The Trinity Site in New Mexico

Where the Nuclear Age began

Trinity was the code name of the first detonation of a nuclear device that took place at 5:29 a.m. MWT (Mountain War Time) on July 16, 1945, as part of the Manhattan Project. The site is located in the Jornada del Muerto desert about 35 miles southeast of Socorro, NM, on what was the Alamogordo Bombing and Gunnery Range. The area was renamed the White Sands Proving Ground on July 9, 1945, and is now a part of the White Sands Missile Range.  

Why Was a Test Necessary?

The Manhattan Project was concentrating on two different types of atomic bombs.  The uranium bomb had a simpler design, and the scientists were confident that it would work without testing.  The plutonium bomb was more complex, however, and worked by compressing the plutonium into a critical mass to sustain a chain reaction.  Project leaders decided that a test of the plutonium bomb was essential before it could be used as a weapon of war.  This was a similar design as the Fat Man bomb later detonated over Nagasaki, Japan, on August 9, 1945.

How the Plutonium Bomb Would be Tested

The plutonium bomb set to be tested at the Trinity Site was known as “The Gadget.”

The first atomic bomb “The Gadget”, 1945

The core of the bomb consisted of a grapefruit-sized ball of plutonium which was delivered to the site on July 11, 1945, and the bomb was assembled on July 13, 1945. The “gadget” was a large 6-foot sphere covered with wires and patched up with tape.  To better understand the likely effect of a bomb dropped from a plane and detonated in air, the bomb was to be detonated atop a 100-foot (30 m) steel tower.

“The Gadget” was lifted to the top of a 100-foot tower for detonation.

I’ll Take That Bet

The scientists set up a betting pool on what the results of the test would be. How big of a blast would it create measured in kilotons of TNT or would the test be a dud?  For instance, Edward Teller (Hungarian-American physicist) was the most optimistic, predicting 45 kilotons of TNT.  Norman Ramsey Jr. chose zero (a complete dud), Robert Oppenheimer chose 0.3 kilotons of TNT. Ultimately, the scientist who had the guess 18 kilotons of TNT turned out to be the winner (Isador Rabi).  

Enrico Fermi offered to take wagers among the top physicists and military present on whether the atmosphere would ignite, and if so whether it would destroy New Mexico, or incinerate the entire planet. This had been previously calculated to be almost impossible, but he did this to bring a little levity to a very serious time. This did, however, frighten some of the military guards some of whom asked to be relieved.

Base Camp at Trinity Test Site

What was Observed

The Trinity Test was a success.  It appeared to have been a blast equivalent to 18 kilotons of TNT.  The blast outshone the sun and was witnessed from as far as 200 miles away and broke windows as far as 160 miles away. The world’s first nuclear mushroom cloud reached more than 50,000 feet into the atmosphere.

Oppenheimer (left) and LTG Groves inspect Ground Zero of the Trinity Site.

The heat from the blast was 14,000 degrees Fahrenheit and it melted the desert sand, turning it into a glass-like substance.  It was primarily quartz and feldspar, tinted sea green with minerals in the desert sand, with droplets of condensed plutonium sealed into it. It became known as Trinitite.  Concerned for its residual radioactivity, the Army bulldozed the site in 1952 and made collecting Trinitite illegal. What’s sold today was collected before the ban. Unless you eat it, scientists report, it isn’t dangerous anymore.

A piece of Trinitite and a warning sign that can be seen at Trinity Site during semi-annual open houses

In an interview of J. Robert Oppenheimer in the 1960’s, he claimed that in the moments after the detonation, a line from the Hindu scripture, the Bhadavad Gita, had come into his mind: “Now I am become Death, the destroyer of worlds.”

Decades Later

The Trinity Site is now part of the White Sands Missile Range and is owned by the U.S. Department of Defense (DOD). Ground zero is marked by an obelisk made of black lava rock, with an attached commemorative plaque. A slightly depressed area several hundred yards across surrounds the monument, indicating where the blast took place. Only a few pieces of the green glass, trinitite, remain in a protected enclosure. 

Obelisk at Ground Zero of Trinity Site

The 51,500-acre area was declared a national historic landmark in 1975.  The landmark includes base camp, where the scientists and support group lived; ground zero, where the bomb was placed to the explosion; and the Schmidt/McDonald ranch house, where the plutonium core to the bomb was assembled.

Visiting Trinity Site

The site is safe for visitation.  Radiation levels are above normal levels; however, they are far below the exposure one would experience during an x-ray or a CT scan.  One hour spent at Ground Zero would expose a person to as much radiation as one would get during a long commercial flight across the United States.

Today, the Trinity Site is part of the White Sands Missile Range and is open to the public two days a year, on the first Saturday in April and October. The next open houses are scheduled for the following dates:

• October 21, 2023

• April 6, 2024

Due to the recent release of the movie Oppenheimer, a larger than normal crowd is expected at the October open house.  The US Army’s site that has information about the event suggests that wait times may be over two hours to get onto the site.  In addition, they say that if you aren’t one of the first 5000 visitors, you may not get through the gate before it closes on that day at 2 pm. 

Trinity Site Open House :: White Sands Missile Range (army.mil)

Alamogordo: Visit the Trinity Site (U.S. National Park Service) (nps.gov)

The Trinity Test Site Is Open One More Time This Year. You Might Not Get In. | Military.com

Next Time

My next post will be about the Manhattan Project National Historical Park. It’s many historical sites within the three main cities where the Manhattan Project took place: Los Alamos, NM; Oakridge, TN; and Hanford, WA.