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National Museum of Nuclear Science & History

Trinity Site

The famous photo of the Trinity test, taken by Jack Aeby.

J. Robert Oppenheimer gave the code name “Trinity” to a remote patch of the Jornada del Muerto Desert as a tribute to a line from a poem by John Donne. Soon after, teams of scientists and soldiers descended on the area, setting up a base camp and installing equipment in preparation for the world’s first nuclear test. After months of dueling with the limits of technology and the region’s harsh weather conditions, the scheduled test date arrived. On July 16, 1945, the “Gadget” nuclear device was detonated from a steel tower, exploding with a force that would forever alter human history.  

The mushroom cloud rose almost eight miles high and left a crater that was ten feet deep and over 1,000 feet wide. Pieces of a green, glass-like and mildly radioactive mineral were scattered in and around the crater. Dubbed “Trinitite,” investigators theorized that desert sand was lifted by the blast, liquefied by the tremendous temperature and rained down on the earth.

Groves and Oppenheimer with his signature porkpie hat returned to the Trinity site about six weeks after the explosion on Sunday, September 9, 1945. The twisted metal rods were all that remained of the 100-foot tower. The press was invited for the first time in part to dispel fears of lingering high radiation levels.

For more on the Trinity test, click here. For rare photographs taken by Marvin Davis, an MP stationed at the Trinity site, click here. For videos of the Trinity test, visit our YouTube channel.


After the War

In 1952, the site of the first atomic explosion was bulldozed and most of the trinitite removed. The site received a National Historic Landmark designation in 1965 and was listed on the Register of Historic Places less than a year later.

Ground Zero at Trinity is marked by a 12-foot obelisk made of lava rock. Its inscription reads: “Trinity Site: Where the World’s First Nuclear Device Was Exploded on July 16, 1945.”

An 80-ton steel vessel, Jumbo, was built to contain the precious 13 pounds of plutonium in the event that the bomb failed to detonate. Jumbo illustrates Groves’ cautious approach to the project, always having a backup plan in case of failure.

Because Jumbo was never needed, General Groves was concerned that Congress would criticize him for spending $12 milllion on a white elephant. He ordered that the vessel be destroyed. However, eight 500-pound bombs succeeded only in blowing off its ends.

The Trinity site is open to the public on the first Saturdays in October and April. Eventually, the site may be affiliated with the Manhattan Project National Historical Park and open more often.

Photo Gallery:

General Leslie R. Groves and J. Robert Oppenheimer after the successful Trinity test

Oppenheimer with the "Gadget" before the Trinity test

Norris Bradbury with the "Gadget" on top of the Trinity test tower

Norris Bradbury with the "Gadget" on top of the Trinity test tower

Moving Jumbo to Trinity site

General Groves, Oppenheimer and other scientists inspecting Ground Zero

William Laurence & General Groves

Trinitite. Photo courtesy of LANL.

Gadget at Trinity

The explosion at Trinity

The Trinity site after the explosion with the crater

Bringing the Gadget to the top of the Trinity site

AHF President Cindy Kelly with her husband Bill Kelly at the Trinity  site monumentt

The partially destroyed Jumbo at Trinity site today

Trinity test shot .1 seconds

Trinity test shot .016 seconds

Trinity test shot .025 seconds

Trinity test shot .053 seconds

Jumbo on train

Moving Jumbo

Jumbo on specially constructed flat-car

Jumbo on freight car

Jumbo suspended in tower

Jumbo and collapsed tower after the Trinity test

Base Camp

Base Camp

McDonald Ranch headquarters

McDonald Ranch

Mess Hall

Optics Group headquarters

Gadget test tower

Gadget being hoisted

Herb Lehr and Harry Daghlian transporting the plutonium core before the Trinity Test

Slug ready for Gadget

Assembly of the Gadget

Lead lined tanks at Pope, NM

Photographic shelter at Point P (10,000 W)

Camera at Campana Hill station

Site B (Timing Control Center)

1000 north after the test

Aerial of the Trinity site crater

Completed assembly of the TNT tower

First layer of high explosives on the TNT test tower

Stacking high explosives on the TNT test tower

Stacking high explosives on the TNT test tower

Herb Lehr with the Active Material

View from the Top of the Tower

10,000 N Shelter

Green Glass - Trinitite - at 200 W after the Test

Related Video:
Color video of the Trinity test explosion.