Neither Little Boy nor Fat Man: the bomb that inaugurated the Nuclear Age was Trinity and was detonated 80 years ago today.
The Manhattan Project is one of the least secret top-secret projects in history . Its mission was to scientifically develop the first atomic bomb , and although it brought together researchers, engineers, and military personnel from various countries, it was primarily spearheaded by the United States.
The fruits of that research, which everyone knows, were seen in Hiroshima and Nagasaki : in August 1945, Japanese cities were victims of nuclear attacks by the United States, marking the end of World War II.
The Little Boy and Fat Man bombs , the only instances of combat use of nuclear weapons in history, killed an estimated 220,000 Japanese citizens outright and more than 200,000 died as a result of the lethal radiation overdose.
But these were not the first nuclear weapon explosions: before them, the United States had tested its power with Trinity .
At 5:29 a.m. on July 16, 1945, in a remote corner of the Alamogordo Desert, New Mexico, a light brighter than a thousand suns lit up the sky. It was the aftermath of Trinity , the first detonation of an atomic bomb.
That 20-kiloton explosion not only confirmed that humanity had entered the Nuclear Age, but also paved the way for the bombings of Hiroshima and Nagasaki weeks later.
Designed as part of the top-secret Manhattan Project, Trinity was a plutonium implosion bomb , a distinct design from Little Boy , which used enriched uranium.
The device, known as The Gadget , used a plutonium-239 core surrounded by high-precision conventional explosives. When these explosives exploded simultaneously from all sides, they compressed the plutonium so tightly that they triggered the desired nuclear reaction.
The explosion vaporized the metal test tower, created a crater more than two meters deep, raised a column of fire and debris 12 kilometers high and was visible more than 60 kilometers away .
It was the first successful experiment demonstrating that atomic energy could be unleashed in a controlled—and devastating—way by human means.
The explosion vaporized the metal test tower, created a crater more than two meters deep, raised a column of fire and debris 12 kilometers high, and was visible from more than 60 kilometers away.
Following the detonation of Trinity in July 1945, an era of nuclear testing began that lasted more than half a century . Between 1945 and 1996 , more than 2,000 nuclear tests were conducted around the world, in a wide variety of environments: deserts, Pacific atolls, underground tunnels, and even under the ocean.
The first tests were carried out outdoors , in the atmosphere. In these explosions, radiation and radioactive debris were freely dispersed, leading to growing concerns about radioactive fallout . The United States and the Soviet Union alone conducted more than 200 atmospheric tests each. France, the United Kingdom, and China also conducted them, until such tests were banned in 1963 by the Partial Nuclear Test Ban Treaty .
From then on, the powers moved their tests underground . There, most of the explosions remained contained, although some released radioactive particles to the outside if the blast wave reached the surface.
Underwater tests were also carried out, although in smaller numbers. The first was Operation Crossroads in 1946, when the United States detonated a bomb off Bikini Atoll to study the effects of a nuclear explosion on warships. In 1955, Operation Wigwam took a bomb to a depth of 600 meters to assess its impact on submarines. These tests generated enormous plumes of water and steam, as well as radioactive contamination that affected nearby towns, vessels, and infrastructure.
Each test provided valuable data on the destructive power, the behavior of the weapon, and the effects on the environment and human health, but it also left an environmental and geopolitical mark that persists to this day . As a result, international pressure mounted until, in 1996, the Comprehensive Nuclear-Test-Ban Treaty (CTBT) was opened for signature , prohibiting all nuclear explosions in any environment.
The CTBT, however, has yet to officially enter into force , as several key countries have not ratified it: China, the US, India, Pakistan, North Korea, Israel, Iran, Egypt, and Russia. However, only six underground nuclear tests have been confirmed since 1996 , all conducted by North Korea between 2006 and 2017.
Trinity's scientific and technological legacyBeyond its geopolitical and military dimensions, Trinity represented an unprecedented milestone in the history of applied science and engineering . The bomb's design involved radical advances in multiple disciplines: nuclear physics, materials chemistry, metallurgy, high-precision explosives, high-speed electronics, and computer modeling.
It was also one of the first large-scale projects to combine scientific research, technological development and industrial infrastructure, anticipating the model of today's international scientific megaprojects .
The test made it possible, for the first time, to observe the real effects of a nuclear explosion : the formation of the mushroom cloud, the generation of electromagnetic pulses (EMP), the propagation of supersonic shock waves and the dangerous dispersion of radioactive material, a phenomenon still little understood at that time.
It also served as the experimental basis for the design of Fat Man , the bomb that would later be dropped on Nagasaki. Little Boy , on the other hand, was not tested before use, as its mechanism was considered simpler.
Trinity also ushered in a new era of scientific instrumentation . High-speed cameras, seismic sensors, radiation meters, and pioneering remote telemetry techniques were used to record real-time data from an unprecedented event.
Today, 80 years later, the world continues to live in the shadow of that flash.
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