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NASA reveals Cold War nuclear testing effects on space weather

The fallout from nuclear weapons testing during the Cold War extended beyond the halls of Washington and Moscow and caused extreme changes to the immediate environment in the space surrounding Earth.

Declassified documents on the testing, as well as scientific records from 1958 to 1962, have allowed NASA researchers to understand more about the effects.

Space weather describes the electromagnetic environment around the planet, including the magnetosphere - a protective magnetic field generated by the rotation of the Earth's core.

It is typically driven by external factors such as solar activity, but nuclear tests conducted up to 250 miles above the surface of the planet during the Cold War had even more extreme effects.

The sun radiates millions of powerful high-energy particles known as the solar wind, but most of these are deflected from the Earth by its magnetosphere.

It can affect satellites by damaging electronics, disrupting communications or navigation signals.

The radiation can also cause auroras - natural light displays in the sky - and induce damaging currents in power grids.

The Cold War nuclear tests caused very similar effects, according to the scientists.

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They were "a human-generated and extreme example of some of the space weather effects frequently caused by the sun", according to Phil Erickson, the assistant director at MIT's Haystack Observatory.

Dr Erickson, who co-authored the study, said: "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."

One detonation conducted over the Pacific Ocean in 1958, known as the Teak test, caused an aurora to be visible in Western Samoa near the equator, despite normally only being visible in polar regions.

Later that same year, the Argus tests were conducted over the South Atlantic Ocean and their effects were witnessed around the world.

These three tests were conducted at higher altitudes than any previous tests, which allowed the particles to travel farther around the Earth.

Sudden geomagnetic storms were observed from Sweden to Arizona and scientists used the observed time of the events to determine the speed at which the particles from the explosion travelled.

NASA hopes that understanding how radiation works in near-space environments will help it protect satellites and astronauts from harm.