After Apollo 11 returned to Earth in 1969, Neil Armstrong spent his 39th birthday behind a glass wall from his wife; NASA kept him in a 3-week quarantine while scientists investigated a Lunar threat that probably never existed

Apollo 11 astronauts underwent a three-week quarantine after returning from the Moon. This precaution was taken due to the unknown biological environment of the lunar surface. Scientists tested lunar samples for potential harmful microorganisms and toxins. The astronauts celebrated a birthday behind glass while remaining in isolation. After testing confirmed safety, the quarantine requirement was discontinued.