Space Flight Center and Endurance project scientist.
Heavier particles are also accelerated: an oxygen ion at the same altitude, immersed in this 0.5 volt electric field, loses half its mass.
In general, scientists have found that bipolar magnetic fields increase what’s called the scale height of the ionosphere by 271%, meaning the ionosphere remains denser up to higher altitudes than it would be without the bipolar magnetic field.
“It’s like a conveyor belt that lifts the atmosphere up into space,” Dr Collinson said.
The Endurance discovery has opened up many new avenues of exploration.
The polarity field, as a fundamental energy field of the Earth alongside gravity and magnetism, may have continually shaped the evolution of the atmosphere in ways that we are only now beginning to explore.
Because it is generated by the internal dynamics of the atmosphere, similar electric fields are expected to exist on other planets, including Venus and Mars.
“Any planet with an atmosphere should have a bipolar magnetic field, and now that we’ve finally measured it we can start to learn how it has shaped our planet and other planets over time,” Dr Collinson said.
Team result Published in a journal Nature.
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G.A. Collinson others2024. Earth’s bipolar electrostatic field and its role in the escape of ions into space. Nature 632, 1021-1025;doi:10.1038/s41586-024-07480-3
This article is a version of a press release from NASA Goddard Space Flight Center.
Source: www.sci.news
