Starfish Prime

Tales from the Nuclear Age

Copyright © 2013 by Charles Glassmire


Mar. 11, 2013

Starfish Prime

            On August 30, 1961, the Soviet Union announced they would no longer honor a three-year moratorium on nuclear testing which they had entered into jointly with the United States. In response, the United States began planning a series of high-altitude nuclear tests to determine whether a nuclear detonation at high altitude could destroy an incoming Intercontinental Ballistic Missile. The series of five shots were code named Operation Fishbowl, and the second test in the series was named Starfish. It was scheduled for the summer of 1962 in the Central Pacific Ocean.

          It was also necessary to gather more information on the electromagnetic effects from a high altitude nuclear burst. Before the first (ground level) test at Alamogordo New Mexico in 1945, Enrico Fermi had predicted a large electromagnetic pulse from the detonation, and required the electrical test instrumentation to be heavily shielded, and sometimes double shielded.(2) Subsequently, the official historical record of the test stated ”…In spite of this [shielding] many records were lost because of spurious pickup at the time of the explosion that paralyzed the recording equipment…”. Later the British observed serious instrumentation failures in their testing, due to an effect they dubbed “Radioflash”.

          Earlier, in the 1950’s, the U.S. had conducted high altitude weapons tests which further confirmed the existence of a phenomenon which was little understood, and which was named “EMP” for electromagnetic pulse.

          In 1962, the Soviet Union also conducted high altitude nuclear testing over inhabited Kazakhstan, including several cities within EMP range. Damage reports were of a geomagnetic storm-like EMP pulse which induced an electric current surge in a long distance underground power line which then caused a fire in the power plant of the city of Karaganda. These results were kept secret by Soviet scientists, and not revealed to western scientists until after the fall of the Soviet Union.

          So it was, on 20 June 1962, the original Starfish test was launched from Johnston Island on a Thor missile. Unfortunately, its rocket engine shutdown after 59 seconds into the launch, necessitating the missile and its W-49 thermonuclear warhead be destroyed by the range safety officer at about 35,000 feet. The detonation was completed safely, without any nuclear yield. Large chunks of the missile and warhead fell to earth, along with some Plutonium onto Johnston Island and nearby Sand Island, requiring thorough decontamination of these areas.(3) Thus, the failed test needed to be repeated, and the new test was code named Starfish Prime.

          Preparations for the Prime test were exhaustive. A large number of United States ships were arrayed in the ocean around Johnston Island. Additional observation ships were stationed to the area of the Pacific north of the test island. Some additional ships were deployed far to the south of the Equator, in the Samoan Islands region, to observe this unique location where the flux lines of the Earth’s magnetic field were suspected of diverting electrons from the test explosion and subsequent atmospheric ionization.

          The Soviet Union attended the test as uninvited guests to the party. One Soviet ship loitered in the region near Johnston Island. Another positioned itself in the southern ocean at the end of the southern magnetic field line conjugate.

          It was necessary to make many data observations at the moment of burst from the high region surrounding the initial thermonuclear event. To that end, some thirty sounding rockets (probably obsolescent Nike Ajax missiles) were outfitted with a variety of measuring instruments. They were arrayed around Johnston Island to be launched at the moment when the Thor missile passed its apogee and began reentering the atmosphere prior to the detonation. In addition, rocket-borne instruments were arranged to launch from Kauai in the Hawaiian Islands, some 900 miles distant from Johnston.(3)

          The test series was to be executed with the utmost secrecy from all civilian population. Surprisingly starfish side viewshowever, on the night of the test, many hotels scattered throughout the Hawaiian Islands were holding what they called “Rainbow Bomb” party events. These were held on the hotel rooftops and all guests invited, so that they might observe the intense atmospheric auroral lighting events visible in the night sky for hours following a nuclear test.

          So it was, on 9 July 1962, at 11 pm Hawaii local time, a Thor missile carrying the Starfish Prime W-59 warhead was launched into the night sky. Shortly thereafter, hugh numbers of measuring missiles were launched to rendezvous with the reentering vehicle. The missile trajectory peaked at about 680 miles altitude, actually far into space, and then the reentry vehicle began accelerating to terminal velocity, Starfish_Prime_aurora_from_Honolulu_1and proceeded to reenter the atmosphere as programmed. Thirteen minutes and 41 seconds after launch, at a downward trajectory position altitude of about 250 miles the thermonuclear warhead detonated, with its design magnitude of 1.4 megatons.(3)

          The Rainbow Bomb partying people on Hawaii, some 900 miles away, were rewarded with a brilliant flash in the night sky, followed by spectacular color changes to the atmosphere. But one guest on the telephone to Kauai discovered that his telephone connection was replaced with static. At that exact same instant, all were startled to note that their lights went out as the Hawaiian Islands were plunged into wide spreading blackout! …

 (to be continued…)


(1)  The Nuclear Weapons Archive, Operation Dominic,

(2)  “Electromagnetic Pulse”,

(3)  “Starfish Prime”, Wikipedia,


One Response to “Starfish Prime”

  1. Chaucer Says:

    Your ‘side view of Starfish Prime’ is actually a view of a Castle Bravo test some eight years earlier. Starfish Prime exploded at an altitude of some 400km, so it would be impossible for there to be clouds above the fireball.

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