Researchers discovered an "invisible shield" about 7,200 miles above Earth that blocks out "killer electrons" that are a threat to satellites and astronauts that venture above.
The barrier was discovered in the Van Allen radiation belts, which are two "doughnut-shaped" rings, which swell and shrink depending on the Sun's energy disturbances, the University of Colorado, Boulder reported.
"It's almost like [these] electrons are running into a glass wall in space," said Professor Daniel Baker, director of CU-Boulder's Laboratory for Atmospheric and Space Physics (LASP). "Somewhat like the shields 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."
The belts, which were discovered in by 1958 by Professor James Van Allen and his team at the University of Iowa. They were found to be comprised of an inner and outer belt extending about 25,000 miles above Earth's surface. In 2013, Baker and his team discovered a third, transient "storage ring."
The researchers are now investigating an "extremely sharp" boundary at the inner edge of the outer belt that seems to block super-fast electrons form entering Earth's atmosphere.
"It's almost like theses electrons are running into a glass wall in space," said Baker, the study's lead author. "Somewhat like the shields 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."
In the past, researchers thought these intruding electrons would drift into the Earth's atmosphere and be wiped out by interactions with present molecules, but these new observations made with the twin Van Allen belt spacecraft disputes that theory. One of the most promising explanations for the phenomenon is the scattering of electrons caused by a cloud of electrically charged gas, called the plasmasphere. This might also be what is creating the white noise-like plasmaspheric "hiss" that is believed to be the sound of electrons scattering.
"I think the key here is to keep observing the region in exquisite detail, which we can do because of the powerful instruments on the Van Allen probes. If the sun really blasts the Earth's magnetosphere with a coronal mass ejection (CME), I suspect it will breach the shield for a period of time," Baker said.
The findings were published Nov. 27 in the journal Nature.