U.S. tests ways to sweep space clean of radiation after nuclear attack

The U.S. military thought it had cleared the decks when, on 9 July 1962, it heaved a 1.4-megaton nuclear bomb some 400 kilometers into space: Orbiting satellites were safely out of range of the blast. But in the months that followed the test, called Starfish Prime, satellites began to wink out one by one, including the world’s first communications satellite, Telstar. There was an unexpected aftereffect: High-energy electrons, shed by radioactive debris and trapped by Earth’s magnetic field, were fritzing out the satellites’ electronics and solar panels.

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