At 6.45am on March 1, 1954, the blue sky stretching over the south Pacific Ocean was split open by an enormous red flash.
Within seconds, a mushroom cloud towered 7.2 kilometres high over Bikini Atoll in the Marshall Islands. The explosion, the US government's first weaponised hydrogen bomb, was 1000 times more powerful than the "Little Boy" atomic bomb blast that flattened Hiroshima - and a complete miscalculation.