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Manhattan Project and the A-Bomb


Just before the beginning of World War II, Albert Einstein 
wrote a letter to President Franklin D. Roosevelt. Urged by 
Hungarian-born physicists Leo Szilard, Eugene Wingner, and Edward 
Teller, Einstein told Roosevelt about Nazi German efforts to purify 
Uranium-235 which might be used to build an atomic bomb. Shortly after 
that the United States Government began work on the Manhattan Project. 
The Manhattan Project was the code name for the United States effort 
to develop the atomic bomb before the Germans did. "The first 
successful experiments in splitting a uranium atom had been carried 
out in the autumn of 1938 at the Kaiser Wilhelm Institute in 
Berlin"(Groueff 9) just after Einstein wrote his letter. So the race 
was on. Major General Wilhelm D. Styer called the Manhattan Project 
"the most important job in the war . . . an all-out effort to build an 
atomic bomb."(Groueff 5) It turned out to be the biggest development 
in warfare and science's biggest development this century. The most 
complicated issue to be addressed by the scientists working on the 
Manhattan Project was "the production of ample amounts of 'enriched' 
uranium to sustain a chain reaction."(Outlaw 2) At the time, 
Uranium-235 was hard to extract. Of the Uranium ore mined, only about 
1/500 th of it ended up as Uranium metal. Of the Uranium metal, "the 
fissionable isotope of Uranium (Uranium- 235) is relatively rare, 
occurring in Uranium at a ratio of 1 to 139."(Szasz 15) Separating the 
one part Uranium-235 from the 139 parts Uranium-238 proved to be a 
challenge. "No ordinary chemical extraction could separate the two 
isotopes. Only mechanical methods could effectively separate U-235 
from U-238."(2) Scientists at Columbia University solved this 
difficult problem. A "massive enrichment laboratory/plant"(Outlaw 2) 
was built at Oak Ridge, Tennessee. H. C. Urey, his associates, and 
colleagues at Columbia University designed a system that "worked on 
the principle of gaseous diffusion."(2) After this process was 
completed, "Ernest O. Lawrence (inventor of the Cyclotron) at the 
University of California in Berkeley implemented a process involving 
magnetic separation of the two isotopes."(2) Finally, a gas centrifuge 
was used to further separate the Uranium-235 from the Uranium-238. The 
Uranium-238 is forced to the bottom because it had more mass than the 
Uranium-235. "In this manner uranium-235 was enriched from its normal 
0.7% to weapons grade of more than 90%."(Grolier 5) This Uranium was 
then transported to "the Los Alamos, N. Mex., laboratory headed by J. 
Robert Oppenheimer."(Grolier 5) "Oppenheimer was the major force 
behind the Manhattan Project. He literally ran the show and saw to it 
that all of the great minds working on this project made their 
brainstorms work. He oversaw the entire project from its conception to 
its completion."(Outlaw 3) Once the purified Uranium reached New 
Mexico, it was made into the components of a gun-type atomic weapon. 
"Two pieces of U-235, individually not large enough to sustain a chain 
reaction, were brought together rapidly in a gun barrel to form a 
supercritical mass that exploded instantaneously."(Grolier 5) "It was 
originally nicknamed 'Thin Man'(after Roosevelt, but later renamed 
'Little Boy' (for nobody) when technical changes shortened the 
proposed gun barrel."(Szasz 25) The scientists were so confident that 
the gun-type atomic bomb would work "no test was conducted, and it was 
first employed in military action over Hiroshima, Japan, on Aug. 6, 
1945."(Grolier 5) Before the Uranium-235 "Little Boy" bomb had been 
developed to the "point of seeming assured of success,"(Grolier 5) 
another bomb was proposed. The Uranium-238 that had been earlier ruled 
out as an option was being looked at. It could capture a free neutron 
without fissioning and become Uranium-239. "But the Uranium-239 thus 
produced is unstable (radioactive) and decays first to neptunium-239 
and then to plutonium-239."(Grolier 5) This proved to be useful 
because the newly created plutonium-239 is fissionable and it can "be 
separated from uranium by chemical techniques,"(6) which would be far 
simpler than the physical processes to separate the Uranium-235 from 
the Uranium-238. Once again the University of Chicago, under Enrico 
Fermi's direction built the first reactor. "This led to the 
construction of five large reactors at Hanford, Wash., where U-238 was 
irradiated with neutrons and transmuted into plutonium."(6) The 
plutonium was sent to Los Alamos. The problem to overcome in the 
development of the plutonium bomb was an isotope of plutonium. The 
scientists feared this isotope would cause premature detonation and 
most of the plutonium would blow apart before it could all fission. 
"To overcome this so-called 'defect of nature, ' the plutonium had to 
be brought into a supercritical mass far faster than conventional 
ballistics could achieve."(Grolier 6) Physicist Seth Neddermeyer and 
mathematician John von Neumann devised the theory of "implosion." A 
subcritical sphere of plutonium was surrounded by chemical 
high-explosives. The 5,300 pounds of explosives were all "carefully 
shaped as 'lenses.' When these were detonated, they focused the blast 
wave so as to compress the plutonium instantly into a supercritical 
mass."(Szasz 25) This was much more complex, and many people doubted 
that it would work. There was a debate at Los Alamos about whether to 
test the new plutonium 'implosion' bomb before it was actually 
dropped. "Harvard explosives expert George B. Kistiakowsky and 
Oppenheimer both argued for such a test, but initially Groves was 
opposed. He was afraid that if the test failed, the precious plutonium 
would be scattered all across the countryside."(Szasz 26) Brigadier 
General Leslie R. Groves, the man the army placed in charge, was 
eventually persuaded. Hanford's plutonium production was increasing 
fast enough so that a test would cause little delay in time. They 
feared that if they dropped the untested plutonium bomb and it failed 
to work, "the enemy would find themselves owners of a 'gift' atomic 
weapon."(Szasz 26) The final agreement for the test was that the bomb 
would be placed in "a gigantic, 214-ton, cylinder-shaped tank (called 
'Jumbo')."(Szasz 26) If the plutonium correctly fissioned, the tank 
would be vaporized. If it did not work correctly, the conventional 
explosives would be contained in the tank and the plutonium would stay 
in the tank. After further development of the implosion design and 
fears that "Jumbo" would dramatically distort all "their complicated 
instrumentation-the raison d'être for the test,"(Szasz 36) the 
world's largest pressure tank was not used. On Monday, July 16, 1945, 
at 5:29:45 A.M., Mountain War Time, the plutonium bomb ignited at the 
Trinity site, a remote site in the New Mexico desert. "The explosion 
created s brilliant flash that was seen in three states."(Szasz 83) 
There were many reports from civilians from all over that described 
the experience. People who saw it said it looked like the sun had 
risen for a few minutes and then went back down. Others thought they 
had seen a large plane or meteor crash. A sheep herder who was laying 
sleeping on a cot fifteen miles away was blown off. "The Smithsonian 
Observatory on Burro Mountain confirmed a shock but noted that the 
vibrations were unlike any earthquake ever recorded."(Szasz 84) An 
eight year-old boy was awakened and ran for his Methodist parents, and 
they considered if this might be the end of the world. The most 
powerful statement that has been cited in practically every coverage 
of the atomic bomb is Georgia Green's experience. She was being driven 
to Albuquerque. "What was that?" she asked her brother-in-law, who was 
driving. This was very unusual because Georgia Green was blind. 
Brigadier General Farrell wrote a letter for the Secretary of War. 
"'No man-made phenomenon of such tremendous power had ever occurred 
before . . . Thirty seconds after the explosion came, first, the air 
blast pressing hard against people and things, to be followed almost 
immediately by the strong, sustained, awesome roar which warned of 
doomsday and made us feel that we puny things were blasphemous to dare 
tamper with forces heretofore reserved to the Almighty. Words are 
inadequate tools for the job of acquainting those not present with the 
physical, mental and psychological effects."(Groueff 355) Upon 
witnessing the explosion, reactions among the bomb's creators were 
mixed. Their mission had been successfully accomplished, however, they 
questioned whether "the equilibrium in nature had been upset -- as if 
humankind had become a threat to the world it inhabited."(Outlaw 3) 
Oppenheimer was ecstatic about the success of the bomb, but quoted a 
fragment from Bhagavad Gita. "I am become Death, the destroyer of 
worlds." Many people who were involved in the creation of the atomic 
bomb signed petitions against dropping the bomb. The atomic bomb has 
been used twice in warfare. The Uranium bomb nicknamed "Little Boy," 
which weighed over 4.5 tons, was dropped over Hiroshima on August 6, 
1945. At 0815 hours the bomb was dropped from the Enola Gay. It missed 
Ground Zero at 1,980 feet by only 600 feet. "At 0816 hours, in the 
flash of an instant, 66,000 people were killed and 69,000 people were 
injured by a 10 kiloton atomic explosion."(Outlaw 4) [See blast ranges 
diagram] Nagasaki fell to the same treatment as Hiroshima on August 9, 
1945. The plutonium bomb, "Fat Man," was dropped on the city. It 
missed its intended target by over one and a half miles. "Nagasaki's 
population dropped in one split-second from 422,000 to 383,000. 39,000 
were killed, over 25,000 were injured. That blast was less than 10 
kilotons as well. Physicists who have studied the atomic explosions 
conclude that the bombs utilized "only 0.1% of their respective 
explosive capabilities."(Outlaw 4) Controversy still exists about 
dropping the two atomic bombs on Japan. Arguments defending the 
Japanese claim "the atomic bomb did not win the war in the Pacific; at 
best, it hastened Japanese acceptance of a defeat that was viewed as 
inevitable."(Grolier 8) Other arguments state that the United States 
should have warned the Japanese, or that we should have invited them 
to a public demonstration. "In retrospect that U.S. use of the atomic 
bomb may have been the first act of the cold war."(Grolier 8) On the 
other side, advocates claimed that the invasion of the Japanese 
islands could and would result in over one million military casualties 
plus the civilian losses based on previous invasions of Japanese 
occupied islands.



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