Mike

The Mike device was a 22-foot-long, 5-foot-diameter cylinder housing canisters of liquid hydrogen fuel. These canisters were surrounded by the atomic trigger. Although MIKE was a thermonuclear, or fusion, device, a significant portion of its energy release resulted from fission processes. Should it function as envisioned, the yield would be 10,000 kt, or 10 Mt, with an outside possibility of 50 Mt. At design yield, the energy release would be 500 times larger than the atomic bombs then in stockpile.

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.

Opponents of fusion weapons argued that the Soviets could be persuaded not to develop these weapons if the United States would refrain. They further argued that such weapons were not much more effective than high-yield fission weapons. Finally, they argued that given the dynamism of the U.S. nuclear program, the Soviets could be quickly overtaken if they pushed ahead with fusion weapons.

The advocates of fusion weapons won the dispute, and MIKE became the cen* terpiece of Operation IVY and the proof test of the new concept. 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 the atomic bomb as a trigger.

Preparations for the shot were extensive and meticulous. As usual with nuclear tests, such things as assembly and detonation of device, necessary evacuation of personnel, reentry, and recovery of samples and data records, and radiological safety in general were rehearsed at length. Preparations included extensive practices in the United States that centered on the explosive device assembly and on air operations.

Mechanical portions of the device were fabricated in Buffalo, New York, by American Car and Foundry Industries (ACF). A mockup of the device with dummy material for the high explosives and the critical nuclear materials was assembled in mid-July 1952 in a building in Buffalo that had dimensions similar to the cab being built on Eluklab. The purpose of the construction of the mockup was to familiarize personnel with assembly procedures and to see if any redesign of the components was necessary.

The MIKE shot was expected to produce a yield far surpassing that of any earlier test, and the radioactive fallout might be a more serious problem both to participants and off-island inhabitants. Surface and near-surface bursts posed radiation exposure problems. These detonations create more radioactive debris because more material is available for activation within range of the ncutrons generated by the explosion. In such explosions the extreme heat vaporizes device materials and activated Earth materials as well. These materials cool in the presence of additional material gouged out of the burst crater. This extra material causes the particles formed as the fireball cools to be larger in size, with radioactivity embedded in them or coating their surfaces. The rising cloud will lift these particles to altitudes that will depend on the particle size and shape and the power of the rising air currents in the cloud, which in turn depend on the yield of the detonation. The largest particles will fall back into the crater or very near the burst area with the next largest falling nearby. It has been estimated that as much as 80 percent of the radioactive debris from a land-surface burst falls out within the first day following the burst.

Bursts on the surface of the seawater generate particles consisting mainly of salt and water drops that are smaller and lighter than the fallout particles from a land-surface burst. As a consequence, water-surface bursts produce less early fallout than similar devices detonated on land. Large-yield surface bursts in the PPG over relatively shallow lagoon waters or on very little truly dry land probably formed a complex comhination of land-surface and water-surface-burst particle-size characteristics.

Weapon diagnosticians used sophisticated techniques to follow the processes that occur during the device explosion. Detectors and collectors were run up to, and sometimes inside, the device case so that the radiation being sampled could be directly channeled some distance away and there be recorded by instrumentation designed to survive the ensuing blast. To enhance its transport, radiation was conducted through pipes (often evacuated or filled with special gases) from the device to stations where recording instrumentation was located or where the information could be retransmitted to a survivable recording station.

The Mike shot occurred on October 31, 1952, and as scientists watched from 40 miles away as the mushroom cloud rose into the stratosphere, the second generation of nuclear weapons was born. The 10.4-MT blast produced a tremendous fireball followed by a gigantic mushroom cloud. The description of the event by the author of History -- Task Group 132.1 and reproduced in History of Operation IVY bears repeating.

"The Shot, as witnessed aboard the various vessels at sea, is not easily described. Accompanied by a brilliant light, the heat wave was felt immediately at distances of thirty to thirty-five miles. The tremendous fireball, appearing on the horizon like the sun when half-risen, quickly expanded after a momentary hover time and appeared to be approximately a mile in diameter before the cloud-chamber effect and scud clouds partially obscured it from view. A very large cloudchamber effect was visible shortly after the detonation and a tremendous conventional mushroom-shaped cloud soon appeared, seemingly balanced on a wide, dirty stem. Apparently, the dirty stem was due to the cora± particles, debris, and water which were sucked high into the air. Around the base of the stem, there appeared to be a curtain of water which soon dropped back around the area where the island of Elugelab [Eluklab] had been.

"The shock wave and sound arrived at the various ships approximately two and one-half minutes after the detonation, accompanied by a sharp report followed by an extended, broken, rumbling sound. The pressure pulse and the reduced pressure period as received by ear were exceptionally long.

"Although the upper cloud first appeared unusually white, a reddish-brown color could soon be seen within the shadows of its boiling mass as it ascended to greater height and spread out over the Atoll area. At approximately H+30 minutes, the upper cloud was roughly sixty miles in diameter with a stem, or lower cloud, approximately twenty miles in diameter. The juncture of the stem with the upper cloud was at an altitude of about 45,000 feet. Numerous projecting fingers could be observed in the neighborhood of the juncture of the stem with the upper cloud. ....

"The cloud had ascended very rapidly and soon appeared, in the words of one observer, to have "splashed" against the tropopause. After approximately fifty-six minutes, the entire cloud appeared to have become stabilizeU at an altitude of over 120,000 feet, though this figure was later questioned also. By this time, deforming effects by winds were becoming apparent though as late as sunset on M-Day distant and high portions of the cloud could still be observed."

Measured amounts of radioactive contamination were puzzlingly small; most of the radioactive debris seemed to have disappeared from the face of the Earth, apparently dispersed into the uppermost reaches of the atmosphere. There were no adverse “geophysical consequences,” such as tsunamis or perceptible effects, on the weather or climate of the Earth; no nuclear test at a Pacific atoll would ever produce damaging seismic sea waves.

The blast destroyed Eluklab Island, leaving a submerged crater about 6,300 feet (1.9 km) in diameter and 160 feet (49 meters) deep, large enough to hold 14 buildings the size of the Pentagon [claims that the hole Mike left was deep enough to hold the Empire State Building are exciting but unsubstantiated]. Although the novelty of the experiment made yield prediction difficult, the device designers expected a yield of at least 4 MT and perhaps as much as 10 MT, assuming a fusion reaction could be trig-gered. Even at the lower yield, MIKE would be by far the most powerful nuclear device ever detonated. Mike's yield was an incredible 10.4 megatons, signaling the expansion of the nuclear arsenal from fission to fusion, the same process that occurs in the Sun.

As designed, MIKE was too heavy (80 tons) to be practical. Following the initial experimental demonstration of the Ulam-Teller design in Operation Ivy (the Sausage device detonated in the Ivy Mike test) both weapon labs rushed to develop a number of deliverable weaponized designs. The original schedule included a weaponized version of the cryogenic fuel system used in Sausage (designated the EC-16, the test device being named JUGHEAD); plus a variety of other extensions and new concepts. Reduction in weight to about 20 tons, and in diameter to about 65 inches may be possible by: engineering with smaller safety factors, reducing the volume of the thermonuclear reaction vessel with a sacrifice of yield, and using Li6D instead of liquid deuterium.

On 12 August 1953, the Soviet Union successfully tested a half megaton RDS-6s thermonuclear device, which unlike the Americans could be made in the form of a bomb, transported by a heavy bomber, and after finalization, could easily be put into series production. In response to this advance, the pace of American research and development quickened.

Operation Redwing, a 17-test nuclear weapons series, was conducted at the Pacific Proving Ground between May 4 and July 21, 1956. The Atomic Energy Commission (AEC) tested high-yield thermonuclear devices that could not be tested at the Nevada Test Site. The AEC's progress in miniaturization of warheads had accelerated to where the equivalent of the 90-ton weight of the MIKE device in Operation Ivy could now be dropped from a bomber. Operation Redwing also further advanced the AEC's designs of nuclear weapons that would produce reduced fallout and provided new information for the design of nuclear warheads for missiles.