The Gadget bomb is a spherical device with a plutonium core, elevated to the top of a 30-meter tower during the famous Trinity test explosion.
The first nuclear test in the world, codenamed Trinity, took place on July 16, 1945, and is often regarded as the beginning of the Atomic Age. The atomic bomb involved in this explosion, known as Gadget, was developed as part of the United States’ Manhattan Project to create nuclear weapons.
Gadget, the first atomic bomb in the world. (Photo: Rare Historical Photos).
Gadget is an implosion-type plutonium device with a design similar to the Fat Man bomb used in the atomic bombing of Nagasaki, Japan, a few weeks after the Trinity test. The two bombs have only a few minor differences, with the most obvious variance being in the detonators and the outer casing.
Gadget is an implosion device shaped like a sphere, consisting of 32 “lenses” made from two different types of high explosives. These lenses surround a plutonium sphere at the center of Gadget. Special detonators are designed to trigger the explosive lenses with perfect synchronization, compressing the plutonium core to cause a nuclear explosion. At the center of Gadget, converging shock waves create a pressure 500,000 times greater than the atmospheric pressure at Earth’s surface.
Assembly of Gadget began on July 13, 1945, at the McDonald Ranch House in New Mexico, USA. After the polonium-beryllium detonator was assembled, physicist Louis Slotin placed it inside the two hemispheres of the plutonium core. Next, metallurgist Cyril Smith inserted the plutonium core into a uranium cylinder. The gaps in the cylinder were sealed with 0.013 mm gold foil, and the two halves of the cylinder were secured with uranium spacers and screws.
For the test, Gadget was raised to the top of a 30-meter tower. (Photo: Rare Historical Photos).
Once Gadget was completed, the Manhattan Project team transported the bomb to the base of the test tower. The bomb was then lifted to the top of the 30-meter tower. Some individuals worried that the Trinity test might ignite Earth’s atmosphere, annihilating all life on the planet, although calculations indicated that this was not possible even with devices far more powerful than the bomb at that time. More conservative estimates suggested that New Mexico would be destroyed. The expected yield of Gadget was estimated to be between 0 (if it failed to detonate) and 20,000 tons of TNT.
At 5:29 AM local time on July 16, 1945, Gadget exploded, leaving a radioactive glass crater 3 meters deep and 340 meters wide in the desert. At the moment of detonation, the surrounding mountains were illuminated “brighter than day” for 1 to 2 seconds, with heat reported to be “as hot as an oven.” The colors of the emitted light changed from purple to green, finally turning white.
The Trinity explosion, 16 milliseconds after activation. The highest point of the mushroom cloud reached approximately 200 meters. (Photo: Rare Historical Photos).
The roar of the shock wave took 40 seconds to reach the observers. The shock wave could be felt as far away as 160 kilometers, and the mushroom cloud reached a height of 12.1 kilometers.
As the initial excitement of witnessing the explosion faded, test director Kenneth Bainbridge remarked to theoretical physicist J. Robert Oppenheimer, a member of the Manhattan Project team: “Now we are all sons of bitches.” Oppenheimer later shared that while watching the test, he remembered a line from the Bhagavad Gita, a Hindu scripture: “Now I am become Death, the destroyer of worlds.”
