Starfish Prime

Strange and obscure history:

Starfish Prime was a high-altitude nuclear test conducted by the United States of America on July 9, 1962, a joint effort of the Defense Atomic Support Agency (DASA) and the Atomic Energy Commission (AEC). Launched via a Thor rocket and carrying a W49 thermonuclear warhead (manufactured by Los Alamos Scientific Laboratory) and a Mk. 4 reentry vehicle, the explosion took place 400 kilometers (250 miles) above Johnston Island in the Pacific Ocean. It was part of Operation Dominic. With the test taking place in such a high altitude, it was one of the five tests conducted by the USA in outer space as defined by the FAI. It produced a yield of 1.4 megatons of TNT.

As for Starfish Prime, because there is almost no air at an altitude of 400 kilometers, no fireball formation occurred, although manifold other notable effects did occur. About 1500 kilometers (930 statute miles) away in Hawaii, the electromagnetic pulse (EMP) created by the explosion was felt as three hundred street lights failed, television sets and radios malfunctioned, burglar alarms went off and power lines fused. On Kauai, EMP shut down telephone calls to the other islands by burning out the equipment used in a microwave link.

snip

While some of the energetic beta particles followed the earth's magnetic field and illuminated the sky, other high-energy electrons became trapped in man-made radiation belts around the earth. There was much uncertainty and debate about the composition, magnitude and potential adverse effects from this trapped radiation after the detonation. The weaponeers became quite worried when three satellites in low earth orbit were disabled. These man-made radiation belts eventually crippled one-third of all satellites in low orbit. Seven satellites were destroyed as radiation knocked out their solar arrays or electronics, including the first commercial communication satellite ever, Telstar.