THE TEST
At 5:29:45 a.m., July 16, 1945, a blinding flash and unbelievable heat seared the New Mexico desert—the world's first nuclear explosion. Code-named Trinity, the Manhattan Project's test of the plutonium implosion bomb was a stunning success. The explosion almost equaled 20,000 tons of TNT, many times what some had expected. General Groves and his Project leaders were jubilant and relieved. But for some, the spectacle also cast an ominous shadow. Los Alamos scientific director Dr. Robert Oppenheimer later said he thought of the lines from the Hindu scripture, the Bhagavad Gita, I am become Death, Destroyer of Worlds.
DESIGNS OF TWO BOMBS
The Manhattan Project produced two different types of atomic bombs, code-named Fat Man andLittle Boy. Fat Man, which was dropped on Nagasaki, was the more complex of the two. A bulbous, 10-ft. bomb containing a sphere of the metal plutonium 239, it was surrounded by blocks of high explosives that were designed to produce a highly accurate and symmetrical implosion. This would compress the plutonium sphere to a critical density and set off a nuclear chain-reaction. Scientists at Los Alamos were not entirely confident in the in the plutonium bomb design, so they scheduled the Trinity test.
The Little Boy type of bomb, which was dropped on Hiroshima, had a much simpler design than the Fat Man model that had been tested at Trinity. Little Boy triggered a nuclear explosion, rather than implosion, by firing one piece of uranium 235 into another. When enough U235 is brought together, the resulting fission chain reaction can produce a nuclear explosion. But the critical mass must be assembled very rapidly; otherwise, the heat released at the start of the reaction will blow the fuel apart before most of it is consumed. To prevent this inefficient pre-detonation, the uranium bomb uses a gun to fire one piece of U235 down the barrel into another. The bomb’s gun-barrel shape was believed to be unquestionably reliable and had never been tested. In fact, testing was out of the question since producing Little Boy had used all of the purified U235 produced to date; therefore, no other bomb like it has ever been built.
Detonated by a mechanism that resembled a cannon, Little Boy had a muzzle or target that was a hollowed-out subcritical mass of uranium. The cannon ball was another subcritical mass of uranium, which fit perfectly into the hollow of the target as a plug. The plug was propelled down the cannon barrel by several thousand pounds of high explosive. When it hit, the combination of compression and increased mass pushed the uranium to the supercritical level and the bomb went off.
FINAL PREPARATIONS
Little Boy was ready for delivery by July 31. On August 2, Hiroshima was specified as the primary target, with Kokura and Nagasaki as alternates. The raid was set for August 6.
While plans for the invasion of Japan were going ahead, preparations were also being made for the use of the atomic bomb. Target recommendations were made by the Target Committee. Among its primary concerns was showing off the bomb’s power to the maximum effect. By the end of May 1945, the Committee selected, in order of priority, Kyoto, Hiroshima, Kokura and Niigata. The Army Air Forces were ordered not to firebomb these cities.
WHY HIROSHIMA?
Hiroshima was chosen as the primary target since it had remained largely untouched by bombing raids, and the bomb's effects could be clearly measured. While President Truman had hoped for a purely military target, some advisers believed that bombing an urban area might break the fighting will of the Japanese people. Hiroshima was a major port and a military headquarters, and therefore a strategic target. Also, visual bombing, rather than radar, would be used so that photographs of the damage could be taken. Since Hiroshima had not been seriously harmed by bombing raids, these photographs could present a fairly clear picture of the bomb's damage.
UNEXPECTED OPPOSITION
Before Little Boy was dropped on Hiroshima, Leo Szilard at Met Lab in Chicago tried to stop its use. Ironically, Szilard had led atomic bomb research in 1939, but since the threat of a German bomb was over, he started a petition to President Truman against bombing Japan. With 88 signatures on the petition, Szilard circulated copies in Chicago and Oak Ridge, only to have the petition quashed at Los Alamos by theoretical physicist J. Robert Oppenheimer.
When General Leslie Groves learned of the petition, he polled the Met Lab scientists and learned that only 15 percent wanted the bomb used "in the most effective military manner." While 46 percent voted for "military demonstration in Japan to be followed by a new opportunity for surrender before full use of the weapon is employed," somehow the figures were manipulated to suggest that 87 percent of the Met Lab scientists favored some sort of military use. Ultimately, Groves sat on Szilard's petition and the poll until August 1, and then had them filed away. President Truman never saw them.
DELIVERING LITTLE BOY
At approximately 2:00 a.m. on August 6, 1945, a modified American B-29 Superfortress bomber named the Enola Gay left the island of Tinian for Hiroshima, Japan. This mission was piloted by Colonel Paul Tibbets, commanding officer of the 509th Composite Group, who named the bomber after his mother. The four-engine plane, followed by two observation planes carrying cameras and scientific instruments, was one of seven making the trip to Hiroshima, but only the Enola Gay was carrying a bomb—a bomb that was expected to knock out almost everything within a 3-mile (5-kilometer) area. Measuring over 10 feet (3 meters) long and almost 30 inches (75 centimeters) across, it weighed close to 5 tons (4.5 tonnes) and had the explosive force of 20,000 tons (18,000 tonnes) of TNT.
The Enola Gay weaponeer, Navy Capt. Deak Parsons, was concerned about taking off with Little Boy fully assembled and live. Some heavily loaded B-29s had crashed on takeoff from Tinian. If that happened to the Enola Gay, the bomb might explode and wipe out half the island. Thus, Parsons, assisted by Lt. Morris Jeppson, finished the assembly and armed the bomb in the bomb bay after takeoff.
After 6:00, the bomb was fully armed on board the Enola Gay. Tibbets announced to the crew that the plane was carrying the world's first atomic bomb. By 7:00, the Japanese radar net detected aircraft heading toward Japan, and the alert was broadcast throughout the Hiroshima area. Soon afterward, a weather plane circled over the city, but there was no sign of bombers. The people began their daily work and thought the danger had passed.
At 7:25, the Enola Gay was cruising over Hiroshima at 26,000 feet. By 8:00, Japanese radar again detected B-29s heading toward the city. Radio stations broadcast another warning for people to take shelter, but many ignored it. At 8:09, the crew of the Enola Gay could see the city appear below and received a message indicating that the weather was good over Hiroshima.
THE BOMB EXPLODES
A T-shaped bridge at the junction of the Honkawa and Motoyasu rivers near downtown Hiroshima was the target. At 8:15 a.m., Little Boy exploded, instantly killing 80,000 to 140,000 people and seriously injuring 100,000 more. The bomb exploded some 1,900 feet above the center of the city, over Shima Surgical Hospital, some 70 yards southeast of the Industrial Promotional Hall (now known as the Atomic Bomb Dome). Crewmembers of the Enola Gay saw a column of smoke rising fast and intense fires springing up. The burst temperature was estimated to reach over a million degrees Celsius, which ignited the surrounding air, forming a fireball some 840 feet in diameter. Eyewitnesses more than 5 miles away said its brightness exceeded the sun tenfold.
IMMEDIATE AFTERMATH
In less than one second, the fireball had expanded to 900 feet. The blast wave shattered windows for a distance of ten miles and was felt as far away as 37 miles. Over two-thirds of Hiroshima's buildings were demolished. The hundreds of fires, ignited by the thermal pulse, combined to produce a firestorm that had incinerated everything within about 4.4 miles of ground zero.
To the crew of the Enola Gay, Hiroshima had disappeared under a thick, churning foam of flames and smoke. The co-pilot, Captain Richard Lewis, commented, "My God, what have we done?"
About 30 minutes after the explosion, a heavy rain began falling in areas to the northwest of the city. This "black rain" was full of dirt, dust, soot and highly radioactive particles that were sucked up into the air at the time of the explosion and during the fire. It caused contamination even in areas that were remote from the explosion.
INSTANT CONFUSION
Radio stations went off the air, and the main line telegraph had stopped working just north of Hiroshima. Chaotic reports of a horrific explosion came from several railway stops close to the city and were transmitted to the Headquarters of the Japanese General Staff. Military headquarters personnel tried to contact the Army Control Station in Hiroshima and were met with complete silence. The Japanese were puzzled. They knew that no large enemy raid could have occurred, and no sizeable store of explosives was in Hiroshima at that time, yet terrible rumors were starting.
A young officer of the Japanese General Staff was instructed to fly immediately to Hiroshima, to land, survey the damage and return to Tokyo with reliable information for the staff. Headquarters doubted that anything serious had occurred, but the rumors were building. When the staff officer in his plane was nearly 100 miles (160 km) from Hiroshima, he and his pilot noticed a huge cloud of smoke from the bomb. In the bright afternoon, the remains of Hiroshima were burning.
The plane soon reached the city and circled it. A great scar on the land was still burning, covered by a heavy cloud of smoke. They landed south of Hiroshima, and the staff officer immediately began to organize relief measures, after reporting to Tokyo
WHAT HAPPENED
Since communications between the Hiroshima and higher military and naval headquarters had been severed, initial news that something frightful had occurred at Hiroshima came into Tokyo from nearby towns. People reported to the navy's underground headquarters in Tokyo a "sinister cloud," an "enormous explosion," a "terrible flash," a "heavy roar." Reports were vague and created more puzzlement than alarm. Finally, from descriptions of the city's destruction, Japanese military began to realize that what happened may have been the result of an atomic bomb-a shock to them, since most thought the Americans' progress in nuclear bomb development to be still in the "scientific investigation" stage.
Truman's public announcement in Washington, D.C., 16 hours after the attack, was Tokyo's first knowledge of what had really happened to Hiroshima:
"Sixteen hours ago an American airplane dropped one bomb on Hiroshima. It is an atomic bomb. We are now prepared to obliterate more rapidly and completely every productive enterprise the Japanese have above ground in any city. If they do not now accept our terms they may expect a rain of ruin from the air the like of which has never been seen on this earth."
The Japanese immediately formed the "Atomic Bomb Countermeasure Committee," which was made up of members of the War, Navy, and Home ministries, and included Technical Board representatives. The committee's first meeting was held on August 7, at which time the latter group "strongly insisted that the bomb was not an atomic bomb." They maintained that even if the Americans had gone so far as to develop an atomic bomb, they wouldn't have brought "such unstable weapons as atomic devices to Japan, across the Pacific." They added, "We do not know what will happen in the future, but to date American technique is not that highly developed." Rather, they claimed, the explosion was the result of a "new type [of] bomb with special equipment, but its content is unknown." Japan's initial public announcement of the bomb did not include the word "atomic."
In the meantime, army and navy personnel had been sent to investigate Hiroshima. Initially, there was disbelief that the destruction was caused by an atomic bomb, but after viewing the degree and nature of the devastation and noting that it was different from that caused by conventional bombs, they knew that the United States had indeed perfected and used the atomic bomb. Japan was quite a bit behind in its own nuclear-bomb development.
PHYSICAL EFFECTS
The survivors, known as hibakusha, sought relief from their injuries. However, 90 percent of all medical personnel were killed or disabled, and the remaining medical supplies quickly ran out. Many survivors began to notice the effects of exposure to the bomb’s radiation. Their symptoms ranged from nausea, bleeding and loss of hair, to death. Flash burns, a susceptibility to leukemia, cataracts and malignant tumors were some of the other effects.
HIBAKUSHA STORIES
First-hand accounts from survivors best convey the bomb’s impact on Hiroshima’s people. The following "Voice of Hibakusha" eyewitness accounts of the bombing of Hiroshima are from the program HIROSHIMA WITNESS produced by the Hiroshima Peace Cultural Center and NHK, the public broadcasting company of Japan.
Mr. Akihiro Takahashi was 14 years old, when the bomb was dropped. He was standing in line with other students of his junior high school, waiting for the morning meeting 1.4 km away from the center. He was under medical treatment for about year and half. And even today black nail grows at his finger tip, where a piece of glass was stuck.
The heat was tremendous . And I felt like my body was burning all over. For my burning body the cold water of the river was as precious as the treasure. Then I left the river, and I walked along the railroad tracks in the direction of my home. On the way, I ran into an another friend of mine, Tokujiro Hatta. I wondered why the soles of his feet were badly burnt. It was unthinkable to get burned there. But it was undeniable fact the soles were peeling and red muscle was exposed. Even I myself was terribly burnt, I could not go home ignoring him. I made him crawl using his arms and knees. Next, I made him stand on his heels and I supported him. We walked heading toward my home repeating the two methods. When we were resting because we were so exhausted, I found my grandfather's brother and his wife, in other words, great uncle and great aunt, coming toward us. That was quite coincidence. As you know, we have a proverb about meeting Buddha in Hell. My encounter with my relatives at that time was just like that. They seem to be the Buddha to me wandering in the living hell.
Eiko Taoka, then 21, was one of nearly 100 passengers said to have been on board a streetcar that had left Hiroshima Station at a little after 8:00 a.m. and was in a Hatchobori area, 750 m from ground zero, when the bomb fell. Taoka was heading for Funairi with her one year old son to secure wagon in preparation for her move out of the building which was to be evacuated. At 8:15, as the streetcar approached Hatchobori Station, an intense flash and blast engulfed the car, instantly setting it on fire. Taoka’s son died of radiation sickness on August 28. The survival of only ten people on the streetcar have been confirmed to date.
When we were near in Hatchobori and since I had been holding my son in my arms, the young woman in front of me said, ‘I will be getting off here. Please take this seat.’ We were just changing places when there was a strange smell and sound. It suddenly became dark and before I knew it, I had jumped outside.... I held [my son] firmly and looked down on him. He had been standing by the window and I think fragments of glass had pierced his head. His face was a mess because of the blood flowing from his head. But he looked at my face and smiled. His smile has remained glued in my memory. He did not comprehend what had happened. And so he looked at me and smiled at my face which was all bloody. I had plenty of milk which he drank all throughout that day. I think my child sucked the poison right out of my body. And soon after that he died. Yes, I think that he died for me.
Ms. Akiko Takakura was 20 years old when the bomb fell. She was in the Bank of Hiroshima, 300 meters away from the hypocenter. Ms. Takakura miraculously escaped death despite over 100 lacerated wounds on her back. She is one of the few survivors who was within 300 meters of the hypocenter. She now runs a kindergarten and she relates her experience of the atomic bombing to children.
Many people on the street were killed almost instantly. The fingertips of those dead bodies caught fire and the fire gradually spread over their entire bodies from their fingers. A light gray liquid dripped down their hands, scorching their fingers. I, I was so shocked to know that fingers and bodies could be burned and deformed like that. I just couldn't believe it. It was horrible. And looking at it, it was more than painful for me to think how the fingers were burned, hands and fingers that would hold babies or turn pages, they just, they just burned away. For a few years after the A-bomb was dropped, I was terribly afraid of fire. I wasn't even able to get close to fire because all my senses remembered how fearful and horrible the fire was, how hot the blaze was, and how hard it was to breathe the hot air. It was really hard to breathe. Maybe because the fire burned all the oxygen, I don't know. I could not open my eyes enough because of the smoke, which was everywhere. Not only me but everyone felt the same. And my parts were covered with holes.
HIROSHIMA TODAY
In 1958, the population of Hiroshima reached 410,000, finally exceeding what it was before the war. It is currently a major urban center with a population of 1.12 million people. Major industries in Hiroshima today are machinery, automotive (Mazda) and food processing. Interestingly enough, one quarter of Hiroshima's electricity is from nuclear power.
Rebuilding efforts over the decades have been fruitful. As early as 1979, the difference between Hiroshima in the immediate aftermath and what it had become was remarkable:
"In today’s Hiroshima, bustling shopping centers line covered pedestrian malls and major department stores feature a range of merchandise almost as great as their Tokyo counterparts," wrote John Spragens Jr., a staff writer for the Corsicana (Texas) Daily Sun, in an article published on August 29, 1979 .
The downtown streets of Hiroshima are now lined with high-rise buildings, and the park is green again. Every year on August 6, the day the bomb was dropped, Hiroshima holds a ceremony in Peace Memorial Park, where the mayor reads his annual Peace Declaration. Determined to fulfill its mission as an international peace culture city, Hiroshima strives to rid the world of nuclear weapons.
The hibakusha who are still alive are becoming quite elderly, averaging over 70 years old. Sadly, some are confined to hospitals due to aftereffects, and many live in fear, wondering when the radiation might strike again. Although it is painful for them to tell their stories, many hibakusha are willing to do so in order to help the next generation understand the importance of peace.
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