Virtually nothing on Earth has escaped human influence, from the oceans to the atmosphere. But a new study suggests that human activity also influences the space around our planet; it’s above the space junk already swirling there. Very low frequency (VLF) emissions have created a planetary cocoon, shielding the planet from high-energy particle radiation, according to a NASA press release.
Like David Grossman at Popular mechanics reports, VLF radio requires a massive antenna for detection, so it is only used for special purposes. A common use is in underwater communication, which works through the penetrating ability of VLF long waves. But they can also travel in space. There, the signals interact with the charged particles, changing their motion.
But the changes may not be all bad. As Marina Koren writes for Atlantic, “The bubble forms a protective barrier around the Earth, shielding the planet from potentially hazardous space weather, such as solar flares and other ejections from the sun.” This ephemeral bubble adds to the already protective magnetosphere, encompassing our planet. Researchers report the discovery this week in the journal Journal of Space Science.
The discovery was made using the Van Allen Probes, a spacecraft launched in 2012 to monitor bands of charged particles surrounding Earth. Data from these probes suggest that the outer edge of the VLF transmission corresponds to a layer of charged particles at the inner edge of the Van Allen belts. But according to satellite data, before VLF signals became more widely used in the 1960s, the Van Allen belts extended closer to Earth. Researchers believe that VLF signals can prevent the belts from getting closer.
But the VLF signal is not the only human activity affecting space. The study also examines other anthropogenic impacts on space weather. According to a press release, between 1958 and 1962, the United States and the USSR conducted high-altitude nuclear explosions. These explosions, which were between 16 and 250 miles above the Earth’s surface, mimicked some of the effects caused by the solar wind, including bombardment of Earth with high-energy particles, distortion of the Earth’s magnetic field and the creation of temporary radiation belts. One test even created an artificial aurora. Researchers hope to understand how these explosions created or disrupted space weather.
“The tests were an extreme, human-generated example of some of the space weather effects frequently caused by the sun,” Phil Erickson, deputy director at MIT Haystack Observatory and study author, said in the press release. “If we understand what happened in the somewhat controlled and extreme event that was caused by one of these man-made events, we can more easily understand the natural variation in the near environment. ‘space.”
But it’s not all bad news. Researchers eventually hope to investigate new ways to use VLF signals to influence space weather to further protect Earth from charged particle bombardment during solar storms.