Bouncy houses or bouncy castles are those big, brightly colored, enclosed trampolines that kids love to jump on at birthday parties, recreation centers, and Chuck E. Cheese. They’re a lot older than you think. American engineer John Scurlock got the idea in 1959. While trying to design a plastic rain cover for tennis courts, he noticed a few of his employees jumping around on one of his prototypes. That goofing off inspired him to create an inflatable floor, purely for recreational purposes. In the ‘60s, with NASA heading for the moon and space-mania at a fever pitch, Scurlock and his wife started a company called Space Walks, rented out the floors as a way to mimic walking on the moon.

Scurlock’s son Frank logically took the idea from floor to fully enclosed structure. In 1974, he joined the family business and created the Jupiter Jump. It consisted of an inflatable floor and columns that supported net walls allowing air to pass through—and the bouncers inside from falling out. Children’s birthday parties were never the same.