Atomic bombing of Nagasaki: Astrological Article and Chart

About this event

Responsibility for the timing of the second bombing was delegated to Tibbets. Scheduled for August 11 against Kokura, the raid was moved earlier by two days to avoid a five-day period of bad weather forecast to begin on August 10. Three bomb pre-assemblies had been transported to Tinian, labeled F-31, F-32, and F-33 on their exteriors. On August 8, a dress rehearsal was conducted off Tinian by Sweeney using Bockscar as the drop airplane. Assembly F-33 was expended testing the components and F-31 was designated for the August 9 mission.

At 03:47 Tinian time (GMT+10), 02:47 Japanese time on the morning of August 9, 1945, Bockscar, flown by Sweeney's crew, lifted off from Tinian island with Fat Man, with Kokura as the primary target and Nagasaki the secondary target. The mission plan for the second attack was nearly identical to that of the Hiroshima mission, with two B-29s flying an hour ahead as weather scouts and two additional B-29s in Sweeney's flight for instrumentation and photographic support of the mission. Sweeney took off with his weapon already armed but with the electrical safety plugs still engaged.

During pre-flight inspection of Bockscar, the flight engineer notified Sweeney that an inoperative fuel transfer pump made it impossible to use 640 US gallons (2,400 l; 530 imp gal) of fuel carried in a reserve tank. This fuel would still have to be carried all the way to Japan and back, consuming still more fuel. Replacing the pump would take hours; moving the Fat Man to another aircraft might take just as long and was dangerous as well, as the bomb was live. Tibbets and Sweeney therefore elected to have Bockscar continue the mission.

This time Penney and Cheshire were allowed to accompany the mission, flying as observers on the third plane, Big Stink, flown by the group's operations officer, Major James I. Hopkins, Jr. Observers aboard the weather planes reported both targets clear. When Sweeney's aircraft arrived at the assembly point for his flight off the coast of Japan, Big Stink failed to make the rendezvous. According to Cheshire, Hopkins was at varying heights including 9,000 feet (2,700 m) higher than he should have been, and was not flying tight circles over Yakushima as previously agreed with Sweeney and Captain Frederick C. Bock, who was piloting the support B-29 The Great Artiste. Instead, Hopkins was flying 40-mile (64 km) dogleg patterns. Though ordered not to circle longer than fifteen minutes, Sweeney continued to wait for Big Stink for forty minutes. Before leaving the rendezvous point, Sweeney consulted Ashworth, who was in charge of the bomb. As commander of the aircraft, Sweeney made the decision to proceed to the primary, the city of Kokura.

The before image looks like a city. In the after image, everything has been obliterated and it is recognisable as the same area only by the rivers running through it, which form an island in the centre of the photographs.

After exceeding the original departure time limit by nearly a half-hour, Bockscar, accompanied by The Great Artiste, proceeded to Kokura, thirty minutes away. The delay at the rendezvous had resulted in clouds and drifting smoke over Kokura from fires started by a major firebombing raid by 224 B-29s on nearby Yahata the previous day. Additionally, the Yahata Steel Works intentionally burned coal tar, to produce black smoke. The clouds and smoke resulted in 70 percent of the area over Kokura being covered, obscuring the aiming point. Three bomb runs were made over the next 50 minutes, burning fuel and exposing the aircraft repeatedly to the heavy defenses around Kokura, but the bombardier was unable to drop visually. By the time of the third bomb run, Japanese anti-aircraft fire was getting close, and Second Lieutenant Jacob Beser, who was monitoring Japanese communications, reported activity on the Japanese fighter direction radio bands.

With fuel running low because of the failed fuel pump, Bockscar and The Great Artiste headed for their secondary target, Nagasaki. Fuel consumption calculations made en route indicated that Bockscar had insufficient fuel to reach Iwo Jima and would be forced to divert to Okinawa, which had become entirely Allied-occupied territory only six weeks earlier. After initially deciding that if Nagasaki were obscured on their arrival the crew would carry the bomb to Okinawa and dispose of it in the ocean if necessary, Ashworth agreed with Sweeney's suggestion that a radar approach would be used if the target was obscured. At about 07:50 Japanese time, an air raid alert was sounded in Nagasaki, but the "all clear" signal was given at 08:30. When only two B-29 Superfortresses were sighted at 10:53 Japanese Time (GMT+9), the Japanese apparently assumed that the planes were only on reconnaissance and no further alarm was given.

A few minutes later at 11:00 Japanese Time, The Great Artiste dropped instruments attached to three parachutes. These instruments also contained an unsigned letter to Professor Ryokichi Sagane, a physicist at the University of Tokyo who studied with three of the scientists responsible for the atomic bomb at the University of California, Berkeley, urging him to tell the public about the danger involved with these weapons of mass destruction. The messages were found by military authorities but not turned over to Sagane until a month later. In 1949, one of the authors of the letter, Luis Alvarez, met with Sagane and signed the letter.

At 11:01 Japanese Time, a last-minute break in the clouds over Nagasaki allowed Bockscar's bombardier, Captain Kermit Beahan, to visually sight the target as ordered. The Fat Man weapon, containing a core of about 5 kg (11 lb) of plutonium, was dropped over the city's industrial valley. It exploded 47 seconds later at 11:02 Japanese Time at 1,650 ± 33 ft (503 ± 10 m), above a tennis court, halfway between the Mitsubishi Steel and Arms Works in the south and the Nagasaki Arsenal in the north. This was nearly 3 km (1.9 mi) northwest of the planned hypocenter; the blast was confined to the Urakami Valley and a major portion of the city was protected by the intervening hills. The resulting explosion released the equivalent energy of 21 ± 2 kt (87.9 ± 8.4 TJ). Big Stink spotted the explosion from a hundred miles away, and flew over to observe.


Urakami Tenshudo (Catholic Church in Nagasaki) destroyed by the bomb, the dome/bell of the church, at right, having toppled off
Bockscar flew on to Okinawa, arriving with only sufficient fuel for a single approach. Sweeney tried repeatedly to contact the control tower for landing clearance, but received no answer. He could see heavy air traffic landing and taking off from Yontan Airfield. Firing off every flare on board to alert the field to his emergency landing, the Bockscar came in fast, landing at 140 miles per hour (230 km/h) instead of the normal 120 miles per hour (190 km/h). The number two engine died from fuel starvation as he began the final approach. Touching down on only three engines midway down the landing strip, Bockscar bounced up into the air again for about 25 feet (7.6 m) before slamming back down hard. The heavy B-29 slewed left and towards a row of parked B-24 bombers before the pilots managed to regain control. Its reversible propellers were insufficient to slow the aircraft adequately, and with both pilots standing on the brakes, Bockscar made a swerving 90-degree turn at the end of the runway to avoid running off it. A second engine died from fuel exhaustion before the plane came to a stop.

Following the mission, there was confusion over the identification of the plane. The first eyewitness account by war correspondent William L. Laurence of The New York Times, who accompanied the mission aboard the aircraft piloted by Bock, reported that Sweeney was leading the mission in The Great Artiste. He also noted its "Victor" number as 77, which was that of Bockscar. Laurence had interviewed Sweeney and his crew, and was aware that they referred to their airplane as The Great Artiste. Except for Enola Gay, none of the 393d's B-29s had yet had names painted on the noses, a fact which Laurence himself noted in his account. Unaware of the switch in aircraft, Laurence assumed Victor 77 was The Great Artiste, which was in fact, Victor 89.

Although the bomb was more powerful than the one used on Hiroshima, its effects were confined by hillsides to the narrow Urakami Valley. Of 7,500 Japanese employees who worked inside the Mitsubishi Munitions plant, including "mobilized" students and regular workers, 6,200 were killed. Some 17,000–22,000 others who worked in other war plants and factories in the city died as well. Casualty estimates for immediate deaths vary widely, ranging from 22,000 to 75,000. At least 35,000–40,000 people were killed and 60,000 others injured. In the days and months following the explosion, more people died from their injuries. Because of the presence of undocumented foreign workers, and a number of military personnel in transit, there are great discrepancies in the estimates of total deaths by the end of 1945; a range of 39,000 to 80,000 can be found in various studies.

Unlike Hiroshima's military death toll, only 150 Japanese soldiers were killed instantly, including 36 from the 134th AAA Regiment of the 4th AAA Division. At least eight Allied prisoners of war (POWs) died from the bombing, and as many as thirteen may have died. The eight confirmed deaths included a British POW, Royal Air Force Corporal Ronald Shaw, and seven Dutch POWs. One American POW, Joe Kieyoomia, was in Nagasaki at the time of the bombing but survived, reportedly having been shielded from the effects of the bomb by the concrete walls of his cell. There were 24 Australian POWs in Nagasaki, all of whom survived.

The radius of total destruction was about 1 mi (1.6 km), followed by fires across the northern portion of the city to 2 mi (3.2 km) south of the bomb. About 58 percent of the Mitsubishi Arms Plant was damaged, and about 78 percent of the Mitsubishi Steel Works. The Mitsubishi Electric Works suffered only 10 percent structural damage as it was on the border of the main destruction zone. The Nagasaki Arsenal was destroyed in the blast. Although many fires likewise burnt following the bombing, in contrast to Hiroshima where sufficient fuel density was available, no firestorm developed in Nagasaki as the damaged areas did not furnish enough fuel to generate the phenomenon. Instead, the ambient wind at the time pushed the fire spread along the valley.

As in Hiroshima, the bombing badly dislocated the city's medical facilities. A makeshift hospital was established at the Shinkozen Primary School, which served as the main medical centre. The trains were still running, and evacuated many victims to hospitals in nearby towns. A medical team from a naval hospital reached the city in the evening, and fire-fighting brigades from the neighboring towns assisted in fighting the fires. Takashi Nagai was a doctor working in the radiology department of Nagasaki Medical College Hospital. He received a serious injury that severed his right temporal artery, but joined the rest of the surviving medical staff in treating bombing victims.