Radiation Risks for Satellites as Solar Storms Breach Boundary

Satellites in Earth’s orbit could face higher radiation risks due to recent discoveries. Scientists found that high-energy electrons breached a once-thought “impenetrable” boundary. A significant solar storm allowed these electrons to move at near-light speeds in areas rarely impacted before.

Recent Discoveries

A severe geomagnetic storm in May 2024 prompted further research. It produced auroras much farther from the poles than usual. The Japan Aerospace Exploration Agency’s Arase spacecraft observed a surge of extremely energetic electrons closer to Earth during the storm. Research led by Nagoya University confirmed this phenomenon.

The Van Allen Radiation Belts

Earth’s magnetic field captures high-energy particles in two zones known as the Van Allen radiation belts. The outer belt mainly consists of high-energy electrons, while the inner belt contains high-energy protons. In 2014, scientists noted a boundary within the outer belt about three Earth radii from Earth’s center, approximately 19,100 kilometers. This boundary previously blocked most energetic electrons.

Scientists speculate that low-frequency radio waves, called plasmaspheric hiss, could drive energetic electrons into Earth’s atmosphere. These waves might explain why this boundary exists, although the exact cause remains unclear.

Impact of the Solar Storm

During the May 2024 storm, Arase identified a spike in electrons speeding close to light inside what was considered a protected area. Some electrons were powerful enough to penetrate specific types of satellite shielding. Researchers investigated how these electrons bypassed the barrier, focusing on two theories.

“One of the key questions was how these highly energetic electrons appeared inside the barrier,” said Yoshizumi Miyoshi, lead author and professor at Nagoya University’s Institute for Space-Earth Environmental Research.

Researchers found evidence supporting the second theory. Electrons already inside the region gained speed and energy. Electromagnetic waves, known as chorus waves, likely assisted in this acceleration. Naturally occurring in space, these waves increase electron energy, causing faster travel.

The storm severely impacted the plasmasphere, disrupting it longer than usual. The outer edge of the plasmasphere approached Earth, reducing surrounding charged particles. This condition enabled hot electrons to move inward and form powerful chorus waves, sustaining for several days.

Implications of the Discovery

The discovery does not compromise Earth’s entire magnetic shield; terrestrial residents were not exposed to radiation. The “impenetrable” boundary pertains solely to the radiation belts.

The findings demonstrate that potent solar storms alter boundary conditions. As a result, energetic electrons may accumulate closer to Earth, an area formerly believed inaccessible. This change holds significance for satellites operating in these regions.

Highly energetic electrons can inflict prolonged radiation damage on spacecraft, affecting satellite solar panels’ electricity generation. Understanding electron behavior during intense solar storms helps anticipate perilous space weather, reducing risks to satellites and other spacecraft.

“This discovery highlights the need to understand and predict how energetic electrons behave under extreme space weather conditions,” Yoshizumi Miyoshi emphasized.

Newsweek’s Martyn, an AI assistant, contributed to this story. Contact editors Daniel Orton and Trevor Davies for more details.