The Manhattan Project

The Manhattan Project was a research and development project during World War II that produced the first nuclear weapons. It was led by the United States with support from Britain and Canada. In 1939, American scientists, many of them refugees from fascist regimes in Europe, organized a project to utilize the newly discovered fission process for military purposes.

Nuclear fission was discovered by the German chemists Otto Hahn and Fritz Strassman in 1938, and scientists realized the theoretical possibility of creating an atomic bomb. There were fears among the scientific community that Nazi Germany would be the first to develop nuclear weapons. Thus, in the summer of 1939, Albert Einstein was persuaded by his fellow scientists to use his influence and present the military potential of an uncontrolled fission chain reaction to President Roosevelt. The Manhattan Project acquired government funding to begin research.

As World War II went on, the Manhattan Project grew in scale, eventually employing over 130,000 people and costing almost $2 billion USD (roughly equivalent to $22 billion USD in 2016). Research and production took place at over 30 sites across the United States, the United Kingdom, and Canada.

Two types of atomic bombs were developed concurrently during the war. One was a relatively simple gun-type fission weapon using uranium-235, and the other was a more complex implosion-type weapon using plutonium. One challenge scientists faced was acquiring the materials required to make the bombs. Uranium-235 is an isotope that needs to be refined from the naturally-occurring uranium, which is mostly uranium-238. However, uranium-235 only makes up 0.7% of natural uranium, and the two isotopes’ chemical identities makes them difficult to separate. Three methods were used for uranium enrichment: electromagnetic separation using a calutron, gaseous diffusion, and thermophoresis separation. In order to make plutonium, uranium needed to be irradiated and transmuted into plutonium, which was then separated from the uranium using the bismuth phosphate process.

The first atomic bomb ever detonated was exploded at 5:30 AM on July 16, 1945 at the Alamogordo air base in New Mexico. The bomb was an implosion-type bomb, and it was detonated on top of a steel tower surrounded by scientific equipment. Scientists occupied bunkers almost 6 miles away to gather data and monitor the explosion. The mushroom cloud created by the bomb rose over 40,000 feet, and the bomb’s explosive power was equivalent to 20,000 tons of TNT. This nuclear test was code named Trinity.

Towards the end of World War II, the United States detonated two nuclear weapons over the Japanese cities of Hiroshima and Nagasaki. The atomic bomb code named “Little Boy” was dropped from a Boeing B-29 Superfortress on Hiroshima on August 6, 1945. It detonated at an altitude of 1,750 feet with a blast estimated to be the equivalent of 13,000 tons of TNT. A second B-29 dropped the atomic bomb code named “Fat Man” on Nagasaki on the morning of August 9, 1945. The explosion had a blast yield equivalent to 21,000 tons of TNT; however, the geographical features of the region limited the area affected. The two bombing killed between 129,000-226,000 people, which was mainly composed of civilians. They remain the only use of nuclear weapons in war. 

Sources:

https://www.britannica.com/event/Manhattan-Project

https://www.atomicheritage.org/history/manhattan-project

https://www.history.com/topics/world-war-ii/the-manhattan-project

https://en.wikipedia.org/wiki/Manhattan_Project

https://upload.wikimedia.org/wikipedia/commons/8/8d/Trinity_shot_color.jpg