Nagasaki Atomic Bomb Museum
The atomic bomb was developed by scientists working under the Manhattan Project. The project was granted funding on December 6, 1941, with American leaders aiming for a new invention that would serve as a wartime weapon. The decision to drop an atomic bomb on Japan had been made by 1943, and a shortlist of candidate target cities was in place in 1945. At the time, it was argued that an atomic bombing would bring about a more rapid end to the war. Hiroshima, the first target, was selected to show the power of America's new weapon. The second bombing, of Nagasaki, was intended to demonstrate that the USA had a large arsenal. At 11:02 A.M. local time on August 9, 1945, the atomic bomb, nicknamed Fat Man as its code name by Robert Serber in the United States (after Sydney Greenstreet's character in "The Maltese Falcon") was dropped on Nagasaki, forever changing the city's landscape. A mushroom cloud rose to an altitude of 45,000 feet above the city.
RDS-1
The RDS-1 explosion yielded 22 kilotons of TNT, similar to the American Gadget and Fat Man bombs. At Lavrentiy Beria's insistence, the RDS-1 bomb was designed as an implosion weapon similar to the Fat Man bomb dropped on Nagasaki, Japan; RDS-1 also had a solid plutonium core. The bomb designers had developed a more sophisticated design (tested later as RDS-2), but rejected it due to the known reliability of the Fat Man type design, the USSR having received extensive intelligence on the design of the Fat Man bomb during World War II.