Eighty years ago today, in the Jornada del Muerto desert of New Mexico — the Journey of the Dead Man — the first nuclear weapon was detonated in the hour before dawn.

The weapon was nicknamed “the Gadget.” It was made of plutonium, an element that had not existed on Earth in any measurable quantity even a few years earlier. Glenn Seaborg and his team at Berkeley had first isolated it in 1941, in quantities so small they were measured in micrograms. By July 1945, the United States had produced enough to build a bomb — through an industrial effort of staggering scale and secrecy, conducted in a city that did not appear on any map.

The Gadget was testing an utterly revolutionary technique called implosion: the simultaneous detonation of carefully shaped conventional explosive lenses surrounding a plutonium core, compressing it faster than it could blow itself apart, driving it through criticality in microseconds. The technique would probably have seemed like utter madness to the same group of scientists and engineers a year earlier. It was madness, in a sense. Many of them had significant doubts that it would work at all. One, the physicist Enrico Fermi, offered side bets to his colleagues on whether the test would ignite the atmosphere — the entire atmosphere, ending all life on Earth. He meant it partly as dark humor. Partly.

The test was called Trinity, a name J. Robert Oppenheimer chose and later said he could not fully explain — perhaps from John Donne, perhaps from the Hindu concept of the Trimurti, the three-faced god of creation, preservation, and destruction. At 5:29 in the morning, the desert turned briefly brighter than the sun. The yield was approximately 21 kilotons — the equivalent of 21,000 tons of TNT, released in a fraction of a second. A steel tower 100 feet tall was vaporized. The desert sand beneath the fireball fused into a glassy, pale green mineral that scientists later named trinitite.

Oppenheimer, watching from a bunker, recalled a line from the Bhagavad Gita: Now I am become Death, the destroyer of worlds. Whether he said it aloud in that moment, or remembered it only afterward, no one can say for certain. He said it later. Many times.

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No one was supposed to be affected by the test. The site had been chosen for its remoteness. The project’s leaders believed — or chose to believe — that the desert around the Jornada del Muerto was empty.

It was not empty.

Ranching families lived in the valleys downwind. Communities of Hispanic and Native American families had worked this land for generations. They did not know what happened that morning. They saw a flash brighter than sunrise in the wrong direction, felt a shock wave that rattled windows and knocked some people from their feet, and then, in the hours and days that followed, they noticed something strange falling from the sky.

It drifted down like snow — fine, white, ash-like particles, settling on skin and hair and clothing, on water tanks and garden vegetables and the mouths of livestock. But no one had ever heard of snow in July in the New Mexico desert. And this snow was warm to the touch.

They didn’t have a word for what was falling on them. The word “fallout” had not yet been coined. No one yet understood how a nuclear detonation near the Earth’s surface — as Trinity was, detonated on a tower just 100 feet above the ground — would vaporize vast quantities of soil and sand, mix them with fission products, and loft them into the upper atmosphere to drift downwind and settle slowly back to Earth over the following days. No one knew about fission products at all, really — the alphabet soup of radioactive isotopes, strontium-90 and cesium-137 and iodine-131, each with its own half-life, each finding its own pathway into the human body. Into bones. Into thyroid glands. Into the developing tissues of children.

Some of those children played in the warm white snow. They came home with it in their hair. Their mothers brushed it off their clothes. They drank the water from cisterns open to the sky.

They were children, and many of them did not live to see their thirtieth birthdays.

The people of the Tularosa Basin — the “downwinders,” as they came to be known — spent decades trying to tell this story and be believed. The government did not warn them. The government, for many years, did not acknowledge them. The survivors and descendants of survivors organized, testified, marched, and waited. It was not until 2024, seventy-nine years after Trinity, that Congress finally extended compensation to the downwinders under the Radiation Exposure Compensation Act — and even then, the program was set to expire within months, leaving the fight unfinished.

They deserved better. They deserved it eighty years ago, and they deserve it now.

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Plutonium could be made into a nuclear explosive. This became its primary identity in the decades after Trinity — the reason nations built reactors, the reason they built enrichment plants, the reason they built the vast and expensive infrastructure of the nuclear weapons complex. The Soviet Union made plutonium. The United Kingdom made plutonium. France and China made plutonium. India made plutonium — using a reactor supplied, with some irony, by Canada and fueled with American heavy water. Israel almost certainly made plutonium. Pakistan made plutonium. North Korea made plutonium and demonstrated it, twice, in tests beneath its mountains. The spread of plutonium around the world is the central anxiety of the nuclear age, the thing that keeps nonproliferation experts awake at night, the reason for treaties and inspections and the whole elaborate architecture of the Nuclear Non-Proliferation Treaty.

And yet here is something that tends to get lost in discussions of nuclear energy and nuclear weapons: plutonium doesn’t have to be a weapon. It is also a fuel.

In fact, for those who genuinely wish to see the world’s plutonium stockpiles reduced — who want those tens of thousands of weapons-worth of separated plutonium to simply go away — there is no more effective mechanism than burning it in a nuclear reactor. Plutonium fissions beautifully. It releases enormous energy. A reactor running on plutonium is consuming it, converting it into fission products that are radioactive but short-lived, rather than storing it indefinitely in a form that can be fashioned into weapons by any state that achieves sufficient technical capability.

The obstacle to using plutonium as fuel in conventional uranium-fueled reactors is that those reactors make more plutonium than they burn. You feed in uranium, and the neutrons that uranium-238 captures — unavoidably, because U-238 makes up more than 99% of natural uranium — produce new plutonium. You can use mixed-oxide fuel, combining plutonium with uranium, and make some progress on drawing down the stockpile. But you are always fighting the tide, because the uranium in the fuel keeps producing more.

Thorium changes this. Thorium is fertile, like uranium-238 — it absorbs neutrons and transmutes into a fissile isotope, in thorium’s case uranium-233. But thorium does not produce plutonium. When you burn plutonium in a thorium-based reactor, the neutrons that would otherwise fall on uranium-238 and breed more plutonium fall instead on thorium-232 and breed uranium-233. The reactor consumes plutonium and produces a different fissile material — one that has never been successfully weaponized by any nation, that is contaminated with uranium-232 whose decay products make it intensely radioactive and nearly impossible to handle covertly.

A thorium molten-salt reactor fueled with plutonium is, in a very real sense, a plutonium elimination machine. It takes the most dangerous legacy of the nuclear weapons age and converts it into electricity — into light and heat and the energy that runs hospitals and factories and the devices on which you are reading these words.

Eighty years after Trinity, the Gadget’s most lasting legacy is the plutonium that spread from its example to arsenals around the world. We made that plutonium in fear and in the heat of a war that had already killed tens of millions of people. We do not have to keep it forever. We do not have to bury it and guard it for ten thousand years while we argue about geology and politics and the instability of human institutions over geological time.

We can burn it. Thorium shows us how.

The warm snow fell on children in the Jornada del Muerto eighty years ago today. We owe it to their memory — and to the children alive now, and the ones not yet born — to do something better with what we built.