This Is What Happens to Your Penis in Space

Owning a penis already comes with plenty of complications, from impromptu erections to still-swirling questions around length and girth. But taking that penis into space adds some interesting layers to the matter, especially when it comes to sexual activity.

The topic has long fascinated those curious about space. It was most recently revived in a Sputnik article that talked to space researchers about the possibilities of sex in zero gravity and, more specifically, potential penile problems during the act. In addition to the not-so-romantic environs and near-total lack of privacy aboard a space shuttle, living in weightlessness does strange things to your body—including your hard-on.

A rush of blood to the penis allows it to become erect, and under normal conditions, the erection “is maintained by restricting blood flow out of the penis, so that it stays hard,” said Adam Watkins, an assistant professor of reproductive biology at the University of Nottingham. But under zero gravity, “fluids within the body tend to relocate to the head and the chest, meaning sending extra blood to the penis could be more difficult.” Hence an unfortunately floppy member.

Men have been dealing with their penises in space ever since Yuri Alekseyevich Gagarin became the first human to travel into the outer reaches in 1961. Yet what exactly happens to your penis in space, while studied by researchers with a certain amount of speculation, still isn’t well understood. Astronauts have been famously tight-lipped on the subject, and NASA has refused to comment on sex in space, telling FiveThirtyEight that it’s not focused on researching the area. (Three former astronauts when asked did not comment for this story, and an email to a NASA spokesperson went unanswered.)

The impact of space travel and zero gravity on the penis “just hasn’t been closely looked at,” Watkins said, “or if it has, NASA and other space agencies haven’t spoken about it.”

In addition to the not-so-romantic environs and near-total lack of privacy aboard a space shuttle, living in weightlessness does strange things to your body—including your hard-on.

It’s simple to see why NASA might be more concerned with promoting important scientific advancements that don’t have to do with genitalia or sexual reproduction. No astronaut—or pair of astronauts or curious group of moonwalkers—has yet copped to doing the biblical deed in space, though a couple has divulged other penis-related details.

During takeoffs, landings, and spacewalks, astronauts wear adult diapers, former NASA astronaut Mike Mullane told Men’s Health in 2014. And with no shower available, cleanup means wiping down the urine-soaked area of your body with a washcloth. “It's incredibly uncomfortable,” Mullane explained. The alternative to the diaper is a condom-like urine-collection device, which is much cleaner. Though the problem with that option is that “you can't feel condoms after hours and hours, so you don't know if it's still attached. So, if that happens, you're just urinating in your suit, which is the last thing you want to do.”

Even without the adult diaper during certain moments of a space session, urination in zero gravity isn’t fun. Urine relieved normally “would all just float about!” Watkins noted. “Instead, astronauts have to pee into special vacuum cups designed for both men and women’s bodies that hover it up into a storage tank.”

Mullane confirmed the shifting of fluid in weightlessness from his experience. Yet when it came to the effects on his horniness, he had the opposite problem of a hard-to-get erection. “A couple of times, I would wake up from sleep periods and I had a boner that could have drilled through kryptonite,” he said.

Other physical issues could hamper regular sexual habits. “Testosterone levels in male astronauts have been shown to decrease during their time in space. This might mean that a man’s sex drive becomes lower while in space,” Watkins said. “No one really knows why this happens, but testosterone levels seem to return to normal once back on Earth, so the effects don’t seem to be permanent.”

One upside for the guys shipping out to the stars? Their penis might get bigger or at least appear that way. “This is because astronauts often ‘grow’ while in space,” Watkins added. “This is due to the lack of gravity’s compressive effects on the spine and so the astronauts essentially relax out a bit. However, even if this effect also acted on the penis, the magnitude would be minimal.”

Whatever the change in penis size, Mullane and fellow former NASA astronaut Leroy Chiao told Men’s Health that they weren’t aware of anyone having sex in space. Chiao is quite certain no one has done it because “if someone had actually done it, that guy would not be able to keep his mouth shut, and we would all know.”

Then there’s the longer view. If we’re to colonize the moon or Mars the way Elon Musk hopes to, sex will eventually have to become a priority. There’s no hope of humans thriving beyond Earth if they can’t have sex. Until then, Watkins suspects that sex won’t be high on NASA’s agenda.

The reproductive biologist, though, does have a suggestion for male astronauts having trouble getting it up: Because sex without an erection is “essentially impossible,” Watkins said, if someone did want to have sex in space and erections were an issue, then using medications and other erection devices could be one way to aid blood flow to the penis and maintain an erection. A familiar solution, to be sure, but one that might prove more vital on a trip to the stars.

The real advancements in space penile function may not come from NASA at all. Future space joy rides, Watkins speculated, may be where that kind of liftoff happens. “Where sex might occur more readily is with the increase in space tourism. It would not surprise me if some people would be very interested in joining the ultimate ‘Mile-High club.’”