On this day in 1945, at 5:29:45 a.m., the most urgent work of the Manhattan Project comes to an explosive end as the first atom bomb is successfully tested in Alamogordo, New Mexico. The scientists and a few dignitaries had removed themselves 10,000 yards away to observe as the first mushroom cloud of searing light stretched 40,000 feet into the air and generated the destructive power of 15,000 to 20,000 tons of TNT. The tower on which the bomb sat was vaporized, and the surrounding desert surface fused to glass for a radius of 800 yards.
Going to origin, in 1939 American scientists, many of whom had fled from fascist regimes in Europe, were aware of advances in nuclear fission and were concerned that Nazi Germany might develop a nuclear weapon. The physicists Leo Szilard and Eugene Wigner persuaded Albert Einstein to send a letter to U.S. President Franklin D. Roosevelt warning him of that danger and advising him to establish an American nuclear research program.
The Advisory Committee on Uranium was set up in response. As such, the beginning of the project could be dated to December 6, 1941 (the day preceding Pearl Harbor), with the creation of the Office of Scientific Research and Development, headed by Vannevar Bush. American physicist J. Robert Oppenheimer headed the specific project to develop the atomic bomb, and Edward Teller was among the first recruited for the task. Leo Szilard and Enrico Fermi built the first nuclear reactor, secreted under the spectator stands of the University of Chicago’s Stagg Field.
Ernest Orlando Lawrence was program chief in charge of the development of the electromagnetic process of separating uranium-235. Other notable researchers included Otto Frisch, Niels Bohr, Felix Bloch, James Franck, Emilio Segrè, Klaus Fuchs, Hans Bethe, and John von Neumann. The person who oversaw the project, however, was not a scientist; Brig. Gen. Leslie R. Groves of the Army Corps of Engineers, the son of a chaplain, was the boss.
Several lines of research were pursued simultaneously in various locales. Both electromagnetic and fusion methods of separating the fissionable uranium-235 from uranium-238 were explored at Oak Ridge in Tennessee. The production of plutonium-239, first achieved at the University of Chicago, was further pursued at the Hanford Engineer Works in Washington.
In the meantime, at Los Alamos, New Mexico, scientists found a way to bring the fissionable material to supercritical mass, and thus explosion, to control the timing, and to devise a weapon to house it. Other than what some could observe as its moral flaws, the test concluded flawlessly on this very day 75 years ago.
The question now became–on whom was the bomb to be dropped? Germany was the original target, but the Germans had already surrendered. The only belligerent remaining was Japan.