Operation IVY (1952)

The island of Elugelab is missing!" President Eisenhower heard this short report on the Mike shot in Operation IVY from Gordon Dean, Chairman of the Atomic Energy Commission.

Mike was the first full-scale hydrogen explosive device to be tested, yet was only a scientific test of a thermofusion implosion device concept. Mike was not a deliverable weapon.

The island where the device was detonated was vaporized. The hole Mike left was big enough to accommodate 14 Pentagon-size buildings and deep enough to hold 17 story building under water, in a crater one mile in diameter and approximately 175 feet deep. Mike's yield was an incredible 10.4 megatons, signaling the proof-tested expansion of the nuclear explosive technology concepts from nuclear fission to thermofusion. Thermofusion is the same process that occurs in the core of the Sun.

This test, however, was not the first test of a liquid thermonuclear explosive. The first test ever conducted into the fusion principle occurred during Operation GREENHOUSE at Eniwetok in 1951, with the 225 kiloton George test. Another test of hydrogen in the center of a nuclear weapon before Mike was during the GREENHOUSE Item test at Eniwetok, proving a critical stockpiling yield efficiency concept, called "boosting."

The detonation of the Mike device was the climax of an intense debate over what would be the nation's correct response to the startling news in 1949 that the Soviet Union had detonated a nuclear weapon. Many wanted the U.S. to develop the means to produce and field a large number of fission bombs of varying yields which could be used for tactical purposes. Others believed that the country should institute a crash program like the Manhattan Project to develop a Super weapon based on the idea of forcing together or fusing light atoms with a fissile device to produce enormous amounts of energy.

After a bitter fight among scientific, government and military officials, the President opted for a crash program to demonstrate the Super bomb, now called a hydrogen or thermonuclear weapon. Many designs were evaluated and rejected until the Mike proposal came along. This concept involved the cooling of hydrogen fuel to a liquid form, near absolute zero, and fusing the hydrogen nuclei into helium using a nuclear fission bomb as a trigger.

The Mike device was a 22-foot-long, 5-foot-diameter cylinder housing canisters of liquid hydrogen fuel. These liquid fuel canisters were heavily encased with the nuclear fission explosive trigger.

The Mike shot occurred on October 31, 1952, as scientists watched from 40 miles away as the mushroom cloud rose into the stratosphere.

Mike was followed on November 15, 1952 by the King shot, the largest all-fission device ever tested by the United States. It was a uranium super oralloy Mark 18 prototype implosion core in a Mark 6D casing, with an advanced warhead that enabled it to produce 500 kilotons of equivalent TNT explosive energy.