10
Loading video...
By Amanda Greenwood
Associate News Editor
0
Share
Newsweek is a Trust Project member
See more of our trusted coverage when you search.Prefer Newsweek on Googleto see more of our trusted coverage when you search.
Satellites around Earth could face a previously underestimated radiation risk after scientists discovered that high-energy electrons had breached a boundary once thought to be "impenetrable.”
A powerful solar storm broke through a space radiation boundary around Earth that scientists had thought the most energetic electrons could not cross.
It caused potentially damaging electrons to travel at almost the speed of light in an area where scientists had rarely seen them before.
Read More on News
The discovery came after a severe geomagnetic storm hit Earth in May 2024, producing auroras much further from the poles than usual. During and after the storm, the Japan Aerospace Exploration Agency’s Arase spacecraft detected large numbers of extremely energetic electrons inside the boundary, closer to Earth, according to research led by Nagoya University.
...
Earth's magnetic field traps high-energy particles in two doughnut-shaped areas called the Van Allen radiation belts. The outer belt mainly contains high-energy electrons, while the inner belt contains mostly high-energy protons.
In 2014, scientists identified a sharp boundary at the inner edge of the outer radiation belt, about three Earth radii from the center of the planet. One Earth radius is the distance from the center of Earth to its surface, about 6,371 kilometers. That means three Earth radii is just over 19,100 kilometers. Because the most energetic electrons rarely cross this boundary, scientists have described it as an "impenetrable wall."
Scientists still don't fully understand what creates this boundary. One possible explanation involves low-frequency radio waves called plasmaspheric hiss. These waves can push energetic electrons out of the radiation belts and into Earth's atmosphere.
What Happened During the Solar Storm?
...
During the May 2024 storm, Arase detected a large increase in electrons traveling close to the speed of light inside the supposedly protected area. Some were powerful enough to pass through some types of satellite shielding.
Scientists wanted to know how these electrons had got inside the barrier. One possibility was that they had been pushed inward from the outer radiation belt. Another was that electrons already inside the area had somehow been given much more energy.
"One of the key questions was how these highly energetic electrons appeared inside the barrier," lead author Yoshizumi Miyoshi, a professor at Nagoya University’s Institute for Space-Earth Environmental Research, said in a statement. He asked: "Were they transported inward from the outer radiation belt, or were they accelerated locally within this region?"
Their observations pointed toward the second explanation. Researchers found evidence that electrons already inside the region were being made faster and more energetic, rather than the high-energy electrons simply moving there from further away.
The researchers concluded that electromagnetic waves called chorus waves probably helped speed up the electrons. These waves occur naturally in space and can give energy to electrons, making them travel faster and reach much higher energies.
The solar storm had also badly disrupted the plasmasphere, an area of relatively cool, electrically charged particles surrounding Earth. The outer edge of the plasmasphere moved much closer to Earth than usual. This left far fewer charged particles around the radiation barrier. That allowed hotter electrons to move inward and create the powerful chorus waves.
The disruption also lasted an unusually long time. According to Miyoshi, the amount of charged particles in this area normally recovers within about two days. After the May 2024 storm, however, it took between 4.3 and 4.7 days for levels to recover to more than half of what they had been before the storm.
These unusual conditions may also have allowed the chorus waves to continue speeding up electrons for several days.
What Does the Discovery Mean?
The discovery does not mean Earth's entire protective magnetic field was broken through, and it does not mean people on the ground were exposed to dangerous radiation. The "impenetrable barrier" is simply a boundary inside Earth's radiation belts.
The new findings show that very powerful solar storms can change conditions around this boundary. This can allow extremely energetic electrons to build up in an area of space close to Earth where scientists had previously thought they would rarely be able to reach.
This could be important for satellites traveling through the region. Very energetic electrons can cause lasting radiation damage to parts of spacecraft and can reduce how much electricity satellite solar panels are able to produce.
Understanding what happens to these electrons during powerful solar storms could therefore help scientists better predict dangerous space weather and understand the risks it poses to satellites and other spacecraft.
"This discovery highlights the need to understand and predict how energetic electrons behave under extreme space weather conditions," Miyoshi said, adding: "Such knowledge is important for assessing radiation risks to spacecraft and improving future space weather predictions."
Newsweek has contacted Miyoshi for comment.
Newsweek’s reporters and editors used Martyn, our AI assistant, to produce this story. Learn more about Martyn here.
Contact Newsweek editors on this story: Daniel Orton and Trevor Davies.
View 0 Comments
Submit Correction
View Editorial & AI Guidelines