Nuke Opera 2020: The Manhattan Project – 1942-1945:
First Things First: Why Was It Called the “Manhattan Project?”: Before I started researching this article, I thought “Manhattan Project” was a code name, like Operation Neptune for the D-Day invasion at Normandy in 1944 or Operation Mincemeat, a British intelligence mission that used a dead body to spread misinformation to the Germans. I assumed that since I’d never heard of anything connected with the Manhattan Project actually happening in Manhattan that the name was meant to misdirect the attention of enemy agents.
Well, you know what happens when you assume, right?
Turns out, it was called the Manhattan Project in part because it was originally headquartered in Manhattan at 270 Broadway – about four-tenths of a mile from New York’s City Hall. But then, it wasn’t called the Manhattan Project.
The Project’s original name was “Laboratory for the Development of Substitute Materials,” but General Leslie Groves, the Project’s head, fearing this name would draw unwanted attention, changed it to “Manhattan Engineering District.” In turn, this name was shortened to the Manhattan Project and the nickname stuck even after the Project’s headquarters were moved to Oak Ridge, Tennessee in 1943.
While it seems strange that such a top-secret project would have been located in the middle of a big city, it does make a certain kind of sense when you think about it. Manhattan was a central location, allowing for access to military personnel and workers as well as refugee scientists who’d fled Europe. Not to mention much of the United States’ uranium stockpile was being warehoused in Manhattan, having been shipped there from the Shinkolobwe mines in what is now the Democratic Republic of the Congo.
Second Things Second: How Much Did It Cost?: All told, the Manhattan Project cost 2 billion dollars in 1945 money or (as of this writing) about 28.7 billion dollars. Which sounds like a lot, but isn’t when compared to how much America spent on World War II as a whole. In 1945 money, the US spent a little under 300 billion dollars on the war, which translates to over 4 trillion dollars in 2020 money. Taken as a percentage of the total spending, the Manhattan Project’s budget equaled about 1% of what was spent on the war. Or, to put it another way, if the US spent $100 on World War II, the Manhattan Project cost about 67 cents.
Over 90% of the total cost of the project went into building factories and producing the fissile material needed to fuel the bombs. The rest went into researching and developing the bombs themselves.
Teamwork Makes the Dream Work:
We generally refer to the Manhattan Project as the United States’ nuclear weapons program, but in actuality it was a group effort between the US, the United Kingdom and Canada. Prior to the establishment of the Manhattan Project, the United Kingdom was doing its own research into feasibility of nuclear weapons and it was at the University of Birmingham where the first technical extrapolation of a practical nuclear weapon was written.
In March 1940, two German refugee scientists, Rudolf Peierls and Otto Frisch (who had confirmed the existence of nuclear fission in 1938), were tasked with determining if an atomic bomb was feasible[(1)].
Peierls and Frisch not only determined that atomic weapons were indeed possible, they also calculated that instead of requiring tons of fissile material, as little as 1 to 10 kilograms (2.2-22 pounds) would be enough to create an explosive yield in the kiloton range. This meant that atomic weapons could be produced much more quickly than originally believed. As in within a couple of years, making them a potentially viable option for use during World War II. [(2)]
Because of Peierls and Frisch’s work, in April 1940, the United Kingdom formed the MAUD Committee to further investigate the feasibility of atomic bombs. The committee issued its final report on July 10, 1941 and passed an advanced copy on to the Americans. However, the report wasn’t brought to Roosevelt’s attention until October 9th of that year. Roosevelt approved of a project to confirm MAUD’s finding and asked that a letter be drafted to arrange for him to speak officially with the British government.
Ordinarily, I’d do a timeline here but unfortunately, a lot of the history of the Manhattan Project seems to boil down to either: “and on this day, a committee was formed to look into the feasibility studies created by this previous committee, after which a new committee was formed to verify the findings of the second committee…” or “a site was chosen in a remote area, a great chunk of land was purchased and construction began on the basic infrastructure needed to support the workers who would be building the necessary factories to produce fissile material.”
Considering how new the science behind atomic reactions was, this makes sense. Almost everything necessary for the project had to be created, often from whole cloth. Calculations had to be checked and rechecked to be sure the science could actually work. And, once the feasibility of a nuclear weapon was confirmed, factories for the refining of uranium ore and reactors for creating plutonium had to be built, as did a location for the designing and testing of the bomb. In addition, because the work being done was so secret, places had to be built to house the workers who were refining the ore, running the reactors and designing the weapons.
From 1942 through 1944, the Manhattan Project’s main efforts were on gathering necessary materials, particularly uranium ore, selecting locations for uranium refining and enrichment, plutonium production and weapons design. During this time, two cities were built – Oak Ridge, Tennessee and Hanford, Washington – to house the workers and the plants necessary for creating fissile material. A third facility, Los Alamos, New Mexico, was built to serve as a weapons laboratory.
It’s not until the latter half of 1944 and into 1945 that researchers become confident that the bomb will probably succeed. On April 12, 1945, Harry S. Truman assumed the role of President of the United States after Franklin D. Roosevelt’s death due to cerebral hemorrhage. It’s also the first Truman learns of the existence of the Manhattan Project, having been kept in the dark while he was serving as FDR’s vice president. He authorizes the continuation of the project and becomes the only US president – for that matter, the only leader of any nation – to authorize the use of atomic weapons during wartime.
On July 16, 1945, the first nuclear weapon was tested at Alamogordo, New Mexico. The test, code-named Trinity, was of an implosion-style plutonium-based nuclear weapon nicknamed the Gadget. Its design was the same one used for the “Fat Man” bomb that would be dropped over Nagasaki. Its yield was 22 kilotons.
Twenty-one days later, “Little Boy” would be dropped over Hiroshima, Japan.
Who Worked On It?: The Manhattan Project itself employed hundreds of thousands of people – at its peak, it was employing about 130,000 people. But as this article by Alex Wellerstein at nuclearsecrecy.com points out peak employment is not cumulative employment. In other words, like any other employer, the Manhattan Project had to deal with employees quitting or being fired and having to hire replacements. By his figures, it’s possible the Manhattan Project employed as many as 600,000 people due to fluctuations in employment.
While the scientists at Los Alamos get much of the attention, much of the necessary work was done by other researchers working at dozens of sites, such as Oak Ridge and Hanford, the University of Chicago. Additionally, people worked in more mundane jobs at many Manhattan Project sites, all of which needed people to build the facilities and equipment needed for the bomb project, to serve as secretaries and administrative staff and even as janitors.
A large number of the people employed by the Manhattan Project were women. They worked, not only as secretaries, nurses and librarians, but also as equipment technicians, scientists and “human computers” who performed calculations that helped with the complex mathematical formulas related to nuclear fission. [(3)]
Cool Link: I found a coloring book of Women of The Manhattan Project.
People of color, particularly African Americans, also assisted with the Manhattan Project – likewise at all levels. On June 25, 1941, Roosevelt signed Executive Order 8802, which prohibited ethnic or racial discrimination in the defense industry and set up the Fair Employment Practice Committee. While it wasn’t a law, it was the first federal action intended to promote equal opportunity and prohibit employment discrimination in the US. Oak Ridge and Hanford employed substantial numbers of black workers in a variety of jobs.
African American scientists and technicians worked at several Manhattan Project sites, including the University of Chicago’s Metallurgic Laboratory (the “Met Lab”), Columbia University and the Ames Laboratory at the University of Iowa. They were physicists like Jasper Jefferies and Carolyn B. Parker; chemists like Harold Delaney and Moddie Taylor; and research assistants like James Forde and Blanche J. Lawrence, who was also the widow of a Tuskegee Airman who’d been killed on a strafing run in Greece.
African Americans also worked as construction workers, laborers, janitors and domestic staff at Oak Ridge and Hanford. While they faced discrimination at both sites, the prospect of doing their part for the war effort and working in jobs that were well-paying and offered chances for advancement were opportunities not to be scorned.
Where Was It Located?: Three of the main sites associated with the Manhattan Project were located in Oak Ridge, Tennessee (Site X), Hanford Washington (Site W) and Los Alamos, New Mexico (Site Y). Oak Ridge and Hanford were sites where fissile materials (uranium at Oak Ridge and the newly discovered plutonium at Hanford) were created and refined. Los Alamos was where the nuclear weapons were developed and, ultimately, tested.
Originally known as the Clinton Engineering Works, Oak Ridge, Tennessee was built in 1942 as a production site for the Manhattan Project. The site, known as the Clinton Engineering Works until 1949, had previously been primarily farmland. It was chosen because the area’s low population meant land would be cheaper to buy but also the area was accessible by highway and rail. Additionally, the recently completed Norris Dam meant water and electricity were readily available – a big selling point, since Oak Ridge would be using a lot of electrical power once it was fully operational.
The remote location meant that it was easier to keep Oak Ridge a secret, even though the population ballooned up from 3,000-4,000 in 1942 to about 75,000 by 1945. The name “Oak Ridge” was chosen because it sounded rural and boring and would hopefully keep curiosity seekers away.
The land for Oak Ridge was acquired by condemning necessary properties rather than simply purchasing them – the rationale being that land could be obtained more quickly than by directly purchasing it from the owners.
So quickly, in fact, that many locals only found out they were being evicted when a representative of the US Army Corps of Engineers’ Ohio River Division (ORD) showed up to tell them the government was acquiring their land. Some people came home from work to find eviction notices tacked up on their door or on a tree in their yard. For some local residents, this would be the third time the government would have seized their land, having been forced to relocate for both the Great Smoky Mountain National Park in the 1920s and again for the Tennessee Valley Authority’s Norris Dam project in the 1930s. Some were forced out before they were properly compensated for their land; others had to leave possessions behind, being unable to transport them due to wartime shortages in vehicles, gas and tires.
At least two hamlets, Elza and Robertsville, were rendered extinct. A third, Scarboro, was given over to African American residents in the 1950s and is still highly contaminated by radioactive waste.
The Hanford Site in Washington state was selected because it possessed the right combination of isolation, a long construction season, access to ready labor, suitable transportation and ready power thanks to the Grand Coulee and Bonneville Dams.
As in Oak Ridge, locals were given eviction notices, giving them between 30 and 90 days to vacate. Most of Hanford’s buildings, with the exception of the local high school, were destroyed. Some landowners took the government to court in order to get better appraisals of their property – which included not only their homes but also their land, crops and equipment. Colonel Franklin T. Matthias, the officer in charge of construction of the Hanford Site decided on settling out of court in these cases, due to time constraints. The plutonium reactors needed to be built and they needed to be built fast.
Additionally, local Native American tribes like the Wanapum were removed from their homelands along the Columbia River and resettled in Priest Rapids. They also lost access to their traditional fishing areas. At the time, they were told that this removal was only temporary but, well, the US government’s track record with keeping promises to Native Americans is nonexistent. A 2012 interview with Rex Buck gives more detail on how this removal affected the tribe over the years.
Acquiring the land for Site Y, the weapons design laboratory/research facility in Los Alamos, New Mexico was slightly cheaper than it was for the other sites since the majority of the land needed was already owned by the federal government. Like the other sites, Los Alamos was chosen because it was isolated and easy to secure – particularly important for bomb design. It would also allow the scientists and technicians to talk more freely amongst themselves.
Hanford and Oak Ridge were secret cities, but they were at least on the map. Los Alamos wasn’t, not during the time of the Manhattan Project, at least. It was not only kept off the maps and workers were forbidden from telling family or friends where they were going, but the entire facility shared the same address (top secret sites still need to get mail, after all).
Everyone at Los Alamos received mail at P.O. Box 1663, Santa Fe, New Mexico. Babies born at Los Alamos during the Manhattan Project [(4)] had the post office box listed as their birthplace– and the fact that everyone shared the address led to some confusion and concern when Sears and Roebuck delivery drivers received a dozen orders for baby bassinets from one address [(5)].
Like the Hanford Site (and Oak Ridge), some of the land for Los Alamos was acquired from locals who didn’t necessarily want to have their land taken from them. In Los Alamos, the two populations affected in this way were local Hispanic homesteaders, some of whom had been in the area since the late 1800s, and Pueblo Indians, whose ancestors had settled the area in the year 1000 BCE.
As in other sites, properties the government deemed necessary to their efforts were acquired by condemning the land and paying the owners set prices for their land, equipment and, in this case, livestock. Though, in this situation, language barriers may have played a role in some people not receiving compensation for their property.
One of the things that was very hard for them to understand is that everything – maybe they wrote letters to them in English, but there was nobody to translate these letters for them. There were all men, you know, and they did not understand most of the stuff. They just agreed, “Sí, sí, sí.” What could they do? The language problem there. – Rosario Martinez Fiorillo.
Los Alamos, like other Manhattan Project sites, provided employment opportunities for the people it displaced, particularly the people of the San Ildefonso Pueblo. Native Americans and homesteaders were hired on as truck drivers, construction and maintenance workers, carpenters, gardeners, maids and child-care providers. Additionally, researchers at Los Alamos became enamored with local artwork, particularly the pottery of artists like Maria Montoya Martinez.
Reliance on local workers was so profound that every year on January 23, the feast day for Saint Ildefonso, the lab would shut down due to a lack of maintenance workers.
And The Rest:
Other sites might not be as well-known but were just as crucial to the Manhattan Project. These include, but are not limited to:
- The University of Chicago where the first ever nuclear reactor went critical and achieved a self-sustaining reaction on December 2, 1942.
- Purdue University in West Lafayette, Indiana did nuclear research using a cyclotron during the early part of the war. Many of the researchers who worked there eventually were moved to Los Alamos.
- Morgantown, West Virginia; Newport, Indiana and Sylacauga, Alabama — heavy water production sites for cooling nuclear reactors (then called atomic piles).
- Dayton, Ohio – The Runnymede Playhouse was used to house research facilities working on polonium initiators meant to serve as triggers for the atomic bomb.
- San Antonio de Los Baños, Cuba – Members of the 509th Composite Group, activated in December 1944, went Batista Field to train for the flight between Tinian Island (being prepared as the staging area for the atomic bomb runs) and Japan. They worked on long-range, over-water flights and flying solo. In 1962, during the Cuban Missile Crisis, the Soviets would use this same field as a staging ground for their own planes.
Want to See More?: The Alsos Digital Library has created a Google Map that contains the locations of offices, mines, mills, plants, labs and test sites used by the US nuclear weapons program from World War II through to 2016.
Getting Down to Business:
The lion’s share of the work done for the Manhattan Project was the lengthy, highly involved, process of obtaining enough fissile material to be useful.
This process began with mining uranium – literally digging it out of the ground. when the Manhattan Project began, there were only four known sources of uranium ore: Colorado, northern Canada, Czechoslovakia and what is now the Democratic Republic of the Congo. In 1940, three out of the four sites were in Allied hands. The richest source of ore was in the Shinkolobwe mine in the DRC. Unfortunately, at this point the mine was not in operation — though the US was able to buy stockpiles of Shinkolobwe ore that were in storage in Staten Island (another reason why Manhattan made a good location for the early nuclear project). Ore was also obtained from mines in Uravan, Colorado and the Eldorado Gold Mines in Port Hope, Ontario.
Once the ore was obtained, it had to be processed to remove impurities and create pure uranium dioxide — which would then be refined into the metallic form of uranium.
The purified uranium would then be enriched to separate out the naturally fissile uranium-235. This could be done in a variety of ways, though the method believed to be the most promising, the centrifuge, was abandoned due to technical difficulties caused by vibrations created by high rotational speeds. Other methods used included electromagnetic separation, gaseous diffusion (developed, in part, by the Chinese-American chemist, Chien-Shiung Wu (also known as the Queen of Nuclear Research) and thermal diffusion.
In addition to being enriched to create uranium-235, uranium ore was also used to create plutonium. This process involved bombarding natural uranium (usually the isotope U-238) with neutrons. This will cause the U-238 to be transmuted into uranium-239, which decays rapidly into first neptunium-239 and then into plutonium-239. The plutonium-239 needs to be chemically separated from the U-238 ore.
All of this is potentially dangerous, not only short-term while people are doing the work but also over the long-term, since uranium and plutonium are long-lasting elements that can contaminate areas for very, very long times. Several Manhattan Project sites are still contaminated and in need of remediation.
Aren’t We Forgetting Something?: Weapons Design:
The work of building the atomic bombs took place at the Los Alamos Laboratory, code named Site Y. It was established by the Manhattan Project and operated by the University of California, with Robert J. Oppenheimer serving as its first director from 1943-1945. A site was chosen in rural New Mexico as a way to preserve security and to allow scientists to be able to discuss their work freely.
Initial work on a design for an atomic bomb focused on the gun-type fission weapon. But instead of using uranium, this one was intended to use plutonium. The design was nicknamed “Thin Man” and was scrapped when it was determined that the bomb would pre-detonate, undergoing a chain reaction before it could be fully assembled.
The next design was an implosion-type bomb that still used plutonium. This would be the design used for “Fat Man,” the bomb dropped on Nagasaki. The gun-type design would be recycled and altered to use uranium-235; this is the design used for the “Little Boy” bomb dropped on Hiroshima.
The “Fat Man” design was also used for the bomb tested on July 16, 1945 in the Trinity nuclear test. The bomb itself was nicknamed “the Gadget.”
Careless Talk Costs Lives: Atomic Espionage and the Manhattan Project:
What You See Here,
What You Do Here,
What You Hear Here,
When You Leave Here,
Let It Stay Here
(Sign from Oak Ridge, Tennessee warning against loose talk)
The United States and the United Kingdom agreed to work together on the atomic bomb, collaborating with each other and sharing research, with Canada also assisting with research and providing uranium from the Port Radium mines in their Northwest Territories. The US was ideally suited to doing certain research since even after Pearl Harbor, we were still largely unscathed by the war. Britain, in addition to waging war in Europe, had also suffered through the Blitz, an eight-month bombing campaign by the Germans meant to destroy British morale and infrastructure.
The British were, however, worried about the security of American atomic sites, fearing that they could be easily infiltrated by spies. Ironically, the British intelligence service had already been compromised by a group of Soviet double-agents known as the Cambridge Five, including one, John Cairncross, who would later pass the MAUD reports and other documents to the Soviet Union.
Additionally, Klaus Fuchs, one of the British delegation of scientists who worked at Los Alamos and was sympathetic to the Communist cause, was a Soviet spy. He provided the Soviets with information on the UK’s atomic program before coming to the US in 1943. It’s believed by some that the information he passed on from the Manhattan Project may have given the Soviet Union the bomb one to two years sooner.
Though, as it turned out, the British were right to be concerned about American security. Several American ‘atomic spies’also operated within the US Manhattan Project, feeding information about the design and building of atomic weapons to the Soviet Union. These included David Greenglass, the brother and brother-in-law of Ethel and Julius Rosenberg. While working as a machinist at Los Alamos, he passed secrets about the bomb on to his brother-in-law Julius, who in turn passed them to the Soviets. Later, he would testify against his sister and brother-in-law in an effort to protect his wife, Ruth, who was also a Soviet agent.
During the Potsdam Conference, on July 24, 1945, Truman informed Stalin that the Manhattan Project has successfully tested an atomic bomb – something Stalin was already aware of thanks to Soviet double-agents working within the program. By this point, the Soviet Union had been fighting with the Allies for nearly three years, having switched allegiances after the events of Operation: Barbarossa.
The world’s first nuclear weapon was detonated at 05:30 am local time on July 16, 1945 at the Alamogordo Bombing and Gunnery Range, 230 miles south of Los Alamos (about 78 miles from Alamogordo, New Mexico and 50 miles from Socorro, New Mexico). The site is located in the Jornada Del Muerto Desert and was chosen, like most other Manhattan Project sites, because it was isolated but also because it was flat and there was little wind [(6)].
By July 1945, 250 people lived and worked at the Trinity site; during the test, that population ballooned to 425.
The test was originally scheduled for 04:00 but was postponed due to rain. Prior to the July 16th test, a “dry run” of sorts occurred on May 7, 1945. This test, called the 100-ton test, detonated 100 tons of TNT and was meant to insure that the actual atomic test would go smoothly.
The 100-ton test’s fireball was visible 60 miles away, but there was little or no shock wave felt at the base camp, which was only ten miles away. This dress rehearsal revealed some scientific and technological issues, such as the need for more test vehicles as well as better roads, and more radios and telephone lines to insure good communication. They also added a teletype machine to insure better communication with Los Alamos and upgraded the mess hall.
In the two weeks prior to the test, preparations were made to evacuate the civilian population if things went wrong. If it had been necessary, they could have evacuated 450 people, with the Alamogordo Army Air Field having been selected as the evacuation site. General Groves went so far as to warn John J. Dempsey, then governor of New Mexico that marital law might need to be declared in the area.
On the day of the atomic test, the Trinity Gadget was hoisted to the top of a 100-foot tower rather than being dropped by plane. The bomb was hauled up the tower with an electric winch – and a truckload of mattresses was placed underneath, just in case the cable broke.
The test was observed at the site from shelters established 10,000 yards from the tower at each of the cardinal directions – north, south, east, and west. Other observers were stationed 20 miles away, with still more scattered at different distances from the site.
A group of VIPs, including General Groves and J. Robert Oppenheimer, watched the test from Compania Hill, around 20 miles northwest of the tower. They set up a betting pool about the results with Edward Teller predicting a yield of 42 kilotons and Oppenheimer choosing 0.3 kilotons. Enrico Fermi offered to take bets on whether or not the blast would ignite the atmosphere and if that happened whether it would only destroy New Mexico or if it would incinerate the world. This outcome had been determined to be almost impossible (but, y’know, that almost…) which the scientists knew the guards didn’t, not having the scientific background to understand that this was (hopefully) a joke.
Fermi wasn’t the only funny one among the observers – Edward Teller showed up wearing sunglasses and brought suntan lotion, which he shared.
At 5:10 am, the final 20-minute countdown to detonation began. The rain ended at 5:30 and the bomb was dropped.
It exploded with a yield of about 22 kilotons, melting the desert sand and turning it into a mildly radioactive glass later named trinitite. It left a crater 5 feet deep and 30 feet wide. For one to two seconds, the area was lit up brighter than daylight and the heat was reported as being “hot as an oven” at the base camp – which, remember, was ten miles away.
The roar of the shock wave took 40 seconds to reach the observers and was felt over 100 miles away. The mushroom cloud reached 7.5 miles in height.
The reaction among the scientists and other observers was one of elation – the project they’d been working on for over three years, the project that nobody was really sure would actually work until it did, had succeeded[(7)].
In 1965, J. Robert Oppenheimer shared this reminiscence of the Trinity test:
“We knew the world would not be the same. A few people laughed, a few people cried, most people were silent. I remembered the line from the Hindu scripture, the Bhagavad-Gita. Vishnu is trying to persuade the Prince that he should do his duty and to impress him takes on his multi-armed form and says, ‘Now, I am become Death, the destroyer of worlds.’ I suppose we all felt that one way or another.” (source: Trinity Test Eyewitnesses at Atomic Heritage.org
There were some unintended observers as well – civilians up to 250 miles away from ground zero heard, saw or felt the explosion. Houses shook and windows were blown out as far away as Gallup, New Mexico (235 miles away). The FBI was brought in to suppress any local news stories that might raise unwanted questions about the blast. A cover story about an ammunition storage site blowing up and was largely accepted in the Southwestern US, though it never made it into Eastern papers or radio broadcasts. (source: The Scientific Conquest of New Mexico: Local Legacies of the Manhattan Project 1942-2015, p. 199)
Of the eyewitness reports we have of the time, I think the best and easily the most poetic, belongs to Brigadier General Thomas F. Farrell, second-in-command of the Manhattan Project. He wrote this description of the Trinity test in a report to the Secretary of War:
“The effects could well be called unprecedented, magnificent, beautiful, stupendous and terrifying. No man-made phenomenon of such tremendous power had ever occurred before. The lighting effects beggared description. The whole country was lighted by a searing light with the intensity many times that of the midday sun. It was golden, purple, violet, gray and blue. It lighted every peak, crevasse and ridge of the nearby mountain range with a clarity and beauty that cannot be described but must be seen to be imagined. It was that beauty the great poets dream about but describe most poorly and inadequately. Thirty seconds after the explosion came first, the air blast pressing hard against the 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 the 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. It had to be witnessed to be realized.”
Now that the bomb has been built, tested and determined to be a success, the question of using it came to the forefront. The world has now entered the nuclear age.
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 Ironically enough, they were given the job because, since they were considered enemy aliens, they couldn’t be given security clearances to work on the project then attempting to develop radar.
 The low estimate was around 12 metric tons (about 13 US tons or 26,500 pounds); the high was 40 metric tons (44 US tons, or 88,200 pounds).
 Some of these women were the wives of researchers at Los Alamos, others were women who had degrees in mathematics and still others had no mathematical training beyond what they received on the job. They used early mechanical calculators to assist them. The job of “human computer” predated the Manhattan Project and was, traditionally, a job performed by women. They were particularly useful to astronomers, assisting with the stellar classification system that is still in use today and the 1969 moon landing (as depicted in the book and movie “Hidden Figures“) among other accomplishments.
 By some estimates, as many as 800 babies were born during the Manhattan Project; all of whom would be members of the Silent Generation.
 this is yet another example of how difficult it can be to keep government secrets; granted, the Sears and Roebuck delivery drivers had no way to make the leap from “ok, we got a dozen baby bassinets going to one PO Box, what the heck is going on there?!” to “I bet they’re working on an atomic bomb!” but the anomaly had to have led to talk. One of the reasons the Soviets figured out that other countries were working on atomic bombs was because suddenly, researchers who’d been publishing on nuclear research, had suddenly stopped publishing. Later, when the US was working on continuity of government sites, the locals around one site, Raven Rock, easily guessed that some kind of nuclear war shenanigans were going on.
– The site is currently known as the Trinity Site, which is probably the easiest way to look it up, if you’re curious. These days, it is possible to visit the site – though it’s only open to tourists one day a year.
: Fearing that the bomb would fizzle, plans were made to transport the plutonium leftover from the fizzle. The containment system, nicknamed “Jumbo”, survived the Trinity test, but the tower it was on didn’t. You can still see it at the site today.
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