While the debate about global warming and climate change rages on, recent declassified data on high-altitude nuclear explosion tests are telling a new story on how we affect space weather. From 1958 to 1962 during the Cold War, the U.S. and U.S.S.R. ran high-altitude tests with code names like Starfish, Argus, and Teak.
Now, that history is providing scientists a better understanding on the complex space system that surrounds us.
Space weather is usually triggered by the sun’s activity, which can change Earth’s magnetic environment. However, with the new declassified data, it has provided a new look at the mechanisms that set off alarms in that magnetic system.
Even though the tests have long since ended, and the goals at the time were military, the information can provide vital information on how humans can affect space. These tests, and other human-induced space weather, are the focus in a new comprehensive study published in Space Science Reviews.
Using the data, scientists believe that it could help NASA’s efforts in protecting satellites and astronauts from the natural radiation inherent in space. Phil Erickson, assistant director at MIT’s Haystack Observatory, Westford, Massachusetts, and co-author on the paper, said in a statement:
“The tests were a human-generated and extreme example of some of the space weather effects frequently caused by the sun.
“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-space environment.”
Space weather mostly affects the region of near-Earth space — this is where astronauts and satellites travel, and is usually driven by outside factors. The sun sends out millions of high-energy particles, called solar wind, which then in-turn race out across the solar system before encountering Earth’s magnetosphere (a protective magnetic field that surrounds the planet).
Most of these charged particles are deflected away from us; however, some make their way into near-Earth space. It is these particles that can have an impact on our satellites, damaging onboard electronics and disrupting communications or navigation signals.
The particles, along with electromagnetic energy that comes with them, can cause auroras, while changes in the magnetic field can induce currents that can cause damage power grids. The Cold War tests detonated explosives at heights from 16 to 250 miles above Earth’s surface, and the test mimicked some of these natural effects.
On detonation, a blast wave ejected an expanding fireball of plasma (a hot gas of electrically charged particles) so powerful it created a geomagnetic disturbance that distorted Earth’s magnetic field lines, inducing an electric field on the surface.
Detonations carried out by the U.S. and the Soviet Union even created artificial radiation belts near Earth, similar to the natural Van Allen radiation belts (a layer of charged particles held in place by Earth’s magnetic fields). Some of the artificially made charged particles persisted for a number of weeks, in one case for years. This resulted in major damage to several satellites.
Even though the radiation belts released by the Cold War tests were similar to the Earth’s own radiation belts, their trapped particles had different energies. Comparing the energies of the particles, it was possible to distinguish the fission-generated particles and those that were naturally occurring in the Van Allen belts.
Two notable tests that mimicked natural phenomena
In 1958 on August 1, the Teak test took place, and resulted in an artificial aurora. The test was conducted over Johnston Island in the Pacific Ocean. However, on the same day, the Apia Observatory in Western Samoa observed a highly unusual aurora (typically only observed at the poles).
It is understood that the energetic particles that were released by the test likely followed the Earth’s magnetic field lines to the Polynesian island nation, inducing the aurora.
Later in the same year, the Argus tests were conducted. This time, the effects were seen around the world. The tests were conducted at higher altitudes than previous tests; this allowed the particles to travel farther around Earth.
Sudden geomagnetic storms were observed from Sweden to Arizona. Scientists used the events to determine the speed at which the particles from the explosion traveled. Two high-speed waves were observed, the first traveled at 1,860 miles per second and the second, less than a fourth that speed.
However, unlike the artificial radiation belts, these geomagnetic effects were short-lived, lasting only seconds.
Thankfully, atmospheric nuclear testing is no longer used, with the present space environment remaining dominated by natural phenomena.
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