Hundreds of artifacts provide a glimpse into the past

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

October 24, 2024

Manhattan Project
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.

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.

Mp2
 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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