Inside the Manhattan Project : Bomb Builders Recall Tense Race With Nazis

Few of Phillip Morrison’s colleagues at Los Alamos ever knew why, beginning in 1943 and on into 1944, the young physicist, who had been hand-picked by J. Robert Oppenheimer to help build the atomic bomb, always stopped whatever he was doing each day and tuned in the short-wave BBC news broadcasts from London.

The answer was not in the United States or Britain but in Germany. Morrison was one of a handful of scientists and intelligence officials who knew that Adolf Hitler had suddenly given top priority to replacing Germany’s V-1 buzz bomb with the V-2, a vastly more lethal missile that could arch high across the fringes of space and plunge down upon its target at supersonic speed, without warning.

Against the V-2, there was no defense. And coming at a time when Los Alamos scientists still faced seemingly insurmountable obstacles, Hitler’s emphasis on the V-2 suggested that Germany might be on the brink of winning the secret race for the world’s first nuclear weapon. Grimly aware of what such a Nazi victory might mean, Morrison monitored the BBC day after day to reassure himself that the capital of the British Empire still existed.

“We had a lot of information on the V-1 and V-2 programs,” Morrison recalled recently, “and we thought there had to be something more behind it, because otherwise it didn’t make sense. If they had a few nuclear weapons coming along, they could really raise hell, and that’s what we feared was the case. I was particularly worried; I thought they were going to do it after D-Day.”

It has been 40 years since the atomic bombs were dropped on Hiroshima and Nagasaki, but personal memories remain sharply etched for those who lived inside the well-guarded circle of the Manhattan Project.

And those memories, along with the often-bitter disputes that later emerged over policy decisions, reflect not only the special hopes and fears--along with the astonishing technical difficulties--of those who built the bomb, but also the larger struggle of the nation to find its way in an infinitely dangerous new world.

The Manhattan Project, history’s most intensive collaboration between science, government and industry, created the weapon that became a pivotal influence in shaping the 20th Century. It also made once-isolated scientists a permanent force in public policy--so much so that physicists and others who played vital roles in developing the first nuclear weapons have remained prominent in debates about arms control and military weapons down to the present day.

Oppenheimer, chief scientist of the super-secret project and first director of the Los Alamos laboratory, later observed that “the physicists have known sin.” But today, four decades after Hiroshima, few personal regrets are heard among those who participated.

Scoff at ‘Star Wars’

Likewise, most veterans of the Manhattan Project decry each new generation of nuclear arms. And many, if not most, scoff at the notion that a similar mobilization today could produce an impregnable “Star Wars” defense against nuclear-tipped ballistic missiles. A Manhattan-like effort is impossible in peacetime, they believe, and even if the nation’s scientific talent could be mobilized behind such a cause, they say the technical obstacles to “Star Wars” appear truly insurmountable.

There does linger within the thinning ranks of project survivors, however, sharp disagreement over whether the United States should have exploded the first bomb on a Japanese city without warning.

Equally strong feelings over the hydrogen bomb have survived the years, dividing Edward Teller, who championed it, from others who saw the U.S. introduction of the enormously more destructive thermonuclear weapon as a failure of diplomacy.

“The first great lost opportunity was clearly the H-bomb,” Morrison said in a recent interview. “Vannevar Bush had a very good suggestion. He said we could prepare everything, get ready to test it, but never test--just simply say we will never test this device unless somebody else tests it. I think that might have avoided the whole problem.”

Such what-might-have-been thoughts are dismissed by some more conservative scientists who continued weapons work after the war. “I can just imagine what screaming there would have been if the Russians had gotten the hydrogen bomb first,” says Norris Bradbury, who succeeded Oppenheimer as director of the Los Alamos laboratory. “I am not defending this as logical, but I am saying there was no easy way to stop it.”

Indeed, the debate over restraint started even before Hiroshima.

Demonstration Urged

During the last few months before the bomb was dropped, several of the top scientists urged that it be demonstrated for Japanese observers before it was unleashed in combat, and the late physicist Leo Szilard circulated a petition saying the first country to use the weapon would “bear the responsibility for opening the door to an era of devastation on an unimaginable scale.”

In a private poll, 46% of the scientists working at the Manhattan Project facility in Chicago supported a proposal for a demonstration explosion off the coast of Japan, and another 23% favored a demonstration before Japanese observers in the United States.

At Oak Ridge, Tenn., where enriched uranium was being produced for the Hiroshima weapon, William A. Nierenberg wrote his own petition opposing the use of the bomb against a populated target. It brought him a quick visit from agents of the FBI.

“I had seen some bomb production data, and I knew what was going on,” said Nierenberg, who is now director of the University of California’s Scripps Institution of Oceanography in San Diego. “In the spring of 1945, I wrote out a long statement asking that it not be used against people, that we have a demonstration instead. I just didn’t want the destruction, the radiation, heat and fire that I knew would result.”

Eugene P. Wigner, one of the delegation of scientists who went to Albert Einstein and urged him to write his now-famous letter in 1939 to President Franklin D. Roosevelt first alerting the President to the possibility of an atomic bomb, supported the call for a demonstration explosion. He was among those unequivocally against dropping the bomb on Hiroshima.

Believes Lives Were Saved

But over the years, Wigner, a Nobel laureate and physics professor emeritus at Princeton University, has changed his mind. He now believes, as supporters of the decision have maintained all along, that both American and Japanese lives were saved because dropping the bomb shortened the war.

“I went to my Japanese friends,” said Wigner, whose uneasiness about Hiroshima first led him to delve into President Harry S. Truman’s decision and then to seek other answers, “and I asked them if they thought it would have been effective to explode it over uninhabited territory in the presence of some Japanese witnesses, and, with one exception, they said no. So I am now afraid that it was the right thing do to.”

Others never doubted.

“Every Aug. 6, I call a lot of my colleagues, and we tell each other, ‘They sure as hell deserved it,’ ” said scientist Harold Agnew, who was a passenger on one of the planes accompanying the B-29 bomber Enola Gay when it dropped the first bomb.

“I also had no doubts about Nagasaki. It was necessary to show them that it wasn’t God or the tooth fairy that dropped the first one. We needed to follow up right away.”

Fear of Germany

From the moment they set to work on the quest for the bomb, the scientists--some of them refugees who had fled Hitler--were driven by a palpable fear that Germany would get the weapon first and thereby possibly change the outcome of World War II.

Those fears of a German bomb did not begin to dissipate until after the Allied invasion of Europe began in June, 1944. By that fall, with the Allied armies relentlessly bearing down, it was clear that the Nazi war machine had failed to capitalize on German scientists’ extensive knowledge of the fission process.

U.S. war plans called for using the bomb against both Germany and Japan as soon as it became available. The knowledge that Germany would not have the bomb took away none of the momentum of the Manhattan Project or the pressure on American scientists involved in it. Indeed, some now believe that only a series of missteps in the unavoidably murky task of guiding the vast project kept the United States from having an atomic bomb before Germany surrendered.

The question of whether the bomb should be used against Japan did not come into focus until after Berlin’s surrender and after scientists secretly exploded the world’s first nuclear device in the New Mexico desert on July 16, 1945.

Staggering Problems

Almost until then, the project faced such staggering problems that the scientists involved with it had few moments to consider the policy implications of their creation.

Columbia University physicist I. I. Rabi, who served as a consultant at Los Alamos, turned down Oppenheimer’s personal invitation to join the bomb project because he was at the Massachusetts Institute of Technology’s radiation laboratory working on the development of radar. But during his long visits to the weapon laboratory in New Mexico, he said recently, implications of the bomb were seldom discussed.

“We didn’t have it,” he said, “and we didn’t sit around and talk about science fiction.”

Chief among the obstacles was the production of enough uranium-235 and enough plutonium to make an explosive mass for each of the two different types of bombs being designed by the scientists at Los Alamos. Equally perplexing was the stupendous technical task of designing an “implosion” device that would force the core of the plutonium bomb into a more compact, perfectly symmetrical mass in less than a millionth of a second, thus producing a nuclear explosion equivalent to 20,000 tons of TNT.

At Oak Ridge, Tenn., and at Hanford, Wash., contractors deployed tens of thousands of workers to build new towns and facilities for producing and handling uranium and plutonium. The construction crews had no idea what they were building and--once the facilities were in production--few of the operators knew what they were producing.

Gigantic Gambles

Maj. Gen. Leslie R. Groves, the Army Corps of Engineers officer who directed the project, was forced to take gigantic gambles. Among them were decisions on facilities for enriching uranium.

From the early days of the project, officials had banked heavily on a process called gaseous diffusion because it had been used earlier to separate isotopes of other elements. But month after month went by with scientists unable to find a satisfactory substance to use in making hundreds of thousands of square yards of material with millions of holes per square inch that could be fashioned into barriers that could separate explosive U-235, in its gaseous form, from the more prevalent U-238.

Harold C. Urey, one of the senior scientists on the project who was in charge of the barrier development, considered it hopeless. But Groves stuck with preparations to build production facilities for massive amounts of the barrier material, even though the material did not exist.

In time, a suitable barrier material was developed and mass produced, and the first gaseous diffusion complex went into operation in time to help produce the uranium fuel for the weapon dropped on Hiroshima.

What was produced by that plant was not pure uranium-235 but only a form of uranium in which U-235 was somewhat more prevalent than it is in nature. And when that slightly enriched uranium came from the plant, the engineers who shipped it away had no idea that it went only over the hill to another complex where an electromagnetic process, discovered by Ernest Lawrence of the University of California, further increased the concentration of U-235.

Major Accomplishment

The electromagnetic separation process represented a major technical accomplishment. It also represented the kind of carefully concealed bureaucratic sleight-of-hand that was the hallmark of the Manhattan Project.

With copper in short supply, designers of the plant’s giant magnets descended on a Treasury official in Washington one day and calmly proposed to borrow several thousand tons of silver from the U.S. mint--which they planned to melt down into wires. The flabbergasted official replied that the proper way to discuss silver was in troy ounces, not tons.

Yet so great was the project’s clout that it got the silver, virtually no questions asked.

(Los Alamos even managed a direct loan from Fort Knox. Frustrated in their search for the metal that would best prevent neutrons from escaping the core of the plutonium bomb, laboratory scientists decided to try gold. They promptly borrowed enough bars of bullion to make a pure gold sphere to contain the bomb’s core. Gold, it turned out, was unsuitable and, not long afterward, the sphere was found in the office of an intensely preoccupied scientist--being used as a doorstop.)

Manson Benedict, an engineer involved with the gaseous diffusion plant from the beginning, learned details of what the facility was all about only after its operators were repeatedly warned against allowing U-235 to accumulate within the huge facility’s maze of plumbing.

“General Groves wasn’t desirous of having us know what the amount was (that would be potentially explosive), or how to figure it,” Benedict recalled. But Teller, one of the project’s leading scientists at Los Alamos, was dispatched to explain the danger in detail.

“I had enormous respect for his intellect and his reputation,” Benedict recalled, “but he could not read engineering drawings. Bit by bit, I had to educate him, and he had to tell me a little bit about how much U-235 at different densities and concentrations would constitute a hazard.”

Needed Plutonium

To make a bomb that would use plutonium as its fuel, scientists first needed enough plutonium, which does not exist in nature but is produced by nuclear reactors. Manhattan Project officials at Hanford launched the construction of reactors to produce plutonium fuel for the bomb at a time when the entire world supply of the newly discovered element could be seen only with the aid of a high-powered microscope.

For most of the Los Alamos scientists, the climax of the Manhattan Project came not with the bombing of Hiroshima and Nagasaki, but with the Trinity test on July 16. A plutonium bomb triggered by the implosion device illuminated the pre-dawn with a blinding flash and a soaring purple mushroom cloud and shook the New Mexico desert.

As the fireball rose onto the stratosphere that morning, Brig. Gen. Thomas Farrell turned to Rabi and said: “The war will be over in six months.”

Within hours of the Trinity test, some of the scientists were on their way to Tinian Island in the Pacific to aid in the preparation of the bombs for Japan--”Little Boy,” a bomb fueled with about 130 pounds of Uranium-235, nearly the entire U.S. supply, for Hiroshima, and a 20,000-pound plutonium bomb called “Fat Man” for Nagasaki.

Scientists Drew Straws

The scientists drew straws for a place aboard the B-29, which was named Enola Gay after pilot Paul Tibbets’ mother.

Agnew saw the Hiroshima explosion from a B-29 flying in formation with the Enola Gay, which released the bomb from an altitude of nearly 30,000 feet.

“I saw the target as we came in,” he recalled. “It was perfectly clear, and we had to run back to our instruments to get them ready to drop and tune the receiver’s signal . . . . I saw the flash, it really lit up the plane, and then we got hit with the blast like two sharp slaps. I remember the solid dust, the tremendous rising cloud. And I wrote, though it was not very profound, “Geez, it really went off.”

Herbert York, later director of the Lawrence Livermore Laboratory and a U.S. delegate in arms negotiations with the Soviet Union, was at Oak Ridge when he heard that the bomb had been dropped on Hiroshima.

He was not surprised when he learned that the bomb had destroyed Hiroshima. After all, he said: “That was what we expected it to do.”