Neil Armstrong didn’t believe in omens, but he got a nasty one anyway the moment he climbed into his Gemini 8 spacecraft on the morning of March 16, 1966. If Armstrong had believed in omens, he might have been better prepared for what the rest of the day held for him.TIME’s Jeffrey Kluger takes you through the Gemini 8 mission and the events that make it one of the most harrowing space missions of all time