The most secret place in the nation in 1945 was a barren stretch of desert in south-central New Mexico known to a handful of people as Trinity Site.
In the pre-dawn hours of Monday, July 16, 1945, some of the most renowned scientists in the world gathered at Trinity Site to witness the result of their labors.On top of a 100-foot-high steel tower rested a device they had built and named The Gadget.
It was the result of an unprecedented three-year, $2 billion crash program to unlock the basic energy source of the universe.
It was the first atomic bomb.
The decision to build the atomic bomb had been made in 1942 by President Franklin D. Roosevelt and his scientific advisers out of fear that Nazi Germany would build one first.
In 1939, at the urging of Albert Einstein and other refugee scientists, Roosevelt had established a committee to study the "uranium problem." By 1942 this committee had become the Office of Scientific Research and Development headed by Vannevar Bush of the Carnegie Institution and James Connant, president of Harvard.
In June 1942, with World War II raging all over the globe, they reported to the president that the atomic bomb not only was feasible but should be built.
The job was code-named the "Manhattan Project." Named to head the effort was the man who had built the Pentagon, Brig. Gen. Leslie R. Groves of the U.S. Army Corps of Engineers.
The first priority for Groves was to establish a secret laboratory where scientists could build the bomb. For help, he enlisted the aid of physicist J. Robert Oppenheimer of the University of California at Berkeley.
Oppenheimer suggested an isolated spot in the Jemez Mountains northwest of Santa Fe - the Los Alamos Ranch School.
After an inspection of the site in October, it was selected for the bomb laboratory, and the school was purchased by the Army.
Soon afterward, Groves selected Oppenheimer to head the new laboratory. By March 1943, Oppenheimer and the first wave of scientists had arrived at Los Alamos.
At Los Alamos the scientists began work on two different types of atomic bomb - one would use the rare metal uranium 235 as its explosive material and the other would use the new man-made element plutonium.
The uranium weapon used a relatively simple triggering device that worked like a gun firing a "bullet" of U-235 into a "target" of U-235. Coming together at extremely high speed, the united pieces would create the two conditions necessary for a nuclear explosion - critical mass and instantaneous chain reaction.
However, the gun-type trigger was too slow for plutonium. Consequently, the plutonium weapon had to use a new and complex method of guiding energy known as implosion.
In the implosion method, the core of the bomb would have to be evenly compressed into a critical mass in a split-second to achieve an atomic explosion.
To make this happen, dozens of detonators had to go off at once. They all had to work. There could be no error.
Work on the gun-type uranium weapon moved confidently ahead to culminate in the explosion over Hiroshima. Work on implosion, however, was slow and frustrating and often seemed hopeless. By late 1943, it was evident that the implosion device would have to be tested.
Kenneth T. Bainbridge, a Harvard physics professor who headed the Explosives Division at Los Alamos, was placed in charge of making arrangements for the test.
By September 1944, Bainbridge's team had found a test site - an 18-by-24-mile stretch of desert in the northwest corner of the Alamogordo Bombing and Gunnery Range. It was 200 miles south of Los Alamos. The nearest large town was Socorro, 42 miles to the northwest.
And thus Trinity Site was born.
By early 1945, a complete scientific laboratory had sprouted from nothing on the barren desert.
Ninety miles of roads were constructed or improved. A communications network with 200 miles of telephone line, loudspeaker systems and two-way radios was established.
At the headquarters of the complex, known as Base Camp, barracks, a warehouse, repair shops and a quartermaster'soffice were built.
There also was a complete technical stock room, officially known as FUBAR. This was World War II GI slang for "fouled up beyond all repair."
Trinity had its own weather bureau, its own electrical generators, and its own water supply.
Nine miles north of Base Camp, in a four-room ranch house that had belonged to a family named McDonald before the war, a laboratory was built for the bomb assembly group. This team was led by Navy Reserve Lt. Cmdr. Norris Bradbury, an explosives specialist with a doctorate in physics and math from Berkeley.
The ranch house-turned-laboratory was only one mile from Ground Zero.
The Trinity test, with Bainbridge as test director and John Williams of the Electrostatic Generator Group as his assistant, became a top priority project of Los Alamos in March 1945. It carried the highest priority rating in the nation - XX.
Security precautions were rigid. All people had to have a War Department pass stamped with a large letter T to enter. For full-time personnel, there were no trips to nearby towns. Even such everyday activities as laundry had to be cleared through security.
Only five people on the project were allowed to phone between Trinity Site and Los Alamos.
Six concrete chambers were erected to protect personnel and test recording equipment. The three major chambers were 10,000 yards north, west and south of the Ground Zero.
The bunker at 10,000 South would be the control center for the test. The bunker had its own telephone switchboard where the final command to fire the bomb would be given.
And in the center of it all stood the shot tower at Ground Zero.
A successful trial-run explosion involving 100 tons of TNT was carried out on May 7, 1945. It provided the scientists with valuable information that helped them get ready for the big show.
By late June the scientists at Los Alamos had finally overcome the problems holding up the implosion program. On June 30, Oppenheimer made the final decision on a date for the test - 4 a.m. July 16. The countdown had begun.
Oppenheimer left for Trinity on July 11, and various components of The Gadget followed soon after-ward.
The detonators arrived on the afternoon of July 11 with Ken Griesen, head of the detonator assembly team. The plutonium core arrived at 9 a.m. July 12 and was delivered to Robert Bacher, head of the nuclear assembly team. At noon, July 13, the explosives assembly arrived in the care of George Kistiakowsky, head of the explosives assembly team.
By 10 p.m. July 13, the bomb assembly group, led by Bradbury, Bacher and Kistiakowsky, had the bomb 90 percent complete. At 8 the next morning, the 10,000-pound object was hoisted to the top of the tower. By 5 that evening, Griesen had finished the assembly with the installation of 64 detonators.
The Gadget, the result of unprecedented effort, ingenuity and precision, was ready at last. It seemed to possess all the qualities of the ultimate weapon. All, that is, except one - the certainty that it would work.
Kistiakowsky bet Oppenheimer a month's pay against $10 that it would.
Despite weather predictions to the contrary, it was raining when Groves, Vannevar Bush and James Connant arrived on the afternoon of Sunday, July 15. Thunder rolled and lightning cracked in the surrounding mountains.
Oppenheimer and Groves were forced to make their own weather prediction. At dusk, they decided to postpone the test for no more than a few hours. They agreed to meet again at 1 a.m. to review the situation.
As rain continued to fall, the arming party - Bainbridge, Kistiakowsky, timing and remote signals chief Joseph L. McKibben, Military Police Lt. Howard Bush, two meteorologists and a guard - left Base Camp at 11 p.m. for the final trip to the tower. McKibben had with him a checklist of 47 jobs to be done before zero hour.
At 2 a.m. on July 16, the weather finally began to clear. The rain stopped at 4 a.m. At 4:45 came the crucial weather report: "Winds aloft very light, variable to 40,000 surface calm. Conditions holding for the next two hours."
From the tower, Bainbridge consulted with Oppenheimer, Groves and John Williams at South 10,000 by telephone. The decision was made. The shot would go at 5:30 a.m.
The arming party returned to South 10,000 at 5 a.m. The Gadget was fully armed.
The audience for the impending event was small but distinguished, numbering around 1,000.
At South 10,000 were Oppenheimer; Brig. Gen. T.J. Farrell, the No. 2 man in the Manhattan Project; Bainbridge, Williams and Kistiakowsky. Also in the bunker were Sam Allison, a director of the implosion program who would give the countdown, and Harvard physicist Donald Horning, who would man the emergency "stop switch."
At Base Camp, Groves, Vannevar Bush, Connant, project consultant I.I. Rabi and Italian refugee physicist Enrico Fermi gathered.
Fermi, winner of the 1938 Nobel Prize, had made one of the major contributions to this moment when he created the world's first controlled nuclear chain reaction at the University of Chicago in 1942.
Twenty miles north of Ground Zero, on a volcanic outcropping known as Compagnia Hill, was a large contingent that had been brought down from Los Alamos Sunday evening.
The group included Hungarian refugee physicist Edward Teller; German refugee physicist Hans Bethe, head of the Theoretical Division at Los Alamos; James Chadwick, head of the British atomic mission to the United States; Ernest Lawrence of Berkeley, inventor of the cyclotron; Charles A. Thomas of Monsanto Chemical; and William L. Laurence of the New York Times, the only newsman assigned by the Manhattan Project to document the development of the bomb.
As they waited for the test in total darkness, someone passed around suntan lotion.
At 5:10 the countdown began.
The voice of Allison boomed out over the intercoms, two-way radios and public-address system: "It is now zero minus twenty minutes."
Everywhere in the Trinity complex, men began to take their places. Vehicles were standing by at the three main bunkers to evacuate the participants in case of an emergency.
At minus 45 seconds, McKibben threw the switch that started the precise automatic timer. At minus 30 seconds, four red lights blinked on in front of Horning. The firing unit was fully charged.
Down to twenty seconds now. The quiet grew more intense.
Fifteen. Men were riveted to their places, lost in their own thoughts, almost afraid to breathe.
Ten. Edward Teller put on heavy gloves and an extra pair of dark glasses.
Nine. Army TSgt. Leo M. Jercenovic wasn't sure the bomb would work, but he wasn't taking any chances as he buried his head in his arms.
Eight. Kistiakowsky climbed to the top of the control bunker feeling he was quite safe at 10,000 yards.
Seven. Connant turned to Groves and said he never realized seconds could be so long.
Six. Groves wondered what he would tell the brass in Washington if the countdown got to zero and nothing happened.
Five. The generator for the camera that motion-picture photographer Julian Mack was operating caught fire. He let it burn.
Four. Physicist Phil Morrison pulled up his socks and pulled down his pant legs so that the least amount of skin would be exposed.
Three. Ken Griesen, who had coolly attached the 64 detonators to the bomb, turned to I.I. Rabi and said, "I'm scared now."
Two. Oppenheimer grabbed a post for support and thought, "I must remain conscious."
One. Gen. Farrell thought of scripture, "Lord I believe, help thou mine unbelief."
Zero.
In that instant, at 5:30 a.m. Mountain War Time, the history of the world was changed forever.
It was as if the sun had come down out of the sky and touched the Earth with its searing heat.
Within 25-thousandths of a second, a seething ball of fire - half a mile wide and growing - had spread out over the desert floor. By now the steel tower already had been vaporized and the sand around Ground Zero turned to glass by the raging furnace.
No one was prepared for the incredible, almost unearthly light that was produced. It was many times greater than the midday sun. It seemed to be coming from everywhere at once, and it lit every peak, crevice and ridge of the nearby mountains.
Heat followed immediately. Even at a distance of 20 miles it was so strong it was as if someone had "opened an oven door."
Seconds after the detonation came the sharp report of the shock wave, followed almost immediately by a sustained awesome roar that sounded like the crack of doom.
Within seconds, tons of dirt and debris had been swept up into the explosion.
At zero plus nine, a white-hot ball of fire began to lift from the desert floor and within 30 seconds, was at 15,000 feet. It eventually would reach 40,000 feet.
Men were stunned and numbed by the experience.
Farrell exclaimed, "The longhairs have let it get away from them."
Groves, Vannevar Bush and Connant exchanged handshakes in awestruck silence as they watched the fireball ascend.
Kistiakowsky, atop the shelter at South 10,000, was flung off the bunker into the mud. Oppenheimer rushed over to pay off his $10 bet. He pulled out his wallet. It was empty.
Bainbridge was overcome by exultation and relief - exultation that The Gadget had worked and relief that he wouldn't have to figure out why it didn't.
Leo Jercenovic looked toward the blast and saw "the whole world filled with light."
A few yards away Charles Thomas of Monsanto Chemical shouted to Ernest Lawrence that they had just seen the greatest single event in the history of man-kind.
Behind them a GI, with more immediate concerns on his mind, said, "Buddy, you just saw the end of the war."
Of all the participants, perhaps William L. Laurence of The New York Times captured the essence best when he wrote:
"On that moment hung eternity. Time stood still. Space contracted to a pinpoint. It was as though the Earth had opened and the skies split. One felt as though he had been privileged to witness the birth of the world - to be present at the moment when the Lord said: Let there be light."
*****
Additional Information
The implosion bomb
A subcritical mass of plutonium is surrounded by a chemical explosive. The detonation of the explosive compresses the plutonium so that it forms a supercritical mass, initiating an explosive chain reation. The splitting of an atom (fission) releases neutrons that then split other atoms, releasing an enormous amount of explosive energy.
Chain reaction
Each time a nucleus splits, some of its mass is converted into energy, or heat- millions of degrees in the case of an atom bomb.