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
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, in the
University of Chicago squash fields (Asimov 783).
Another type of atomic bomb was also constructed using the
synthetic element plutonium. Fermi built a reactor at Chicago in late
1942, the prototype of five production reactors erected at Hanford,
Wash. These reactors manufactured plutonium by bombarding uranium-238
with neutrons. At Los Alamos the plutonium was surrounded with high
explosives to compress it into a super dense, super critical mass far
faster than could be done in a gun barrel. The result was tested at
Alamogordo, New Mexico, on July 16, 1945, and was the first explosion
of an atomic bomb code-named Trinity (Beyer 55).
However, all was not that easy coming up to this milestone
point. Security restrictions bound both workers and townspeople.
Everybody had the same address where all mail was censored (Wood 4).
Everybody was restricted to a 200 mile radius, and residents of Los
Alamos were prohibited from telling friends and relatives where they
lived (Wood 4). There were serious issues of security of documents,
due to failure to lock up (Wood 4).
The one serious incident was the hiring of Klaus Fuchs. He
was later found, and convicted of obtaining secret documents and
sending them to the Soviet Union. A competent and hardworking
scientist himself, Fuchs enabled the Soviet Union to create their own
atomic bomb (Beyer 45). Names were not allowed to be mentioned
outside of the laboratory. Everybody was a "sir" or "mister" instead
of their own name (Wood 4). Unless they worked at the lab themselves,
wives knew nothing of their husbands' research (Wood 4).
Decisions to drop the atomic bomb went through several
personalities, yet ultimately rested upon president Truman. The man
whose decisions created the Manhattan Project, never lived to see the
results of his labor. FDR died on April 12, three months before the
first successful Trinity test (Beyer 56). The responsibilities were
soon placed upon Truman, the next president. Truman knew nothing
about the bomb and its effects yet hastily decided that the bomb be
used on Japan, considering Germany was no longer a target with the war
in Europe over. Initiated by Szilard, a petition was made to offer
the opinion that the bomb should be used only if Japan refused to
surrender, even after being informed of the bomb's destructive
capabilities (Beyer 65). Nevertheless, the decision was made that the
bombs would be used until Japan surrendered.
The Hiroshima model is known as a gun-barrel-type atomic bomb.
Due to its long and narrow shape, the Hiroshima model was called "Thin
Man" at first, but during the manufacturing process the original plans
were modified, shortening the length and giving rise to the name
"Little Boy." (Beyer 48).The energy released from the Hiroshima
A-bomb was originally thought to be equivalent to the destructive
power of 20,000 tons of TNT. Later estimates, however, put the energy
equivalent to approximately 15,000 tons of TNT, based on damage done
to buildings and research on the bomb's composition. Despite the
release of such enormous energy, it is believed that less than one
kilogram of the 10 to 30 kilograms of uranium 235 housed in the bomb
The fissionable material used in the Nagasaki bomb was
plutonium 239. The plutonium 239 was divided into below-critical-mass
units and packed into a spherical case. At the time of detonation, the
units were compressed to the center with a gun-powder explosion to
achieve fission. The Nagasaki model is known as an implosion-type
atomic bomb. Compared to the Hiroshima A-bomb, the one used in
Nagasaki was larger in diameter and round so it was called "Fat Man."
Only slightly more than one kilogram of the plutonium 239 is thought
to have achieved fusion, but the energy released is estimated to be
equivalent to the destructive power of about 20,000 tons of TNT
Little boy killed about 100,000 people outright, wounded
another 100,000, and destroyed about 90 percent of Hiroshima (Hewlett
216). Yet, while the first atomic bomb was a roaring success, it
raised many ethical and controversial issues. Most of the people in
the United States of America supported the use of the atomic bomb,
even President Truman called it, "the greatest thing in history"
(Beyer 75). Many people, including the scientists that developed the
bomb, opposed the bombings and felt that it was immoral to kill that
many innocent people just to get an influence in the war.
The Manhattan Project was one of the most important parts of
American History. It was the first effort to create an atomic bomb,
that helped end the war in the Pacific. I enjoyed researching the
topic and learned a lot from my readings. Now I understand the atomic
bomb better and also understand the motives behind it. Researching
helped me understand the sheer strength and power of what a small
element can do. All of our lives have changed through the development
and bombing of the atomic bomb. The cold war, nuclear restrictions,
nuclear energy, are all results of the first nuclear breakthrough.
However, the controversial issues will still rage on. Nuclear
testing, nuclear power, and nuclear waste are still being debated for
over 50 years, and the United States, the only country to actually use
the bomb, is the leader.