In 1957, during Operation Plumbbob, scientists detonated an underground nuclear test called Pascal-B. To seal the shaft, they used a 2,000-pound steel manhole cover. When the bomb went off, the pressure had nowhere to go. A high-speed camera caught the cover for one single frame—moving so fast it may have become the first human-made object to leave Earth. This was just 1 of 29 nuclear tests conducted in 1957 alone. ⸻ #OperationPlumbbob #HiddenHistory #ColdWar #ScienceFacts #DidYouKnow