Sex in space taken seriously

Back on July 2008 I posted Sex in space--amusing but a problem somewhat lightheartedly suggesting that "sex in space" could be a real problem for extended space travel and thanks to stringer Tim's referenced article it is suggested that "sex in space" is a bona fide issue.

"Complicating Factors: Issues Relating to Romance and Reproduction During Space Missions"

by

Kira Bacal, MD, PhD, MPH

January 2nd, 2009

Medscape Internal Medicine

Introduction

The popular imagination has always been titillated by the notion of sexual relations in a low gravity environment. Science fiction authors from Isaac Asimov to Larry Niven have speculated about it; movies, such as the James Bond film "Moonraker", have offered salacious images for our entertainment. Persistent rumors have been spread about sexual hijinks on the Shuttle, as well as claims about fictitious government research into "sex in space."[1]

Beyond the sensational nature of these stories, however, are genuine concerns pertaining to issues related to sexual activity in space, such as behavioral health, team dynamics, and pregnancy and embryogenesis, with their unknown complications.[2,3] In addition, sexual relations are a key aspect of most adults' lives, and it is unrealistic to ignore both the psychosocial impact of sexual activity on space operations and the potential physiological consequences.[4-6] Early research suggested that human conception and development away from Earth may be significantly problematic,[7] yet data are still insufficient to answer the crucial question posed by Jenks: "Can development from fertilization through the formation of viable gametes in the next generation occur in the space environment?[8]"

Performance of the sex act in an extraterrestrial environment will require potentially complex mechanics.[9-12] Past generations of motivated humans have been able to overcome similar challenges relating to issues of geometry and access, whether posed by chastity belts, the backseats of compact cars, or airplane lavatories. It is thus unlikely that logistical issues of the extraterrestrial environment will prove insurmountable. However, serious questions remain. For example, what impact will an in-flight sexual relationship have on team dynamics and efficiency? What are the chances of a successful pregnancy and delivery? Is the risk of STD transmission higher or lower in space? What about the risk of ectopic pregnancy, miscarriage, or other complications?

As life developed and spread across the Earth, humans adapted to a wide range of climates, altitudes, diets, and habitats. Yet there were absolutes throughout this period: gravity, radiation (or lack thereof), atmospheric composition, and a relatively narrow band of temperature and ambient pressure. As we move beyond the atmosphere, however, these parameters change abruptly. Can millions of years of evolution keep pace and permit reproduction to occur in such a different environment? If human life is not able to reproduce itself away from our home planet, what will be the implications for our space programs and long-term goals?

If and when sexual relationships within a space crew become acknowledged, the medical system will have to reflect this. It will need to be augmented to reflect the increased medical risks created by sexual activity. Unfortunately, the previous medical system designs have deliberately not included planning for such conditions. Diagnostic and therapeutic capabilities will now need to reflect all the possible conditions, ranging from STD to pregnancy and its potential complications, as well as the increased risk of interpersonal conflicts arising from the more complicated relationships. Training for both ground and flight crews will also need to be adapted to address these issues. Furthermore, in case of pregnancy, although the amount of research on this topic has been limited,[13] many studies suggest that the space environment may have significant and deleterious effects on a developing fetus.

Psychosocial Issues

The psychosocial implications of in-flight sex and reproduction are at least as problematic as the related physiological challenges. For the foreseeable future, space crews will be relatively small in number. If pairing off occurs within the crew, it can have serious ramifications on the crew's working relationships, and therefore, on mission success and crew operations.[4,11,14,15] Former astronaut Norman Thaggard commented, "[Issues associated with romantic relationships are] just one more problem that can potentially cause the whole thing to come apart."[4]

As we have seen in recent years, even professional astronauts on active flight status can develop serious mental health issues related to interpersonal relationships,[2,16] and the extreme, prolonged stressors of the long-duration spaceflight environment will only make such situations worse.[4] Previous long-duration missions have demonstrated that minor nuisances can lead to huge conflicts, and the addition of sexual tension will create even more challenges for the crew.[17] The limited social networks can lead to problems, such as privacy issues, the odd man out, and triangles.[15] Break-ups, which must be considered an inevitable corollary to romantic pairings, can further contribute to widespread inter-personal conflicts.[11,17]

Behavioral health has long been recognized as a major challenge to long-duration spaceflight.[17-20] An International Space Station astronaut Dan Bursch commented, "Most of the challenges are more mental and psychological." In this, he echoed the earlier sentiments of cosmonaut Valerie Ryumin, "All one needs to effect a murder is lock two men into a cabin, 18 ft by 20 ft, and keep them there for two months.[17]" How much more challenging will it be to maintain crew performance and healthy interpersonal relationships when the group becomes coeducational, semi-permanent, and sexually involved?

There are also issues with regards to a spouse, partner, or family left behind.[14,19,20] If an adulterous relationship develops within the crew, what will be the implications for the other flight crew members?[11] Can they discuss the affair, and its impact on them, with others, knowing that the gossip might spread back to the other astronauts' families? What is the role of the ground crew in maintaining a polite fiction? Mission control teams often assist flight crews and their families, for example, by arranging family teleconferences.[19] What if they are asked to help conceal an affair? If a family member becomes suspicious and seeks evidence -- perhaps in support of a divorce proceeding -- the resulting interpersonal conflicts could seriously compromise the mission.

The close quarters, limited crew numbers, and lack of privacy on space missions may create high levels of interpersonal tension around any romantic liaison, particularly if the relationship is one to which a fellow crew member personally objects.[11] Although some may be willing to adopt a "don't ask, don't tell" philosophy,[2,11] willingness to remain mute about colleagues' activities is likely to decrease sharply depending on the extent of the behavior the other person is forced to witness. As any college roommate can attest, this approach is much easier to embrace when you do not have to personally observe the behavior of which you disapprove. Unfortunately, in the space environment, there is likely to be only a single, relatively cramped habitation module for all crew members.[12] Permissiveness towards "whatever two consenting adults choose to do" may decline sharply when the clause "in the privacy of their own home" no longer applies.[18] Additionally, the number of people willing to turn a blind eye to colleagues' affairs could decrease sharply if, for example, it is a homosexual affair, or if young children are likely to be affected.

As mentioned above, the highly limited amount of privacy, both among the flight crew and between the flight and ground crews, makes secrecy very difficult to achieve. This may have a dampening effect on illicit relationships, as well as the disclosure of medically relevant information, such as STD symptoms; even public, above-board relationships may suffer from the "fish bowl" nature of a space mission. Given the amount of public speculation about celebrity relationships and pregnancies, what kind of attention should the first pregnant woman or the first married couple on a long-term space mission expect?

Gender and Cultural Issues

Cultural differences can also loom large in this issue, whether they are related to differences in gender, nationality, age, profession, religion, or training.[15,17,18] Space crews have become more multi-cultural, and are likely to remain so.[20] Interpersonal difficulties associated with cultural issues have already been documented, and more misunderstandings are likely to occur, particularly if and when relationships are no longer "strictly professional."[14,15,17,20] Not only do different cultures have very different views regarding privacy (e.g. personal space, inappropriate questions, etc), but there is also a wide range of beliefs regarding appropriate gender roles and behaviors.[15,21] For example, promiscuity has historically had very different definitions when applied to men versus women; many cultures still tolerate a much higher level of sexual activity from men than they do from women.

Mission success may be threatened by conflicts over what is acceptable behavior; indeed, different cultural values around gender norms have already "been a source of strain on international teams in analogue environments and space missions."[15] Difficulties related to mixed gender crews include episodes of sexual stereotyping during space missions and sexual harassment in analogue studies.[18,22] In one example "an unwanted sexual approach by a male team member to the sole woman in the group occurred, resulting over time in several members dropping out of the experiment."[22] What would have occurred during an actual mission, where withdrawing is not an option?

Thus, the potential for sexual behaviour during space missions to have a negative impact on mission operations is high, yet there has been little research into methods to avoid or defuse such issues. Military operations, Antarctic expeditions, or wilderness treks can be utilized as analogue environments to test the effects of different training programs, codes of conduct, or pre-arranged rules of engagement.

Physiological Issues

Numerous physiological changes have been noted during spaceflight, many of which may affect sex and procreation, although it remains unclear whether such effects are due to gravity changes, radiation, noise, vibration, isolation, disrupted circadian rhythms, stress, or a combination of these factors.[3,13] What is known is that "virtually every organ system functions differently" in space,[23] and "existing data suggest that spaceflight is associated with a constellation of changes in reproductive physiology and function."[24] A great deal of research still needs to be done on the mammalian development cycle, from copulation to conception to birth, and growth through reproduction by the next generation.[25,26]

When the issue of off-Earth reproduction arises, immediate concern must be given to the most obvious difference: the lack of a 1G gravitational field. Ronca writes, "life on Earth, and thus the reproductive and ontogenetic processes of all extant species and their ancestors, evolved under the constant influence of the Earth's 1G gravitational field...[It is thus imperative to determine] how the space environment affects critical phases of mammalian reproduction and development, viz. those events surrounding fertilization, embryogenesis, pregnancy, birth, postnatal maturation, and parental care."[27] If, as postulated, gravity affects the regulation of mammalian gene expression (and therefore all aspects of vertebrate development, including cell structure and function, organ system development, and even behavior),[28-30] then there are significant implications for successful procreation in an extraterrestrial environment.

Effects of Space on Fertilization

Reproduction begins with the existence of viable gametes. In a very small sample (n = 4) of male astronauts, significant decreases in testosterone levels and sexual drive during flight were documented.[31]

It is known that spermatogonia are radiosensitive.[3,13,25] However, research data from animal models are mixed. Some studies found evidence that male fertility is not diminished in space,[32] while others using rats and wasps suggested that there are negative impacts,[33-35] including reduction in testosterone during flight.[24] Research aboard Cosmos 1887 indicated that rat gonadal function may be compromised, and there was a decrease in rat spermatogonial cells noted in research performed aboard the Space Shuttle (STS-51B).[35] Biosatellite II documented changes in wasps' mutation frequencies and sperm cells, as well as disorientation in male wasp mating behavior post-flight.[35]

In terms of female fertility, it is known that ovarian function can be adversely affected by environmental conditions.[24] Research in rats, however, suggested that females ovulated and cycled normally in space, even though no births resulted from mating.[36] Unfortunately, data on the humanovulatory cycle in space is limited.[13] Many female astronauts have used contraceptive drugs to suppress menstruation on orbit during both short and long-duration missions.[13,24,37] To date, this has remained a reasonable method by which female astronauts have avoided the logistical challenges of menstruating on orbit, but it means that relatively little is known about how fertility cycles may be affected by the space environment, including the impact of flight-associated circadian changes.[3,25]

Research flown on the Cosmos 1129 satellite showed no evidence that rats mated during flight, despite opportunities to do so.[35] This may be due to heightened stress or diminished ability, as well as the logistical difficulties associated with microgravity. Regardless of cause, the data suggest that mating and reproduction in space may be difficult.[7]

Assuming that functional sperm are introduced to a viable ovum, the next question is whether fertilization will occur normally in the space environment. There is some evidence that sperm (and other flagellates) swim faster in microgravity and are otherwise sensitive to small changes in gravitational forces, presumably due to microgravity-associated biochemical changes in the axonemal proteins.[38,39] Some research suggests that fertilization may be unaffected,[40,41] but other studies indicate that the space environment has deleterious effects.[39] For example, although Aimar and colleagues found that fertilization in a microgravity environment did occur in their animal model, they also noted that "several characteristics of the fertilization process" were different in space.[40] Mammalian studies of fertilization in simulated microgravity showed no statistically significant differences in vitro, but in vivo studies showed significant decreases in embryo survival to the morula and blastocyst stages, suggesting that spaceflight may cause a higher rate of embryo lethality.[42]

If fertilization is successful, will implantation occur? If so, where? Is the zygote more likely to implant in an inappropriate location without the influence of gravity?[3] Should the in-flight medical system be designed to treat an ectopic pregnancy? If implantation is successful, will the placenta develop properly? There is limited evidence that the development, growth, and function of the placenta in rats may not be affected by a brief exposure to the space environment during gestation.[43]

Effects on Embryogenesis

Embryogenesis is another concern. There is good evidence that the space environment is teratogenic.[25,41,44-46] Concerns include exposure to toxins in the "closed loop" cabin environment, risk of decompression, and the largely unexplored effects of micro- or partial-gravity on embryogenesis. Quail eggs flown aboard Mir 18, Mir 19, and STS-76/77 demonstrated increased rates of developmental abnormalities and mortality.[35] Although some of the observed problems may have been due to equipment difficulties on specific flights, there was an absence of normal angiogenesis. More recent studies performed in a simulated microgravity environment demonstrated embryonic failure between days 0-5 in avian eggs,[13,47] as well as other changes to the normal development process.[47] Wasp studies on Biosatellite II documented an excess of deaths in offspring born to flown females, suggesting that there are lasting, lethal changes associated with the space environment.[35]

Unfortunately, much of the data on the impact of the space environment on embryo development is mixed or inconclusive. The NIH.R2-1 study showed that brief exposure to microgravity did not appear to affect certain aspects of bone development in rats,[43] but other research documented several differences, including decreased length of calcified long bone regions.[44]

Other organ systems are also affected by changes in gravitational forces, including the vestibular and neuro-endocrine systems.[43] Bruce and Fritzch agree that "gravity appears to be a critical factor in the normal development of the vestibular system" of rat embryos, where "synaptogenesis in the medial vestibular nucleus is retarded" by exposure to microgravity during development.[48]

In other animal models, abnormalities were found in the development of Aurelia jellyfish and frogs.[43] Gualandris-Parisot also reported abnormalities in salamander embryos,[49] although these changes were noted to be reversible upon returning to 1G. However, the fact that the space environment had effects on embryo formation, especially during cleavage and neurulation, suggests that changes may occur in many animals, not all of whom may tolerate the differences as well as the salamander appears to do.

Shimada et al discovered a developmental period during which time the lens in zebrafish was susceptible to gravitational changes, suggesting that gravity does affect gene expression and differentiation in the lens during specific developmental periods.[29] Additional work documented similar changes in other systems,[28,50,51] leading the authors to conclude that "exposure to microgravity can cause changes in gene expression in a variety of developing organ systems in live embryos and that there are periods of maximum susceptibility to the effects."[28]

Astronauts and rats exposed to microgravity have experienced endocrine imbalances, such as hypothyroidism.[52] Such abnormalities in a pregnant woman can have significant effects on the fetus. For example, cerebellar development is regulated by thyroid hormones, and deficiencies in the neonatal brain can lead to cretinism and other abnormalities.[52] By contrast, other studies have suggested that spaceflight initiated during the post-implantation phase of pregnancy does not affect ovarian-hypophyseal function in rats.[53]

Of particular concern are findings that exposure to spaceflight at certain times and for certain durations in young, postnatal rats led to long-term problems in their motor function.[54,55] This is consistent with well-established notions of "critical developmental periods," during which specific events are required for the normal development of certain systems.[50,55] If these events (such as exposure to a 1G field) do not occur, irreversible, long-term deficits may result. This suggests that even after birth, an infant's normal growth and development can be profoundly affected by the space environment. Similarly, other research suggests that interactions between rat mothers and their neonatal offspring are altered in the space environment,[27] which may also lead to suboptimal development. Unfortunately, there has been very little research on development after birth in microgravity,[25] and a great deal more will be required.[56]

Space radiation, including galactic cosmic rays, solar particles, and geomagnetically trapped particles, is another important factor in embryogenesis.[57] All astronauts, including those in low Earth orbit, are classified as radiation workers, and their exposure increases as exploration missions move beyond the protective Van Allen belts. For example, the crew on a Mars mission will likely exceed a radiation dose of 50 rem/year,[37] while crew members on the International Space Station reportedly receive about 25-40 rem/year[37] or 1 mSv/day, roughly 150 times the value absorbed on Earth.[57]

Guidelines recommend that pregnant women be exposed to no more than 0.2-0.5 rem, due to evidence that exposure to greater than 10 rem can lead to fetal defects, such as microcephaly and retardation.[37,58] Radiation is known to cause DNA damage, cell death, and chromosomal abnormalities, as well as developmental deformities.[57] Some studies suggest that a synergistic effect may exist between radiation and microgravity, leading to greater than expected abnormalities from either factor alone.[57] One theory posits that the microgravity environment impairs cellular repair mechanisms that would otherwise be better able to address the radiation-induced DNA damage. However, other studies challenge these findings, leading to difficulties in developing reliable guidelines.

Even if the fetus can develop normally in the space environment, many potential dangers remain. How will the physiological adaptations to pregnancy interact with the physiological adaptation to microgravity?[3,23,25] Are they synergistic, additive, or oppositional? Rat studies suggest that pup mass at birth was significantly decreased by spaceflight,[59] leading to concerns of low birth weight or growth-retarded babies. Hyperemesis gravidarum and space motion sickness could certainly combine to threaten a pregnancy, as could the cardiovascular changes, bone demineralization, and alterations to red cell mass.

Other studies mated post-flight male rats with non-flown females. The offspring displayed both growth retardation and higher rates of abnormalities, such as hemorrhage, hydrocephaly, and renal malformations.[24] Male progeny were also noted to have reduced epididymis weight at 30 days of age, though not at 100 days.[24] These effects were apparently transient, because when the flown rats were mated approximately 3 months after spaceflight, no such abnormalities in offspring were seen.[24]

Although both male and female human astronauts have produced healthy offspring after spaceflight, studies suggest that the space environment may have transient post-flight effects on reproductive health. Further research on this topic would be of benefit to astronauts and their families, particularly because these issues could persist if crews leave microgravity for a partial gravity environment, such as the moon or Mars, rather than returning to Earth.

Issues Involved With Pregnancy

The risk of pregnancy exemplifies how sexual relations and their sequelae can affect a mission's logistical requirements. Conditions, such as preeclampsia, gestational diabetes, or Rh incompatibility, will likely be difficult to treat in such a remote location. Based on astronaut demographics, it is also likely that a pregnant crew member will be older than average,[13] therefore the pregnancy may be classified as high-risk on that basis alone. The overall spontaneous abortion rate has also been high (40%) among US astronauts following spaceflight.[13] What will these findings mean to the mission as a whole?

Antarctica is considered an analogue environment for space, due to its remote location, hostile environment, small teams, and evacuation difficulty. Antarctic expedition medical personnel acknowledge that pregnancy among female team members creates risks to the individual, the fetus, and to the success of the expedition.[60] As one Antarctic physician said, "No one wants to become pregnant down there [in Antarctica], no one wishes a baby to be born down there. I think it would just put that much bigger burden on the station and the station medical officer."[60] In the same way, the sequelae of sexual relations on orbit must be considered not only from the standpoint of the individuals involved, but also from the standpoint of the mission, program, and agency.

For example, the need for contraceptives raises questions not only of those regarding efficacy and side effects, but also of issues related to supplies, stowage, and (depending upon the type of contraceptives) discard of used materials.[37] The known physiological changes of spaceflight are also likely to have effects on the pharmacokinetics and pharmacodynamics of medications.[25,61] Likewise, there is also evidence to suggests that some drugs deteriorate more rapidly in space, perhaps due to the radiation environment, leading to additional issues for (re)supply and storage,[62] as well as the reliability of the contraceptive.

Pregnancy test kits are currently part of the standard medical kit flown in space, though their inclusion has historically been for the diagnostic work up of abdominal pain in a female crew member rather than any anticipated detection of a pregnancy. An onboard ultrasound can be of diagnostic assistance in documenting the existence and location of a pregnancy, but what other devices, pharmaceuticals, and training will be required?

The terrestrial rate of ectopic pregnancy is 19.7 cases per 1,000 pregnancies in North America,[63] but it is unclear whether extraterrestrial rates will be higher or lower. Under these conditions, should the medical system include nonsurgical treatments, such as methotrexate, for the termination of ectopic pregnancies?[58] Similarly, what are the ethics involved in offering elective termination with mifepristone, as well as pregnancy support options to an expectant mother who is concerned about the teratogenic effects of the space environment?[37,44] Given these concerns, should the medical system include capabilities for amniocentesis and other pre-natal testing?

And of course, if we are talking about the possibility of an in-flight pregnancy, the corollary question also rises: what about in-flight terminations? Should mifepristone be in the medical kit? Given the real concerns about the teratogenic effects of the space environment,[10,22] what are the ethics involved in (not) offering termination?

One immediate question if a member becomes pregnant is whether to abort a mission, thus expanding the criteria for mission termination to include pregnancy of a crew member. Pregnancy is a disqualifying factor even for many aspects of ground-based NASA mission training, including extra-vehicular activity (spacewalk) training in the Neutral Buoyancy Laboratory, altitude chamber training, T-38 training, parabolic flights, and shuttle emergency egress training.[37,58] If an astronaut assigned to a mission becomes pregnant prior to the launch date, she is immediately replaced.[13,58]

But what should be done in the case of a pregnancy that occurs during a mission? Repatriation is recommended for women who become pregnant during an Antarctic expedition.[60] In the US military, pregnancy is grounds for medical disqualification from certain activities, such as flying status or worldwide deployment status.[64] In the event that a service member becomes pregnant while deployed, only she is withdrawn from her duties; the rest of her unit continues with the mission. That is not the case on many space missions, however, where evacuation capabilities may be designed for either the entire crew or no one.

The International Space Station, for example, has a single "life boat," the Soyuz, and protocol states that even if a single crew member is ill, the entire crew must abandon the station. Similarly, a Mars mission or a lunar base may have only a single means of evacuation. If it is used to evacuate a single crew member the rest of the team would have no way to abandon the platform should an emergency arise. Therefore, would it be appropriate to abandon the entire mission in order to bring home a pregnant woman?

If there is a higher than average risk of fetal malformations, and particularly if the risk is cumulative due to increased exposure to the environment, then it could be argued that there is an ethical obligation to return mother and fetus to Earth as quickly as possible, regardless of the astronaut's personal preferences, the cost of the mission, and the risk to the rest of the crew from implementing an emergency evacuation plan. This last risk is not inconsequential. Australia's Antarctic program dealt with a female expedition member who developed severe hyperemesis gravidarum during a crossing of the Southern Ocean. Serious consideration was given to the ship returning to Hobart, Australia, despite the risk to the entire vessel of spending more time in those extremely dangerous waters and the impact such a step would have had on the whole expedition.[60]

Even if plans are to immediately return a pregnant crew member to Earth, it can take days or months for her to arrive back on the planet, depending on the type of mission. Therefore, the medical system will need to afford some assistance and services during that time, regardless of the desired long-term outcome.

How would the mission be affected if the decision is made for the entire crew to continue the operation? Based on current standards, a pregnant woman would not be allowed to engage in extra-vehicular activities. So, for example, if the pregnant crew member was assigned to spacewalking duties, that role would need to be transferred to her backup, thereby compromising that person's other activities. Furthermore, if a swap of activities were to occur between the two crew members, additional training would be required for both of them, thus affecting mission timelines.

In addition, the pregnancy is likely to place additional, potentially unexpected demands upon the medical system. Supplies such as intravenous fluids and analgesics might need to be rationed or withheld in preparation for an obstetrical event, rather than being available for use during nominal mission activities or in the case of an emergency or another pregnancy.

As the pregnancy progresses, there could be additional issues involving human factors. For example, the Soyuz has a potential landing impact of up to 30G, which requires individualized, form-fitted seat liners to help attenuate the effects of landing forces on the crew. A heavily pregnant crew member is unlikely to fit in her seat liner, let alone be able to withstand those kinds of G forces. This could affect evacuation options and landing protocols when the crew arrives at their destination.

What if there were complications of pregnancy? At present, part of the rationale for pregnancy being a disqualification for even short duration spaceflight is concern for potential complications that could overwhelm the platform's medical capabilities, such as miscarriage, preterm labor, and ectopic pregnancy.[37] In addition, there are concerns about the impact of the environment on both the developing fetus and the mother's physiologic adaptation.[37]

If a normal pregnancy were carried to term in an off-Earth environment, how would childbirth take place? Should the mission's medical system be designed with such a possibility in mind? If delivery occurs in the microgravity environment, will labor be unduly prolonged? Ronca and Alberts found that pregnant rats that delivered on Earth after flying during gestation were in labor longer than control rats[65] although other changes of significance were relatively few.[59,65] This was presumably due to less effective uterine contractions,[65] which would be in accord with other observed changes to the neuromuscular system and may be rooted in gravity-related modifications to intracellular architecture.[23,30] What are the implications for a woman delivering while still in a low-G environment? Pain control may be an issue, especially if labor is prolonged as well as the potential for caesarean section, risk of damage to surrounding structures (e.g. bladder injury, fistula formation, etc), and hemorrhage. The issue of hygiene and risk to other crew members from exposure to blood and body fluids should also not be underestimated.[3]

What about care for the newborn? Would they need to stock neonatal resuscitation equipment, baby clothes, and diapers? If there are problems such as prematurity or birth defects, what resources should be available for the baby's care? How would this situation affect crew morale, and what would be the public reaction?

Given these manyserious considerations, one option might be to make pregnancy impossible on space missions. There are obvious ethical and practical issues to implementing such a requirement. However, the fact remains that for a long-term human presence in space, reproduction off-Earth will be needed, so these questions can only be deferred, not ignored.

Conclusion

Suggested Research Directions

Given the lack of definitive evidence, there are numerous opportunities for future research. First, studies could explore how to best minimize the impact of sexual activity on team performance and mission operations. Secondly, studies into procreation are still needed at virtually every stage from fertilization to successful reproduction by the next generation. These include studies on fertilization, implantation, embryogenesis, fetal development, pregnancy, childbirth, parental care, post-natal growth, and sexual maturation.

It is widely accepted that the space environment is teratogenic, but the extent of these teratogenic effects, as well as the development of countermeasures, remains largely unexplored. In particular, the potential synergistic effect of stressors on living systems must be studied. These range from the combined effects of radiation and microgravity to the interaction of hyperemesis gravidarum with space motion sickness.

In addition to the space environment's physical stressors (e.g. gravity, radiation, vibration, disrupted circadian rhythms, etc), there are also causes of significant psychosocial stress, such as danger, isolation, confinement, spartan conditions, limited social interactions, loss of communication, cultural conflicts, and separation from family and friends.[2] To this list, we must now add "sexual tension" and "reproductive concerns," because it is unrealistic to consider a long-term human presence in space without anticipating both issues.

Some research findings suggest that behavioral health is a major challenge to long-duration flight. Sexual relationships (and tensions) will provide additional stressors to the efficient functioning of crews. In addition to these psychosocial effects, there are also documented physiological issues. The space environment itself is teratogenic, and may have significant, deleterious effects on a developing fetus. In addition, there may be a synergistic, negative effect between some of these stressors.

Summary

Gravity's effect on mammalian gene expression may have significant ramifications on procreation, and exposure to microgravity at certain times and for certain durations may lead to long-term abnormalities in organ system development and function.

Data from animal models suggest that mating and reproduction in space may be difficult, which has implications not only for humans engaged in these activities, but also for the development of self-sustaining ecosystems with in situ agricultural production. This may be partly due to possible decreases in male fertility and sexual drive in space.

Significant changes in embryologic development have been noted in multiple animal models, including jellyfish, wasps, zebra fish, frogs, salamanders, quail, and rats. Furthermore, early studies suggest that interactions between rat mothers and pups are different in space, creating potential problems for post-natal pup development as well.

All of these findings will not only have impacts on medical system design and pre-flight training, but also on evacuation and contingency planning.

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Sex in space--amusing but a problem