Nuclear fission Mexico, which was the scientific hub for research on bomb development and design. Other sites, notably the Berkeley Radiation Laboratory and the Metallurgical Laboratory at the University of Chicago, played important contributing roles. Overall scientific direction of the project was managed by the physicist J. Robert Oppenheimer. In July 1945, the first atomic explosive device, dubbed "Trinity", was detonated in the New Mexico desert. It was fueled by plutonium created at Hanford. In August 1945, two more atomic devices – "Little Boy", a uranium-235 bomb, and "Fat Man", a plutonium bomb – were used against the Japanese cities of Hiroshima
Mark 39 nuclear bomb Mark 39 nuclear bomb The Mark 39 nuclear bomb and W39 nuclear warhead were versions of an American thermonuclear weapon, which were in service from 1957 to 1966. The Mark 39 design was a thermonuclear bomb (see Teller-Ulam design) and had a yield of 3.8 megatons. The design is an improved Mark 15 nuclear bomb design (the TX-15-X3 design and Mark 39 Mod 0 were the same design). The Mark 15 was the first lightweight US thermonuclear bomb. The W39 warhead is in diameter and long, with a weight of to . It was used on the SM-62 Snark missile,