Ivy Mike was the codename given to the first full-scale test of a thermonuclear device, in which a significant fraction of the explosive yield comes from nuclear fusion. Ivy Mike was detonated on November 1, 1952, by the United States on the island of Elugelab in Enewetak Atoll, in the now independent island nation of the Marshall Islands, as part of Operation Ivy. It was the first full test of the Teller–Ulam design, a staged fusion device.

Due to its physical size and fusion fuel type (cryogenic liquid deuterium), the "Mike" device was not suitable for use as a deliverable weapon. It was intended as a "technically conservative" proof of concept experiment to validate the concepts used for multi-megaton detonations. A date within 1952 seemed feasible. It has been reported that Soviet engineers derisively referred to "Mike" as a "thermonuclear installation". It weighed approximately . The cryogenic deuterium provided the fuel for the "secondary" (fusion) stage of the explosion. The maximum radius was reached several seconds after the detonation, during which the hot fireball lifted up due to buoyancy. While still relatively close to the ground, the fireball had yet to reach its maximum dimensions and was thus approximately wide. The mushroom cloud rose to an altitude of in less than 90 seconds. One minute later it had reached , before stabilizing at with the top eventually spreading out to a diameter of with a stem wide.

The blast created a crater in diameter and deep where Elugelab had once been; the blast and water waves from the explosion (some waves up to high) stripped the test islands clean of vegetation, as observed by a helicopter survey within 60 minutes after the test, by which time the mushroom cloud and steam were blown away. Radioactive coral debris fell upon ships positioned away, and the immediate area around the atoll was heavily contaminated.

Close to the fireball, lightning discharges were rapidly triggered.

The entire shot was documented by the filmmakers of Lookout Mountain studios. A post-production explosion sound was overdubbed over what was a completely silent detonation from the vantage point of the camera, with the blast wave sound only arriving later, as akin to thunder, with the exact time depending on its distance. The film was also accompanied by powerful, Wagner-esque music featured on many test films of that period and was hosted by actor Reed Hadley. A private screening was given to President Dwight D. Eisenhower who had succeeded President Harry S. Truman in January 1953. In 1954, the film was released to the public after censoring, and was shown on commercial television channels. He was able to receive first notice that the test was successful by observing a seismometer, which picked up the shock wave that traveled through the earth from the Pacific Proving Grounds. In his memoirs, Teller wrote that he immediately sent an unclassified telegram to Dr. Elizabeth "Diz" Graves, the head of the rump project remaining at Los Alamos during the shot. The telegram contained only the words "It's a boy," which came hours earlier than any other word from Enewetak.

Scientific discoveries

thumb|Mike [[mushroom cloud.]]

An hour after the bomb was detonated, U.S. Air Force pilots took off from Enewetak Island to fly into the atomic cloud and take samples. Pilots had to monitor extra readouts and displays while "piloting under unusual, dangerous, and difficult conditions” including heat, radiation, unpredictable winds and flying debris. "Red Flight" Leader Virgil K. Meroney flew into the stem of the explosion first. In five minutes, he had gathered all the samples he could, and exited. Next Bob Hagan and Jimmy Robinson entered the cloud. Robinson hit an area of severe turbulence, entering a spin and barely retaining consciousness. He regained control of his plane at 20,000 feet, but the electromagnetic storm had disrupted his instruments. In rain and poor visibility, without working instruments, Hagan and Robinson were unable to find the KB-29 tanker aircraft to refuel.

Fuel tanks on the airplane's wings had been modified to scoop up and filter passing debris. The filters from the surviving planes were sealed in lead and sent to Los Alamos, New Mexico for analysis. Radioactive and contaminated with calcium carbonate, the "Mike" samples were extremely difficult to handle. Scientists at Los Alamos found traces in them of isotopes plutonium-246 and plutonium-244.

A simplified and lightened bomb version (the EC-16) was prepared and scheduled to be tested in operation Castle Yankee, as a backup in case the non-cryogenic "Shrimp" fusion device (tested in Castle Bravo) failed to work; that test was canceled when the Bravo device was tested successfully, making the cryogenic designs obsolete.

<gallery class="center" widths="220">

File:Ivy Mike (Eniwetok-Atoll - 31. Oktober 1952).jpg

File:Ivy Mike 002.jpg

File:Ivy Mike fallout map.png|Nuclear fallout map of Mike test.

File:Ivy Mike fireball.jpg|Mike fireball.

File:Enewetak Atoll 2005-09-01, EO-1 bands 10-8-2-1.png|Mike test crater, relative to Enewetak Atoll.

File:Ivy Mike overshooting top.jpg|Mike mushroom cloud central stem's updraft tropopause overshoots.

</gallery>

See also

  • History of nuclear weapons
  • Operation Castle
  • RDS-6s – first Soviet thermonuclear test, coming less than a year later

Notes

References

Further reading

  • – formerly classified.
  • Sonicbomb.com: "Ivy Mike test" video
  • Technical Photography on Operation Ivy by EG&G – &nbsp;