Starfish Prime

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 one of five tests conducted by the USA in outer space as defined by the FAI. It produced a yield of 1.4 megatons of TNT.

Operation Fishbowl

The Starfish test was one of five high altitude tests grouped together as "Operation Fishbowl" within the larger Operation Dominic, a series of tests in 1962 begun in response to the Soviet announcement on August 30, 1961 that they were ending a three year moratorium on testing.One Fishbowl test (Checkmate) used a Strypi rocket; the final test (Tightrope) used a Nike Hercules surface-to-air missile. The other three tests (Bluegill, Starfish, and Kingfish) used the Thor IRBM, which had been deployed in 1958-59. The missile set a dismal reliability record in these tests, with the poorest case being the Bluegill test, requiring four attempts; the second Bluegill shot on July 25 (Bluegill Prime) caused the worst damage, as the missile had to be detonated on the launch pad, destroying the complex and extensively contaminating it with plutonium from the missile's warhead.

The initial Starfish launch attempt on June 20 was also aborted due to failure of the launch vehicle. In this case thrust failed one minute after launch, and safety detonation brought pieces of the missile and some radioactive contamination falling upon Johnston Atoll and nearby Sand Island. A second launch on July 9 was successful. Starfish Prime was the first successful Fishbowl test, and the highest altitude and highest yield explosion in the series.

The explosion itself

Because there is almost no air at an altitude of 400 kilometers, no fireball formation occurred, although there were many other notable effects. 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. Also, the sky in the Pacific region was illuminated by an artificial aurora for more than seven minutes. In part, these effects were predicted by Nicholas Christofilos, a scientist who had earlier worked on the Operation Argus high-altitude nuclear shots.

According to U.S. atomic veteran Cecil R. Coale, some hotels in Hawaii offered "rainbow bomb" parties on their roofs for Starfish Prime, contradicting some reports that the artificial aurora was unexpected. According to the U.S. Department of Energy's (DOE) Office of Scientific and Technical Information (OSTI), the aurora was also visible and recorded on film from the Samoan Islands, about 3200 kilometers (2000 statute miles) from Johnston Island.

Pages 19-21 of "A 'Quick Look' at the Technical Results of Starfish Prime", August 1962 states :

"At Kwajalein, to the west, a dense overcast extended the length of the eastern horizon to a height of 5 or 8 degrees. At 0900 GMT a brilliant white flash burned through the clouds rapidly changing to an expanding green ball of irradiance extending into the clear sky above the overcast. From its surface extruded great white fingers, resembling cirro-stratus clouds, which rose to 40 degrees above the horizon in sweeping arcs turning downward toward the poles and disappearing in seconds to be replaced by spectacular concentric cirrus like rings moving out from the blast at tremendous initial velocity, finally stopping when the outermost ring was 50 degrees overhead. They did not disappear but persisted in a state of frozen stillness. All this occurred, I would judge, within 45 seconds. As the greenish light turned to purple and began to fade at the point of burst, a bright red glow began to develop on the horizon at a direction 50 degrees north of east and simultaneously 50 degrees south of east expanding inward and upward until the whole eastern sky was a dull burning red semicircle 100 degrees north to south and halfway to the zenith obliterating some of the lesser stars. This condition, interspersed with tremendous white rainbows, persisted no less than seven minutes."

"At zero time at Johnston, a white flash occurred, but as soon as one could remove his goggles, no intense light was present. A second after shot time a mottled red disc was observed directly overhead and covered the sky down to about 45 degrees from the zenith. Generally, the red mottled region was more intense on the eastern portions. Along the magnetic north-south line through the burst, a white-yellow streak extended and grew to the north from near zenith. The width of the white streaked region grew from a few degrees at a few seconds to about 5-10 degrees in 30 seconds. Growth of the auroral region to the north was by addition of new lines developing from west to east. The white-yellow auroral streamers receded upward from the horizon to the north and grew to the south and at about 2 minutes the white-yellow bands were still about 10 degrees wide and extended mainly from near zenith to the south. By about two minutes, the red disc region had completed disappearance in the west and was rapidly fading on the eastern portion of the overhead disc. At 400 seconds essentially all major visible phenomena had disappeared except for possibly some faint red glow along the north-south line and on the horizon to the north. No sounds were heard at Johnston Island that could be definitely attributed to the detonation."

"Strong electromagnetic signals were observed from the burst, as were significant magnetic field disturbances and earth currents."

In 2006, Palmer Dyal described the particle and field measurements of the Starfish diamagnetic cavity and the injected beta flux into the artificial radiation belt in the Journal of Geophysical Research . His measurements describe the explosion from 0.1 milliseconds to 16 minutes after the detonation.


While some of the energetic beta particles followed the earth's magnetic field and illuminated the sky, other high-energy electrons became trapped and formed 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 relay communication satellite ever, Telstar. Detectors on Telstar, TRAAC, Injun, and Ariel 1 were used to measure distribution of the radiation produced by the tests.

In 1963, Brown et al. reported in the Journal of Geophysical Research that Starfish Prime had created a belt of MeV electrons, and Bill Hess reported in 1968 that some Starfish electrons remained for five years. Others reported that radioactive particles from Starfish Prime descended to earth seasonally and accumulated in terrestrial organisms such as fungi and lichens.

Scientific discoveries resulting

  • The Starfish bomb contained Cd-109 tracer which helped work out the seasonal mixing rate of polar and tropical air masses. The early data are reviewed at
  • The Starfish EMP waveform measured by Richard L. Wakefield of Los Alamos led to a revolution in understanding this nuclear effect and is now available at Wakefield's 1962 report is Measurement of time interval from electromagnetic signal received in C-130 aircraft, from burst, at 11 degrees 16 minutes North, 115 degrees 7 minutes West, 24,750 feet.

See also


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