"He cites a confidential Nasa report on a space shuttle mission in 1996. A project codenamed STS-XX was to explore sexual positions possible in a weightless atmosphere. Twenty positions were tested by computer simulation to obtain the best 10, he says. “Two guinea pigs then tested them in real zero-gravity conditions. The results were videotaped but are considered so sensitive that even Nasa was only given a censored version.” Only four positions were found possible without “mechanical assistance”."