At 7:15 in the morning local time on 1 November 1952, the United States detonated the first true hydrogen bomb on the island of Elugelab, in Enewetak Atoll in the Marshall Islands. Code-named Mike and nicknamed the Sausage, it was not a weapon anyone could drop. It was an experiment the size of a small house, and it yielded 10.4 megatons, around 700 times the Hiroshima bomb. When the cloud cleared, Elugelab was gone.

A Building, Not a Bomb

Mike was the first full-scale test of the Teller–Ulam idea of staged radiation implosion: an atomic bomb, here a TX-5, whose radiation compresses and ignites a separate fusion stage. The fusion fuel was liquid deuterium, which has to be kept at about minus 250°C, held in a giant thermos-like Dewar flask with a plutonium rod down its centre and a natural uranium tamper weighing more than five tonnes around it. The whole device weighed about 82 tons. It was designed by a Los Alamos team under J. Carson Mark. Most of the yield, about 77 percent, came not from fusion itself but from fast fission of that uranium tamper by the neutrons the fusion released.

“The Island of Elugelab Is Missing”

Within 90 seconds the cloud had climbed to 57,000 feet and it eventually stabilised at around 120,000 feet, spreading some 60 miles across. Where Elugelab had stood there was a crater about 1.9 kilometres wide and 50 metres deep in the reef.

Atomic Energy Commission chairman Gordon Dean’s summary for Dwight D. Eisenhower became the line everyone remembers: “The island of Elugelab is missing!” One detail is usually garbled. Eisenhower was not yet president when Mike was fired; he won the election three days later, on 4 November 1952, and took office in January 1953. Dean was briefing the president-elect.

Into the Cloud

Measuring what Mike had done meant collecting debris from inside its cloud. About an hour and a half after the shot, four F-84G Thunderjets of “Red Flight”, fitted with sampling pods on their wingtips and directed from a B-36, flew into the stem. Flight leader Lt. Col. Virgil Meroney went in first, at around 40,000 feet; the top of the cloud was far above anything the jets could reach. Inside, one of the pilots later recalled, it was dark and boiling.

Capt. Jimmy Priestly Robinson, 28, had the worst of it. His autopilot disengaged in the turbulence and his F-84G stalled; he recovered only at about 20,000 feet. Short of fuel after the extra manoeuvring, the flight headed back for Enewetak. Robinson’s engine flamed out at 13,000 feet. A rescue helicopter saw his jet gliding in wings-level north of the atoll before it hit the water, skipped, flipped and sank. Robinson was never found. He received a posthumous Distinguished Flying Cross.

The Film

Mike was filmed in colour from many angles, and the US government produced an hour-long film, Operation Ivy, about the test series. The version held in the Department of Energy archive is officially “sanitized”. It is this footage, of the fireball rising over the reef and the cloud spreading across the sky, that circulates online today.

What the Popular Version Gets Right

The account being shared is accurate on the essentials: 1 November 1952, a building-sized, undeliverable device nicknamed the Sausage, cryogenic liquid deuterium ignited by an atomic primary, 10.4 megatons, Elugelab erased and a crater 6,240 feet wide and 164 feet deep. Two details need correcting. Eisenhower was president-elect, not president, when Gordon Dean told him the island was missing. And the 82-ton weight is the figure most often quoted, but some histories put the device at 65 to 70 tons.

Sources: Carey Sublette, Nuclear Weapon Archive, “Operation Ivy”; Atomic Archive, “The Hydrogen Bomb”; Joanne Lamm, “The Island is Missing”, US Army Heritage and Education Center (28 October 2010); Mark Wolverton, “Into the Mushroom Cloud”, Air & Space Magazine (August 2009); Pacific Wrecks, F-84G 51-1040; US Department of Energy, Operation Ivy film record 0800012.