The Story of Hiroshima

Transcription

1 THE TEST The Story of Hiroshima 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 and Little 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.

2 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. THE ORDER IS GIVEN When the Japanese military ignored the Potsdam Declaration s threat of "prompt and utter destruction," Groves drafted the orders to use the bomb and sent them to General Carl Spaatz, commander of air forces in the Pacific. Upon approval by Army Chief of Staff George C. Marshall, Secretary of War Stimson and President Truman, the order to drop Little Boy on Hiroshima had officially been given. 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

3 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.

4 To the crew of the Enola Gay, Hiroshima had disappeared under a thick, churning foam of flames and smoke. The co-pilot, Captain Robert 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

5 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. INFRASTRUCTURE DAMAGE Hiroshima was in ruins. The T-bridge's barriers had been knocked awry; utility poles stood at odd angles, and familiar landmarks were gone or unrecognizable. Buildings even strong modern structures had suffered significant damage, some pushed off their foundations, some gutted by fire, others utterly destroyed. Many steel and concrete buildings appeared intact at first glance, but their outer walls hid internal damage due to the downward pressure of the air burst. Cemeteries were uprooted, and churches had become rubble. The Story of Nagasaki INVADE OR BOMB? By May of 1945 an exhausted and overrun Germany had surrendered. The war in Europe was over. The United States, aided by Great Britain, moved closer and closer to Japan. Massive suicide attacks by the Japanese caused great losses to the Pacific Fleet, but did not deter its drive. Japan, thinking the Soviet Union was a friendly neutral in the war in the Pacific, submitted unofficial peace feelers to the United States through them. The Soviet Union, secretly wanting to join the war against Japan, suppressed the feelers. Ironically, the Japanese military made it impossible to pursue peace directly, as they arrested or killed anybody who tried to extend official peace offerings. As it was, these unofficial feelers were completely unacceptable to the U.S. as they merely made vague offering to return conquered territories in exchange for peace. The big strategic question was how to force Japan's surrender.

6 Japan's major cities had been fire-bombed almost nightly. The islands were blockaded and the Japanese Navy had been destroyed. Planning for a massive invasion by Allied forces was underway. But was that the best answer? The cost in lives for both Allied forces and Japanese civilians would be heavy. Harry S. Truman had just become the U.S. Presidency following Franklin Roosevelt's death. The United States wanted the Soviet Union to enter the war, but was concerned that it would dominate too much of East Asia if the war dragged on. There were two atomic bombs available. Truman made a quick decision: drop both bombs as soon as possible, allowing a short time between missions for Japanese surrender. THE BOMBS Little Boy was a relatively simple, uranium 235-based bomb, and was never tested before being exploded over Hiroshima. Fat Man, the Nagasaki bomb, was a more complex plutonium bomb and Manhattan Project scientists decided it needed to be tested. A prototype, code-named Gadget, was exploded at Alamogordo New Mexico, 110 miles southwest of Albuquerque, on July 16, 1945 during the now-famous Trinity test. THE MISSIONS From the beginning the mission that resulted in the atomic bombing of Hiroshima overshadowed Nagasaki. The Target Committee at Los Alamos selected Hiroshima as one of five possible targets for the first mission, along with Yokohama, Kokura, Niigata, and the city of temples, Kyoto (which was subsequently eliminated at the insistence of Secretary of War Henry L. Stimson against the advice of General Groves, the Manhattan Project's military leader). When a second mission was approved, Kokura was the primary target Nagasaki was the secondary target. The Hiroshima mission went off smoothly. On August 6, 1945, The Enola Gay lifted off from Tinian Island in the Northern Marianas at two A.M. The flight was uneventful, the weather cooperated, and, at 8:15 A.M. bombardier Major Thomas W. Ferebee released Little Boy. The Enola Gay landed uneventfully at Tinian. The crew was greeted by an excited crowd. Generals Carl A. "Tooey" Spaatz and Curtis E. LeMay had flown in from Guam. Pilot Paul W. Tibbets, Jr. was awarded the Distinguished Service Cross by General Spaatz. Following the ceremony the fliers were feted at a star-studded debriefing where General LeMay told the men, "Kids, go eat, take a good shower, and sleep as much as you want!" The Nagasaki mission couldn't have been more different. Originally scheduled for August 11, 1945, the mission was advanced to August 9 due to weather concerns. That day, when one would have expected all attention to be focused on the

7 Nagasaki strike, yet another ceremony took place to honor Tibbets and the crew of the Enola Gay. There was some confusion at the outset of the Nagasaki mission. Major Charles W. Sweeny was to command the mission in his plane The Great Artiste. But The Great Artiste was still outfitted with scientific gear left over from being the support plane for the Hiroshima mission and there wasn't time to outfit it to carry Fat Man. So Sweeney and his crew took over Captain Frederick C. Bock, Jr.'s plane Bock's Car, while Bock's crew switched to The Great Artiste. A typhoon was threatening Iwo Jima, the mission rendezvous point. Yakushima, off the Kyushu coast, became the new rendezvous point and four B-29's were deployed as rescue planes in case crews needed to ditch over water. Just before takeoff from Tinian, flight engineer Master Sergeant John D. Kuharek discovered that one of the fuel pumps was not operating, effectively cutting Bock's Car's fuel supply by 640 gallons. This could jeopardize a safe return and under other circumstances would have meant canceling the mission. But, to convince the Japanese that Hiroshima was not a onetime occurrence, it was decided to proceed. Fat Man was aptly named. Bock's Car was overloaded by the heavy bomb. The plane lumbered down the runway. Everyone on Tinian had seen B-29s overloaded with mines and explosives crash and explode at the end of the runway when just one engine failed. The crew must have had this on their minds. Finally, at 1:56 A.M. on August 9, 1945, with scant yards of runway left, Bock's Car lifted off. Dr. Robert Serber, Los Alamos physicist and J. Robert Oppenheimer's right hand man (Serber briefed physicists of the Manhattan Project on how to build an atomic bomb), was assigned as the mission's high-speed camera specialist. He was supposed to be in Major James T. Hopkins's support plane The Big Stink, but was scratched from the mission because he had forgotten his parachute. Radio silence had to be broken to instruct Hopkins on how to operate the camera. While the two weather planes, Up an' Atom and Laggin' Dragon, were reporting favorable conditions over both Kokura and Nagasaki, Bock's Car was the scene of a heart-stopping discovery: the red arming light on the black box connected to Fat Man was lit, indicating that the firing circuit had closed. A half hour later weaponeer Captain Frederick L. Ashworth and his assistant 2nd Lieutenant Phillip M. Barnes had isolated the failed switch that had caused the malfunction and corrected the problem. Bock's Car and The Great Artiste rendezvoused at Yakushima and waited for Hopkins's plane. Bock, aboard The Great Artiste, caught a glimpse of it, but Sweeney never saw the plane and circled the area for forty minutes, wasting yet more precious fuel, before finally taking off for Kokura. Sweeney and his crew were under orders to only bomb visually. When they got to Kokura they found the haze and smoke obscuring the city as well as the large ammunition arsenal that was the reason for targeting the city. They made three unsuccessful passes, wasting more fuel,

8 while anti-aircraft fire zeroed in on them and Japanese fighter planes began to climb toward them. The B-29s broke off and headed for Nagasaki. The phrase Kokura's Luck was coined in Japan to describe escaping a terrible occurrence without being aware of the danger. OVER NAGASAKI Nagasaki was a city on the west coast of Kyushu on picturesque Nagasaki Bay. It was famous as the setting for Puccini's beautiful opera Madame Butterfly. It was also home to two huge Mitsubishi war plants on the Urakami River. This complex was the primary target, but because the city was built in hilly, almost mountainous terrain, it was a much more difficult target than Hiroshima. Clouds covered Nagasaki when Bock's Car arrived. Contrary to orders, weaponeer Ashworth determined to make the drop by radar if they had to due to their short fuel supply. At the last minute a small window in the clouds opened and bombardier Captain Kermit K. Beehan made the drop at 10:58 A.M. Nagasaki time. Fat Man exploded at 1,840 feet above Nagasaki and approximately 500 feet south of the Mitsubishi Steel and Armament Works with an estimated force of 22,000 tons of TNT. Unlike Hiroshima, there was no firestorm at Nagasaki. Despite this, the blast was more destructive to the immediate area, due to the topography and the greater power of Fat Man. However, the hilly topography limited the total area of destruction to less than that of Hiroshima, and the resulting loss of life, though horrifically high, was also less. The exact number of casualties was impossible to determine. The Japanese listed only those they could verify and set the official estimate at 23, 753 killed, 1,927 missing, and 23, 345 wounded. U.S. Strategic Bombing Survey figures were much higher, but still less than those for Hiroshima. Within a minute of Fat Man's explosion, a brilliant fireball boiled skyward. Sweeney banked sharply to avoid it. The two B-29s were battered by five successive shockwaves and the radioactive cloud surged toward them. Both planes turned away and headed home. HOMECOMING The crew of Bock's Car should have felt some release from tension, but they had only 300 gallons of fuel remaining not enough to get them back to Tinian, and perhaps not even to Okinawa. Sweeney had his radio operator, Sergeant Abe M. Spitzer, contact the air-sea rescue teams to alert them to the possibility of ditching. There was no answer. The rescue teams had shut down, apparently deciding Bock's Car had long returned to Tinian. When they reached Okinawa, repeated attempts to raise the tower for landing instructions went unanswered. Sweeney watched other planes taking off and landing, but knew he didn't have enough gas for protracted circling. He set off flares and finally somebody on the ground noticed. Bock's Car landed at two P.M. local time. The number two engine ran out of fuel while they were on the runway. They had a total of seven gallons of fuel left.

9 They refueled, took off for Tinian, and landed without further incident at 11:39 P.M. local time. No one was on hand to greet them. There was no ceremony. No one had even thought to have food ready for the famished crews who hadn't eaten in almost twenty-four hours. JAPAN'S REACTION Despite the horror of Hiroshima, there were many in the Japanese government that disbelieved the United States had the technical ability to develop, yet alone transport and drop, an atomic bomb. The events of August 9 changed all that. ] Japanese Foreign Minister Shigenori Togo called the ninth of August "a bad day." The Soviet Union declared war on Japan, overrunning the Kwantung army in Manchuria. Sumihisa Ikeda, Director of the Imperial Cabinet Planning Board, described the once invincible army as "no more than a hollow shell." When news of the Nagasaki bombing reached Tokyo, Togo proposed acceptance of the Potsdam Declaration which set out terms of surrender for Japan and was signed by the United States, Great Britain, and China (U.S.S.R. ruler Joseph Stalin was a principal participant at Potsdam but did not sign the declaration). Japan's Supreme War Direction Council was deadlocked on a decision. Debate continued throughout that day and night. Finally, at 2 A.M. August 10, 1945, Prime Minister Admiral Baron Kantaro Suzuki respectfully begged His Imperial Majesty Hirohito to make a decision. Hirohito did not hesitate, "...I do not desire any further destruction of cultures, nor any additional misfortune for the peoples of the world. On this occasion, we have to bear the unbearable." The emperor had spoken. Unfortunately antisurrender sentiment and objections from much of the Japanese military was widespread. Vice Admiral Takijiro Onishi, founder of the kamikazes, argued the Japanese "would never be defeated if we were prepared to sacrifice 20,000,000 Japanese lives in a 'special attack' effort." He later committed suicide rather than surrender. Hirohito was determined. Against all precedent, the emperor himself convened an Imperial Conference and at noon on August 15, 1945, announced Japan's surrender. The war was over.