约翰斯顿环礁
Between 1958 and 1975, Johnston Atoll was used as an American national nuclear test site for atmospheric and extremely high-altitude nuclear explosions in outer space. In 1958, Johnston Atoll was the location of the two "Hardtack I" nuclear tests firings. One conducted August 1, 1958 was codenamed "Hardtack Teak" and one conducted August 12, 1958 was codenamed "Orange." Both tests detonated 3.8-megaton hydrogen bombs launched to high altitudes by rockets from Johnston Atoll.