Numerous atmospheric nuclear tests during the Cold War affected space weather. Explosions at an altitude of 25 to 400 kilometers caused the release of high-energy charged particles, disturbed the geomagnetic field and induced currents on the Earth's surface. An article analyzing the recently declassified information was published in the journal Space Science Reviews.
"The tests were like extreme examples of some solar-generated phenomena that affect space weather," said Phil Erickson, assistant director of the Haystack Observatory and co-author of the work. "If we understand what happened in the partially controlled and man-made events, we can better understand the natural changes in the nearest space."
Due to individual tests, artificial radiation belts were formed, similar to the natural Van Allen belts (the radiation belt is the region of the magnetospheres of the planets, in which high-energy charged particles, mainly protons and electrons, that have penetrated the magnetosphere are accumulated and retained). They contained a significant amount of charged particles for weeks, and in one case even for several years. Regardless of their origin, these particles can affect satellites. Apparently, some of them even failed for this very reason. Despite the general similarity of the belts, the energies of particles in artificial ones differ, so they can be determined.
The tests also led to other effects: for example, the American tests of Argus, carried out in 1958 at the highest altitude at that time (the maximum height was 794 kilometers), allowed particles to fly away from the center, which caused geomagnetic storms in Sweden and Arizona. Knowing the time of these events, scientists were able to determine the speed of the particles. It turned out that they were moving in two waves: one at a speed of 3000 kilometers per second, and the other had a fourfold smaller one. Unlike long natural events, those caused by the explosions lasted only seconds.