A certain variety of communications, called very low frequency (VLF) radio communications, have been found to interact with particles in space, affecting how and where they move. At times, these interactions can create an extra protective barrier around Earth against natural high energy particle radiation in space.
VLF signals are transmitted from ground stations at huge powers to communicate with submarines deep in the ocean. While these waves are intended for communications below the surface, they also extend out beyond our atmosphere, shrouding Earth in a VLF bubble. This bubble can be seen by spacecraft high above Earth’s surface, such as NASA’s Van Allen Probes, which study electrons and ions in the near-Earth environment.
The probes have detected that the outward extent of the VLF bubble corresponds almost exactly to the inner edge of the Van Allen radiation belts. Baker called this inner edge an “impenetrable barrier,” and speculates that if there were no human VLF transmissions, the boundary would likely stretch closer to Earth. In fact, the researchers compared the modern extent of the radiation belts with satellite data from the 1960s, when VLF transmissions were more limited, and found that the bubble had expanded.
The scientists suggested that VLF transmissions may serve as a way to remove excess radiation from the near-Earth environment. Plans are already underway to test VLF transmissions in the upper atmosphere to see if they could remove excess charged particles from intense, naturally induced space weather.
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The researchers did stress that despite these human impacts, space weather is dominated by natural phenomena from the sun. Our local star sends out millions of high-energy particles, called the solar wind, which races out across the solar system before reaching Earth. Our planet’s magnetosphere provides a protective magnetic field that surrounds us, deflecting most of the charged particles.
During stronger solar storm events such as solar flares and coronal mass ejections some particles can make their way into near-Earth space and can impact our satellites by damaging onboard electronics and disrupting communications or GPS signals. These particles, along with electromagnetic energy that accompanies them, can also cause auroras, while changes in the magnetic field can induce currents that damage power grids.
These natural events from the sun pose a risk mainly to the advanced technology we’ve developed. Even in the largest events, no “killer” solar storm that would strip away Earth’s atmosphere is possible. The relatively thick atmosphere and the planet’s magnetosphere can stop the harmful radiation.
But even if the VLF radio emissions could help protect Earth, the consensus is that it is best not to interfere with natural phenomena, as any human-caused changes to this region could ultimately have disastrous effects. Even the further expansion of this protective VLF bubble could have consequences in the future.
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“As new techniques are considered for human modification of elements of Earth’s space environment,” the paper says, “it is important to carefully assess the short-term and long-term implications of anthropogenic modifications in order to arrive at final experiment design and the decision to proceed.”
“Humans and their activities have had quite a few deleterious effects over the years and decades,” Baker told Seeker. “And even thought it appears that human VLF radio emissions may help to ‘scrub’ the electron radiation belts to some extent, more study is being done to clarify this feature.”
He and his colleagues generally believe that it is best to keep the near-Earth space environment as free from human contamination as possible.
“For example, trapped radiation from nuclear explosions or space debris were (and will continue to be) huge problems,” Baker said. “It would be highly desirable to be able to study and understand fully the natural space environment before we have to deal with the human-affected environment.”
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