Invisible, Star Trek-like Shield Protects Earth from 'Killer Electrons'

An invisible, science fiction-like shield has been discovered about 7,200 miles above Earth's surface. The shield, which was found in the Van Allen radiation belts, shields our planet from "killer electrons" that whip around Earth at near-light speed and threaten astronauts, fry satellites and degrade space systems during solar storms.

The Van Allen radiation belts themselves are filled with high-energy electrons and protons. These belts are held in place by Earth's magnetic field and periodically swell and shrink in response to incoming energy disturbance from the sun. There's both an inner and an outer belt that, overall, extend about 25,000 miles above Earth's surface. There's also a third, transient "storage" ring between the inner and outer belts that appears and disappears depending on space weather.

Now, though, it seems as if there's more than these belts. The scientists discovered an "extremely sharp" boundary at the inner edge of the outer belt that appears to block the ultrafast electrons from breeching the shield and moving deeper towards Earth's atmosphere.

"It's almost like these electrons are running into a glass wall in space," said Daniel Baker, one of the researchers, in a news release. "Somewhat like the shield created by force fields on Star Trek that were used to repel alien weapons, we are seeing an invisible shield blocking these electrons. It's an extremely puzzling phenomenon."

Originally, the scientists thought that the highly charged electrons, which are looping around the Earth at more than 100,000 miles per second, would slowly drift downward into the upper atmosphere and gradually be wiped out by interactions with air molecules. However, the shield stops the electrons before they get that far.

"Nature abhors strong gradients and generally finds ways to smooth them out, so we would expect some of the relativistic electrons to move inward and some outward," said Baker. "It's not obvious how the slow, gradual processes that should be involved in motion of these particles can conspire to create such a sharp, persistent boundary at this location in space."

The findings reveal a bit more about this shield. Now, scientists want to learn more about this barrier and continue observations.

The findings are published in the journal Nature.

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