Our troops guarded [the atomic bombs], but we didn’t own them…. Civilian-controlled, completely. I remember sending somebody out… to have a talk with this guy with the key. I felt that under certain conditions — say we woke up some morning and there wasn’t any Washington or something — I was going to take the bombs. I got no static from this man. I never had to do it or anything, but we had an understanding.
The arrangement seemed necessary, given the rudimentary nature of command and control in those days. “If I were on my own and half the country was destroyed and I could get no orders and so forth,” LeMay explained, “I wasn’t going to sit there fat, dumb, and happy and do nothing.”
Work on the hydrogen bomb gained more urgency after it became clear that the Soviet Union was trying to build one. A few days after Truman’s announcement that the United States would develop the Super, the British physicist Klaus Fuchs confessed to having spied for the Soviets. At Los Alamos, Fuchs had worked on the original design of the implosion bomb and conducted some of the early research on thermonuclear weapons. In January 1951, despite a year of intense effort, American scientists were no closer to creating a hydrogen bomb. Teller had proposed using a fission device to initiate the process of fusion. But he could not figure out how to contain the thermonuclear reaction long enough to produce a significant yield. The mathematician Stanislaw Ulam suggested a couple of new ideas: the hydrogen fuel should be compressed before being ignited, and the detonation of the bomb should unfold in stages. Teller was greatly inspired by Ulam’s suggestions, and in March 1951 the two men submitted a paper at Los Alamos that laid out the basic workings of a thermonuclear weapon — “On Heterocatalytic Detonations I: Hydrodynamic Lenses and Radiation Mirrors.” And then they applied for a patent on their H-bomb design.
Ulam had called his initial proposal “a bomb in a box.” The Teller-Ulam design that emerged from it essentially placed two fission bombs in a box, along with hydrogen isotopes like deuterium and tritium to serve as thermonuclear fuel. Here is what would happen, if everything worked as planned: an implosion device would detonate inside a thick metal canister lined with lead. The X-rays emitted by that explosion would be channeled down the canister toward hydrogen fuel wrapped around a uranium-235 “spark plug.” The fuel and the spark plug would be encased in a cylindrical layer of uranium-238, like beer inside a keg. The X-rays would compress the uranium casing and the hydrogen fuel. That compression would make the fuel incredibly dense — and then would detonate the uranium spark plug in the middle of it. Trapped between two nuclear explosions, the first one pressing inward, the second one now pushing outward, the hydrogen atoms would fuse. They would suddenly release massive amounts of neutrons, and that flood of neutrons would accelerate the fission of the uranium spark plug. It would also cause the uranium casing to fission. All of that would occur within a few millionths of a second. And then the metal canister holding everything together would blow apart.
The physics and the material science behind the Teller-Ulam design were highly complex, and there was no guarantee the bomb would work. It relied on a concept, “radiation implosion,” that seemed plausible in theory but had never been accomplished. X-rays from the detonation of the first device, called the “primary,” would have to be accurately focused and reflected onto the “secondary,” the cylinder housing the fuel and the spark plug. Using X-rays to implode the secondary was a brilliant idea: the X-rays would move at the speed of light, traveling much faster than the blast wave from the primary. The difference in speed would prolong the fusion process — if the interaction of the various materials could be properly understood.
The steel, lead, plastic foam, uranium, and other solids within the bomb would be subjected to pressures reaching billions of pounds per square inch. They would be transformed into plasmas, and predicting their behavior depended on a thorough grasp of hydrodynamics — the science of fluids in motion. The mathematical calculations necessary to determine the proper size, shape, and arrangement of the bomb’s components seemed overwhelming. “In addition to all the problems of fission… neutronics, thermodynamics, hydrodynamics,” Ulam later recalled, “new ones appeared vitally in the thermonuclear problems: the behavior of more materials, the question of time scales and interplay of all the geometrical and physical factors.” And yet the Teller-Ulam design had an underlying simplicity. Aside from the fuzing and firing mechanism that set off the primary, there were no moving parts.
In May 1951 a pair of nuclear tests in the South Pacific demonstrated that a nuclear explosion could initiate thermonuclear fusion. A device nicknamed “George,” containing liquefied tritium and deuterium, produced the largest nuclear yield ever achieved: 225 kilotons, more than ten times that of the Nagasaki bomb. Although fusion was responsible for just a small part of that yield, radiation implosion did occur. The detonation of “Item” a few days later had a much lower yield, but enormous significance. It confirmed Teller’s belief that fission bombs could be “boosted” — that their explosive force could be greatly magnified by putting a small amount of tritium and deuterium gas into their cores, right before the moment of detonation. When a boosted core imploded, the hydrogen isotopes fused and then flooded it with neutrons, making the subsequent fission explosion anywhere from ten to a hundred times more powerful. Boosted weapons promised to be smaller and more efficient than those already in the stockpile, producing larger yields with much less fissile material.
A full-scale test of the Teller-Ulam design took place on November 1, 1952. One of the world’s first electronic, digital computers had been assembled at Los Alamos to perform many of the necessary calculations. The machine was called MANIAC (Mathematical Analyzer, Numerical Integrator, and Computer), and the device that it helped to create, “Mike,” looked more like a large cylindrical whiskey still than a weapon of mass destruction. Mike was about twenty feet tall and weighed more than 120,000 pounds. The device was housed in a corrugated aluminum building on the island of Elugelab. When Mike detonated, the island disappeared. It became dust and ash, pulled upward to form a mushroom cloud that rose about twenty-seven miles into the sky. The fireball created by the explosion was three and a half miles wide. All that remained of little Elugelab was a circular crater filled with seawater, more than a mile in diameter and fifteen stories deep. The yield of the device was 10.4 megatons, roughly five hundred times more powerful than the Nagasaki bomb.
The Teller-Ulam design worked, and the United States now seemed capable of building hydrogen bombs. “The war of the future would be one in which man could extinguish millions of lives at one blow, demolish the great cities of the world, wipe out the cultural achievements of the past,” President Truman said, a couple of months later, during his farewell address. Then he added, somewhat hopefully, “Such a war is not a possible policy for rational men.”
• • •
THE THOUGHT OF USING nuclear weapons may have seemed irrational to Truman, but a credible threat to use them lay at the heart of deterrence. And planning for their use had become a full-time occupation for many of America’s best minds. Fundamental questions of nuclear strategy still hadn’t been settled. Project Vista, a top secret study conducted by the California Institute of Technology, revived the military debate about how to defend Western Europe from a Soviet invasion. In 1950 the North Atlantic Treaty Organization (NATO) had agreed to create an allied army with 54 divisions — enough to stop the Red Army, which was thought to have 175 divisions. The European members of NATO, however, failed to supply the necessary troops, and by 1952 the alliance seemed incapable of fielding anywhere near the requisite number. The small U.S. Army contingent in Western Europe served on the front line as a “trip wire,” a “plate glass wall.” American troops would be among the first to encounter a Soviet attack, and they’d be quickly overrun, forcing the United States to enter the war. The Strategic Air Command would respond by destroying most of the Soviet Union. But the Red Army would still conquer most of Europe, and civilian casualties would be extraordinarily high.
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