| Original caption: “Jumbo” atomic device being positioned for “Trinity” test at Alamogordo, New Mexico. “Jumbo” container housing the “gadget” nuclear implosion device being positioned for the Trinity Test. Responsibility for the design of a containment vessel for an unsuccessful explosion, known as “Jumbo,” was assigned to Robert W. Henderson (April 10 1915 – June 10, 2002) and Roy W. Carlson (September 23, 1900 – November 21, 1990) of the Los Alamos Laboratory’s X-2A Section. The bomb would be placed into the heart of Jumbo, and if the bomb’s detonation was unsuccessful the walls of Jumbo would not be breached, making it possible to recover the bomb’s plutonium. Hans Bethe (July 2, 1906 – March 6, 2005), Victor Weisskopf (September 19, 1908 – April 22, 2002), and Joseph O. Hirschfelder (May 27, 1911 – March 30, 1990) made the initial calculations, followed by a more detailed analysis by Henderson and Carlson. They drew up specifications for a steel sphere 13 to 15 feet (4 to 4 1/2 meters) in diameter, weighing a 100 a 50 short tons and capable of handling a pressure of 50,000 pounds per square inch (340,000 kilopascals). After consulting with the steel companies and the railroads, Carlson produced a scaled-back cylindrical design that would be much easier to manufacture. Carlson identified a company that normally made boilers for the Navy, Babcock & Wilcox; they had made something similar and were willing to attempt its manufacture. As delivered in May 1945, “Jumbo” was 10 feet (3 meters) in diameter and 25 feet (7.6 meters) long with walls 14 inches (356 millimeters) thick, and weighed 214 short tons. A special train brought it from the Babcock & Wilcox plant in Barberton, Ohio, to the siding at Pope, where it was loaded on a large trailer and towed 25 miles (40 kilometers) across the desert by crawler tractors. At the time, it was the heaviest item ever shipped by rail. “Jumbo” was not used for its originally intended purpose in the Trinity test but was in a tower some distance from the bomb when it went off. For many of the Los Alamos scientists, Jumbo was “the physical manifestation of the lowest point in the Laboratory’s hopes for the success of an implosion bomb.” By the time it arrived, the reactors at the Hanford Engineer Works produced plutonium in quantity, and Los Alamos Laboratory Director J. Robert Oppenheimer (April 22, 1904 – February 18, 1967) was confident that there would be enough for a 2nd test. The use of “Jumbo” would interfere with the gathering of data on the explosion, the primary objective of the test. An explosion of more than 500 tons of TNT (2,100 Gigajoules) would vaporize the steel and make it difficult to measure the thermal effects. Even 100 tons of Trinitrotoluene (TNT) (420 Gigajoules) would send fragments flying, presenting a hazard to personnel and measuring equipment. It was therefore decided not to use it. Instead, “Jumbo” was hoisted up a steel tower 800 yards (732 meters) from the explosion, where it could be used for a subsequent test. In the end, Jumbo survived the explosion, although its tower did not. “Jumbo” was destroyed on April 16, 1946, when an Army ordnance team detonated 1,300 pound bombs in the bottom of the steel container. “Jumbo,” with its steel banding around the middle, had been designed to contain the 5,000 pounds of high explosive in the atomic bomb while it was suspended in the center of the vessel. With the conventional bombs placed in the bottom of Jumbo, the resulting blast sent fragments flying in all directions as far as 3/4 of a mile. Who authorized the destruction of “Jumbo” remains controversial. Los Alamos scientists were upset that such an expensive tool was expended uselessly. United States Army General Leslie R. Groves (August 17, 1896 – July 13, 1970) reportedly was upset at the cost of building and transporting “Jumbo” and may have ordered it destroyed to prevent it being used for the United States Navy’s Operation Crossroads tests at Bikini Atoll of atomic weapons or to turn it into a bathysphere. The rusting skeleton of Jumbo sits in the parking lot at the Trinity site on the White Sands Missile Range, where it was moved in 1979. | |
| Image Filename | wwii2178.jpg |
| Image Size | 677.48 KB |
| Image Dimensions | 2062 x 2952 |
| Photographer | |
| Photographer Title | Department of Energy |
| Caption Author | Written or Adapted by Jason McDonald |
| Date Photographed | July 16, 1945 |
| Location | |
| City | Alamogordo |
| State or Province | New Mexico |
| Country | United States |
| Archive | National Archives and Records Administration |
| Record Number | NWDNS-434-N-61(6380) |
| Status | Caption ©2026 MFA Productions LLC Please Do Not Duplicate or Distribute Without Permission; Image in the Public Domain |
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