So I understand there’s a modicum of interest in sex and NASA. I can’t imagine why that’s the case. Any way, here’s a sex-in-space primer for those wondering about the topic.

We’re not talking about spacecraft mating.

First of all, is sex in space possible? Sure. One NASA physician, Dr. James Logan, recently addressed the topic at a Las Vegas Convention. Live Science reports, though, that it might be messy:

“Sex in micro-g might be a little underwhelming. That is, the fantasy might be vastly superior to the reality. It’s a pretty messy environment…for every action there’s an equal and opposite reaction,” Logan told an attentive audience over the weekend at the NewSpace 2006 meeting in Las Vegas, Nevada, sponsored by the Space Frontier Foundation. Sex in zero-g is going to have to be more or less choreographed, “otherwise it’s just going to be a wild fling,” Logan advised. But for those looking forward to space migration and setting up self-perpetuating civilizations off-Earth, the space physician raised several warning flags.

Is conception possible? Is it safe? Sex in Space author Laura Woodmansee says it’s unclear whether conception is possible, but that it’s quite possible such a conception would be unsafe:

Will a fertilized embryo attach properly to the uterus wall? Are life-threatening ectopic pregnancies more likely in weightlessness? How will reentry acceleration affect a mother and fetus? Are the higher radiation levels of Earth orbit likely to cause problems with the first cell divisions? It may be perfectly safe to conceive in orbit, but we just don’t know enough to take that chance with the health and happiness of a child.

And now, for the big question: has anyone ever had sex in space before? Possibly. The crew of STS-47 included a married couple, N. Jan Davis and Mark C. Lee, who declined interviews after the flight. But whether it actually happened is only answered by a universe of rumor, innuendo and legend. There’s been no kissing and telling — yet.

Finally, might some astronauts have masturbated? Not only is it possible, it’s probable as at least one mission physician recommended it to the astronauts out of concern for infected prostate glands. I’m not making this up. The Apollo 11 command module pilot Michael Collins, writing in his book Liftoff, states about the Skylab mission:

“One doctor advised regular masturbation, advice [Skylab crew member] Joe [Kerwin] ignored.” Later, he writes: “There was no sex on Skylab.” And still later, he addresses the possibility of recreation in space: “And lovemaking! I don’t think any astronauts have yet been privileged to sample the ultimate use of weightlessness.”

Note that he only states that one of the astronauts ignored the advice on masturbation, not all of them. Hmmm.

My personal view — not that I’ve given this a whole lot of thought — is that sex has probably happened. I mean, come on, have you seen Top Gun? The early astronauts were flyboys, chock full of testosterone and machismo, and they presumably would have wanted to push the envelope with women when they first arrived in space.

For those who haven’t yet had their fill on this topic, head on over to the Sex in Space blog, where you can keep up all the comings and goings.