We don’t know for sure if anyone has ever tried to have sex in space. NASA once did send a married couple, Jan Davis and Mark Lee, above Earth together, but the now-divorced astronauts have taken the same track as the other 540-odd people who have been off the planet: total silence.
What would happen if someone really did it up there? Well, gravity, it turns out, is a pretty essential element of sex. NASA and the Kinsey Institute have done some stealth speculation on the subject. In the video above, explore how problems with blood flow, pregnancy, exertion, and sweat could complicate the interstellar act.