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.
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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