Ivy Mike was the codename given to the first full-scale test of a thermonuclear device, in which part of the explosive yield comes from nuclear fusion.[1][2][3]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.[4]
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.[4]
Samples from the explosion had traces of the isotopes plutonium-246, plutonium-244, and the predicted elements einsteinium and fermium.[5]
Beginning with the Teller–Ulam breakthrough in March 1951, there was steady progress made on the issues involved in a thermonuclear explosion and there were additional resources devoted to staging, and political pressure towards seeing, an actual test of a hydrogen bomb.[6]: 137–139 A date within 1952 seemed feasible.[7]: 556 In October 1951 physicist Edward Teller pushed for July 1952 as a target date for a first test, but project head Marshall Holloway thought October 1952, a year out, was more realistic given how much engineering and fabrication work the test would take and given the need to avoid the summer monsoon season in the Marshall Islands.[8]: 482 On June 30, 1952, United States Atomic Energy Commission chair Gordon Dean showed President Harry S. Truman a model of what the Ivy Mike device would look like; the test was set for November 1, 1952.[7]: 590
One attempt to significantly delay the test, or not hold it at all, was made by the State Department Panel of Consultants on Disarmament, chaired by J. Robert Oppenheimer, who felt that avoiding a test might forestall the development of a catastrophic new weapon and open the way for new arms agreements between the United States and the Soviet Union.[6]: 139–142 The panel lacked political allies in Washington, however, and no test delay was made on this account.[6]: 145–148
There was a separate desire voiced for a very short delay in the test, for more political reasons: it was scheduled to take place just a few days before the November 4 holding of the United States presidential election, 1952.[8]: 497 Truman wanted to keep the thermonuclear test away from partisan politics but had no desire to order a postponement of it himself; however he did make it known that he would be fine if it was delayed past the election due to "technical reasons" being found.[7]: 590–591 [8]: 497–498 Atomic Energy Commission member Eugene M. Zuckert was sent to the Enewetak test site to see if such a reason could be found, but weather considerations – on average there were only a handful of days each month that were suitable for the test – indicated it should go ahead as planned, and in the end no schedule delay took place.[7]: 590–592 [8]: 498