The Trinity Test
On July 16, deep in the deserts of New Mexico, Pandora’s Box was opened, and the Atomic Age was born
The United States became the first country to successfully detonate an atomic weapon, signaling the beginning of a new era in warfare and in politics. In the early 1940s, the U.S. government authorized a top-secret program of nuclear testing and development, codenamed “The Manhattan Project”. Its goal was the development of the world’s first atomic bomb. Much of the research and development for the project occurred at a facility built in Los Alamos, New Mexico. In July 1945, Los Alamos scientists successfully exploded the first atomic bomb at the Trinity test site, located in nearby Alamogordo.
When the atomic bomb was tested, scientists were the first humans to witness the power of a nuclear weapon. Even 32 kilometers (20 miles) away, observers felt the heat of the explosion on exposed skin. The radiation level in the rising mushroom cloud was so intense that it emitted a blue glow.
The code name “Trinity” was assigned by J. Robert Oppenheimer, the director of the Los Alamos Laboratory, inspired by the poetry of John Donne. The test was of an implosion-design plutonium device, informally nicknamed “The Gadget”, of the same design as the Fat Man bomb later detonated over Nagasaki, Japan, on August 9, 1945. The complexity of the design required a major effort from the Los Alamos Laboratory, and concerns about whether it would work led to a decision to conduct the first nuclear test.
No one was completely sure what would happen when Gadget went off. For a while, there was worry that the chain reaction would be unstoppable and react with the entire atmosphere. Before the test, Enrico Fermi took bets from some of the physicists and high ranking military personnel on whether the bomb would destroy the whole state of New Mexico, or the entire planet. The math seemed to show fairly conclusively that the world wouldn’t be destroyed, but a lot of the guards who didn’t know that became anxious.
The gadget was hoisted atop a 100-foot tower for detonation in order to better simulate a bomb being dropped from a plane. When it exploded at 5:29 am, the mushroom cloud plumed to over seven miles high. About 240 people on the project directly watching the blast reported the early morning dawn being lit up brighter than full daylight for one to two seconds and felt a wave of heat roll over them that was “as hot as an oven”, even at a distance of 10 miles away. The shock wave took 40 seconds to propagate to the observers and was felt up to 100 miles away. With a power equivalent to around 21,000 tons of TNT, the bomb completely obliterated the steel tower on which it rested. The nuclear age had begun.
Because of the novelty and complexity of the plutonium bomb that was to be exploded during the Trinity test, Manhattan Project officials, directed by Kenneth Bainbridge, realized that a calibration explosion using ordinary high-explosives would be incredibly useful. The test, which called for slightly over 100 tons of TNT, was designed to practice timing sequences and calibrate the instruments that would detect energy release, thermal radiation and other factors that were independent of nuclear radiation.
The team placed 100 tons of TNT on a tower 20-feet in the air, arranged in the form of a massive cube. The detonation occurred on May 7, after an observation plane launched from the Alamagordo Army Air Field was in position. The explosion was visible 60 miles away at the air field, but was barely felt at the base camp, only 10 miles away from the detonation site.
The Gadget bomb used at the Trinity site involved two explosions: first a conventional TNT explosion and then a nuclear explosion, if the chain reaction started by the first explosion was maintained. The Jumbo device was designed by the X2-A section of the Los Alamos laboratory to act as a failsafe device for the Trinity test explosion. General Groves spent $12 million on Jumbo, a steel cylinder 10 feet in diameter and 25 feet long. Its walls were 14 inches thick and the entire device weighed at least 80 tons.
Jumbo was designed to contain the Gadget and prevent the loss of the precious plutonium in the case that the conventional explosion succeeded, but the nuclear explosion failed. It took a combination of rail and a specially constructed 64-wheel trailer to deliver Jumbo to Trinity.
However, by the time of the actual Trinity test, Manhattan Project officials were confident enough in the plutonium bomb and secure enough in the stream of plutonium coming from Hanford, that Jumbo was deemed unnecessary. Jumbo was suspended from a tower during the test, but it survived the nuclear explosion.
General Groves was concerned that Congress would criticize him for spending $12 million on what was essentially a white elephant, so he ordered Jumbo destroyed. After the war, the Army blew the ends off Jumbo in an unsuccessful attempt to destroy it, and today its remains can be seen at the Trinity Site.
Trinity Test -1945
At 5:29:45 on July 16, 1945, “Gadget” exploded and the Atomic Age began.
The efforts of the Manhattan Project finally came to fruition in 1945. After three years of research and experimentation, the world’s first nuclear device, the “Gadget,” was successfully detonated in the New Mexico desert. This inaugural test ushered in the nuclear era.
The Alamogordo Bombing and Gunnery Range, 230 miles south of Los Alamos, is most famous for its landmark role as the birthplace of nuclear weapons. The site, located in the Jornada Del Muerto Desert, was chosen for its isolation, flat ground, and lack of windy conditions.
Manhattan Project leaders also considered sites elsewhere in New Mexico, as well as in Texas and California. There were very few people living near the Trinity site, and all were paid to leave their land when Manhattan Project officials began constructing the test facility.
Robert Oppenheimer, Director of the Los Alamos Laboratory during the Manhattan Project, called the site “Trinity.” The Trinity name stuck and became the site’s official code name. It was a reference to a poem by John Donne, a writer cherished by Oppenheimer as well as his former lover Jean Tatlock.
The nuclear device detonated at Trinity, nicknamed “Gadget,” was shaped like a large steel globe. Like the Fat Man bomb dropped on Nagasaki, it was a plutonium implosion device. Plutonium implosion devices are more efficient and powerful than gun-type uranium bombs like the Little Boy bomb detonated over Hiroshima.
Plutonium implosion devices use conventional explosives around a central plutonium mass to quickly squeeze and consolidate the plutonium, increasing the pressure and density of the substance. An increased density allows the plutonium to reach its critical mass, firing neutrons and allowing the fission chain reaction to proceed. To detonate the device, the explosives were ignited, releasing a shock wave that compressed the inner plutonium and led to its explosion.
There was a considerable amount of construction that needed to be done in order to prepare the barren desert for its role as a nuclear test site. Kenneth Bainbridge was assigned to lead the test site’s development. In addition to the myriad technical materials required for the Gadget’s successful detonation, a base camp was constructed with ample security measures, albeit Spartan living conditions. Additionally, miles of roads were paved to transport materials to the test site, and multitudes of electrical wires and cables were constructed in order to provide the power that would detonate the gadget during the eventual test.
Much of the preparation for the Trinity test encountered setbacks. The challenges faced in developing the Trinity site were numerous and multifaceted, and there were often close calls that could have jeopardized the outcome of the entire project. Some were almost comical, such as when Kenneth Greisen was pulled over for speeding in Albuquerque while he was driving detonators to Trinity four days before the test. He could have been delayed by several days had the officer checked the contents of his trunk.
A more ominous event was the actual process of winching the Gadget to the top of its tower at the test site. As it was being raised to the top, it came partially unhinged and began to sway. Many observers were stricken with panic at the possibility of the bomb accidentally falling from the tower and detonating, but the Gadget was eventually righted and made its way to the top of the tower without further incident.
Yet Manhattan Project officials were probably most concerned about several failed preliminary tests as they prepared for the actual test. Just two days before the scheduled date for the Trinity test, Edward Creutz led a dress rehearsal practice test without any nuclear materials. Despite the success of a 100-ton TNT blast in May, Creutz’s test was unsuccessful, and the device failed to detonate.
Fortunately for the scientists concerned by this result, Hans Bethe was able to demonstrate the next day that the test failed because of overworked practice equipment. Since the equipment for the Trinity test was comparatively unused, many scientists were comforted by Bethe’s findings.
Scientists were also frustrated by a test run on the fourteenth by Don Hornig. After spending several months working on the X-5 firing unit that would trigger the bomb’s detonation, Hornig had conducted several tests of his device with no problems. However, his final test failed, provoking many of the same fears as Creutz’s failed experiment. The same issue plagued both tests: the practice materials simply had become worn down after several months of experimentation.
The plutonium core was taken to the test area in an army sedan. The non-nuclear components left for the test site. During the day on the 13th, final assembly of the “Gadget” took place in the McDonald ranch house. By 5:00 p.m. on the 15th, the device had been assembled and hoisted atop the 100-foot firing tower. Leslie Groves,Vannevar Bush, James Conant, Ernest Lawrence, Thomas Farrell, James Chadwick, and others arrived in the test area, where it was pouring rain. Groves and Oppenheimer, standing at the S-10,000 control bunker, discussed what to do if the weather did not break in time for the scheduled 4:00 a.m. test. To break the tension, Fermi began offering anyone listening a wager on “whether or not the bomb would ignite the atmosphere, and if so, whether it would merely destroy New Mexico or destroy the world.” Oppenheimer himself had bet ten dollars against George Kistiakowsky’s entire month’s pay that the bomb would not work at all.
Pessimism swirled around the test site. Unfortunately for the scientists at Trinity, it wasn’t the only thing in the air. A dedicated meteorology team, led by Jack Hubbard, had been stationed at the Trinity site since the end of June. They tracked weather patterns and made critical analyses in order to predict what the weather would be doing on July 16. Their reports called for a storm.
As predicted, wind and rain began to batter the Trinity tower on the night of July 15. Many were worried that the test would be forced to be postponed for several days. Any delay would have been a major psychological strain on a project that had become tremendously stressful for its participants as the project entered its final leg.
The imminence of the Trinity test also caused anxiety within the scientific community. Many were concerned about the new bomb’s deadly potential. The fears ranged in scope, but none were more dramatic than Edward Teller’s stated worry that a nuclear bomb could accidentally ignite the atmosphere, causing global destruction. Teller’s fears of a nuclear apocalypse notwithstanding, the Manhattan Project’s leadership—particularly General Groves—were more concerned with the statement being made by another prominent physicist.
Leo Szilard, a Hungarian-American physicist, had long held strong moral objections to the use of the atomic bomb. It was the reason that, despite his early contributions to nuclear physics and the project, Groves sought to limit his role. Now, with the world on the precipice of its first nuclear detonation, Szilard was disturbed. He did not want to see the weapon used in combat, and so he drafted a petition for President Truman demanding that the Japanese be warned before the atomic bomb was used on them. His petition was signed by dozens of employees at the Chicago Metallurgical Lab and the Oak Ridge project site. The petition never made it to President Truman, and Szilard and several of the petition’s signatories were criticized by Groves and others.
Many at the Trinity site, despite the hundreds of man-hours spent preparing for this moment, were still unsure that the bomb would detonate the way it was designed to. There were many theoretical variables that no one at the site could be sure how to predict. Many precautions were taken to prepare for all sorts of doomsday scenarios. Soldiers were posted in several nearby towns in the event that they needed to be evacuated. Groves, who was already concerned for the safety of Amarillo, Texas, a city of 70,000 only 300 miles away, placed a call to New Mexico Governor John J. Dempsey explaining that martial law might need to be implemented in the event of an emergency at the site. The Army Public Relations Department prepared somber explanations in the event that disaster occurred and lives were lost.
On July 16, a thunderstorm delayed the test, which was initially scheduled for 4:00 AM. Hubbard’s team determined that the optimal weather conditions would be only be present between 5:00 and 6:00 AM. Groves famously told Hubbard that “I will hang you” if he was incorrect. Luckily for Hubbard, the weather did clear.
The weather seemed to hold, and the scientists and soldiers took their positions for the test a few hours before the rescheduled 5:30 AM detonation. The closest were stationed at shelters 10,000 yards north, west, and south from the tower. These shelters were populated by soldiers and led by Manhattan Project Scientists who were testing for the effects of radiation. The project’s leadership observed the shelter from Compania Hill, about twenty miles from the tower.
During the final seconds, most observers laid down on the ground with their feet facing the Trinity site and simply waited. As the countdown approached one minute, Isidore Rabi said to the man lying next to him, Kenneth Griesen, “Aren’t you nervous?” “Nope” was Griesen’s reply. As Groves later wrote, “As I lay there in the final seconds, I thought only of what I would do if the countdown got to zero and nothing happened.” Conant said he never knew seconds could be so long. As the countdown reached 10 seconds, Griesen suddenly blurted out to his neighbour Rabi, “Now I’m scared.” Three, two, one, and Sam Allison cried out, “Now!”
At 5:29:45, Gadget detonated with between 15 and 20 kilotons of force, slightly more than the Little Boy bomb dropped on Hiroshima. The Atomic Age had begun.
After years of difficult work, everything finally went according to plan. The test actually yielded more kilotons of TNT than it was predicted to. The complex array of cables, wires, switches, and detonators all worked in unison to create an explosion of energy unlike any the world had ever seen.
Brigadier General Thomas F. Farrell was bewildered by how “the whole country was lighted by a searing light with the intensity many times that of the midday sun. It was golden, purple, violet, gray and blue. It lighted every peak, crevasse and ridge of the nearby mountain range with a clarity and beauty that cannot be described but must be seen to be imagined. It was that beauty the great poets dream about but describe most poorly and inadequately.”
The most common immediate reactions to the explosion were surprise, joy, and relief. Lawrence was stepping from his car when, in his words, everything went “from darkness to brilliant sunshine in an instant”; he was “momentarily stunned by the surprise.” (Click here to read Lawrence’s thoughts on the Trinity test.) A military man was heard to exclaim, “The long-hairs have let it get away from them!” Hans Bethe , who had been looking directly at the explosion, was completely blinded for almost half a minute. Norris Bradbury reported that “the atom bomb did not fit into any preconceptions possessed by anybody.” The blast wave knocked Kistiakowsky (who was over five miles away) to the ground. He quickly scrambled to his feet and slapped Oppenheimer on the back, saying, “Oppie, you owe me ten dollars.” The physicist Victor Weisskopf reported that “our first feeling was one of elation.” The word Isidor Rabi used was “jubilant.” Within minutes, Rabi was passing around a bottle of whiskey. At base camp, Bush, Conant, and Groves shook hands. Rabi reported watching Oppenheimer arrive at base camp after the test:
You’ve seen pictures of Robert’s hat. And he came to where we were in the headquarters, so to speak. And his walk was like “High Noon” — I think it’s the best I could describe it — this kind of strut. He’d done it.
When they met, Groves said to Oppenheimer, “I am proud of you.” Groves’s assistant, Thomas Farrell, remarked to his boss that “the war is over,” to which Groves replied, “Yes, after we drop two bombs on Japan.” Probably the most mundane response of all was Fermi’s: he had calculated ahead of time how far the blast wave might displace small pieces of paper released into it. About 40 seconds after the explosion, Fermi stood, sprinkled his pre-prepared slips of paper into the atomic wind, and estimated from their deflection that the test had released energy equivalent to 10,000 tons of TNT. The actual result as it was finally calculated — 21,000 tons (21 kilotons) — was more than twice what Fermi had estimated with this experiment and four times as much as had been predicted by most at Los Alamos.
Soon shock and euphoria gave way to more sober reflections. Rabi reported that after the initial euphoria, a chill soon set in on those present. The test director, Kenneth Bainbridge, called the explosion a “foul and awesome display” and remarked to Oppenheimer, “Now we are all sons of bitches.” Expressions of horror and remorse are especially common in the later writings of those who were present. Oppenheimer wrote that the experience called to his mind the legend of Prometheus, punished by Zeus for giving man fire, and said also that he thought fleetingly of Alfred Nobel’s vain hope that dynamite would end wars. Most famously, Oppenheimer later recalled that the explosion had reminded him of a line from the Hindu holy text, the Bhagavad-Gita: “Now I am become Death, the destroyer of worlds.” The terrifying destructive power of atomic weapons and the uses to which they might be put were to haunt many of the Manhattan Project scientists for the remainder of their lives.
Trinity was only the first nuclear detonation of the summer of 1945. Two more followed, in early August, over Hiroshima and Nagasaki, killing as many as a quarter of a million people. By October, Norris Bradbury, the new director of Los Alamos, had proposed that the United States conduct “subsequent Trinity’s.” There was more to learn about the bomb, he argued, in a memo to the new coördinating council for the lab, and without the immediate pressure of making a weapon for war, “another TR might even be FUN.” A year after the test at Alamogordo, new ones began, at Bikini Atoll, in the Marshall Islands. They were not given literary names. Able, Baker, and Charlie were slated for 1946; X-ray, Yoke, and Zebra were slated for 1948. These were letters in the military radio alphabet—a clarification of who was really the master of the bomb.
Berlyn Brixner was hired into Los Alamos National Laboratory’s Manhattan Project in 1942 in the first year of World War II. He designed and engineered extremely high speed cameras under the direction of Professor Julian Mack, a former professor at the University of Wisconsin. At the time Brixner began working with Mack, there was no camera with the microsecond resolution needed for research purposes in the development of the first atomic bomb. They had the Mitchell camera capable of operating at 100 feet per second (fps), a Fastax at 10,000 fps, and a Marley at 100 000 fps. In addition, the drum streak (moving slit image) had 10-5 second resolution, and electro-optical shutters providing 10-6 second resolution. Julian Mack invented a rotating-mirror camera for 10-7 second resolution, which was in use by 1944. Small rotating mirror changes secured a resolution of 10-8 second. Photography of oscilloscope traces soon recorded 10-6resolution, which was later improved to a resolution of 10-8 seconds. Brixner and Mack would eventually design and build framing cameras having the ability to operate at speeds of 50,000, 1,000,000, 3,500,000, and 14,000,000 fps.
The film strip that captured the complete detonation of the Trinity atomic bomb test as a result of Brixner’s efforts is not generally considered to be as artistically important as it is scientifically important. But from a moral, sociological, and political point of view, it contains some of the most significant images captured on celluloid film of the twentieth century. Brixner’s images of Trinity captured the intensity, violence, and horror of the first nuclear weapon ever detonated. Beryln Brixner was the first atomic photographer.
Following World War II, Brixner worked until his retirement at Los Alamos National Laboratory (LANL), as head of the Optical Engineering Group. His photography and scientific work are contained in the LANL Historical Archives.
- Julian Mack and Berlyn Brixner were responsible for photography. The photography group employed some fifty different cameras, taking motion and still photographs. Special Fastax cameras taking 10,000 frames per second would record the minute details of the explosion. The Fastax cameras were basically very-high-speed movie cameras and took lots of images separated by tiny amounts of time.
- The T (Theoretical) Division at Los Alamos had predicted a yield of between 5 and 10 kilotons of TNT (21 and 42 TJ). Immediately after the blast, the two lead-lined Sherman tanks made their way to the crater. Radiochemical analysis of soil samples that they collected indicated that the total yield (or energy release) had been around 18.6 kilotons of TNT (78 TJ).
- With the Trinity test and the Atomic bombing of Hiroshima and Nagasaki in 1945, and then subsequent nuclear weapons testing during the early years of the Cold War, background radiation levels increased across the world. Modern steel is contaminated with radionuclides because its production used atmospheric air. As a result, low background steel must be salvaged from prewar uses (usually sunken pre-1945 battleships) in order to be used in applications requiring low contamination levels (medical apparatus, scientific equipment, aeronautical and space sensors).
On the morning of August 6, 1945, the United States Army Air Forces dropped the nuclear weapon “Little Boy” on the city of Hiroshima, Japan. Three days later, the “Fat Man” bomb was detonated over Nagasaki.
In estimating the death toll from the attacks, there are several factors that make it difficult to arrive at reliable figures: inadequacies in the records given the confusion of the times, the many victims who died months or years after the bombing as a result of radiation exposure, and not least, the pressure to either exaggerate or minimize the numbers, depending upon political agenda. That said, it is estimated that by December 1945, as many as 140,000 had died in Hiroshima by the bomb and its associated effects. In Nagasaki, roughly 74,000 people died of the bomb and its after-effects.
In both cities, most of the casualties were civilians. The intentional killing of civilians by the Allies of World War II—who claimed that their cause was just—raised moral questions about the just course of the war, as had the Bombing of Dresden, Germany.
The role of the bombings in Japan’s surrender, as well as the effects and justification of them, has been subject to much debate. In the United States, the prevailing view is that the bombings ended the war months sooner than would otherwise have been the case, saving many lives that would have been lost on both sides if the planned invasion of Japan had taken place. In Japan, the general public tends to think that the bombings were needless as the preparation for the surrender was in progress in Tokyo. Many people determined that the Hiroshima and Nagasaki bombings should remain the first and last hostile use of atomic weapons. During the Cold War, although the competing superpowers stockpiled huge nuclear arsenals, only testing took place.