Hundreds of Manhattan Project artifacts provide a glimpse into the past

Findings from Manhattan Project work at Los Alamos National Lab give insight into average wartime worker

September 17, 2024

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Jonathan Creel, of the Lab’s Environment and Waste Programs, lines up artifacts recently found on Lab property where the inner workings of Little Boy and Thin Man were tested during the Manhattan Project. From left, a steel target used during testing; a slug used as a projectile inside the gun-type device's cannon; and another steel target with the slug's indentation.

Los Alamos National Laboratory archaeologists recently found nearly 500 unrecorded artifacts at a historic site where non-nuclear parts for Little Boy and Thin Man, the gun-style bombs built as part of the Manhattan Project, were tested during World War II.

Combined with household items carried over from the Homestead-era Anchor Ranch, once located about a quarter mile away, Jeremy Brunette, from the Lab’s Environmental Stewardship group, said the artifacts highlight the "human aspect of working in Los Alamos during the wartime expediency of a world-changing event."

An experimental spot during the urgent World War II years

Located in a flat, forested area on the western end of the Lab, the historic firing range, called “Gun Site,” comprised two gun emplacements where mounted cannon barrels shot projectiles containing high explosives. Steel targets were mounted about 20 feet away, while sand pits — called catcher boxes — laid behind the guns and targets to collect the projectiles. The cannon barrels, when not in use, were covered by enclosures that could be rolled back and forth on tracks, like a rolling garage.

The goal was to test the guns' inner workings and then refine Little Boy and Thin Man's designs accordingly.

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 The failed plutonium gun-type design, called Thin Man. 

Once testing of the weapons was complete and the U.S. government gave its directive, Little Boy, made with uranium, was dropped over Hiroshima on Aug. 6, 1945. The plutonium-based Thin Man never came to fruition due to the conclusion that plutonium was too energetic for the gun-style bomb to work. This turnabout led to the focus on Fat Man, which used plutonium in a more predictable, implosion-style device. That bomb was dropped over Nagasaki on Aug. 9, 1945.

When the war ended, the Manhattan Project also concluded. The Gun Site firing range was cleaned up and the naval guns buried.

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 Today, the area surrounding Gun Site is lush with native grasses, wildflowers and trees.   

A tale of two histories

Recently found artifacts include pieces of tracks on which the gun emplacement enclosures ran; cables that transmitted data from the firing range to a building just down the hill; nearly a dozen slugs, or large steel casings that contained the high-explosive projectiles; and part of a steel target that still shows an indentation from the projectile's impact.

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 Left: Jeremy Brunette examines a recently discovered Manhattan Project-era slug found at the historic firing range. Right: Also found were the remnants of a rail that facilitated the movement of the garage-type apparatuses that covered the gun emplacements. 

Brunette and the Lab's Cultural Resources team also found several items from the nearby Anchor Ranch, built after the Homestead Act of 1862, when the federal government gave tracts of land to U.S. citizens who agreed to live on and improve their newfound property through farming or other means. The existing infrastructure of the ranch was a big boon to the War Department when scouting the area as they were able to use the buildings and cleared land.

Archeologists found pieces of bowls and other stoneware, as well as a medicine bottle and broken soda bottle, likely connected to the ranch. Brunette said the items could have been taken from the homestead site by Manhattan Project workers.

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Homestead-era artifacts were also recently found at Gun Site, including the medicine bottle on the left and pieces of a broken Coca-Cola bottle, pictured on the right. 

"This location was used prior to the Manhattan Project, and our findings help us understand multiple depths of history," Brunette said. "It's really interesting to find these things and think about how people moved around the site — what sodas they drank, what their material suppliers were."

Environmental sampling, potential remediation spurs findings

The catalyst for the findings was a survey by Lab archeologists that preceded the collection of soil samples from DOE's Environmental Management Los Alamos Field Office and its contractor N3B. Both are tasked with addressing the Lab's legacy environmental impacts from the Manhattan Project and Cold War eras. Following results of the soil samples, the cleanup agencies will assess whether soil remediation at Gun Site is necessary.

"For some reason, the area surrounding the Gun Site was never surveyed for artifacts," Brunette said. "We found much more than we assumed we would. We expected to find 100 artifacts, at most."

Brunette said the coordination with DOE’s Los Alamos Field Office and N3B to protect the artifacts while collecting environmental samples has been seamless.

"N3B used ground-penetrating radar to locate where the guns are buried and where they want to collect samples to determine if contaminants have leached into the ground," Brunette said.

Such targeted analysis meant the area was disturbed as little as possible before soil samples were collected.

Adding another layer of protection

Now, the Lab's Cultural Resources Program is working to record details on the artifacts — their physical descriptions, where they were located and their historical significance. Then, per federal guidelines, they'll submit a report of their findings to the State Historic Preservation Office. That office will collaborate with its federal counterpart to determine if Gun Site meets eligibility criteria to be listed on the National Register of Historic Places, which would offer an additional layer of protection, specifically to the artifacts.

The entities will also determine the best method for preserving the artifacts based on their classification status and other criteria — in a museum; their original location in the field, which lies in the Manhattan Project National Historical Park managed by the Lab in concert with the National Park Service; or elsewhere.

If they are able to find funding, the team hopes to eventually exhume and decontaminate the guns, then place them on recreated gun emplacements at the site, covered by garage apparatuses that they also rebuild.

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The team that helps preserve Manhattan Project National Historical Park sites on Lab property hopes to recreate the gun emplacement pictured above. The two gun emplacements in the area comprised Little Boy and Thin Man prototypes for testing purposes during World War II. 

"Seeing these prototype guns in place would not only add to the overall interpretation at this unique site, but also allow our program to connect current and future employees to one of the places where Los Alamos’s work began," said Jonathan Creel, Manhattan Project National Historical Park program manager.

"When people think about the Manhattan Project, they often think of the big names: Robert Oppenheimer, Emilio Segrè, Enrico Fermi. But there were many others, too — just people out here doing their day-to-day jobs, just like we're doing today," Brunette noted. "Our findings humanize the Manhattan Project."

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Still standing today are three buildings at Gun Site where data from the gun-style device tests were transmitted and high explosives were stored.

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