The Manhattan Project

On the morning of August 6, 1945, a B-29 bomber named Enola
Gay flew over the industrial city of Hiroshima, Japan and dropped the
first atomic bomb ever. The city went up in flames caused by the
immense power equal to about 20,000 tons of TNT. The project was a
success. They were an unprecedented assemblage of civilian, and
military scientific brain power—brilliant, intense, and young, the
people that helped develop the bomb. Unknowingly they came to an
isolated mountain setting, known as Los Alamos, New Mexico, to design
and build the bomb that would end World War 2, but begin serious
controversies concerning its sheer power and destruction. I became
interested in this topic because of my interest in science and
history. It seemed an appropriate topic because I am presently
studying World War 2 in my Social Studies Class. The Hiroshima and
Nagasaki bombings were always taught to me with some opinion, and I
always wanted to know the bomb itself and the unbiased effects that it
had. This I-search was a great opportunity for me to actually fulfill
my interest.
The Manhattan Project was the code name for the US effort
during World War II to produce the atomic bomb. It was appropriately
named for the Manhattan Engineer District of the US Army Corps of
Engineers, because much of the early research was done in New York
City (Badash 238). Sparked by refugee physicists in the United
States, the program was slowly organized after nuclear fission was
discovered by German scientists in 1938, and many US scientists
expressed the fear that Hitler would attempt to build a fission bomb.
Frustrated with the idea that Germany might produce an atomic bomb
first, Leo Szilard and other scientists asked Albert Einstein, a
famous scientist during that time, to use his influence and write a
letter to president FDR, pleading for support to further research the
power of nuclear fission (Badash 237). His letters were a success,
and President Roosevelt established the Manhattan Project.
Physicists from 1939 onward conducted much research to find
answers to such questions as how many neutrons were emitted in each
fission, which elements would not capture the neutrons but would
moderate or reduce their velocity , and whether only the lighter and
scarcer isotope of uranium (U-235) fissioned or the common isotope
(U-238) could be used. They learned that each fission releases a few
neutrons. A chain reaction, therefore, was theoretically possible, if
not too many neutrons escaped from the mass or were captured by
impurities. To create this chain reaction and turn it into a usable
weapon was the ultimate goal of the Manhattan Project.
In 1942 General Leslie Groves was chosen to lead the project,
and he immediately purchased a site at Oak Ridge, Tenn., for
facilities to separate the necessary uranium-235 from the much more
common uranium-238. Uranium 235 was an optimal choice for the bomb
because of its unusually unstable composition. Thus, the race to
separate the two began. During that time, the work to perfect the
firing mechanism and structure of the bomb was also swiftly underway.
General Groves’ initial task had been to select a scientific
director for the bomb project. His first two choices, Ernest O.
Lawrence, director of the electromagnetic separation project, and
Arthur H. Compton, director of Chicago Metallurgical Laboratory, were
not available. Groves had some doubts regarding the next best
candidate, J. Robert Oppenheimer (Wood 2). Finally, Groves gambled
on Oppenheimer, a theoretical mathematician, as director of the
weapons laboratory, built on an isolated mesa (flat land area) at Los
Alamos, New Mexico.
After much difficulty, an absorbent barrier suitable for
separating isotopes of uranium was developed and installed in the Oak
Ridge gaseous diffusion plant. Finally, in 1945, uranium-235 of bomb
purity was shipped to Los Alamos, where it was fashioned into a
gun-type weapon. In a barrel, one piece of uranium was fired at
another, together forming a supercritical, explosive mass. To achieve
chain-reaction fission, a certain amount of fissile material, called
critical mass, is necessary. The fissile material used in the
Hiroshima model was uranium 235. In the bomb, the uranium was divided
into two parts, both of which were below critical mass. The bomb was
designed so that one part would be slammed into the other by an
explosive device to achieve critical mass instantaneously (Badash
238). When critical mass is achieved, continuous fission (a chain
reaction) takes place in an extremely short period of time, and far
more energy is released than in the case of a gun-powder explosion
(Badash 238). On December 2, 1942, the first self-sustaining chain
reaction with cadmium took place, overseen by Enrico Fermi,