The Day We Lost the H-Bomb: Cold War, Hot Nukes, and the Worst Nuclear Weapons Disaster in History

The bomb was torpedo-shaped and dull silver in color, twelve feet long and twenty inches around. It had a nine-inch gash in its rounded nose, and three of its four tail fins had shorn away. The tail plate, a flat piece of metal that sealed the parachute compartment at the rear end of the bomb, had also torn away, and one of the parachutes lay spilled nearby. The ready/safe switch — part of the arming mechanism — was in the “safe” position. Except for the cosmetic damage, the bomb seemed intact.

Howe checked for radiation and found none. He called some EOD — Explosive Ordnance Disposal — men, who also checked for radiation and rendered the bomb safe. Howe posted some Air Force guards around the weapon. It became known as bomb number one, because it was the first one the Americans found.

The “H” in “H-bomb” stands for hydrogen, the smallest atom in the universe and the simplest of the elements. The hydrogen nucleus consists of one solitary proton, which is circled by one electron—

its own tiny, whirring solar system. Hydrogen makes up most of the gas in the universe and most of the mass of stars, and is found in all living things on Earth.

Hydrogen has an isotope — a sort of half sister — called deuterium. Though nearly identical to hydrogen, deuterium has a small but critical difference: its nucleus carries one proton and one neutron. For this reason, deuterium is often called “heavy hydrogen.” It is this tiny extra neutron that makes the hydrogen bomb possible.

In 1934, a physicist named Ernest Rutherford and two of his colleagues were working in England and discovered something curious about deuterium. When Rutherford sped up two deuterium atoms and smashed them together, they fused and became a new element: helium. This surprised Rutherford, because the deuterium atoms, each with one positively charged proton in its nucleus, had an immense repulsive force and should have stayed apart. Yet accelerating or heating the atoms gave them enough extra energy to overcome their repulsion and fuse together. Because the reaction required acceleration or heat to fuse the nuclei, Rutherford called it a thermonuclear reaction. He called the whole process hydrogen fusion.

Oddly, the fused helium nucleus weighed slightly less than the two separate deuterium nuclei. The missing mass, Rutherford discovered, had been converted into energy. A lot of energy. Theoretically, each gram of deuterium, when fused, would release energy equivalent to 150 tons of T.N.T. This is about 100 million times as much firepower as a gram of ordinary chemical explosive. To put this into perspective, the firepower of Curtis LeMay's biggest raid on Japan, involving hundreds of planes and thousands of bombs, would have required only 20 grams of deuterium, about the weight of a robin's egg. The bomb dropped on Hiroshima: just 100 grams, equivalent to two jumbo chicken eggs. The numbers scale up quickly as the analogy moves on to heavier forms of produce. Twenty-six pounds of deuterium — the weight of about half a sack of potatoes — would yield 1 million tons of T.N.T. That yield — one megaton — is about seventy times the power of the bomb dropped on Hiroshima. It was also close to the yield of bomb number one, which Sergeant Howe had found on the soft bank of the dry Almanzora River.

Back in the 1930s, when Rutherford discovered fusion, however, the idea of a fusion bomb seemed nearly impossible. Rutherford needed a massive amount of energy to fuse just two atoms. It seemed unlikely that humans could find a source of energy hot enough to trigger a large-scale thermonuclear reaction and fuse a few kilograms of heavy hydrogen. Then came the atom bomb.

Atom bombs — the type of bombs dropped on Hiroshima and Nagasaki — work through fission, splitting the atom, rather than fusion. Every atom (except for hydrogen) has a nucleus made up of protons and neutrons, like a ball of marbles stuck together with glue. This nuclear glue has a name: binding energy. Because protons, with their positive charge, want to repel one another, it takes a lot of binding energy to hold a nucleus together, especially a big one. Nuclear fission splits the nucleus of an atom, breaking the marbles apart and releasing the nuclear energy in the form of heat, light, and radiation.