This is the second in a three-part series about sex and gender issues in space.
With public and private entities jostling to bring humans to places like asteroids, Mars and even Venus, longterm human spaceflight is getting sexy. Except so far, there's not much sex. That's a problem: Even before future Mars colonists begin contemplating extending the human germ line elsewhere in the solar system, astronauts and scientists will need to confront not only astronauts' physical and psychological health but the matter of coitus and reproduction outside of Earth's atmosphere. So far, that doesn't seem like a very good idea.
"[Space] is a dangerous environment [and] people don't really recognize that," says Paul Root Wolpe, the director of the Center for Ethics at Emory University and a senior bioethicist at NASA. "It's not an ideal place to have a child, and as far as we know might not be an ideal place to be pregnant."
Humanity has sent everything from rats, geckos, sea urchins and birds (although not bees) into space to study the effects of microgravity on non-human embryonic and fetal development, and the results have been far from promising. While reproduction has generally been successful, the mortality rates and gross abnormalities among the experiments' progeny continue to suggest that space might not be the ideal environment to put a bun in the oven.
In fact, the concept of procreating in space can sometimes seem like a callous, unethical, and terrible idea. It has long been known that microgravity environments contribute to a range of other adverse physiological effects in humans, such as bone and muscle deterioration. Combined with the uniquely stressful environment that is life aboard a spacecraft or at a colony, these influences on fetal and infant development could lead to serious physical abnormalities and mental handicaps in future extraterrestrials.
The risk of pregnancy in space isn't idle speculation: between 1989 and 2006, seven pregnancies were documented at Australian Antarctic research stations, an environment which is frequently used as a space analog due to its isolation. It's a staggering number and suggests that dangerous environs alone aren't significant deterrents for their horny inhabitants. NASA has already taken this into consideration.
Traveling to space pregnant is expressly forbidden by the space agency, so much so that female astronauts are routinely tested for pregnancy in the 10 days leading up to a mission launch. Once in space, many women continue to use the various contraceptives they were taking on Earth, albeit for different reasons.
"Part of the recommendation [to take contraceptives in space] is practical, much like competitive athletes take contraception continuously to prevent menstruation," said Marjorie Jenkins, a NASA advisor who serves as Chief Scientific Officer at the Laura W. Bush Institute for Women's Health. "Since we do not have human data about menstrual cycling in regard to long or short term space travel, it is not correct to assume that space travel would act as a natural contraceptive."
In addition to the difficult mechanics of giving birth in space, extraterrestrial pregnancy raises a host of thorny moral questions. Every astronaut who goes into space with NASA is not only a government employee, but also a human test subject. This means they are protected by "the Common Rule," the portion of the Code of Federal Regulations which outlines the scope of experimentation that can be legitimately performed on human subjects. The Common Rule has a specific clause pertaining to when it is legitimate to perform scientific experiments on a pregnant woman or fetus, which basically boils down to determining whether the woman or fetus will directly benefit from the research and whether they are subject to more than a minimal level of risk by partaking in the experiment.
Extended stays in space—and the prolonged exposure to radiation that comes with it—also have the potential to damage human reproductive organs. While spending several months in space has not been shown to limit the fertility of astronauts, there are concerns that when this time is increased to a number of years, radiation exposure could prove to be very damaging to the reproductive organs of astronauts.
Astronauts spending six months at the ISS will be exposed to roughly 40 times the amount of radiation experienced during a year on Earth, and on a six-month journey to Mars, astronauts' exposure to radiation would be the equivalent of about 15 times the annual exposure limit for a worker in a terrestrial nuclear power plant.
Graham Scott, the Vice President and Chief Scientist at the National Space Biomedical Research Institute, claims that "men and women can both be very well adapted to space," although he also notes that women are typically limited to flying only 50 percent the number of missions of their male counterparts because of effects that radiation can have on the female body, particularly the ovaries.
Despite these unpromising initial results, the scientists who think about these things aren't giving up. "If we intend for people to live on other planets the rest of their lives, we can expect that they're going to want to raise families there," said Wolpe. "It's a very interesting methodological question as to how we determine what kind of impact reproduction in lower gravity environments might have on gestation and child rearing."
While studies have shown the risks of making babies in free space, other research indicates that extended exposure to hypogravity—a decrease in gravitational force—does not adversely affect the ability to procreate upon return to Earth.
"A significant number of astronauts have conceived children after going to space," said Scott. "People worry that the radiation could be doing something to the female's eggs or the male's sperm, but children are able to be conceived after spaceflight." However, he notes, NASA recently began offering astronauts the opportunity to bank their eggs or sperm, "so we don't always know if these are in vitro fertilizations or natural conceptions."
Inbreeding In Outer Space
Despite the reasonable expectation that future space colonists will want to raise families, they would have to be incredibly wary of reproductive habits on other planets to prevent another very real threat to the colony's success: inbreeding.
Genetic diversity is essentially what contributes to a healthy human population—conventional wisdom suggests the larger the community, the more genetic diversity you'll find among the population. In small, isolated groups on earth, interbreeding among relatives has been shown to severely limit the population's genetic diversity, making it much more susceptible to diseases that would otherwise be very rare in a genetically diverse population.
If the goal is to maintain as much genetic diversity as possible to promote a population's survival for centuries, what is the population threshold that must be reached before people can start breeding on other planets?
In 2002, anthropologist John Moore calculated that, to maintain a stable population and minimize the risks associated with inbreeding, a colony would need to host approximately 160 unrelated people to maintain a high level of genetic diversity over a time span of 200 years. A more recent calculation performed by Portland State University anthropologist Cameron Smith suggests that Moore had wildly miscalculated.
According to Smith, the ideal population is somewhere between 10,000 and 40,000 inhabitants if the goal is to maintain near 100 percent genetic variation over a time span of 300 years. When that population size drops to 500, the remaining genetic variation is at about 50 percent. At 150 persons, the genetic variation in 300 years will be roughly 20 percent of the starting variation. Should a plague hit these smaller populations, the lack of genetic diversity could prove to be disastrous for future Martians, suggesting that the first colonists might want to lay off the hanky panky until they are joined by more Earthlings—at least 10,000 more, to be exact.
Of course, 100 percent genetic variation would be optimal, but the simple fact of the matter is that we are far from capable of transporting tens of thousands of people to other planets or moons.
At the moment, our ambition for long-term space exploration far exceeds the knowledge necessary to make it a successful venture, especially when it comes to sex and reproduction. What little we do know about reproduction in space seems to suggest that it is probably not a good idea. But as human history is wont to tell us, the mere fact that something is a terrible idea is far and away a reason to refrain from doing it. This seems especially true when sex is involved.
Barring technological or pharmaceutical interventions, it seems that future space travelers and Martian colonists will need to resort to a technique as familiar to astronauts on Earth as it is to astronauts on the ISS: masturbation.
Hoping that future Martians will stick to masturbation is a rather unrealistic fantasy, however. The facts of human (and animal) nature suggest that humans will eventually give in to their more primal urges, and this does not bode well for the extraterrestrial societies of the future, given that un-tampered sexual relations in a microgravity environment are likely to produce a generation of mentally and physically handicapped inbreeds.
There remains a lot of testing to be done in the area of reproduction in space, so for the near future, it's safe to say that it's probably best to leave the baby making to the Earthlings.
Read and watch documentaries about humanity's encounter with outer space in Motherboard's Spaced Out series.