Asked by: Adrian Hayes, Ireland
No. Spacecraft are too cramped and too public to keep any unauthorised zero-g shenanigans secret, and being caught would almost certainly guarantee that the participants would never go into space again. Officially sanctioned research has begun into two-person sleeping bags that might allow weightless sex, but so far nobody has actually tested them.
Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.
