This article is part of a series that will delve into the history of the Trinity Site Test, which marked its 80th anniversary on July 16, 2025, and the commemoration of the growth and evolution of White Sands Missile Range, which marked its 80th anniversary on July 9, 2025. A commemoration of the establishment of White Sands Proving Ground, now called White Sands Missile Range, will take place on Oct. 17 at WSMR and an observance for the test at Trinity Site will take place on Oct. 18 at the Trinity Site Open House.
The device designed to be tested at Trinity Site involved two steps: First there would be a conventional ignition involving TNT, and a fraction of a second later, the nuclear ignition if a chain reaction were maintained. This two-step process created a problem. The Manhattan Project scientists and engineers were sure the TNT would ignite but were initially unsure if the plutonium core inside the device would ignite as planned. If the chain reaction failed to occur, the TNT would release the exceedingly rare plutonium. Of note, it is estimated the plutonium within the device would be valued at more than a billion dollars today.
Because of this possibility, Jumbo was designed and constructed. Originally it was 25 feet long, 10 feet in diameter and weighed 214 tons. Scientists were planning to suspend the device in the center of this huge steel barrel so it could contain the plutonium if the chain reaction failed to materialize, thus preventing the plutonium from being lost. If the test occurred as planned, Jumbo would be vaporized.
Jumbo was built in Ohio and brought by train to the now abandoned railroad siding in Pope, N.M. It was unloaded and a specially built trailer with 64 wheels was used to slowly move Jumbo 25 miles to ground zero.
As the scientist and engineers gained confidence in the design of the device, they decided Jumbo was not needed. Jumbo was then suspended under a steel tower 800 yards from ground zero. The blast destroyed the tower, but Jumbo survived intact. The remnants of the tower location are still visible today.
When you now view Jumbo, you will notice the ends are missing. This is because in 1946, the Army attempted to destroy Jumbo by using eight 500-pound bombs. At the time, Jumbo was standing on end, and the bombs were stacked from the bottom. This asymmetrical detonation only blew the ends off but left the body intact. Just like before, Jumbo survived the explosion and lay abandoned in the desert.
Jumbo remained at the tower location until 1979, when White Sands Missile Range personnel moved it to its current location next to the entrance to ground zero. After the obelisk, Jumbo is the most visited and photographed feature available during the Trinity Site Open House.
Social Sharing