In the 1960s, scientists first hypothesized the existence of an ambipolar electric field that drives the leakage of Earth's atmosphere into space. The theory was based on a stream of particles “flowing” out of the atmosphere at the poles. This “polar wind” was a major mystery because the particles inside it were moving at supersonic speeds and were also cold. Now, thanks to observations made by NASA's Endurance suborbital rocket, the ambipolar field hypothesis has been confirmed. This electric field is considered as fundamental to our planet as its better-known magnetic and gravitational fields, and by studying it, scientists hope to better understand how Earth's atmosphere evolved and what is happening to it today. Here are the details!
NASA scientists have discovered a planet-scale electric field around Earth that is throwing particles from the Earth's atmosphere into space. Image: www.thebrighterside.news
Polar wind is a steady stream of charged particles into space that originates above the Earth's poles.
Contents
- 1 Particle flow
- 2 New electric field
- 3 NASA's Endurance mission
- 4 What's next?
Particle flow
Since the late 1960s, spacecraft flying over the Earth's poles have recorded a stream of particles escaping from the atmosphere into space. At the time, scientists assumed that there was a small “outflow” of air from the Earth's atmosphere into space, since intense, unfiltered sunlight should contribute to this, like steam evaporating from a pan of water.
The observed polar wind, however, was more mysterious – many of the particles inside it were cold and moving at supersonic speeds. Researchers then suggested that the particles could be pulled into space by an electric field that has not yet been discovered.
It took scientists many years to detect and measure the Earth's ambipolar field. Image: i.gadgets360cdn.com
Physicists believed that it must be incredibly weak, and that it occurs at a distance of about 250 kilometers above the planet's surface. Alas, but to detect the hypothetical electric field, powerful technologies were required, which simply did not exist at that time. Fortunately, in 2016, a team of scientists from NASA began working on inventing a suitable device.
Read even more interesting articles about the latest discoveries in astronomy and physics on our channel in Yandex.Zen – articles that are not on the site are regularly published there!
New electric field
In our planet's ionosphere, at an altitude of about 250 kilometers, atoms disintegrate into negatively charged electrons and positively charged ions. Remember that electrons are incredibly light – even the slightest burst of energy can send them into space. Ions are at least 1836 times heavier and, as a rule, sink to the surface.
If gravity alone acted on them, the two populations of particles would move away from each other over time. Their opposite electric charges, however, have resulted in an electric field that binds them together and prevents any separation of charges. Moreover, it counteracts some of the effects of gravity.
Earth's ambipolar field “works” in both directions – up and down. Image: techspot.com
The “new” electric field gets its name from its bidirectionality, or “ambipolarity,” since it “acts” in both directions. This means that ions, falling under the influence of gravity, attract electrons to themselves, and the electrons, in turn, lift the ions to a great height, desperately trying to escape into space.
The net effect of the ambipolar field is to increase the altitude of the atmosphere, causing some ions to rise high enough to be carried away by the polar wind, the NASA researchers explain.
NASA Endurance Mission
To understand the origins of the polar wind and study the ambipolar field in detail, researchers launched the Endurance rocket from a test site in Svalbard, near the North Pole, in 2022, sending it 475 miles (768.03 kilometers) above the Earth before landing in the Greenland Sea 19 minutes later. “Svalbard is the only rocket site in the world where you can fly through the polar wind and make the measurements you need,” said Susie Imber, a physicist at the University of Leicester.
The Endurance mission collected data over the course of its 320-mile (518-kilometer) flight and detected a tiny voltage change of 0.55 volts, about the same as a watch battery draining. Yet it’s this voltage difference that pushes hydrogen ions, the most common particles in the solar wind, out with a force 10.6 times greater than gravity.
By studying the ambipolar field, scientists hope to better understand how Earth's atmosphere evolved and how it behaves today. Image: images.twnmm.com
That difference was more than enough to defy gravity — enough, in fact, to launch atmospheric particles into space at supersonic speeds. Heavier particles also gain momentum. Oxygen ions at the same altitude immersed in this half-volt field weigh half as much, study co-author Alex Gloser, a NASA Endurance project scientist, said in a statement.
Overall, the scientists found that the ambipolar field increases the so-called scale height of the ionosphere by 271%. This means that the ionosphere remains denser at higher altitudes than it would be without it. The results of the work confirming the hypothesis from the 1960s can be found in the journal Nature.
This is interesting: When the Earth got a magnetic field – you will be surprised
What next?
Now that the ambipolar field has been proven to exist, scientists will study it further to understand how it has changed Earth's atmosphere throughout our planet's history. Researchers also expect to find similar electric fields in the atmospheres of planets such as Venus and Mars.
Our planet has an ambipolar electric field that ejects a stream of charged particles from the atmosphere into space. Image: svs.gsfc.nasa.gov
The thing is that any planet with an atmosphere must have an ambipolar field, and understanding the complex movements and evolution of the Earth's atmosphere provides the key to its history. Moreover, this electric field will allow researchers to learn the secrets of other planets and determine which of them may be habitable.
By the way, last year astronomers discovered as many as five potentially habitable planets outside the solar system! Details here, don't miss it!