Enola Gay’s ‘Little Boy’

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Little Boy” was the codename for the atomic bomb dropped on the Japanese city of Hiroshima on 6 August 1945 during World War II by the Boeing B-29 Superfortress Enola Gay, piloted by Colonel Paul W. Tibbets, Jr., commander of the 509th Composite Group of the United States Army Air Forces.

Captain Paul Tibbets in the Enola Gay minutes before takeoff to drop the first atomic bomb on Hiroshima, changing the world forever. 1945

It was the first atomic bomb to be used in warfare. The Hiroshima bombing was the second artificial nuclear explosion in history, after the Trinity test, and the first uranium-based detonation. It exploded with an energy of approximately 15 kilotons of TNT (63 TJ). The bomb caused significant destruction to the city of Hiroshima and its occupants.

Little Boy was developed by Lieutenant Commander Francis Birch’s group of Captain William S. Parsons’s Ordnance (O) Division at the Manhattan Project’s Los Alamos Laboratory during World War II.

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Parsons flew on the Hiroshima mission as weaponeer. The Little Boy was a development of the unsuccessful Thin Man nuclear bomb. Like Thin Man, it was a gun-type fission weapon, but derived its explosive power from the nuclear fission of uranium-235. This was accomplished by shooting a hollow cylinder of enriched uranium (the “bullet”) onto a solid cylinder of the same material (the “target”) by means of a charge of nitrocellulose propellant powder. It contained 64 kg (141 lb) of enriched uranium, of which less than a kilogram underwent nuclear fission. Its components were fabricated at three different plants so that no one would have a copy of the complete design.

After the war ended, it was not expected that the inefficient Little Boy design would ever again be required, and many plans and diagrams were destroyed, but by mid-1946 the Hanford Site reactors were suffering badly from the Wigner effect, so six Little Boy assemblies were produced at Sandia Base. The Navy Bureau of Ordnance built another 25 Little Boy assemblies in 1947 for use by the Lockheed P2V Neptune nuclear strike aircraft (which could be launched from, but not land on, the Midway-class aircraft carriers). All the Little Boy units were withdrawn from service by the end of January 1951.

Hiroshima before and after.

 

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At the time of its bombing, Hiroshima was a city of both industrial and military significance. A number of military units were located nearby, the most important of which was the headquarters of Field Marshal Shunroku Hata’s Second General Army, which commanded the defense of all of southern Japan, and was located in Hiroshima Castle. Hata’s command consisted of some 400,000 men, most of whom were on Kyushu where an Allied invasion was correctly anticipated.

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Hiroshima was a minor supply and logistics base for the Japanese military, but it also had large stockpiles of military supplies. The city was also a communications center, a key port for shipping and an assembly area for troops. It was a beehive of war industry, manufacturing parts for planes and boats, for bombs, rifles, and handguns; children were shown how to construct and hurl gasoline bombs and the wheelchair-bound and bedridden were assembling booby traps to be planted in the beaches of Kyushu. A new slogan appeared on the walls of Hiroshima: “FORGET SELF! ALL OUT FOR YOUR COUNTRY!”. It was also the second largest city in Japan after Kyoto that was still undamaged by air raids.

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The center of the city contained several reinforced concrete buildings and lighter structures. Outside the center, the area was congested by a dense collection of small timber-made workshops set among Japanese houses. A few larger industrial plants lay near the outskirts of the city. The houses were constructed of timber with tile roofs, and many of the industrial buildings were also built around timber frames. The city as a whole was highly susceptible to fire damage.

The population of Hiroshima had reached a peak of over 381,000 earlier in the war but prior to the atomic bombing, the population had steadily decreased because of a systematic evacuation ordered by the Japanese government. At the time of the attack, the population was approximately 340,000–350,000.

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On August 6, 1945, a mushroom cloud billows into the sky about one hour after an atomic bomb was dropped by American B-29 bomber, the Enola Gay, detonating above Hiroshima, Japan. Nearly 80,000 people are believed to have been killed immediately, with possibly another 60,000 survivors dying of injuries and radiation exposure by 1950.

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A Japanese woman and her child, casualties in the atomic bombing of Hiroshima, lie on a blanket on the floor of a damaged bank building converted into a hospital and located near the center of the devastated town, on October 6, 1945.

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Hiroshima

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8.15 AM 6 August 1945 is the date that changed the lives for everyone in Hiroshima. This is the time when the first ever atom bomb’Little Boy’, was dropped.

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The explosion wiped out 90 percent of the city and immediately killed 80,000 people; tens of thousands more would later die of radiation exposure.

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Hiroshima, a manufacturing center of some 350,000 people located about 500 miles from Tokyo, was selected as the first target. After arriving at the U.S. base on the Pacific island of Tinian, the more than 9,000-pound uranium-235 bomb was loaded aboard a modified B-29 bomber christened Enola Gay (after the mother of its pilot, Colonel Paul Tibbets). The plane dropped the bomb–known as “Little Boy”–by parachute at 8:15 in the morning, and it exploded 2,000 feet above Hiroshima in a blast equal to 12-15,000 tons of TNT, destroying five square miles of the city.American President Harry S. Truman called for Japan’s surrender 16 hours later, warning them to “expect a rain of ruin from the air, the like of which has never been seen on this earth”.

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By the time of the Trinity test(was the code name of the first detonation of a nuclear weapon) the Allied powers had already defeated Germany in Europe. Japan, however, vowed to fight to the bitter end in the Pacific, despite clear indications (as early as 1944) that they had little chance of winning. In fact, between mid-April 1945 -when President Harry Truman took office

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-and mid-July, Japanese forces inflicted Allied casualties totaling nearly half those suffered in three full years of war in the Pacific, proving that Japan had become even more deadly when faced with defeat. In late July, Japan’s militarist government rejected the Allied demand for surrender put forth in the Potsdam Declaration, which threatened the Japanese with “prompt and utter destruction” if they refused.

Hiroshima’s devastation failed to elicit immediate Japanese surrender, however, and on August 9 Major Charles Sweeney flew another B-29 bomber, Bockscar, from Tinian.

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Thick clouds over the primary target, the city of Kokura, drove Sweeney to a secondary target, Nagasaki, where the plutonium bomb “Fat Man” was dropped at 11:02 that morning. More powerful than the one used at Hiroshima, the bomb weighed nearly 10,000 pounds and was built to produce a 22-kiloton blast. The topography of Nagasaki, which was nestled in narrow valleys between mountains, reduced the bomb’s effect, limiting the destruction to 2.6 square miles.

The survivors of the bombings are called hibakusha , a Japanese word that literally translates to “explosion-affected people”. As of March 31, 2015, 183,519 hibakusha were recognized by the Japanese government, most living in Japan.The government of Japan recognizes about 1% of these as having illnesses caused by radiation. The memorials in Hiroshima and Nagasaki contain lists of the names of the hibakusha who are known to have died since the bombings. Updated annually on the anniversaries of the bombings, as of August 2015 the memorials record the names of more than 460,000 hibakusha; 297,684 in Hiroshima.

Hibakusha and their children were (and still are) victims of severe discrimination in Japan due to public ignorance about the consequences of radiation sickness, with much of the public believing it to be hereditary or even contagious.

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This is despite the fact that no statistically demonstrable increase of birth defects or congenital malformations was found among the later conceived children born to survivors of Hiroshima and Nagasaki. A study of the long-term psychological effects of the bombings on the survivors found that even 17–20 years after the bombings had occurred survivors showed a higher prevalence of anxiety and somatization symptoms.

The medical effects of the atomic bomb on Hiroshima upon humans can be put into the four categories below, with the effects of larger thermonuclear weapons producing blast and thermal effects so large that there would be a negligible number of survivors close enough to the center of the blast who would experience prompt/acute radiation effects, which were observed after the 16 kiloton yield Hiroshima bomb, due to its relatively low yield:

  • Initial stage—the first 1–9 weeks, in which are the greatest number of deaths, with 90% due to thermal injury and/or blast effects and 10% due to super-lethal radiation exposure.
  • Intermediate stage—from 10–12 weeks. The deaths in this period are from ionizing radiation in the median lethal range – LD50
  • Late period—lasting from 13–20 weeks. This period has some improvement in survivors’ condition.
  • Delayed period—from 20+ weeks. Characterized by numerous complications, mostly related to healing of thermal and mechanical injuries, and if the individual was exposed to a few hundred to a thousand Millisieverts of radiation, it is coupled with infertility, sub-fertility and blood disorders. Furthermore, ionizing radiation above a dose of around 50-100 Millisievert exposure has been shown to statistically begin increasing ones chance of dying of cancer sometime in their lifetime over the normal unexposed rate of ~25%, in the long term, a heightened rate of cancer, proportional to the dose received, would begin to be observed after ~5+ years, with lesser problems such as eye cataracts and other more minor effects in other organs and tissue also being observed over the long term.

The burns on this survivor took on her kimono pattern; the lighter areas of the cloth reflected the intense light from the bomb, causing little to no burns. The tighter fitting parts of clothing, such as the shoulders, are the most severe. Loose fitting sections show no burning.

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During the war, Japan brought many Korean conscripts to both Hiroshima and Nagasaki to work as slaves. According to recent estimates, about 20,000 Koreans were killed in Hiroshima and about 2,000 died in Nagasaki. It is estimated that one in seven of the Hiroshima victims was of Korean ancestry.For many years, Koreans had a difficult time fighting for recognition as atomic bomb victims and were denied health benefits. However, most issues have been addressed in recent years through lawsuits.

It was a common practice before the war for American Issei, or first-generation immigrants, to send their children on extended trips to Japan to study or visit relatives. More Japanese immigrated to the U.S. from Hiroshima than from any other prefecture, and Nagasaki also sent a high number of immigrants to Hawai’i and the mainland. There was, therefore, a sizable population of American-born Nisei and Kibei living in their parents’ hometown of Hiroshima  at the time of the atomic bombings. The actual number of Japanese Americans affected by the bombings is unknown — although estimates put approximately 11,000 in Hiroshima city alone — but some 3,000 of them are known to have survived and returned to the U.S. after the war.

As of 2014, there are about 1,000 recorded Japanese American hibakusha living in the United States. They receive monetary support from the Japanese government and biannual medical checkups with Hiroshima and Nagasaki doctors familiar with the particular concerns of atomic bomb survivors. The U.S. government provides no support to Japanese American hibakusha.