Ivy Mike was the codename given to the first test of a thermonuclear device, in which part of the explosive yield comes from nuclear fusion. It was detonated on November 1, 1952 by the United States on Enewetak, an atoll in the Pacific Ocean, as part of Operation Ivy. The device was the first full test of the Teller-Ulam design, a staged fusion bomb, and was the first successful test of a hydrogen bomb.
The blast created a crater 6,240 feet (1.9 km) in diameter and 164 feet (50 m) deep where Elugelab had once been; the blast and water waves from the explosion (some waves up to twenty feet 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 35 miles (48 km) from the blast, and the immediate area around the atoll was heavily contaminated for some time. Produced by intensely concentrated neutron flux about the detonation site were two new elements, einsteinium and fermium.
The nuclear explosion was photographed by high-speed rapatronic cameras less than 1 millisecond after detonation. Developed by Dr. Harold Edgerton in the 1940s, the rapatronic photographic technique allowed nuclear explosion’s fireball growth to be recorded on film. The exposures were often as short as 10 nanoseconds, and each rapatronic camera would take exactly one photograph.