In 1975, NASA sent a pocket calculator on Apollo-Soyuz as a backup if its main computer failed; 37 years later, it ended up at the Smithsonian

NASA utilized an HP-65 calculator as a crucial backup system during the Apollo-Soyuz mission. This programmable device carried essential guidance equations in case the main computer failed. The Apollo-Soyuz mission marked the first joint spaceflight between American and Soviet crews. While the calculator never performed its backup function, its presence ensured mission safety. This historic calculator now resides in the Smithsonian National Air and Space Museum.