a good reason not to try sex in space. yet.

January 14, 2011

chicken embryo

Reproduction is a complicated business, and for many creatures on our world, its a rather lethal and painful experience, complete with disembowelment and impalement on genitals that could double as weapons in a typical Medieval arsenal. Thankfully, we humans tend to have it relatively easy and generally have the making babies thing down so much so, what when we’re talking about venturing into space, we wonder if we can take our kids with us and give birth to new generations as we travel to the stars. In fact one of the dominant ideas for getting to another solar system within the next few centuries involves the generation ship, vast spacecraft designed to function as their own, self-contained colonies and housing thousands of humans for very long stretches of time, ideally with all the comforts of home. And one of those comforts better be gravity because it turns out that if humans were to start reproducing without that familiar acceleration of 9.8 m/s/s or pretty close to it, their children are likely to be born with cranial defects, collapsed jaws, and buckled spines, among some of the other pleasantries of embryos’ inability to cope with a lack of gravity during the development process.

Building on some previous research into reproduction in space, a Canadian graduate student working with a sample of zebrafish embryos decided to temporarily free them from gravity at a developmental stage in which their skulls were being shaped. After spinning them in a bioreactor designed to simulate the perpetual freefall astronauts experience in space, she found that their heads simply didn’t form properly. Jaws were warped, and a number of bones at the base of the skull were deformed and buckled as the fish grew into adulthood. It seems that without the effects of gravity, the scaffolding for the diving cells is altered and the resulting bones, cartilage, and other structures assembled themselves on a faulty foundation. And the damage isn’t just to the skeletons either. An earlier experiment with zebrafish also found that the lack of gravity means that their basic senses were also severely affected. The improper distribution of fluids in the embryos damaged what would become their vestibular system. With a defective internal gyroscope, the fish has problems with stabilizing the movement of their retinas. Humans with a similar defect would be unable to keep track of objects in their line of sight were they to turn their head because their eyes couldn’t adjust. For most zebrafish, these effects were temporary if they were taken out in time, but the longer they stayed in microgravity, the more permanent those effects became. Human embryos in space are very likely to suffer the same fate as well.

Oh and by the way, all this is just from the development process. In the depths of space, as a spacecraft gets pelted with cosmic rays and solar winds, it’s hard to tell what radical and very likely deadely mutations would start surfacing in a floating embryo. Now of course, all these problems aren’t insurmountable and don’t say anything about our future in space. Spacecraft which rotate around a central axis, using centrifugal force as a stand-in for gravity could be built, and an electromagnetic shield would keep out a good deal of radiation. But that said, there would still be very serious risks when it comes to raising new generations away from Earth. It your craft were to break and find itself unable to keep spinning or a sudden power outage leaves the artificial magnetosphere severely reduced or down for any significant length of time, your descendants may suffer the consequences. How do we know that human children may be deformed as embryos in microgravity if we did the experiments on zebrafish? Because zebrafish and other vertebrates share a very similar set of key stages in development and thanks to evolution, we know that what affects the zebrafish is also far more likely to have an effect on us than not. So if we ever want to colonize and populate space, we better start building some very redundant and very reliable spacecraft that won’t just come with some of the comforts of home, but require all of them for the sake of our future astronauts children and grandchildren…

See: Moorman, S., Cordova, R., & Davies, S. (2002). A critical period for functional vestibular development in zebrafish Developmental Dynamics, 223 (2), 285-291 DOI: 10.1002/dvdy.10052

[ photo illustration by Tomas Pais de Azevedo ]

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  • No comprendo. How does spinning in a bioreactor replicate freefall? On the contrary.

    There is no way to cancel gravity. This appears to be nonsense.

  • amphiox

    Cervantes, spinning produces centripetal/centrifugal (whichever way you prefer to describe it) force/acceleration. One of the main tenets of relativity is that all forms of acceleration are indistinguishable from within the accelerating reference frame. So inside a rotating space ship, the centripetal/centrifugal forces will be experienced as a force pushing things inside against the outer wall that will be indistinguishable from gravity by those inside. (The inner surface of the outside wall becomes the “ground”, and outwards becomes “down”).

  • Greg Fish

    “How does spinning in a bioreactor replicate freefall?”

    Well, here’s a study which describes exactly how microgravity bioreactors work. They suspend a cell culture or embryo in fluid and rotate to keep it in freefall-like conditions.

  • Stephan

    Of all the reasons that might actually discourage sex in space, this one must be the least compelling…

  • Peeweep

    Amphiox: It’s true that a centrifuge can simulate a gravitational field, however it cannot be used to cancel out the acceleration due to gravity at the earth’s surface (well, technically it could if it were the size of the earth itself.) The setup this experiment uses doesn’t eliminate gravity, it tumbles the specimen around so that there isn’t a consistent gravitational pull from any particular direction. I can’t say it really seems quite as definitive as a true free-fall experiment would be.

  • Greg Fish

    “I can’t say it really seems quite as definitive as a true free-fall experiment would be.”

    Problem is that a true free-fall experiment would cost tens of millions of dollars in the least since you’d actually have to go out to, well, space to do it. It’s not perfect, but it does give you a very good idea of what would happen.

    And Stephan, you don’t find that serious birth defects due to a lack of gravity are a compelling reason to really think things through before having procreational sex in space? What would you find more compelling than that?

  • Don Roberto

    This may be a reason not to try reproduction in space, but it certainly ain’t a reason not to try sex in space. I suspect even impregnation in space wouldn’t be a problem as long as you got the mother back into gravity before things were too far along.

  • Samantha Vimes

    Greg, there’s non-reproductive sex as an option. It’s called recreational sex. Now, maybe they didn’t tell you about this option when you were growing up, but sometimes two adults decide they want to have sex when they aren’t ready for a baby. They use something called “birth control”. There are many options for birth control, including hormonal pills, condoms, and IUDs.

    … sorry to get sarcastically condescending, but you *do* know those things, right? You do get why everyone is pointing out your title does NOT reflect the contents of your post? I mean, it was very interesting, but we expected it to be about sexual activity and the direct problems, not trying to grow a fetus in 0G.

  • Okay, so what happens when you let the fetuses continue to develop in microgravity, and start a colony? How long before we get mutations evolved to orient and function in such conditions? How long before we have a zero gee capable species?

    Then, of course, long interstellar trips don’t bother you (and presumably, you have bred out the tendency to go capsule-happy as well – they’ll be able to deal with the confinement.) As you get closer to your destination, you start to reverse the process by simulating gravity again – the vestiges of the systems should still be present and eventually reactivate. It’s just Darwin’s Finches on a floating island.

    I just think we’re being shortsighted, here. We need to get used to babies that can’t coordinate hand-eye movement and have a lot of tics. ‘Course, we’ll have to give up boxing…

  • Greg Fish

    “You do get why everyone is pointing out your title does NOT reflect the contents… ?”

    I do, and I had second thoughts about the title when I published it, but I naively thought that many of my readers wouldn’t act on their more pedantic urges. Besides, you have to remember that the reason why sex in space was brought up in space agencies both in the U.S. and the USSR was because the scientists wondered if humans could ever reproduce in space and raise new generations away from our home world, so there is something there, even for the pedant in you.

    As for the problems with actual sexual intercourse in space, I wrote about that a while ago on Ian O’Neill’s blog and go into plenty of detail as why it would be a pretty messy affair without at least some gravity and creature comforts.

    “… I just think we’re being shortsighted, here. We need to get used to babies that can’t coordinate hand-eye movement and have a lot of tics.

    Or, or… just a crazy thought here, how about we build spacecraft which simulate some of the planet’s gravitational pull and avoid most of these pleasantries altogether? We want to have an extension of the human species in space, not some bizarre colony of beings we wouldn’t recognize and would never want to meet, right?

  • “We want to have an extension of the human species in space, not some bizarre colony of beings we wouldn’t recognize and would never want to meet, right?”

    Beauty is in the nystagmic eye of the beholder…

  • Pierce R. Butler

    Just Al: How long before we get mutations evolved to orient and function in such conditions?

    Since mutations are not goal-driven, and the reported effects are so extreme, it seems quite likely that the free-fall population would become extinct long before all the necessary genetic changes could be effected.

    That’s if we leave it all to random mutation (even as accelerated as that would be in a higher-radiation environment), of course. By the time humans are ready to try permanent space existence, we may well have moved beyond present DNA manipulation into something which could truthfully be called genetic engineering, and be able to produce something like the no-legged/four-armed zero-G “quaddies” of Lois McMaster Bujold’s sf novel Falling Free (link shows most illustrative cover of multiple editions). The ethics of such a transfiguration are left as an exercise for the reader – along with the ethics of committing a human subsociety to a generation ship in the first place.

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