The study of space weather has taken on an increased importance in recent decades, as the importance of the effects of the day-to-day conditions of our immediate solar system continue to be uncovered, with the effects here on Earth ranging from the awe-inspiring beauty of an aurora borealis display, to the potential nightmare a large-scale solar flare could unleash on our technology.
However, in much the same way that human-based activity has affected Earth-based weather through climate change, it turns out that we’ve also been affecting the nature of space weather in the immediate vicinity around our planet, in the form of a forcefield-like bubble that has been pushing away the natural radiation bands that circle Earth, high in the magnetosphere.
Data from satellites that monitor the Van Allen radiation belts has revealed that since monitoring of these radiation zones began in the early 1960s, the very low frequency (VLF) radio transmissions used by our culture has created a sort of bubble that has been pushing the Van Allen belts outward from the planet.
The Van Allen Probes are twin satellites that orbit the Earth, keeping tabs on the radiation belts they’re named after. Recently, they found that that radiation was being pushed to a higher altitude by some sort of low-frequency barrier. Upon investigating, researchers found that this low-frequency field was being generated by our technology’s own VLF transmissions.
"A number of experiments and observations have figured out that, under the right conditions, radio communications signals in the VLF frequency range can in fact affect the properties of the high-energy radiation environment around the Earth," explains Phil Erickson, a researcher with MIT’s Haystack Observatory.
Primarily consisting of two doughnut-shaped zones encircling our planet at an altitude of between 1,000 to 60,000 kilometers (620 to 37,300 miles), the Van Allen belts are comprised of charged particles originating from the solar wind that become trapped in Earth’s magnetosphere. The radiation emitted from the belts poses a serious hazard to satellites passing through the radiation, requiring higher-altitude spacecraft to be hardened against radiation exposure.
VLF transmissions are radio frequencies in the 3 to 30 kilohertz range: these frequencies are not utilized by consumer-level technology, as they lack the bandwidth to carry audio transmissions. However, their importance to military and scientific fields have increased over the last half-century, due to their ability to be transmitted over long distances through the atmosphere, and their ability to be transmitted underwater.
This discovery is one of the odd times where what amounts to human-generated pollution has had a beneficial effect on our planet, where we have inadvertently carved out our own little piece of the sky. This has also inspired NASA to consider studying the use of VLF transmissions to clear the upper atmosphere of harmful radiation that can result from periods of increased solar activity.