Caroline L Herzenberg & Ruth H Howes. Technology Review. Volume 96, Issue 8, November-December 1993.
As the large-scale mobilization of young men into the military during World War II led to serious labor shortages at home, American women eagerly donned trousers and took on jobs that had previously been off-limits. Women doing “men’s” work became the glamour figures of World War II posters. But some of the women who held unconventional jobs were never memorialized on posters. Among these were the female scientists who joined in all aspects of war research, including the secret crash research program—code-named the Manhattan Project—to develop the first nuclear weapons.
Widely regarded as one of the great scientific and technical adventures of all time, the Manhattan Project is still shrouded in secrecy, and some of its history, not least significantly the contributions of female scientists, has never been told. Although at least 85 women helped design and construct the atomic bomb, contributing significantly to the project’s success, you can read through authoritative accounts of the program and never see a word about a woman.
Nor do histories often acknowledge how much of the physics research that led to nuclear fission was conducted by women. Marie Curie laid the groundwork with her study of radioactivity, and her daughter Irene Joliot-Curie was, with her husband Frederic, codiscoverer of the artificial production of radioactivity. Physicist Mileva Einstein-Maric, Albert Einstein’s first wife, may well have helped develop the ideas of relativity that are fundamental to understanding nuclear energy. German physicist Ida Noddack first proposed the idea that nuclear fission—the actual splitting of atoms—might explain the results of neutron bombardment of uranium.
And finally, Lise Meitner played a particularly crucial role among the pioneers of nuclear fission. She and German colleagues Otto Hahn and Fritz Strassman began a series of experiments bombarding uranium with neutrons and chemically analyzing the exposed material. In 1938, after Meitner fled Nazi Germany for Stockholm, she and her nephew Otto Frisch interpreted Hahn and Strassman’s latest results to show that the uranium atoms had indeed been split, just as Noddack had suggested. Meitner’s theoretical interpretation of nuclear fission pointed out the key fact that fission releases stupendous amounts of energy.
The military implications of this work were not lost on other scientists, who speculated that it might be possible to set up a chain reaction. That is, neutrons released in one fission reaction might initiate other fissions, which might initiate still others, resulting in a large-scale explosion. With political tensions mounting in Europe, three of the most eminent physicists of the era—Enrico Fermi, Leo Szilard, and Eugene Wigner, all of whom by then were in the United States—described that possibility in a letter and persuaded Albert Einstein, the world’s most famous physicist, to sign it. The letter was then delivered to President Roosevelt in August of 1939, just nine months after Meitner and her colleagues had discovered fission and one month before World War II officially began.
Roosevelt acted promptly to begin funding for research that might produce the world’s first atom bombs, and the U.S. entry into the war in December 1941 was decisive in stepping up the effort. Soon after June 1942, the real start of the Manhattan Project, officials realized that it would have to develop rapidly into the largest single-purpose technological enterprise ever established. By the end of the war, the program consisted of experiments at several universities, work at three major laboratory sites, and a vast array of pilot plants and manufacturing facilities. Not only did the Manhattan Project build nuclear weapons, but it produced the materials to be used in them. And it also confirmed what, at the outset, scientists only suspected: that a nuclear-fission chain reaction could be made to occur.
Women performed research in all the above areas. As female physicists, we want to set the record straight on those unknown scientists and engineers, not only because their story is interesting but because its omission from histories of the Manhattan Project perpetuates cultural misconceptions that have type-cast women and prevented young girls from considering careers in such fields. With the technological competition the United States will face in the next century, we cannot afford to discourage half the population from studying the physical sciences.
Preparing the Way
The first major task of the Manhattan Project—that of producing a controlled, self-sustaining fission chain reaction—meant designing, building, and testing the world’s first nuclear reactor. This mission was undertaken by Enrico Fermi’s group, which was moved from Columbia University to the University of Chicago, where the participants worked under the stands of Stagg Field. Among them was physicist Leona Woods, drafted to help construct detectors for monitoring the flux of neutrons from the atomic “pile”—the large stack of graphite and uranium blocks from which the group was building the first reactor. These detectors were crucial in determining when the pile had produced a fission chain reaction, the first step toward demonstrating the feasibility of nuclear weapons.
Woods was present when that chain reaction occurred, on December 2, 1942. After the atomic pile was dismantled and rebuilt in a remote area in the forest preserves outside Chicago for further research, Woods followed. When she became pregnant—she was by then married to physicist John Marshall—she continued to conduct experiments on the pile, hiding her condition under overalls and a denim jacket. She worked until two days before the birth of her first son in 1944.
Meanwhile, other Manhattan Project scientists were focusing on the isotopes capable of undergoing fission that would be used to build the bombs. Plutonium and U-235 were being pursued simultaneously, and women helped meet the formidable scientific and technical challenges that both presented.
One difficulty with building a bomb based on U-235 was that it required scientists to produce large quantities, perhaps hundreds of kilograms, of that rare lighter isotope of uranium. Not even a visible speck of it existed in pure form then. In some ways, the task was clear: U-235 had to be separated from the much more abundant isotope U-238. Scientists knew they could not do this by chemical means and would have to use physical means. But no one had ever separated radioactive isotopes on a scale greater than microscopic. A range of potential separation methods had to be analyzed and evaluated.
Maria Goeppert Mayer participated in the first stages of this work. Maria Goeppert grew up in Germany and studied physics in Gottingen, where she met and married Joe Mayer, an American who was also a student there. After they completed their degrees and moved to the United States, Maria Mayer faced the usual difficulties of female scientists in finding professional employment. A theoretical physicist, she was teaching half-time at Sarah Lawrence College when she joined the isotope separation project at Columbia University in 1942. But she was not given a full-time appointment, even though she became a senior member of a research group.
Mayer performed theoretical studies on the thermodynamic properties of the uranium hexafluoride gas to be used in one process for separating U-235 from U-238. In this process, known as gaseous diffusion, molecules of uranium hexafluoride gas drifted through acres of nickel barriers riddled with pinholes, and the slightly heavier molecules containing U-238 lagged behind those containing U-235. Mayer also investigated the possibility of using photochemical reactions for isotope separation, which turned out to be less feasible. Her later theoretical work focused on the energy a nuclear explosion emits as electromagnetic radiation, which, she noted, was enormous. Although these results were considered unimportant at the time, they provided the basis for designing the hydrogen bomb.
Because secrecy was essential—and because the isotopic separation processes required large, complex facilities and huge amounts of electricity—the Clinton Engineer Works was built on a large tract of land along the Clinton River in eastern Tennessee, in the Appalachian outback. The methods of separation eventually developed and put into use there included gaseous diffusion and electromagnetic separation, in which uranium atoms are ionized and then move through magnetic fields—the lighter U-235 ions tend to be deflected more by the magnetic fields, thus becoming separated from U-238 ions. Many women participated in the scientific work supporting these isotope separation projects in Tennessee. One was Susan Chandler Herrick, who had studied physical chemistry with Maria Mayer and secured a job in the Manhattan Project through her influence. Herrick had worked in Mayer’s group on problems in uranium chemistry, which included synthesizing and crystallizing compounds of uranium that might be of interest to the separation project, and developing techniques to produce single crystals of U-235 from a few hundreds of milligrams. Herrick contributed to the development of improved nickel barriers for the gaseous diffusion plants used at the Clinton Engineer Works.
The research and development directed toward building a nuclear bomb based on plutonium also required complex facilities. As plutonium, which is not a naturally occurring element, had to be created artificially, large reactors were built for this purpose in an isolated area of the state of Washington that became the Hanford Engineering Works, or Hanford Reservation. Leona Woods Marshall, who had worked on the first nuclear reactor, moved to Hanford to join her husband in overseeing the operation and construction of the plutonium production reactors. Physicist Jane Hamilton Hall, employed first at the Metallurgical Laboratory at Chicago, became a senior supervisor of the reactors under construction.
Another woman who played a vital role in developing the plutonium production reactors was the metallurgist Nathalie Michel Goldowski. Born in Moscow in 1908 to parents who were part of the Russian aristocracy, Goldowski escaped with her mother from the Russian Revolution in 1917. She went on to receive a doctoral degree in physical chemistry from the University of Paris and then worked for the French Air Force, where she became chief of metallurgical development at age 32. When Hitler occupied France, she again escaped, this time to the United States, where she joined the Manhattan Project in 1943.
Metallurgy, Goldowski’s specialty, was central to learning how to deal with the unfamiliar metals uranium and plutonium. Uranium presented a particular problem at Hanford: slugs of uranium had to be used inside the reactors as the raw material for plutonium production, yet it corroded quickly if exposed to the cooling water. Goldowski, who had previously developed innovative solutions to corrosion problems for aluminum and aluminum alloys, was able to address the corrosion dilemma on several fronts; she contributed to defining the necessary purity requirements on cooling water for the reactors, and she helped develop multilayered metallic canning of the uranium. This new canning method made it possible to maintain effective separation of the uranium and the coolant while providing for good thermal transfer between them. Her work enabled plutonium production to proceed at Hanford.
Other female physicists played important roles in solving an equally vexing problem that became apparent in September of 1944, when the first plutonium production reactor at Hanford was turned on and within hours turned itself off: the nuclear chain reaction tended to cease when a reactor was operated at high levels of neutron flux, as was necessary for the production of plutonium. Understanding this dilemma, which turned out to be caused by absorption of neutrons by one of the byproducts of fission, took several months and was perhaps one of the more exciting scientific accomplishments of World War II. The women who had a hand in it include the distinguished experimentalist Chien-Shiung Wu, whose knowledge of the nuclear properties of noble gases proved invaluable—it was an isotope of xenon, one of these rare gases, that was absorbing the neutrons. Katherine (Kay) Way, who had helped analyze data from the earliest atomic piles, and who had done theoretical work on reactor design that was used in building the production reactors at Hanford, contributed a wealth of expertise as well. Way worked on evaluating reactor constants—the parameters used in defining the probabilities of the various processes that together determine reactivity and thus are necessary to calculate reactor characteristics. She also collaborated with Eugene Wigner on the Way-Wigner formula for calculating the amount of heat that fission products will generate in a given period after reactor shutdown.
Contributions at Los Alamos
Before 1943, work on the design and functioning of the bombs was largely theoretical, based on reactor experiments. But in that year a new laboratory specifically for designing and building the weapons was established on an isolated mesa at Los Alamos in New Mexico.
Many women, some with degrees in mathematics or physics and others with little technical background, helped perform the extensive calculations needed for the design of the first nuclear bombs. Naomi Livesay, who had a degree in mathematics and experience in using electric calculating machines in the analysis of survey data, was typical. In 1944 she began work at Los Alamos as an assistant scientist and soon was supervising a team using electric calculating machines to track the blast wave of the conventional explosion through the fissile material at the core of the bomb, and then track the shock wave of the fission detonation back out. Because these calculations were so critical they were done under extraordinary time-pressure, in 24-hour shifts 6 days a week.
Physicist Ella Anderson worked at Los Alamos on questions about the fission process, such as how many neutrons are produced per fission. She also prepared the first sample of nearly pure U-235 for use in experiments at Los Alamos. Mary Argo, a theoretical physicist, worked with Edward Teller’s group, which was investigating the possibility of building a weapon based not on nuclear fission but on nuclear fusion. Theoretical physicist Jane Roberg contributed calculations for the fusion weapon as well.
Testing the explosives was one of the most important aspects of the Los Alamos work. Frances Dunne, an aircraft mechanic at Kirtland Air Force Base, was recruited by George Kistiakowsky as an explosives technician because her manual dexterity and small hands enabled her to adjust the trigger in the high-explosive shell of model weapons. She and her group tested various configurations of the conventional explosives assembly that would be used to detonate both Fat Man and Little Boy. They also composed the assembly crew for the world’s first nuclear explosion, code-named Trinity, which took place at the Alamogordo Bombing Range in a desert area of south-central New Mexico on July 16, 1945. The bomb was a plutonium weapon with a reported yield of 15 to 20 kilotons.
Among the scientists assigned to monitor the Trinity test was Elizabeth Riddle Graves, a young nuclear physicist who had earned her PhD from the University of Chicago. Her first task at Los Alamos had been to help determine what kind of neutron reflector should surround the core of the bomb so as to scatter neutrons back into the fissioning core—she was one of the few physicists in the country with the necessary background. At the time of the Trinity test she was pregnant, so she conducted radiation monitoring off-site, focusing on the airborne plume of radioactivity. She and her husband checked into a cabin in a tourist court in Carrizozo, N.M., about 40 miles east, with a short-wave radio, a portable electric generator, a seismograph, and a Geiger counter. They watched the Geiger counter go offscale as the radioactive cloud passed over the small town after the explosion.
Joan Hinton, another young physicist, got a closer look. Los Alamos had recruited Hinton from her graduate research at the University of Wisconsin early in 1944 and assigned her to a group headed by Fermi that worked in a canyon, building the first reactor at Los Alamos and the first anywhere to be fueled by material enriched in U-235. Hinton piled beryllium blocks around the spherical reactor core, designed and constructed control rods, and built electronic circuits.
She and the other graduate students in her group were not invited to view the Trinity test, but they knew when and where it would take place and sneaked in to observe it from a low hill about 25 miles from ground zero. Dodging the army guards in jeep patrols, Hinton rode to the mound at sundown on the back of a friend’s motorcycle. The students waited all night as the detonation was delayed past the midnight target hour because of thunderstorms. Just before dawn, they witnessed the amazing heat and light of the world’s first nuclear explosion. In Hinton’s words, “It was like being at the bottom of an ocean of light. We were bathed in it from all directions. The light withdrew into the bomb as if the bomb sucked it up. Then it turned purple and blue and went up and up and up. We were still talking in whispers when the cloud reached the level where it was struck by the rising sunlight so it cleared out the natural clouds. We saw a cloud that was dark and red at the bottom and daylight at the top. Then suddenly the sound reached us. It was very sharp and rumbled and all the mountains were rumbling with it. We suddenly started talking out loud and felt exposed to the whole world.”
After the War Was Over
Weeks later, a bomb based on the fission of U-235 was dropped on Hiroshima, and then, a few days after that, a plutonium bomb was dropped on Nagasaki. The war came to an end. Some of the Manhattan Project scientists, including Joan Hinton, were shocked by the destructive force of nuclear weapons and became active in the movement to internationalize atomic energy for peaceful purposes. Because women were not allowed to study graduate-level physics at the University of Illinois, Hinton could not complete her PhD there with her friends from Los Alamos, so she accepted Fermi’s offer of a position at the University of Chicago. But after two years she became so repulsed by the militarization of American science that she emigrated to China, where she still works today as a designer of dairy farms.
The other women tended not to stray so far from their origins. Some went on to complete their degrees, some took university positions, some continued their work in the national laboratories. A few attained distinction. For example, Maria Mayer, who taught at the University of Chicago and worked at Argonne National Laboratory, developed the theory of nuclear structure known as the nuclear shell model, for which she was awarded a Nobel Prize in physics. Jane Hamilton Hall went on to do physics research at Los Alamos and eventually became associate director of the laboratory. She also was a long-time member of the General Advisory Committee of the Atomic Energy Commission.
But many of the women who had worked on the Manhattan Project dropped out of science. As men returned from the armed forces and began looking for civilian jobs, women found they had worn out their welcome in the labor force. The propaganda machine that at the beginning of the war had made work seem glamorous now discouraged women from jobs and careers and pushed them back into the home. The disincentives were such that even some of the most gifted and accomplished women abandoned scientific and technical work.
After earning a master’s degree in chemistry from Columbia University and working for two years as an organic chemical analyst, Susan Chandler Herrick began to stay at home when the first of her four children was born. Eleanor Eastin Pomerance, who had worked as a technician at both Lawrence Radiation Laboratory and Oak Ridge, became a draftsperson at Oak Ridge, where she designed the three-bladed magenta and yellow fan that symbolizes radioactivity, but then retired for maternity. She went on to design jewelry, theater props, and masks as a hobby.
Among the women who performed the mathematical calculations for the design of the bomb, Eleanor Ewing Ehrlich, Betty Inglis, Kay Manley, and Mici Teller all returned to roles as wives and mothers. Naomi Livesay married Anthony French, a British physicist, and early in her marriage she worked on establishing a computer link between Harwell and Teddington in England, even though her salary was 30 percent below that which would have been paid to a man for the same job. She left to have the first of her children. Some years later, when she and her husband were back in the United States and she was offered a teaching position, she found that after paying childcare expenses, which were not tax deductible for women as they were for men, she would retain very little of her salary. She gave up the attempt to pursue a career in mathematics.
During World War II, women scientists had their day in the sun and demonstrated their technical ability. Their roles in the Manhattan Project were almost as widely varied as those of men, and they made significant contributions to the development of nuclear energy and nuclear weapons. But unfortunately, the post-war era showed that even capable women will leave science if they are strongly discouraged. To resist the post-war barrage of cultural messages to find fulfillment solely in the home took a degree of fortitude, independence, self-confidence, luck, and sheer love of science that men rarely, if ever, have to possess; it should hardly seem surprising that few women had it. In fact, many of those who did—like biologist and Manhattan Project veteran Ellen Cleminshaw Weaver—attest to how worn down they felt, and how seriously they themselves considered quitting. If industries, universities, and national laboratories seriously hope to remove obstacles to women’s full participation in science, they must absorb this lesson of how easily talent can go to waste.
Trying Times at Oak Ridge and Beyond
THE Manhattan Project may have created opportunities for female scientists and technicians, but the attitudes that would drive many of these same women out of the work force at the end of the war were nonetheless in evidence. Ellen Cleminshaw Weaver, who worked as a chemist at Oak Ridge, points out that in her own case, one needed to look no further than the pay scale.
“I was paid 70 cents an hour, which was low even in those days. It was insulting,” she says. “And I got docked an hour’s pay if I was as much as one minute late.” By contrast, men with her qualifications were paid a salary rather than an hourly wage, and ended up taking home roughly twice what she did.
Weaver learned that two other women she worked with were in the same boat, and when she decided to protest on behalf of both them and herself, she met with immediate resistance. “My superior told me, ‘Look, this is the way it is, and if you don’t like it, you can quit,'” she remembers. “Everyone thought women should be grateful just to be allowed to work. Equal pay was a completely foreign concept.”
But Weaver persisted, taking her protest up the chain of command until she reached the chief honcho—the president of Monsanto Chemical Co., which ran the section of Oak Ridge where she was employed. She recounts that she was in and out of his office in about two minutes. “There I was, quite young, quite junior, newly hired and complaining about my pay. My palms were all wet. But he said that yes, the situation was obviously unfair. He said, ‘You can stop punching the time clock today. We’ll put you on salary immediately, and the two other women, too.’ And that was the end of the interview.”
Sadly, however, it was not the end of the story. “When it was time for me to pick up my pay-check that month, I got nothing but a big pile of pink slips that said, ‘Why didn’t you punch in?’ and ‘Why didn’t you punch out?’ So I went to the same man and he told me he had taken the matter to the U.S. Army, which had refused to okay a salary for me and the other women because it would amount to too big a raise.”
After the war, Weaver went on to experiences in academia that were even more disheartening. By that time, she had developed an interest in biology as well as a realization that she would not be happy spending her life as a technician, which was all she’d ever be able to do with her bachelor’s degree in chemistry. “I came to the conclusion that I just had to be in a position where I could make the decisions and ask the scientific questions,” she says. And then something unprecedented happened: she met a woman with a PhD in biochemistry. “A lightbulb went off in my head. I thought maybe I could get a PhD myself.”
So Weaver applied to the University of California at Berkeley in biology, was accepted, and enrolled. But she received little encouragement, save from her husband and one or two exceptionally kind professors. “This was the early fifties and there was a strong feeling that women should be at home,” she says. “The general attitude of the family and other people was, ‘Well the war’s over, so why are you bothering with this?’ One particular problem was that I had a thesis adviser who was extremely negative and told me that no woman out of his department had ever amounted to anything.” Further aggravating her relationship with this adviser was her decision to have children while working toward her degree. “He was appalled. He would have nothing to do with me, especially when I became pregnant the second time.” He didn’t even attend her orals.
Weaver wound up failing the test—she took it too early in a desperate attempt to finish the program as soon as possible—and that was when she thought it might be best to just throw in the towel. “I mean you love science,” she recalls, “but it’s a lot of pain and conflict, and I thought maybe I wasn’t smart enough.” The primary reason she continued was that her husband was supportive. “He said, ‘You’ve got too much invested in this. Go back and try the orals one more time.’ And I did, did well, and I got through the doctorate.” She also had a third child, who was born soon after the end stage of her degree work.
Though the rest of her career was hardly smooth sailing—she encountered not only discrimination but, on more than one occasion, sexual harassment—Weaver did become well respected in her field, publishing about 30 papers on photosynthesis and related subjects. When she retired last year, she was teaching biology at San Jose State University. She was also the national president of the Association for Women in Science (AWIS), an organization based in Washington, D.C., with nearly 5,000 members and more than 50 chapters. She will retain the post until January 1994.
Weaver asserts that AWIS, whose goal is to help women realize their ambitions in science, fills a real need—she is unimpressed with the progress toward accepting women that scientific institutions have made on their own. “When you look at boards of directors, deans of medical schools, deans of colleges of science, there are very few women,” she notes. She says that one of the most effective steps those institutions could take to remedy the matter would be to abandon their rigid ideas about qualifications. For example, when organizations are trying to fill a leadership position, they may stipulate that they won’t consider anyone who has never been a dean or a department head. “This automatically excludes a lot of women, because women have been kept out of those jobs. A better idea would be to interview in depth and give credit to candidates who have been innovative or shown themselves to work hard, learn quickly, and get along with people. The female talent is there, but the men in charge need to be creative about tapping it. And they also need to make sure the newly appointed women have continuing support.”
She adds that if the scientific establishment adopts this approach, science itself is likely to change for the better. “The flexibility that institutions must develop to help women advance their careers in science is bound to attract a range of people—male and female—who are willing to be unconventional.” Such people are the ones most inclined to ask interesting questions, she remarks. And in science, “the questions you ask are enormously important.”