By David Grogan
July 17, 1995 12:00 PM

Today at Ground Zero in central New Mexico there is little but desolation—chunks of weathered concrete, some twisted steel and a black stone obelisk with a brass plaque reading Trinity Site: Where the world’s first nuclear device was exploded on July 16, 1945.

Fifty summers have passed since the dawn in the desert that day. That first atomic bomb test—code-named Trinity—was the result of 28 months of research at a secret base 200 miles to the north. There on a mesa at Los Alamos, 2,500 young scientists and technicians—led by physicist Robert Oppenheimer and other veterans of the Manhattan Project—had labored frantically to build the weapon they hoped would end World War II. After the bombs were dropped on Hiroshima and Nagasaki—instantly causing an estimated 110,000 deaths—it did. What follows is the story of Trinity, told by people who were there.

Robert Wilson was a physicist at Princeton University. Now 81, he is a professor emeritus at Cornell University in Ithaca, N.Y: When Robert Oppenheimer came to Princeton just after Christmas 1942 and asked me to join a group of scientists who would be working out how to assemble a nuclear bomb, it sounded very romantic. Oppie explained that everything about the project was to be clothed in deepest secrecy, and we were to disappear to a mountain-top laboratory in New Mexico—Los Alamos.

Edward Teller was a Hungarian physicist schooled in Germany who fled the Nazis. Now 87, he lives in Stanford, Calif: I was eager to come to Los Alamos because I had a very full knowledge of what Hitler meant. The Germans knew about nuclear fission, and we certainly wanted to build a bomb before Hitler.

Mary Lehman was a member of the Women’s Army Corps. Now 75, she lives in Rolling Hills Estates, Calif.: I was one of the WACs who chauffeured the scientists around. It took a long time to figure out what was going on since nobody ever told me what they were doing. I had heard a news report on the radio, though, and they were talking about splitting the atom. So one day when I was driving Dr. Enrico Fermi and a couple of other scientists, I said, “By the way, have we ever split the atom?” There was dead silence, almost a gasp. Finally, Fermi said, “No, we’re not going to do anything about that until after the war.” [In fact, Fermi had already produced the world’s first self-sustaining chain reaction in a secret experiment at the University of Chicago several months earlier.]

Val Fitch was a technical sergeant in the Army Special Engineer Detachment. Now 72, he is a professor emeritus of physics at Princeton: On May 7, 1945 we did a rehearsal explosion, using 100 tons of TNT, in order to calibrate some of the instruments for the nuclear test. By chance it was the day the Germans surrendered.

Teller: Even though Hitler had been defeated, it did not diminish our sense of urgency. This terrible war had already cost millions of lives, and an invasion of the Japanese home islands would have cost many more. We all felt it was extremely important to end the war as rapidly as possible.

Hans Bethe was a physicist who left Nazi Germany. He is 89 and a professor emeritus at Cornell: We were still somewhat doubtful as to how well the bomb would work. There was a pool of bets about how much energy the bomb might produce, and the guesses ranged from zero to 50 kilotons of TNT. [A kiloton is 1,000 tons.] I bet eight kilotons, which was well short of the actual 20 kilotons.

Donald Hornig had recently received his Ph.D. in physical chemistry from Harvard where, at 75, he is now a professor emeritus: As we got up to the Trinity test itself, the pressure was fantastic. We had been staying round the clock at the test site. The base camp was set up around an old ranch house 10 miles from Ground Zero. The place was dusty and hot, and we slept in tents at night.

Kenneth Greisen was a physics instructor at Cornell where, at 77, he is now a professor emeritus: My group had prepared and tested the 92 detonators that were to set off the bomb, which we called the gadget. On July 11, five days before the test, I took these detonators from our lab in Los Alamos and loaded them in the trunk of an old Oldsmobile to make the long drive to the Trinity test site. On the way I got stopped by a cop for speeding, and I was very worried that he would ask me to open the trunk because I wouldn’t be allowed to say what those things were. Fortunately, he just gave me a ticket.

Philip Morrison had been a physicist at the University of Illinois. Now 79, he is a professor emeritus at the Massachusetts Institute of Technology: On Thursday, July 12, I checked out the plutonium core for the bomb from the vault at Los Alamos and traveled to the test site in a Plymouth staff car with a WAC driver and an armed escort. The core had been packed in a special metal container with rubber stoppers all over it. Behind us was a car full of armed guards and another car in front. We drove up to 80 miles an hour to an old one-story ranch house where the next morning we loaded the plutonium in a pluglike device designed to fit inside the bomb.

Finally, we carried this plug by car to the blast site. But when we tried to lower it into the bomb, it didn’t fit. I was quite worried the first few seconds. We had tried it many times before, and it always went in. Quickly everyone came to the same conclusion: the plug was hotter than the outer shell of the bomb. As soon as the plug cooled enough, it fit perfectly.

Hornig: The 14th was when it all came together. The bomb was hoisted to an enclosure at the top of a l00-foot tower. Since the bomb weighed five tons, there was all sorts of worry that the cable might break. So after they’d hauled it part of the way up, they unloaded truckloads of mattresses that had been taken off the beds of GIs and piled them up in 15-foot-high stacks.

William Caldes had been studying chemical engineering at Princeton. Now 73, he lives in Tijeras, N. Mex.: That evening, Fermi and some other physicists got on this kick: “What if we made a mistake and this thing sets off a chain reaction in the atmosphere?” They were passing the time making calculations about how long it would take such a fireball to hit New York, then London, and then encompass the earth. It was just a brainteaser, but it was scaring the hell out of me.

Hornig: Oppenheimer had become increasingly worried that the damn thing would be so easy to sabotage. So he decided one of us ought to babysit the bomb that night. Since I was the youngest and probably knew the firing unit better than anyone else, I had to go up. I took along a book of slightly ribald essays—Desert Island Decameron by H. Allen Smith—so I would have something to do while I was up there.

They had forecast this thunderstorm, and it started when I climbed up the tower. There was the bomb and me and a 60-watt bulb hanging from a wire. It was about 9 at night, and the thunderstorm really kicked up. I would see a flash of lightning and then count—one thousand, two thousand, three thousand—until I heard the thunder crack. As the time between the flash and the crack seemed to keep getting closer, I thought, “What if the bomb gets hit by lightning?” The happiest moment of the night came around midnight when my little phone rang and I heard, “Hornig, you can come down now.”

Joseph McKibben had recently received his Ph.D. in physics from the University of Wisconsin. Now 82, he lives near Los Alamos: Since I was the person responsible for activating the timing system for the bomb, I spent the night at the base of the tower. I fell asleep about 2 a.m. and dreamed that one of my colleagues was sprinkling the bomb with a garden hose. When [Trinity director Kenneth] Bainbridge woke me up 2 hours later, the weather had cleared enough to proceed with the test, and the other scientists had gone to their prearranged stations around the area. We turned on a set of switches at the tower to arm the bomb and then drove to the command bunker 10,000 yards south of Ground Zero.

At 5:10, I threw the switch that started the countdown at minus 20 minutes.

Hornig: I had been up for about 48 hours and was fearfully tired. But I had to stay alert because I was monitoring a control board in the command bunker, and if anything at all went wrong, my job was to open a so-called chicken switch, which would stop the test. Oppie was standing right behind me, and I didn’t know if he was going to last. He was so tense. I thought I would relieve some of the tension by saying, “You know what’s going to happen, Oppie, is that as we come up to the firing, I’m going to crack and turn off my switch.” But it didn’t make him any more relaxed. He debated for a minute whether to get someone else to take over for me.

Finally, with 30 seconds to go, my meters came up. And I said to myself, “This is it.”

Joe Lehman was a master sergeant in the Army Special Engineer Detachment. Now 74, he lives in Rolling Hills Estates: I heard a lot of people around me talking, but not to each other. People were praying because we didn’t know if we were about to take our last breaths on this earth.

Fitch: I was tending to my final duties in the main control bunker. Just before the final countdown everything was on automatic mode, and I was no longer needed, so I went outside to watch the show. I stretched out on a little mound of earth to the right of the bunker. Suddenly, there was a fantastic flash of light—like a thousand suns.

Bethe: My main thought was, “So it worked!” I was impressed by the enormity of the spectacle—the whirling masses of dust with a strange purple light.

Marvin Davis was an Army MB Now 72, he lives in Bartonville, Ill.: The heat was so intense it felt like when you open your oven door. I could see the sagebrush swirling around. And there was this shock wave coming through.

Jack Aeby was a civilian technician from Mound City, Mo. Now 71, he lives near Espanola, N.Mex.: Enrico Fermi was standing near me dribbling little pieces of paper, like confetti, to make a rough calculation of the blast yield by measuring the distance the paper moved as the shock wave passed.

J. Lehman: Then came the roar of the explosion. Oh, the roar! We all wanted to put our fingers in our ears as the roar started. It was not just a boom. It was a gathering crescendo, and it seemed like it lasted for 5 or 6 seconds.

McKibben: There were many echoes off all those mountains around. If somebody had been smart enough to record that, it would almost have been like a piece of music.

Hornig: In a few minutes the sun started to come up and began to spoil the spectacle. I noticed Oppenheimer standing behind a barricade, looking with dark glasses, and suddenly I thought, “Now we’ve opened a can of worms. Having this kind of thing available to the world is going to be real trouble.”

Kenneth Bainbridge was director of the Trinity test. Now 90, he is a professor emeritus of physics at Harvard: I had a feeling of exhilaration. I would not have to go to the tower to see what had gone wrong. I wouldn’t worry any longer. I went over to congratulate Oppenheimer on the success of the test, and I finished by saying, “Now we are all sons of bitches.” In other words, we would not be viewed as people who saved anything, but as people without feeling.

Wilson: I was in a bunker 10,000 yards north of Ground Zero, and the wind was blowing in our direction. Minutes after the bomb went off, I began to get apprehensive because a section had peeled off from the mushroom cloud and was coming straight at us. Meanwhile, the doctor was reading that the radiation was much higher than he expected. We had about 10 trucks, so I ordered people to get in them and leave immediately. There were some soldiers stationed outside who told me they had to stay until they were relieved by a military officer, but using a vocabulary everyone could understand, I convinced them to get into a truck. As we left, that cloud of radioactive debris was right on top of us, and it was spooky. We were lucky though. About 25 miles later it came down on a bunch of cattle and turned their hair white.

Caldes: Later that morning, back at the base camp, Hans Bethe was going around saying, “Just like the book!” In other words, all the calculations, all the theory had been correct. But some of the plumbers and carpenters were at a table, their platters heaped with food, and every one of them was just sitting there, staring off into nothing.

My own feeling was one of relief. I thought, “Well, it’s finally done. It shouldn’t be long before the war is over.”