Astronaut, Lisa Marie Nowak, drove 1450 km from Houston, Texas to Orlando Florida on 4-5 February 2005. In her car were latex gloves, a black wig, a BB pistol and ammunition, pepper spray, a hooded tan trench coat, a 2-pound hammer drill, black gloves, rubber tubing, plastic garbage bags, $585 in cash, her computer and an 8-inch Gerber folding knife. She was crossing the country to confront and kidnap her rival for the affection of another astronaut, Bill Oefelein. With the kidnapping foiled, upon her arrest she admitted to investigators to being in a relationship with Bill Oefelein which was "more than a working relationship, but less than a romantic relationship"
Nowak and Oefelein were never in the same space mission, so they could never have a sexual encounter in space. However, rumours abound of a secret history of astronauts doing the deed in zero gravity.
NASA has an official stance of forbidding sexual activity in space. In 1991 the first married couple, Jan Davis and Mark Lee, were allowed to fly on the same mission. NASA would usually not allow married couple to fly together, although not for such reasons but with the argument that it disrupts team morale. At the time, Davis and Lee having married so close to launch time might have pushed the circumstances beyond NASA's disciplinary rigor.
Current and former astronauts often avoid questions of this nature. In a live interview in 1997 conducted by C-Span with American and Russian crew carrying out re-supplying mission on Mir Space Station, a caller asked if "anybody had ever thought about having sex in space". Col. Charles J. Precourt alluded to the manic schedule on board of the shuttle to the topic not usually arising. As he turned to cosmonaut Elena Kondakova, she shrugged off the subject almost completely.
A respected French scientist Pierre Kohler published a hoax report of a secret experiment conducted on board the Mir Space Station in 1996. Project codenamed STS-XX was to explore possible sexual positions in a weightless atmosphere. This report is now widely available online.
But, is sex in space even desirable? An MSNBC report, quoting Laura Woodmansee's book "Sex in Space", concluded in 2006 that sex in space would be (unpleasantly) "hotter and wetter" as scientists found that people perspire more in microgravity. The physics of zero gravity makes even the act of kissing very difficult. To maintain their position the couple would have to be strapped together, which is inconducive to love-making. Zero gravity would also lower your blood pressure which will in turn reduce the blood flow to the male member, resulting in a rather deflated performance. Bodily fluids are also dangerous in a space shuttle as they can slip into electricals, short circuiting important machinery. The more conservative of these romantics would also be deterred by the general lack of privacy in the tiny quadrants of a space shuttle. On a more serious note, conceiving in space (if it is even possible) could be very dangerous for the fetus and the mother. Fetal development could be adversely affected by zero gravity.
NASA's "don't ask don't tell" policy prevents these endless speculations from being answered anytime soon.