Operation Plumbbob’s “Manhole Test” (officially known as Pascal-B) was a U.S. nuclear test conducted in 1957 at the Nevada Test Site. It involved detonating a small nuclear device in a deep underground shaft capped with a steel manhole cover. The goal was to study high-energy explosive effects and containment methods. The test unintentionally launched the steel cap at an extraordinary speed, possibly exceeding Earth’s escape velocity (~11.2 km/s), making it one of the fastest manmade objects. Wh