Past, present and future of human reproduction and development in space

1 Introduction

As humanity moves toward a future of long-duration space exploration and extraterrestrial settlement, one of the greatest unresolved challenges will be the ability to safely reproduce, develop, and adapt across generations under space conditions. While sustaining individual survival beyond Earth remains a major objective, the long-term future of extraterrestrial populations will ultimately depend upon their capacity to conceive, develop, and thrive under environmental conditions fundamentally different from those experienced on Earth. Consequently, understanding how space environments influence reproduction, development, and adaptation may become one of the defining biological challenges of future human expansion beyond Earth.

Space environments expose biological systems to ionizing radiation, altered gravity, circadian disruption, atmospheric variation, isolation, and other stressors that may profoundly affect gametogenesis, fertilization, embryogenesis, pregnancy, fetal development, and postnatal development (Ferraz, 2025; Jain et al., 2023; Palmer et al., 2026; Sharma et al., 2024; Tou et al., 2002). Among these factors, radiation and gravity constitute two of the most important environmental determinants of reproductive and developmental success beyond Earth. Exposure to ionizing radiation can induce DNA damage, oxidative stress, genomic instability, developmental abnormalities, and long-term health risks, while altered gravity may disrupt cellular organization, mechanobiological signaling, tissue formation, physiological regulation, and developmental processes (Li et al., 2021; Lyons et al., 2026). Consequently, sustaining healthy reproduction and development under space conditions may represent one of the most complex biomedical challenges associated with the long-term expansion of humanity beyond Earth.

To date, no human conception or pregnancy has occurred during spaceflight, and the feasibility of sustaining healthy multigenerational human reproduction beyond Earth remains unknown. However, future adaptation to space environments may depend not only on protecting reproduction and development from space-associated stressors, but also on understanding how environmental conditions influence developmental trajectories throughout early life.

This article combines a narrative review of the current evidence regarding mammalian reproduction and development under space conditions with a forward-looking conceptual perspective exploring future technological pathways that may eventually enable human reproduction, development, and long-term adaptation beyond Earth. Rather than presenting new experimental findings or a systematic review, the manuscript integrates current scientific evidence with emerging concepts from developmental biology, artificial intelligence, reproductive biotechnology, synthetic biology, cybernetics, and space systems engineering to stimulate future research and interdisciplinary discussion.

Building upon the current state of knowledge, three complementary future pathways are explored ((A) modifying extraterrestrial environments to recreate Earth-like physiological conditions through approaches such as artificial-gravity systems and advanced habitat engineering (B) enabling human reproduction, development, and adaptation beyond Earth through advanced cybernetic technologies; and (C) directly modifying human biology to enhance reproduction and developmental adaptation to space environments through synthetic biology and genetic modification. Together, these pathways provide a conceptual framework for discussing possible future strategies while identifying scientific challenges and research priorities for sustaining human reproduction and development beyond Earth.

1.1 Scope and literature selection

This manuscript presents a narrative review combined with a forward-looking conceptual perspective. The literature was identified through searches of peer-reviewed publications related to developmental space biology, reproductive medicine, developmental biology, reproductive biotechnology, artificial intelligence, synthetic biology, bioengineering, and space medicine. References were selected based on their scientific relevance to mammalian reproduction, development, and adaptation under space conditions, while also including seminal historical studies that have shaped the field.

2 Major biological challenges to natural reproduction and development in space

2.1 Open questions on developmental space biology

Developmental Space Biology investigates how space environments impact key developmental processes, offering important insights into the effects of altered gravity and radiation conditions on different animal species. Research has encompassed stages from fertilization to early postnatal growth, and in certain instances, across multiple generations. Research in this field has drawn upon numerous model organisms, among them fruit flies, sea urchins, fish, amphibians, birds, and rodents. Areas of investigation span cellular, molecular, genetic, morphological, physiological, and central nervous system sensory and vestibular processes (Alberts and Ronca, 2005; Amann et al., 1992; Crawford-Young, 2006; Dournon et al., 2001; Horn, 2013; Ijiri, 1995; Jain et al., 2023; Jung et al., 2009; Kojima et al., 2000; Kurotani-Izumi and Kiyomoto, 2003; Lei et al., 2020; Li et al., 2021; Ma et al., 2008; Moody and Golden, 2000; Ning et al., 2015; Ogneva et al., 2020; Ricci and Boschetti, 2003; Ronca, 2003; Ronca et al., 2013; Sapp et al., 1990; Schenker and Forkheim, 1998; Serova and Denisova, 1982; Sharma et al., 2024; Tou et al., 2002; Wakayama et al., 2009; Wakayama et al., 2017; Wakayama et al., 2023; Wakayama and Wakayama, 2025; Wong and DeSantis, 1997; Yoshida et al., 2021).

Reproductive experiments have demonstrated that fertilization and embryonic development can take place in space in sea urchins, fish, frogs, newts, and birds; however, minor developmental anomalies have been reported, particularly in the long-term, with the underlying molecular mechanisms largely unclear (Alberts and Ronca, 2005; Dournon et al., 2001). Notably, medaka fish were the first vertebrates to successfully reproduce in space during a 15-day mission aboard the Space Shuttle. This mission resulted in fertilization rates that were comparable to those of Earth-based controls (Ijiri, 1995).

Conversely, Crawford-Young (2006) provides a comprehensive review indicating that microgravity can significantly and negatively affect embryonic development across multiple species. The review highlights how microgravity may lead to changes in cellular structure and gene expression, resulting in a spectrum of developmental issues such as embryonic death, neural tube closure failures, and morphological deformities that impact the overall health and appearance of the offspring.

Together, these findings reflect a complex picture: while reproductive processes can occur in space in certain species, the risk of developmental abnormalities remains a concern, emphasizing the notable challenges of reproduction and development in space environments.

Next, we will explore the effects of space environments on developing mammalian species, namely, rodent models, which share closer molecular and genetic mechanisms with humans. This similarity makes them vital for understanding the impact of space conditions on developmental dynamics. By focusing on these models, we can gain valuable insights into the mechanistic effects of space conditions on development, identify potential developmental vulnerabilities, and evaluate biological processes relevant to future human reproduction and development beyond Earth.

2.1.1 Mammalian reproduction and development in rodent models under space conditions

Researchers emphasise that conditions such as altered gravity, ionising radiation, noise, isolation, disrupted circadian rhythms, and psychological stress may affect reproductive functions in mammals (Sharma et al., 2024; Tou et al., 2002). Mammalian fertilization and development in microgravity present a complex picture, with studies indicating mixed outcomes. Although fertilization and development are not completely inhibited, research involving rats and mice has demonstrated notable effects.

To investigate whether mammals can conceive in microgravity, the uncrewed biosatellite Cosmos 1129, launched in 1979, created an environment for rats to mate in vivo during flight. Upon returning to Earth, two out of five female rats exhibited signs of early pregnancy with resorption, however, there was no monitoring of fertilization in space (Alberts and Ronca, 2005; Wakayama and Wakayama, 2025). Subsequent missions demonstrated that late-gestational mammalian exposure to spaceflight has produced viable offspring after return to Earth. Notably, Cosmos 1514, launched in 1983, along with the NIH.R1/STS-66 and NIH.R2/STS-70 missions in 1994 and 1995, respectively, resulted in successful fetal development and parturition upon their return to Earth. The resulting offspring were able to reproduce successfully; however, some variability was observed in litter size and neonatal weight. Further space missions involving nursing rat mothers and their pups, specifically NIH.R3/STS-72 in 1996 and Neurolab/STS-90 in 1998, encountered significant challenges, including high infant mortality rates and feeding difficulties, which required intervention from the astronauts (Alberts and Ronca, 2005; Ronca, 2003; Ronca et al., 2013).

A study examined the effects of spaceflight, specifically microgravity and radiation, on pregnant Sprague-Dawley rats that were in space during days nine to twenty of gestation (middle - and late-stage pregnancy). The findings showed that, immediately upon returning to Earth, the rats exhibited reduced locomotion, and their offspring had a higher incidence of perinatal morbidity. Although differences in growth rates between the flight and control groups could partly be attributed to variations in sex ratios, key developmental milestones such as walking and eye opening occurred on schedule in both groups. Gait development patterns were similar, indicating that prenatal exposure to space conditions during this critical window did not disrupt these motor development processes. Overall, while spaceflight may increase perinatal morbidity, fundamental postnatal motor development appeared to remain unaffected (Wong and DeSantis, 1997).

Li et al. (2021) summarized the effects of microgravity on mouse embryonic stem cell function and development in spaceflight and simulated microgravity. Their review indicates that in early pregnancy, mice fail to develop, and mothers are unable to produce offspring, whereas mid- and late-stage pregnancies can yield viable fetuses and result in live births on Earth. In addition, microgravity influences embryonic development through cytoskeletal alterations and the modulation of key signaling pathways, including WNT, Cadherin, and Nitric Oxide, which together coordinate cell proliferation, differentiation, adhesion, and vascular development - processes essential for proper embryo growth and tissue formation. The review demonstrates that microgravity encourages differentiation into mesoderm and endoderm, which are essential for the formation of various tissues and organs. However, additional research is necessary to fully understand its effects on ectodermal differentiation, which is crucial for the development of the skin and nervous system. These findings suggest that gravity acts not only as a physical force but also as an important mechanobiological signal regulating cellular orientation, cytoskeletal organization, and developmental processes.

Wakayama et al. (2023) examined the differentiation of mammalian embryos into the inner cell mass (ICM) and trophectoderm during the 8-16 cell stage (compaction) to assess normal development in microgravity. Using an assisted reproduction device, astronauts thawed and cultured frozen two-cell mouse embryos in the International Space Station (ISS) for 4 days. After a total of 13 days, 9 days of cryopreservation and 4 days of culture, the embryos accumulated a radiation dose of 4.29 mGy (7.15 mSv). The study concluded that under the tested conditions, no clear increase in DNA damage was observed, as the embryos developed into blastocysts with normal characteristics: two-cell mouse embryos developed into blastocysts at a rate comparable to those in a simulated 1 g environment. However, the distinct effects of radiation exposure during cryopreservation and culturing on development were not separately evaluated.

Ning et al. (2015) investigated the effects of short-term hypergravity, simulating spacecraft launch conditions, on the development of 2-cell mouse embryos. Embryos in CZB solution, contained in 1.5 mL tubes, were subjected to centrifugation at 1000 rpm (approximately 100 g), 3500 rpm (approximately 1000 g), and 10,500 rpm (approximately 10 kg) for 20 min. Despite significant hypergravity exposures, no notable differences were observed in blastocyst formation rates or live birth rates after embryo transfer compared to a 1 g control group. Additionally, the actin filament structure within the embryos remained normal, suggesting that short bursts of intense hypergravity during launch may not adversely affect early mouse embryo development.

The previous findings suggest partial development resilience in embryos under space conditions. Nonetheless, other studies have shown that early embryo development in mammals can be compromised in space conditions, as described next.

Wakayama et al. (2009) investigated the effects of simulated microgravity on mouse fertilization and preimplantation development using a 3D clinostat. In vitro fertilization (IVF) rates were comparable to controls (84% success rate), suggesting that microgravity does not impair gamete function. However, preimplantation embryo development was affected. Transferring embryos cultured under simulated microgravity to recipient females revealed significantly lower live birth rates (35% vs. 63% for 1G controls) when embryos were transferred at the 2-cell stage. Similarly, blastocyst formation rates were lower for embryos cultured under simulated microgravity (30% vs. 57% for 1 g controls), although a smaller percentage of these developed into seemingly healthy offspring (16% versus 37% for 1 g controls). While the offspring from microgravity-cultured embryos appeared to have normal weights and fertility, immunostaining showed slower development and reduced trophectoderm cell numbers compared to 1 g controls. This study demonstrated, for the first time in mammals, that fertilization can occur normally under simulated microgravity but that subsequent preimplantation development is impaired.

The findings of Wakayama et al. (2009) align with other studies showing that while IVF in mice is possible under simulated microgravity (free-swimming sperm are able to move in microgravity, with gamete adhesion and fusion) (Kojima et al., 2000), subsequent preimplantation development is compromised (Jain et al., 2023; Jung et al., 2009; Kojima et al., 2000). This negative impact on preimplantation development has also been observed in experiments involving two-cell stage mouse embryos sent into space (Lei et al., 2020; Ma et al., 2008; Schenker and Forkheim, 1998).

Lei et al. (2020) examined mouse preimplantation development during the SJ-10 satellite mission, launched 6 April 2016, and orbiting at 252 km with microgravity levels of 10^-4 to 10^-6 g0 and radiation doses of 0.15 mGy/day. While blastocyst formation occurred, rates and quality were lower due to significant DNA damage and global hypomethylation, primarily caused by radiation, not solely microgravity. Ground-based low-dose radiation mimics these effects. On Earth, in utero irradiation causes persistent genomic instability in directly exposed mice and transgenerational effects in F1 offspring, with paternal exposure showing stronger transgenerational transmission than maternal exposure due to differential epigenetic mark erasure (Barber et al., 2009). These outcomes highlight radiation risks for mammalian reproduction in space.

Jain et al. (2023) conducted a review on various studies examining the effects of space conditions, particularly radiation and microgravity, on fetal and neural development in rodents. Their review highlights that radiation exposure during gestation is particularly harmful, potentially leading to structural malformations such as microcephaly and central nervous system defects, resulting in cognitive impairments. Studies examining embryonic neurons in simulated space conditions indicate changes in neuronal plasticity, morphology, and viability, with significant effects identified after prolonged exposure. While neurons show some adaptation to microgravity, they require extended recovery periods to readjust to Earth’s gravity. Collectively, these findings suggest that normal brain development in rodents is altered in space, affecting both structural integrity and functionality.

In the realm of vestibular system formation, prenatal exposure to microgravity delays the onset of gravistatic responses and alters central morphology, with some reported partial postnatal recovery (Ronca et al., 2008; Ronca and Alberts, 1997).

Other studies showed postnatal microgravity exposure in rats to cause reduced unmyelinated fibers in the cardiovascular system, muscle atrophy, and altered cortical synapse morphology (Amann et al., 1992; Sapp et al., 1990; Tou et al., 2002).

Notably, no studies directly evaluated the effects of partial-gravity environments (lunar or martian) on reproduction and development in mammals. Instead, predictions based on theoretical analysis suggest that reduced gravitational loading could lead to muscle, bone, and cardiac hypotrophy during late gestation (Sekulic et al., 2005). Importantly, most available studies investigate either Earth gravity or near-microgravity conditions, whereas the effects of partial gravity environments such as lunar (0.16 g) or Martian gravity (0.38 g) on reproduction and development remain almost entirely unknown.

Next, we will examine the impact of space conditions on the reproductive health of both male and female rodents and humans.

2.1.2 Male and female reproductive health in rodents and humans under space conditions

We start by describing the effects of altered gravity and radiation in rodents.

Studies have shown microgravity to reduce rat testosterone levels and sperm counts, and decrease testicular weight (Amann et al., 1992; Sapp et al., 1990; Tou et al., 2002). A study examining the effects of 35 days of spaceflight on male mice found that space travel induces changes in testicular transcription factor ATF7 binding, a regulator of heterochromatin formation, as well as altered small RNA expression in spermatozoa. Furthermore, the offspring of these space-traveling males exhibited increased hepatic expression of genes associated with DNA replication, indicating that spaceflight can have intergenerational effects (Yoshida et al., 2021).

Researchers investigated the effects of both simulated microgravity and hypergravity on mouse sperm motility to understand potential impacts on reproductive health during deep space exploration. Mouse sperm samples on Earth were exposed to microgravity using a random position machine and to hypergravity at 2 g with a centrifuge for durations of 1, 3, and 6 h. Results showed that hypergravity induced more pronounced effects: sperm speed decreased after 1 h, and the percentage of motile sperm declined after 3 h. In contrast, microgravity did not affect sperm speed within the same period, but there was a reduction in motile sperm after 6 h. The observed changes are likely linked to alterations in the microtubule cytoskeleton and adaptive shifts in energy metabolism (Ogneva et al., 2020). Overall, hypergravity seemed to have a greater and faster impact on sperm motility than microgravity.

A recent study investigating simulated microgravity in human, mouse, and pig reproductive models demonstrated that altered gravity conditions impair sperm navigation and fertilization efficiency, while also negatively affecting early embryo development. Using a dual-axis 3D clinostat and clinically relevant IVF culture systems, the authors found that sperm exposed to simulated microgravity showed a significantly reduced ability to navigate microchannels mimicking the female reproductive tract, despite largely preserved motility parameters. This was one of the study’s most important findings, as it suggests that sperm require Earth-like gravitational cues for effective directional guidance and successful fertilization. Furthermore, embryos generated under microgravity conditions exhibited developmental delays and altered blastocyst quality, particularly in mice and pigs, indicating that peri-conception exposure to microgravity may compromise embryogenesis and implantation potential (Lyons et al., 2026).

Exposure to microgravity during spaceflight and simulated on Earth tends to disrupt spermatogenesis and testicular testosterone synthesis, as well as estrous cycling and follicle development in rodents (Mishra and Luderer, 2019).

Research involving mice subjected to simulated microgravity showed a notable decrease in oocyte maturation rates (8.94% compared to 73.0%). This indicates that gravity seems to play an important role in meiotic spindle formation, although the overall structure and function of microtubules did not appear to be impacted (Burden et al., 1998). Similarly, research conducted during the STS-131 (2010), −133 (2011), and −135 (2011) missions, revealed negative impacts of microgravity on female C57BL/6 and BalbC mice exposed to space from 12 to 15 days. Oocyte maturation and production were disrupted, and long-term recovery following spaceflight remains unclear. The effects included compromised oocyte health, reduced estrogen receptor levels, and decreased HSPH-1 stress marker expression (Ronca et al., 2013).

More recently, Ge et al. (2025) demonstrated that simulated microgravity significantly impairs oocyte quality through mitochondrial dysfunction and oxidative stress in mice. Simulated microgravity causes elevated oxidative phosphorylation, mitochondrial membrane hyperpolarization, and mislocalization in mice oocytes, leading to meiotic arrest, spindle defects, increased aneuploidy, and reduced developmental potential. However, the authors also found that by extending the duration of metaphase I (an early stage of cell division) using a technique that inhibits the anaphase-promoting complex (APC), they were able to improve oocyte quality. Specifically, blocking the APC allowed the microtubule-organizing center (MTOC) - a key component for spindle formation - to assemble correctly and facilitated proper spindle formation. This intervention significantly improved the oocyte maturation rates despite the simulated microgravity conditions, showing that such reproductive challenges can potentially be mitigated through targeted artificial methods.

A study investigating the effects of space radiation on freeze-dried mouse spermatozoa stored on the ISS for 9 months found that, although DNA damage to the sperm and male pronuclei was slightly increased, fertilization and birth rates remained comparable to controls. Next-generation sequencing revealed only minor genomic differences between offspring from space-preserved sperm and control animals, and all offspring developed to adulthood with normal fertility. These findings suggest that, despite DNA damage caused by space radiation, viable offspring can be produced after extended sperm storage in space (Wakayama et al., 2017).

A recent experiment involving adult female mice spent 37 days aboard the ISS revealed that their estrous cycles and ovarian estrogen levels remained similar to those of control animals. However, the space-exposed mice exhibited lower progesterone levels compared to the control group (Hong et al., 2021).

Conversely, studies on Earth have demonstrated that cosmic radiation, particularly high-charge and energy (HZE) particles, has a negative effect on differentiating testicular spermatogenic cells and oocytes and their surrounding ovarian somatic cells in rodents. Such radiation exposure has been linked to depletion of the ovarian reserve and premature ovarian failure (Mishra and Luderer, 2019). Space radiation is recognized for causing oxidative injury to testicular germ cells, stimulating p53 activation, and leading to apoptosis in these cells (Sharma et al., 2024). Research in cultured cells showed radiation to cause DNA damage to sperm and oocytes (Yatagai et al., 2011).

A comprehensive review on reproductive biomedicine in space highlighted that spaceflight conditions, including microgravity, ionizing radiation, circadian disruption, and psychological stress, pose substantial risks to both male and female fertility. The review summarized evidence showing impaired sperm DNA integrity, altered hormonal regulation, ovarian follicular depletion, and abnormal embryonic development under spaceflight conditions. The authors also emphasized that ethical and regulatory challenges surrounding conception, pregnancy, and reproductive autonomy during commercial spaceflight remain largely unresolved, underscoring the need for multidisciplinary collaboration between reproductive medicine, aerospace science, and bioethics for future long-duration missions and extraterrestrial settlements (Palmer et al., 2026).

Similarly, another recent review examining reproductive health during spaceflight reported that microgravity and ionizing radiation adversely affect gametogenesis, hormonal regulation, fertilization, and embryonic development. The authors described how space-related stressors impair sperm motility, increase DNA fragmentation, and induce epigenetic alterations that may have transgenerational consequences. Female reproductive systems were also shown to be highly vulnerable, with radiation accelerating ovarian follicular loss and microgravity disrupting folliculogenesis and ovulation. Although animal studies indicate that fertility may still be possible under space conditions, the long-term developmental and multigenerational effects on offspring remain poorly understood (Ahn et al., 2025).

The existing literature on human reproductive health in the context of space exploration is notably sparse, with no documented instances of human conception occurring in spaceflight. Although limited in scope, human data offers some suggestive evidence of trends similar to those observed in rodents’ reproduction and development under space conditions.

A systematic review and meta-analysis by Ahrari et al. (2022), alongside a recent review by Jain et al. (2023), provides a critical assessment of how spaceflight impacts mammalian male reproductive health. The collective research, encompassing human observational studies, animal models (mice, rats, and ram lambs), and in vitro investigations, highlights several key considerations. Exposure to microgravity and ionizing radiation in humans leads to decreased sperm motility - except for frozen sperm where sperm integrity was shielded by cryoprotectants - sperm DNA fragmentation, and to decreased hormone levels that can cause testicular dysfunction by changing testicular blood flow and disrupting the functioning of the hypothalamic-pituitary-gonadal (HPG) axis. Further underscoring this risk, Jain et al. (2023) emphasize the potential for spaceflight stressors to influence the HPG axis in humans, with studies in mice and rats noting impacts on germ cell maturation and differentiation. Epigenetic alterations within sperm also present a concern, as indicated by dysregulation of genes in offspring following murine spaceflights.

Gimunová et al. (2024) conducted a systematic review to assess the effects of space travel, microgravity, and space radiation on human reproductive functions, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and Space Biomedicine Systematic Review methods. Their findings indicate that female astronauts may face increased risks such as thromboembolism in combined oral contraceptive users, decreased decidualization, functional insufficiency of corpus luteum, and decreased progesterone and LH levels, while male reproductive health may be affected by decreased testosterone and hormone-binding globulin levels, sperm motility, sperm vitality, and increased sperm DNA fragmentation.

Other factors may compromise human reproduction and development in space.

According to Jain et al. (2023), space travel may lead to increased oxidative stress, which has been linked to placental dysfunction on Earth, potentially causing complications such as pre-eclampsia, restricted fetal growth, preterm delivery, and gestational diabetes - especially considering the heightened insulin sensitivity associated with space environments. Additionally, factors like diet, psychological stress, and exposure to teratogenic substances can influence the success of implantation and the risk of miscarriage. Increased stress is detrimental to natural gestation. In a review by Tou et al. (2002), it was observed that prenatal stress is linked to increased fetal and postnatal mortality in rats. The unique challenges of space - such as altered gravity, radiation exposure, and limited medical support - could heighten anxiety and stress related to conception, gestation, and childbirth. These factors could create substantial emotional and physical burdens for women, emphasizing the need for comprehensive research and support systems to address reproductive health challenges in space environments.

Space exposure may induce significant physiological adaptations in human females that could compromise the maintenance of a healthy pregnancy. During pregnancy, the maternal cardiovascular system undergoes major physiological adaptations, including increased heart rate, stroke volume, cardiac output, plasma volume expansion, and reduced vascular resistance, in order to ensure adequate uteroplacental blood flow and oxygen delivery to the developing fetus (Brislane et al., 2021). These adaptations are essential for supporting fetal growth, placental perfusion, nutrient exchange, and maternal-fetal homeostasis throughout gestation.

In microgravity, however, the absence of gravitational loading produces profound physiological deconditioning, including skeletal muscle atrophy, bone mineral loss, cardiac atrophy, reduced plasma volume, fluid redistribution toward the upper body, and vestibular dysfunction affecting particularly the otolith organs (Tanaka et al., 2017). Such alterations may interfere with the maternal cardiovascular adaptations required for pregnancy. For example, reductions in plasma volume and cardiac function could impair uteroplacental circulation, limiting oxygen and nutrient delivery to the fetus and potentially increasing the risk of fetal growth restriction, placental dysfunction, miscarriage, or preterm birth. Similarly, microgravity-induced bone demineralization and altered calcium metabolism may affect fetal skeletal development, while fluid redistribution and altered vascular regulation could compromise implantation and placental attachment. Because placental development depends heavily on vascular remodeling, cellular migration, and mechanobiological signaling, altered gravity may significantly disrupt trophoblast invasion and placental vascularization.

Furthermore, the vestibular and neuroendocrine alterations induced by microgravity may disrupt hormonal regulation of pregnancy and maternal physiological stability. The combined effects of radiation exposure, oxidative stress, immune dysregulation, circadian disruption, psychological stress, and limited medical support could further increase the risks associated with conception, gestation, and childbirth in space environments. Consequently, although mammalian reproduction may be partially possible under space conditions, the physiological adaptations induced by microgravity suggest that maintaining a healthy human pregnancy in space could be substantially more difficult than achieving fertilization alone.

Currently, the feasibility of human reproduction and development in space remains uncertain.

In conclusion, research into reproduction and development under space conditions reveals an inconclusive picture:

• Fertilization and embryonic development can proceed in microgravity in several non-mammalian species, including sea urchins, fish, frogs, newts, and birds. While reproductive processes can occur in space in the above noted species, the risk of developmental abnormalities and adverse effects remains a concern.
• Mammalian reproduction and development in rodents under space conditions presents a complex picture, with studies indicating mixed outcomes. Although reproduction is not completely inhibited, research involving rats and mice has demonstrated notable effects. Rodents seem to be able to develop in microgravity during middle- and late-stage pregnancy, resulting in viable offspring capable of apparently healthy development and reproduction on Earth. In addition, prenatal exposure to space conditions may increase perinatal morbidity on Earth, but core motor development remains intact. Research on embryonic development indicates that microgravity and radiation affect cellular and signalling pathways, influencing tissue differentiation and stress responses, yet many embryos can develop into blastocysts with normal characteristics. Additionally, short-term hypergravity exposures tend to have minimal impact on early embryo formation and viability, suggesting some resilience of mammalian reproductive and developmental processes to hypergravity-like stresses. Conversely, other studies reveal that microgravity and space radiation can significantly impair preimplantation embryo development, namely, linked to lower blastocyst formation (in some cases due to DNA damage and global hypomethylation), lower live birth rates, slower development and reduced trophectoderm cell numbers, genomic instability in utero and transgenerational effects in F1 offspring, and structural malformations such as microcephaly and central nervous system defects resulting in cognitive impairments. Additional studies showed postnatal microgravity exposure in rats to cause reduced unmyelinated fibers in the cardiovascular system, muscle atrophy, and altered cortical synapse morphology, highlighting the complex and sometimes conflicting effects of space environments on mammalian reproduction. Moreover, the effects of radiation on developing mammalian species are still not fully clarified, particularly given that the maximum time rodents have spent in space thus far is 3 months (Wakayama et al., 2021).
• Regarding male and female reproductive health in rodents in space, studies show that spaceflight and simulated microgravity impair reproductive health, affecting sperm and oocyte quantity, quality and development, testicular and ovarian function, and causing intergenerational effects. Overall, hypergravity appears to have a greater and faster impact on sperm motility than microgravity. Exposure to microgravity during spaceflight and simulated on Earth disrupts spermatogenesis and testicular testosterone synthesis, as well as estrous cycling and follicle development, including decrease in oocyte maturation and production rates, reduced estrogen receptor levels, and decreased HSPH-1 stress marker expression. Space radiation, particularly HZE particles, further exacerbates these effects by damaging spermatogenic cells and oocytes, depleting the ovarian reserve, and causing premature ovarian failure. Conversely, research also suggests that while space radiation causes DNA damage to sperm and oocytes, fertilization and offspring development can still occur from freeze-dried mouse spermatozoa in space; reproductive functions, like estrous cycles and ovarian estrogen levels in spaceflight remain similar to those of controls. Targeted artificial interventions like APC inhibition seem to improve oocyte quality. Overall, these findings highlight significant challenges but also potential for mitigation through artificial means, supporting the possibility of reproductive survival in mice in space. Recent evidence also suggests that gravity may play a critical role in sperm directional navigation and fertilization efficiency, even when sperm motility itself remains largely preserved, indicating that Earth-like gravitational cues may be important for successful mammalian fertilization.
• Current literature on male and female reproductive health in humans under space conditions is limited, with no documented cases of conception occurring during spaceflight. However, existing data from human studies suggests that microgravity and space radiation adversely affect male reproductive parameters, such as decreased sperm motility - except for frozen sperm where sperm integrity was shielded by cryoprotectants - sperm DNA fragmentation, and decreased hormone levels that can cause testicular dysfunction by changing testicular blood flow and disrupting the functioning of the HPG axis. Women in space may face increased risks, including thromboembolism in combined oral contraceptive users, decreased decidualization, functional insufficiency of corpus luteum, and decreased progesterone and LH levels, and placental issues, compounded by the psychological and physical stresses of space travel. These conditions could impact conception, pregnancy, and fetal development, with space-related oxidative stress potentially contributing to complications like pre-eclampsia and preterm birth. Recent reviews further emphasize that the expansion of commercial spaceflight raises major ethical and regulatory questions concerning human conception, pregnancy, reproductive autonomy, and reproductive safety beyond Earth, highlighting the urgent need for multidisciplinary collaboration between reproductive medicine, aerospace science, and bioethics.
• In addition, the effects of partial-gravity environments on skeletal development, including long-bone growth and cranial development, remain largely unknown and warrant further investigation.
• In addition to altered gravity and ionizing radiation, deep-space missions expose biological systems to hypomagnetic environments resulting from the absence or marked reduction of Earth’s geomagnetic field. Although the specific contribution of altered magnetic environments to mammalian reproduction and development remains poorly understood, future studies should consider their potential interaction with other spaceflight stressors (Hart, 2024).
• To this date, there have been no successful observations of fertilization in mammals, such as rodents or humans, during spaceflight; in fact, no attempts have been made to fertilize humans in space.

Collectively, these findings highlight the intricate and multifaceted impact of space environments on mammalian reproduction and development. The evidence demonstrates that microgravity, cosmic radiation, and other space stressors pose significant risks to both male and female reproductive capabilities.

The preceding chapter reviewed the current experimental evidence regarding mammalian reproduction and development under space conditions. Building upon this evidence, the following chapter intentionally adopts a forward-looking conceptual perspective, exploring scientifically plausible technological pathways that may contribute to enabling human reproduction, development, and long-term adaptation beyond Earth.

3 Future strategies for human reproduction and development in space

The evidence reviewed in Chapter 2 suggests that human reproduction and development beyond Earth may face major biological challenges. Although current findings remain incomplete and in many cases inconclusive, research indicates that natural mammalian reproduction and long-term development under space conditions may be significantly compromised without technological intervention.

Future scenarios to facilitate human reproduction and development in space may broadly follow three complementary adaptive pathways.

• Modifying extraterrestrial environments to recreate Earth-like physiological conditions through approaches such as artificial-gravity systems and advanced habitat engineering.
• Enabling human reproduction, development, and adaptation beyond Earth through advanced cybernetic technologies; and,
• Directly modifying human biology to enhance reproduction and developmental adaptation to space environments through synthetic biology and genetic modification.

These approaches are not mutually exclusive and may likely operate synergistically. Collectively, they may form the technological and biological foundation required to sustain human reproduction, development, and potentially multigenerational evolution beyond Earth.

The following sections explore these future scenarios through both current scientific research and speculative technological frameworks.

3.1 Modifying extraterrestrial environments to recreate earth-like physiological conditions through approaches such as artificial-gravity systems and advanced habitat engineering

3.1.1 Engineering gravity: artificial-gravity systems as research and countermeasure platforms for reproduction in space

As previously discussed, the space environment exposes biological systems to multiple stressors capable of affecting human reproduction and development. Current evidence from animal studies and cellular models suggests that altered gravity, ionizing radiation, circadian disruption, isolation, and physiological deconditioning may interfere with gametogenesis, fertilization, embryogenesis, placentation, pregnancy maintenance, neurodevelopment, and long-term offspring health.

Although multiple space stressors tend to interact simultaneously, growing evidence suggests that altered gravity may represent one of the central mechanobiological variables influencing mammalian reproduction and development. Beyond its role as a physical force, gravity regulates cellular organization, mechanotransduction, gene expression, and tissue homeostasis, making the elucidation of gravity-perception mechanisms a major priority in space biology (Davis et al., 2024). These mechanobiological processes may ultimately underpin many of the reproductive and developmental alterations observed under space conditions.

On Earth, human physiology evolved under the constant influence of a 1 g gravitational environment (Adamopoulos et al., 2021). In contrast, the gravitational force on Mars is approximately 0.38 g, representing nearly a 62% reduction relative to Earth gravity. The Moon presents an even more extreme condition, with a gravitational force of approximately 0.16 g, corresponding to nearly an 84% reduction compared with Earth (Jet Propulsion Laboratory, 2026). Although the Moon and Mars are currently the primary targets for long-duration human exploration and eventual extraterrestrial settlement (European Space Agency, 2025; National Aeronautics and Space Administration, 2022; Neukart, 2024), space habitats may ultimately extend to orbital stations, deep-space transit systems, and other planetary environments characterized by highly variable gravitational conditions.

Despite increasing evidence that microgravity negatively affects reproductive and developmental processes, the biological effects of partial gravity remain largely unknown. Consequently, it remains unclear whether partial gravity may be sufficient to support healthy conception, pregnancy, fetal development, and multigenerational adaptation during prolonged habitation beyond Earth.

Because gravity appears to play a central role in maintaining normal physiological, reproductive, and developmental processes, artificial gravity is increasingly considered one of the most promising strategies for supporting long-term human habitation beyond Earth. By recreating Earth-like gravitational loading through rotating habitats, centrifugal systems, or adaptive gravity environments, artificial-gravity systems may support healthy conception, pregnancy, embryonic and fetal development, childhood growth, and multigenerational human habitation in future extraterrestrial settlements. Current evidence also suggests that the partial gravity conditions present on the Moon and Mars may be insufficient to fully maintain long-term human physiological conditioning (Clément et al., 2015; Evans et al., 2018; Mane, 2025; Waisberg et al., 2024).

The following section examines the historical evolution, scientific foundations, current limitations, and speculative future potential of artificial gravity as a strategy for sustaining healthy human habitation beyond Earth.

3.1.2 Historical origins of artificial gravity concepts

The concept of artificial gravity emerged long before modern human spaceflight became technologically feasible and has accompanied the history of human space exploration for more than a century. Early concepts of permanent human habitation beyond Earth appeared in nineteenth-century speculative literature, including works by Edward Everett Hale, Jules Verne, and Kurd Lasswitz, which introduced some of the earliest visions of orbital habitats and artificial worlds in space (Hale, 1869; Lasswitz, 1897; Verne, 1878).

The first scientifically grounded proposals for artificial gravity and long-duration space habitation were later developed by Konstantin Tsiolkovsky, one of the founders of modern astronautics. In 1895 and 1903, Tsiolkovsky proposed rotating space habitats capable of generating artificial gravity through centrifugal acceleration while also envisioning closed ecological systems, space greenhouses, and self-sustaining extraterrestrial settlements (Tsiolkovsky, 1895; Tsiolkovsky, 1903). Importantly, Tsiolkovsky proposed rotational habitats as a means of recreating Earth-like gravitational conditions in space while also anticipating that rotational radius and movement within rotating environments would influence human physiological adaptation.

Throughout the 20th century, the concept evolved from speculative theory into increasingly sophisticated aerospace engineering proposals. Hermann Oberth expanded the potential role of space stations as platforms for scientific research and long-duration habitation (Oberth, 1923), while Hermann Noordung introduced one of the first detailed rotating wheel-shaped station concepts specifically designed to generate artificial gravity through rotation and continuous habitation in orbit (Noordung, 1928). During the mid-twentieth century, Wernher von Braun further popularized large rotating wheel stations designed to support permanent human habitation in space (von Braun, 1952). These early concepts established many of the engineering principles that continue to influence modern artificial-gravity research, including centrifugal rotation, modular habitat architecture, and closed environmental life-support systems.

The emergence of large-scale space colonization concepts during the 1960s and 1970s further expanded artificial-gravity research toward multigenerational extraterrestrial settlements. Dandridge Cole proposed rotating hollowed asteroids capable of functioning as self-contained human habitats with internal ecosystems and simulated gravity (Cole, 1963). Later, Gerard O’Neill proposed massive rotating cylindrical habitats positioned at Lagrangian points capable of supporting thousands of inhabitants within self-sustaining ecosystems powered by solar energy and extraterrestrial resources (O’Neill, 1974; O’Neill, 1975). Similarly, the Stanford Torus and NASA Ames space settlement studies envisioned rotating habitats capable of supporting stable long-term human communities under Earth-like gravitational conditions, including family life, agriculture, and permanent habitation in space. These studies marked a major transition from temporary orbital stations toward large-scale self-sustaining extraterrestrial habitats designed for permanent human settlement (National Aeronautics and Space Administration, 1977).

Although many of these historical concepts remained theoretical or technologically inaccessible during their time, they established the conceptual and engineering foundations for contemporary artificial-gravity research.

More recent engineering investigations demonstrate continued engineering interest in artificial-gravity technologies for future human space exploration. Large-scale rotating habitat concepts have been proposed to simultaneously address gravitational loading, radiation protection, agriculture, and long-term habitation through adaptable orbital infrastructures (Goyal et al., 2017). NASA and other aerospace groups have also explored modular habitat systems capable of operating under microgravity, artificial gravity, and partial-gravity conditions, emphasizing adaptable architectures for future lunar and Martian missions (Gonzalez Marquez and Smitherman, 2020). More speculative proposals, including the MAGICIAN Mars habitat concept, further illustrate growing efforts to engineer rotational systems capable of recreating near-Earth gravitational conditions during planetary habitation (Arias et al., 2024).

In parallel, biomedical and physiological research strongly supports the rationale for artificial gravity as a multisystem countermeasure against the multisystem physiological deconditioning associated with prolonged exposure to weightlessness. Artificial gravity generated through centrifugation has been investigated for its capacity to mitigate cardiovascular deconditioning, orthostatic intolerance, musculoskeletal loss, vestibular dysfunction, and other physiological consequences associated with prolonged microgravity exposure (Clément et al., 2015; 2022; Evans et al., 2018; Hall, 2016). The International Academy of Astronautics has similarly identified artificial gravity as one of the most promising integrated countermeasures for enabling long-duration human exploration missions (Young et al., 2009).

However, despite these advances, current evidence also suggests that artificial gravity may not constitute a complete or perfect solution to the biological challenges of space. Importantly, artificial gravity environments remain physiologically and mechanically distinct from natural terrestrial gravity. Rotational systems generate gravity gradients, Coriolis forces, vestibular disturbances, and perceptual disorientation that may themselves produce significant physiological and architectural challenges, particularly in smaller-radius habitats (Hall, 1999; Hall, 2002).

Experimental findings also indicate that artificial gravity may provide only partial biological protection. In a NASA study using Drosophila melanogaster aboard the ISS, artificial gravity generated through inflight centrifugation partially mitigated neurological deficits associated with microgravity exposure, but did not fully prevent cellular stress responses, neuronal alterations, oxidative damage, or progressive neurological dysfunction after return to Earth (Mhatre et al., 2022). Similarly, human artificial-gravity studies performed using centrifugation and bed-rest analogs suggest beneficial effects on several physiological systems, yet also reveal incomplete protection, variability between individuals, and uncertainty regarding the optimal gravity levels, exposure durations, and long-term adaptation required for sustained human health beyond Earth (Evans et al., 2018; Clément et al., 2022).

Collectively, current literature suggests that artificial gravity remains one promising strategy for long-duration human space habitation. Nevertheless, existing evidence indicates that present artificial-gravity systems may provide only partial mitigation of space-induced physiological dysfunctions. Further multidisciplinary research will therefore be essential to determine whether artificial gravity can ultimately support long-term human habitation, reproduction, and development beyond Earth.

Building upon the previous research, the following sections explore speculative future frameworks in which rotational artificial-gravity systems may eventually be applied to investigate the requirements for healthy reproduction and development under various space conditions.

3.1.3 Emerging artificial-gravity biological research platforms

Despite growing evidence that altered gravity may significantly influence mammalian reproduction and development, many of the gravitational thresholds required for healthy conception, embryogenesis, placentation, fetal development, and multigenerational adaptation remain poorly understood. Previous studies have demonstrated the effects of simulated microgravity and hypergravity on gametes, embryos, cellular organization, mechanotransduction, and developmental physiology using clinostats, centrifuges, and other ground-based simulation systems (as discussed in Chapter 2). However, systematic long-duration reproductive and developmental studies performed under continuously controlled partial-gravity conditions, including lunar and Martian gravity levels, and other artificially generated gravitational environments remain largely absent.

Critically, it remains unclear whether Earth gravity represents the optimal gravitational condition for all reproductive and developmental processes, or whether alternative gravitational levels may under certain circumstances enhance, stabilize, or impair these biological functions. Furthermore, even when artificial gravity systems are designed to replicate Earth-equivalent gravitational loads, it remains uncertain whether they reproduce the full spectrum of biological effects associated with natural terrestrial gravity.

Consequently, dedicated autonomous variable-gravity experimental platforms may become essential not only for determining the minimum gravitational conditions required to sustain healthy reproduction and development beyond Earth, but also for identifying gravitational ranges that may support, impair, or otherwise influence these biological processes. These infrastructures may operate both on Earth and in space, combining terrestrial simulation facilities with orbital and deep-space research systems.

Emerging concepts may include orbital variable-gravity biological research platforms designed for cellular, molecular, and developmental studies. Such systems could range from larger orbital laboratories supporting multiple biological samples and experimental configurations to smaller nanosatellite and CubeSat-based autonomous platforms enabling lower-cost distributed experimentation in space. These systems may reproduce microgravity, hypergravity, lunar, Martian, or custom gravitational environments while incorporating controlled radiation exposure or shielding systems, autonomous environmental regulation, biosensor networks for real-time physiological monitoring, and AI-assisted experimental control systems.

Such technologies may help investigate how altered gravitational and space environments influence reproductive and early developmental stages, including fertilization, preimplantation embryo development, and early embryogenesis. Research involving later developmental stages remains subject to increasing ethical and regulatory concerns associated with primitive streak formation, gastrulation, neural development, and the progressive emergence of organismal complexity and developmental individuality (Appleby and Bredenoord, 2018; Hyun et al., 2021).

Orbital and deep-space platforms may become particularly important because authentic combinations of partial gravity, long-duration microgravity, space radiation, thermal fluctuations, magnetic variability, and extraterrestrial environmental conditions cannot yet be fully reproduced simultaneously under terrestrial laboratory conditions. Future autonomous variable-gravity experimental platforms could eventually operate in LEO, cis-lunar space, lunar and Martian surface environments, deep-space transit missions beyond the Van Allen radiation belts, Martian orbital infrastructures, and other extraterrestrial settlements distributed across orbital, planetary, and deep-space environments.

As an illustrative example, a future autonomous variable-gravity research platform could operate as a closed-loop experimental system integrating centrifuge-based variable-gravity systems, biomimetic reproductive culture and incubation platforms, environmental regulation and life-support systems, biosensor networks, and AI-assisted monitoring within a continuously controlled environment. Biological models ranging from gametes and early-stage embryos to stem-cell systems, organoids, engineered tissues, and organ-on-chip platforms, under strictly controlled biomedical and ethical frameworks, could be maintained within microfluidic and/or biomimetic culture systems designed to reproduce selected maternal physiological conditions during early development under altered gravitational environments.

Notably, microfluidic technologies are already being explored in assisted reproductive technologies (ART) and IVF on Earth as controlled microscale environments capable of mimicking aspects of the natural reproductive system, including fluid dynamics, biochemical signaling, oxygen regulation, nutrient exchange, and embryo culture conditions, making them promising candidates for future space reproductive biology platforms (Pensabene et al., 2026). In parallel, their miniaturization, automation capabilities, low-volume fluid handling, and compatibility with autonomous orbital experimentation systems have also expanded their application to orbital and microgravity research, including CubeSat-based biological and microscopy platforms (Kuang et al., 2022; Wareing et al., 2025).

Different gravitational conditions could be generated through centrifuge-based rotational systems in which the biological incubation platform rotates around a central axis, producing centrifugal acceleration capable of simulating different gravitational loads. By adjusting rotational velocity, rotational radius, and exposure duration, such systems could experimentally reproduce Earth, lunar, Martian, microgravity, hypergravity, or custom gravity levels during biological experimentation, consistent with the rotational artificial-gravity principles originally proposed in early artificial-gravity habitat concepts and later developed throughout aerospace engineering research (Tsiolkovsky, 1903; Noordung, 1928; Hall, 2016).

Simultaneously, radiation exposure could be experimentally regulated through controlled exposure systems and adjustable shielding architectures depending on specific experimental objectives (Ferraz, 2025). Potential approaches may include selectively shielded incubation compartments and advanced shielding materials such as hydrogen-rich polymers, high-density polyethylene (HDPE), boron-based composites, or hydrogenated nanomaterials capable of modulating radiation exposure under space conditions (Montesinos et al., 2021).

Furthermore, integrated biosensor networks could continuously monitor environmental and biological parameters including temperature, oxygen concentration, pH balance, metabolic activity, radiation exposure, mechanical stress, fertilization dynamics, and developmental progression in real-time. These datasets could then be processed by AI-assisted control systems integrating machine-learning and deep-learning models capable of identifying biological patterns and analyzing complex physiological and environmental interactions (Chavez-Badiola et al., 2020; Cohen et al., 2025). Such systems could support experimental standardization, automated data analysis, and adaptive regulation of environmental and operational parameters including rotational velocity, atmospheric composition, radiation exposure, nutrient delivery, and incubation conditions, thereby improving the precision, stability, and reproducibility of artificial-gravity reproductive biology experiments across terrestrial and extraterrestrial environments.

Collectively, these technologies may enable integrated investigation of how gravity, radiation, and other environmental variables influence reproduction and development under space conditions. By combining variable-gravity systems, biological culture platforms, biosensor networks, and AI-assisted experimentation within a single framework, such platforms may help identify the environmental requirements necessary to support healthy reproduction and development beyond Earth. Figure 1 presents a conceptual illustration of a near-future autonomous variable-gravity research platform designed to investigate reproductive and developmental biology under controlled spaceflight conditions.

3.1.4 AI-driven digital twins and predictive gravitational biosimulation

As previously discussed, important ethical and biological constraints continue to limit direct investigation of later developmental stages under both Earth and space conditions. In response to these limitations, future research may increasingly incorporate digital twin technologies as complementary predictive frameworks capable of extending reproductive and developmental investigations beyond the boundaries of direct biological experimentation. The large-scale biological, physiological, and environmental datasets generated by future variable-gravity research platforms may provide the empirical foundation required for training, validating, and continuously refining these digital twin systems.

Digital twins are computational physiological and biological models that continuously integrate experimental, clinical, environmental, and biological data to simulate, predict, and dynamically update representations of living systems and their responses to changing conditions (Métayer et al., 2026). Future AI-driven digital twin systems could integrate multiscale datasets derived from physiological monitoring, developmental and reproductive biology, mechanobiological analyses, multi-omics profiling, stem-cell and organoid models, animal studies, and clinical investigations to simulate reproductive and developmental responses across different mammalian species, including humans, under diverse spaceflight conditions.

Recent research in reproductive medicine on Earth has already begun exploring digital twin technologies for ART applications including embryo assessment, IVF optimization, placental physiology modeling, pregnancy pharmacokinetics, and personalized reproductive prediction systems (Vallée et al., 2026). These developments may provide an initial conceptual and technological foundation for future space reproductive biosimulation research.

Unlike direct biological experimentation under space conditions, AI-driven biosimulation digital-twin systems could provide a more ethically sustainable, scalable, and lower-risk framework for late-stage space reproductive research. These systems could also theoretically incorporate individualized biological profiles, including genomic, physiological, developmental, metabolic, and reproductive variability, allowing personalized simulations of biological adaptation under different extraterrestrial and gravitational environments. This may become particularly important for future space reproduction because ongoing research may eventually reveal that individual biological variability can influence reproductive stability, developmental resilience, radiation sensitivity, and long-term physiological adaptation beyond Earth.

As an illustrative example, a digital twin could integrate genomic, physiological, reproductive, and environmental data from a biological model and predict developmental outcomes under different extraterrestrial conditions. Such a system might estimate how fertilization success, embryonic development, radiation sensitivity, or pregnancy-associated physiological adaptations vary across different gravitational and environmental scenarios. Experimental observations obtained from biological studies could then be continuously incorporated into the model, progressively improving predictive accuracy and enabling increasingly refined simulations of reproductive and developmental processes beyond Earth.

The AI-driven biosimulation digital-twin systems could operate on Earth using extraterrestrial environmental datasets acquired through orbital, lunar, Martian, and deep-space missions, including measurements related to gravity, radiation, thermal fluctuations, magnetic variability, and other space-associated stressors. Using these datasets, the systems could simulate reproductive and developmental responses across Earth, lunar, Martian, microgravity, hypergravity, and custom artificial-gravity environments without requiring direct biological exposure to space conditions.

Autonomous orbital or deep-space digital twin platforms operating under authentic extraterrestrial environments could also support long-duration biosimulation research by continuously integrating real-time environmental variability that cannot yet be fully reproduced or dynamically modeled under terrestrial conditions. Such systems could help identify critical gravitational, radiobiological, environmental, and mechanobiological thresholds influencing fertilization, embryogenesis, pregnancy maintenance, postnatal development, and long-term adaptation beyond Earth.

Although these systems would not fully replicate living biological organisms, they may function as predictive research platforms for hypothesis testing, experimental optimization, and risk assessment under diverse space conditions. These approaches could help optimize experimental design, accelerate hypothesis generation, reduce the need for extensive direct biological experimentation, and support future investigations into long-term reproductive and developmental adaptation across diverse orbital, planetary, and deep-space environments.

An additional potential application of these systems may involve the predictive investigation of somatic and germline gene-editing strategies under extraterrestrial conditions. Somatic gene editing involves modifications to non-reproductive cells that affect only the treated individual, whereas germline editing involves embryos or reproductive cells and may be inherited across generations (Doudna and Charpentier, 2014). Future biosimulation platforms could be used to explore how such interventions might influence developmental stability, radiation tolerance, physiological resilience, and reproductive outcomes under different gravitational and environmental conditions. By enabling preliminary hypothesis testing and risk assessment without direct biological experimentation, these systems could provide a more controlled framework for investigating gene-editing strategies, particularly given the ethical and biological concerns associated with germline modification, off-target effects, mosaicism, and long-term multigenerational consequences (Konrad et al., 2019; Musunuru, 2019). Figure 2 presents a conceptual illustration of an AI-driven biosimulation digital twin system designed to simulate reproductive and developmental responses under diverse gravitational and space environmental conditions.

Collectively, the emerging variable-gravity research platforms and AI-driven biosimulation systems discussed in Sections 3.1.2, 3.1.3 may serve as important precursors to future artificial-gravity extraterrestrial habitats. By identifying the gravitational, environmental, developmental, and mechanobiological requirements necessary to sustain reproduction and long-term adaptation beyond Earth, these technologies may help inform the design of rotating habitats, multifunctional orbital infrastructures, deep-space transit systems, and multigenerational settlements intended to support sustainable human life in space.

Future artificial-gravity infrastructures may range from dedicated reproductive and developmental modules integrated within orbital stations and spacecraft to large rotating habitats inspired by concepts such as O’Neill cylinders, Stanford torus structures, and rotating ring architectures. These systems could generate stable and adjustable gravitational environments optimized to support adult physiological health, conception, pregnancy, embryonic and fetal development, childhood maturation, and long-term adaptation beyond Earth. Adaptive gravity architectures informed by experimentally derived developmental and mechanobiological thresholds may further allow gravitational conditions to be tailored to specific life stages. Such environments may ultimately become the first extraterrestrial habitats specifically designed to support the complete human reproductive and developmental life cycle across multiple generations. More recent engineering proposals have also explored implementing large rotating circular or toroidal structures on planetary surfaces and during prolonged space transit to recreate Earth-like physiological environments under extraterrestrial conditions. Some projections suggest that early operational implementations may emerge during the second half of the twenty-first century, potentially first within lunar infrastructures (Human Spaceology Center, 2022). Figure 3 illustrates how autonomous variable-gravity research platforms and AI-driven biosimulation digital twin systems may collectively inform the development of future extraterrestrial infrastructures for human reproduction and development.

Building upon the preceding discussion, the following sections explore speculative future strategies for supporting human reproduction, development, and adaptation beyond Earth. First, Synthetic Reproductive Adaptive Enhancement Technology (SRAET) is introduced as a cybernetic reproductive-developmental framework for space environments. Subsequently, the potential contributions of synthetic biology, somatic gene editing, and germline modification to long-term adaptation under extraterrestrial conditions are discussed.

3.2 Enabling human reproduction, development, and adaptation beyond earth through advanced cybernetic technologies

3.2.1 Synthetic reproductive adaptive enhancement technology (SRAET)

As discussed throughout the previous sections, reproduction and development beyond Earth may be significantly compromised by space-associated stressors. Although artificial-gravity infrastructures may eventually mitigate some space challenges by recreating more stable physiological environments for humans, environmental engineering alone may not fully eliminate the health risks associated with reproduction and development in space. In particular, the maternal physiological adaptations required to sustain healthy pregnancy on Earth may themselves become destabilized under prolonged exposure to space environments.

Consequently, future extraterrestrial civilizations may progressively explore autonomous reproductive biotechnologies designed not merely to assist reproduction in space, but to externalize, stabilize, regulate, and/or cybernetically augment key maternal physiological functions during conception, gestation, and pre-natal development. Such systems may operate as closed-loop adaptive developmental ecosystems capable of maintaining developmental homeostasis (Billman, 2020) in space conditions. Importantly, this concept represents a speculative technological extension of several existing biomedical and engineering trajectories already under investigation on Earth. Recent advances in ART capable of mimicking aspects of maternal physiology, combined with AI-assisted embryo assessment and autonomous biosensing technologies (Kuang et al., 2022; Pensabene et al., 2026; Wareing et al., 2025), further support the conceptual plausibility of future cybernetic reproductive systems capable of operating in space.

Future advances in human enhancement technologies may progressively transform how human reproduction and prenatal and postnatal development are supported beyond Earth (Ferraz, 2025). Human enhancement technologies broadly involve the augmentation of biological capacities through natural, artificial, or technological interventions designed to improve physiological resilience and adaptive performance under challenging environmental conditions (Balistreri and Umbrello, 2023; Daniels, 2000; Raisamo et al., 2019). Within the context of space, human enhancement approaches have increasingly been proposed as complementary strategies to environmental engineering, emphasizing the stabilization, regulation, and augmentation of biological systems rather than relying exclusively on recreating Earth-like environments (Almeida and Diogo, 2019; Braddock, 2020; Gouw, 2020; Konrad et al., 2019).

For example, earlier cybernetic frameworks proposed for space medicine already explored the integration of technological systems with biological regulation in order to maintain human homeostasis under extraterrestrial environments. The concept of cybernetic systems for humans in space has been explored, particularly by Clynes and Klyne (1960), who introduced the notion of “cyborg” organisms. These cyborgs are envisioned to integrate technology with biological systems to maintain homeostasis and support human functions in challenging space conditions. Their framework includes examples such as osmotic pressure pumps for blood pressure regulation, psychic energizers for wakefulness, and pharmacological agents like epinephrine for cardiovascular regulation. These systems are designed to continuously monitor physiological parameters and adapt in real-time, theoretically ensuring that the body’s internal environment remains balanced.

More recently, the Adaptive Enhancement Technology (AET) framework proposed the integration of cybernetic architectures with AI-assisted predictive modeling capable of dynamically maintaining physiological homeostasis across a range of extraterrestrial conditions (Ferraz, 2025). Building upon the previous concept, future autonomous reproductive systems may eventually extend adaptive enhancement principles toward conception, gestation, and prenatal development in space. Herein, this speculative framework is designated as Synthetic Reproductive Adaptive Enhancement Technology (SRAET): a closed-loop cybernetic reproductive-developmental system integrating autonomous reproductive biotechnology, artificial-womb (ectogenetic) developmental systems, physiological-exchange subsystems, adaptive environmental regulation, biosensor networks, AI-assisted physiological control architectures, and predictive developmental biosimulation systems designed to maintain prenatal developmental homeostasis in the context of space.

As an illustrative example, a near-future SRAET system could operate as a fully autonomous reproductive-developmental ecosystem capable of supporting the entire reproductive continuum from conception to birth within a continuously regulated environment.

The reproductive process could begin within a biomimetic reproductive system designed to reproduce key structural, biochemical, physiological, and mechanobiological properties of the human reproductive tract. By combining advanced tissue-engineering, organ-on-chip, microfluidic, and synthetic biological technologies, the system could recreate aspects of the ovarian, tubal, and uterine microenvironments involved in gamete maintenance, fertilization, and early embryonic development.

Embedded biosensing systems, AI-assisted image analysis, and predictive developmental models could continuously monitor gamete quality, fertilization dynamics, and early embryonic progression, while simultaneously regulating oxygen concentration, pH balance, nutrient exchange, hormonal signaling, temperature stability, fluid dynamics, and other environmental parameters required to maintain optimal developmental conditions (Kuang et al., 2022; Pensabene et al., 2026; Wareing et al., 2025). In more advanced implementations, such systems could potentially assist in selecting natural, modified, or synthetically generated gametes according to predicted developmental outcomes, physiological compatibility, or germline traits intended to enhance adaptation to specific environments in space.

As development progresses, the same SRAET platform could seamlessly transition from fertilization and early embryonic development to ectogenetic gestation within an integrated artificial-womb system designed to reproduce key uterine physiological functions. In this manner, conception, preimplantation development, implantation-equivalent processes, gestation, and fetal development could occur within a single continuously regulated reproductive-developmental ecosystem.

Artificial-womb technology represents one technological approach to ectogenesis, the process of gestation occurring partially or entirely outside the body, and is an emerging reproductive biotechnology currently in early developmental stages. Existing research has focused primarily on supporting extremely premature infants through systems designed to reproduce selected uterine physiological functions including oxygenation, nutrient delivery, fluid circulation, and waste removal (Zhang, 2025). Within the context of space reproduction, such technologies may eventually help reduce maternal physiological risks associated with radiation exposure, altered gravity, cardiovascular deconditioning, and placental instability during gestation (Kendal, 2021). Translational frameworks applying Technology Readiness Levels and Manufacturing Readiness Levels to associated biotechnologies, including tissue engineering and bioprinting systems, further suggest gradual progress toward clinically relevant developmental-support platforms (Wu et al., 2017). Nevertheless, major technical, biomedical, ethical, legal, and political challenges remain unresolved, particularly regarding long-term developmental safety, physiological complexity, biomaterial integration, and large-scale clinical implementation (Gibson and Campo-Engelstein, 2023). Overcoming these challenges will likely be necessary before artificial-womb technologies can be safely incorporated into future autonomous reproductive-developmental systems such as SRAET.

The artificial-womb component of SRAET could consist of a developmental chamber functioning as a continuously regulated ectogenetic environment. Within this chamber, the developing fetus could be maintained in a synthetic amniotic environment engineered to reproduce key physical, biochemical, and physiological properties of natural gestation. An integrated physiological-exchange subsystem could simultaneously perform essential placental functions, including oxygen transfer, nutrient delivery, metabolic exchange, endocrine signaling, immune regulation, biochemical communication, and waste removal. Rather than replicating the anatomical placenta itself, such systems may utilize bioengineered interfaces, microfluidic exchange networks, synthetic biological components, and adaptive physiological-control architectures designed to achieve equivalent developmental-support functions. Surrounding these systems, the developmental chamber could continuously regulate oxygenation, nutrient composition, fluid pressure, circadian cycling, thermal stability, biomechanical stimulation, microbial control, radiation shielding, and developmental-stage-specific environmental conditions required to maintain prenatal developmental homeostasis throughout gestation.

Similar to the Artificial Membrane proposed within the AET framework developed by Ferraz (2025), the developmental chamber itself could operate as a selectively adaptive environmental interface capable of continuously responding to both internal developmental physiology and external environmental conditions. Rather than functioning as a passive gestational enclosure, the chamber could actively participate in environmental regulation by dynamically adjusting shielding, atmospheric composition, thermal balance, fluid-circulation dynamics, and other environmental parameters according to the changing physiological requirements of the developing fetus.

The developmental chamber could incorporate a multilayered adaptive membrane architecture containing integrated environmental sensors capable of continuously monitoring radiation exposure, atmospheric composition, carbon dioxide accumulation, pressure variation, thermal fluctuations, and gravitational conditions acting upon the developing organism. The chamber walls could integrate advanced shielding materials, including hydrogen-rich composites, doped silica structures, high-density polyethylene (HDPE), water-layer shielding systems, and hydrogenated boron nitride nanotube materials previously proposed for space-radiation mitigation (Montesinos et al., 2021). The chamber architecture could dynamically regulate shielding and environmental conditions in real-time. For example, if environmental sensors and biosensing systems detected increased oxidative stress, inflammatory biomarkers, or abnormal physiological and cellular responses in the developing organism, the chamber could autonomously adjust shielding distribution, and/or redistribute shielding fluids to reduce radiation dose and preserve prenatal developmental homeostasis.

Within the SRAET framework, prenatal developmental homeostasis would refer to the maintenance of physiological, biochemical, mechanobiological, and developmental stability under changing space environments. Environmental variables including gravity, radiation exposure, atmospheric composition, temperature, and pressure could directly influence developmental outcomes. For example, elevated carbon dioxide concentrations may disrupt fetal oxygenation and neural development, whereas excessive radiation may increase oxidative stress and DNA damage. Likewise, gravitational conditions outside biologically tolerable thresholds may interfere with mechanobiological signaling and fetal development. Consequently, maintaining developmental stability would require continuous regulation of atmospheric, gravitational, radiological, and physiological conditions.

Biosensing systems integrated within the physiological-exchange subsystem, synthetic amniotic environment, and selected regions of the developmental chamber could continuously monitor fetal physiological and developmental states in real-time. Because the physiological-exchange subsystem would function as the primary interface between the developing organism and its surrounding gestational environment, it could provide continuous access to cardiovascular function, oxygenation status, metabolic activity, endocrine signaling, and molecular biomarkers associated with developmental progression. In parallel, amniotic fluid-circulation systems could continuously sample biochemical and developmental indicators released into the synthetic intrauterine environment (Turco and Moffett, 2019).

Key developmental indicators could include fetal heart-rate variability, neurobehavioral activity, mechanobiological loading, placental function, inflammatory and oxidative-stress responses, endocrine factors, and markers of fetal growth, providing information regarding developmental maturation, physiological stability, and emerging pathological trajectories (DiPietro et al., 2015; Estrela et al., 2025; Patel et al., 2025). Additional molecular biomarkers, including cell-free fetal DNA, placental proteins, and multi-omics signatures derived from genomics, proteomics, metabolomics, and transcriptomics, could further characterize developmental responses to altered gravitational, radiobiological, and environmental conditions throughout gestation (Bar et al., 2025; Chiotis, 2024).

These physiological, developmental, molecular, and environmental datasets could then be continuously transmitted to AI-assisted biosimulation systems capable of identifying correlations between environmental conditions and developmental responses. Similar to the AET framework, predictive models integrating physiological, omics, and environmental data could continuously estimate biologically tolerable developmental thresholds under different space conditions. Rather than eliminating all environmental stressors, SRAET would seek to maintain environmental exposure within adaptive and physiologically safe ranges capable of supporting both developmental stability and progressive biological acclimatization.

For example, controlled exposure to altered gravity, radiation, atmospheric composition, or other space-associated stressors could be maintained when physiological and molecular biomarkers indicated stable developmental responses. Conversely, if predictive models detected excessive deviations from developmental homeostasis, increased oxidative stress, inflammatory activity, abnormal growth trajectories, or other indicators of developmental instability, the system could dynamically reduce environmental exposure in order to restore physiological balance. In this manner, environmental regulation would emerge through continuous closed-loop interactions between biosensor networks, predictive AI systems, environmental-control architectures, and the developmental state of the organism itself, allowing prenatal development to occur under controlled environmental pressure while minimizing unacceptable biological risk. By maintaining environmental exposure within adaptive physiological thresholds, SRAET could potentially promote developmental plasticity, facilitating progressive acclimatization and biological adaptation to diverse extraterrestrial environmental conditions.

Machine-learning algorithms, regression-based predictive models, pattern-recognition systems, and deep-learning architectures could be trained using physiological, developmental, environmental, and multi-omics datasets to identify relationships between environmental stressors and developmental outcomes (Ferraz, 2025; Russo and Lax, 2022). Regression models could quantify the influence of individual environmental variables on developmental outcomes, whereas pattern-recognition and deep-learning systems could detect complex nonlinear interactions, recurring adaptive responses, and early indicators of developmental instability that may not be apparent through conventional statistical approaches. More advanced implementations could additionally integrate digital-twin and biosimulation frameworks capable of continuously updating developmental predictions in response to incoming physiological and environmental data.

Future implementations could additionally incorporate advanced nanoscale or molecular biosensing technologies capable of monitoring genomic, proteomic, and metabolomic biomarkers in real-time (Chen et al., 2023; Fan et al., 2025; Saerens et al., 2008; Stawicki et al., 2021). These data streams could further improve the ability of AI systems to characterize developmental responses to environmental stressors and distinguish adaptive physiological changes from pathological trajectories. For example, if molecular monitoring detected abnormal gene-expression patterns, dysregulated developmental signaling pathways, altered protein-expression profiles, epigenetic modifications associated with stress responses, or metabolic signatures indicative of impaired cellular function, the AI system could identify emerging developmental instability before overt physiological abnormalities became apparent. Conversely, when genomic, proteomic, and metabolomic biomarkers remained within adaptive thresholds, controlled environmental exposure could be maintained in order to facilitate acclimatization and long-term biological adaptation.

Because extensive human developmental data from deep-space environments remain unavailable, simulations, synthetic data generation, in vitro experimentation, and eventually quantum-computing-assisted biosimulation systems could help train predictive AI architectures capable of forecasting prenatal and postnatal developmental responses under different space conditions before real implementation.

Importantly, early development may represent one of the most biologically responsive periods for adaptation to space environments. To date, there is no conclusive evidence that adult humans can achieve substantial long-term biological adaptation to space conditions, with prolonged exposure to microgravity and other space-associated stressors continuing to produce significant physiological deterioration despite the use of existing countermeasures (Clément, 2011; Demontis et al., 2017; Mader et al., 2011).

In contrast, research in Evolutionary Developmental Biology and Eco-Evo-Devo suggests that early developmental stages exhibit elevated biological plasticity, allowing environmental conditions to influence developmental trajectories, physiological organization, and long-term adaptive potential. Fundamentally, early development enhances a species’ capacity to adapt to diverse environmental conditions by fostering increased biological plasticity, which is defined as the ability of a given genotype to produce different phenotypes in response to varying environments (Hall, 2003; Hochberg, 2009; Hochberg et al., 2011; West-Eberhard, 2005). Consequently, early development stages may constitute a particularly important window during which controlled exposure to space conditions could facilitate developmental acclimatization and potentially contribute to longer-term adaptive responses. This developmental plasticity is reflected in processes such as neuroplasticity, synaptic remodeling, growth, and body composition, all of which remain highly responsive to environmental conditions during early life (Black et al., 1998; Hochberg et al., 2011; Waber et al., 2007).

Over long developmental and multigenerational timescales, the capacity of SRAET to regulate and potentially enhance adaptive developmental processes could theoretically increase the likelihood that advantageous biological adaptations become progressively stabilized within populations inhabiting specific extraterrestrial environments. Such processes could eventually contribute to the emergence of distinct human populations characterized by biological traits increasingly adapted for different gravitational, radiobiological, atmospheric, or planetary environments.

Although environmental regulation and developmental plasticity may come to facilitate physiological adaptation to space conditions, adaptive responses may not always be sufficient to maintain developmental stability under more extreme environmental stressors. In such circumstances, future implementations of SRAET could theoretically integrate synthetic biological and genetic-intervention systems designed to complement natural developmental adaptation. For example, adaptive-enhancement frameworks have proposed synthetic biological systems functioning as controlled auxiliary mechanisms capable of supporting physiological resilience when natural adaptive processes become insufficient (Pio-Lopez, 2021). If predictive models identified persistent radiation-associated damage, impaired DNA-repair activity, excessive oxidative stress, metabolic dysfunction, or other developmental risks that could not be adequately mitigated through environmental regulation alone, engineered cellular systems or targeted genetic interventions could potentially be activated to enhance protective biological responses. Figure 4 presents the proposed SRAET framework as a conceptual closed-loop system for supporting human reproduction and prenatal development beyond Earth.

The potential integration of synthetic biology, somatic modification, and germline engineering within SRAET systems is explored in the following section.

3.3 Directly modifying human biology to enhance reproduction and developmental adaptation to space environments through synthetic biology and genetic modification

Following the discussion of adaptive developmental regulation within SRAET, future space reproductive systems may progressively integrate somatic and germline genetic-modification strategies designed to complement environmental and developmental regulation.

Somatic genetic modifications could permit targeted and potentially reversible interventions during prenatal and postnatal development without directly altering the inherited germline. Current somatic gene-editing technologies, including CRISPR-Cas9 systems, already allow targeted insertion, deletion, or modification of specific genes within non-reproductive cells (Doudna and Charpentier, 2014). Within the SRAET framework, such interventions could be deployed in response to developmental challenges associated with space environments, including radiation-induced cellular damage, oxidative stress, impaired DNA-repair activity, immune dysregulation, or metabolic dysfunction. Delivery could occur through the physiological-exchange subsystem or synthetic amniotic environment, allowing targeted therapeutic agents, engineered cells, gene-editing constructs, or synthetic biological platforms to reach the developing organism under continuous physiological monitoring and adaptive developmental regulation. For example, such interventions could theoretically target genes and pathways associated with antioxidant protection, DNA repair, radiation resistance, immune regulation, oxygen utilization, or metabolic adaptation (Howarth et al., 2010; Lubos et al., 2011).

Successes in pediatric applications demonstrate the potential of somatic gene therapy for treating inherited disorders. Advances in safer viral vectors, such as lentiviruses and adeno-associated viruses (AAV), have paved the way for clinical success. For instance, AAV-based gene therapy has significantly improved survival and motor function in infants with spinal muscular atrophy (SMA). Similarly, clinical trials for children with Leber’s congenital amaurosis (LCA) have shown significant visual improvement following AAV-mediated gene transfer. Furthermore, lentiviral vector-based therapy has been effective in treating severe combined immunodeficiency (SCID), particularly adenosine deaminase-deficient SCID (ADA-SCID), offering hope for young patients affected by life-threatening conditions (Dunbar et al., 2018; Mohammadian Gol et al., 2024). These applications reflect significant progress in somatic gene therapy at younger ages.

In parallel, germline genetic modifications could theoretically establish inheritable baseline adaptations intended to improve long-term reproductive and developmental resilience in space. Within the SRAET framework, such interventions could potentially be implemented at the gamete or early embryonic stages within the biomimetic reproductive platform, where genetic modifications could be introduced and continuously monitored prior to subsequent developmental stages. Potential targets could include genes and regulatory pathways associated with radiation resistance, enhanced DNA repair, oxidative-stress regulation, metabolic efficiency, oxygen utilization, cardiovascular adaptation, immune resilience, or mechanobiological tolerance under altered gravitational conditions. Although such modifications could theoretically contribute to the emergence of human populations increasingly adapted to extraterrestrial environments, germline interventions remain highly controversial and are currently unsuitable for clinical application due to major ethical, biological, and safety concerns, including pleiotropy, mosaicism, off-target mutations, irreversible developmental consequences, and multigenerational unpredictability (Galis, 2007; Musunuru, 2019). Future advances in genome engineering may nevertheless permit carefully controlled investigations into whether targeted hereditary modifications could enhance long-term resilience under space conditions.

Genetic variation among individuals is expected to influence not only the extent but also the manner in which they exhibit phenotypic plasticity. While the expression of phenotype primarily arises from differential gene regulation, it is essential to understand that this regulation extends beyond the genetic material within the embryo. External environmental factors, such as temperature, light duration, dietary availability, population density, can also induce specific phenotypic variations by affecting gene expression (Gilbert, 2001; Mateus et al., 2014; West-Eberhard, 2005).

West-Eberhard (2005) argues that understanding the origin of species differences is more effectively achieved by focusing on the emergence of novel phenotypic traits rather than solely on reproductive isolation. She proposes that these novel traits arise through “developmental recombination,” which reorganizes existing developmental pathways, followed by “genetic accommodation” that stabilizes and refines the new trait. This process highlights the importance of phenotypic variation, including environmentally induced changes, as the primary substrate for natural selection rather than just genetic mutation. West-Eberhard contends that environmentally induced novelties may hold greater evolutionary potential than genetic mutations because they can simultaneously affect many individuals. If the resulting phenotypic variation has a fitness effect, meaning it correlates with survival or reproductive success, then selection occurs, favoring differential reproduction among individuals with varying phenotypes.

Importantly, within the SRAET framework, genetic modification would not necessarily replace developmental plasticity, environmental interaction, or natural adaptive processes. Rather, long-term adaptation to space may emerge through continuous interactions among controlled environmental exposure, developmental plasticity, cybernetic regulation, and targeted biological modification. In this context, space environments would remain active evolutionary and developmental forces, continuously shaping biological responses across individual lifetimes and successive generations.

As noted by Hochberg (2009), developmental plasticity extends from conception through childhood and may, under certain circumstances, exert transgenerational influences. Consequently, understanding how genetic, developmental, and environmental factors interact during these critical periods may prove essential for facilitating long-term adaptation to space environments. This indicates that these key periods not only facilitate the installation of adaptive traits in response to environmental challenges but may also set the stage for future generations to inherit these adaptations. Therefore, utilizing the mechanisms of developmental plasticity during these critical periods will be essential for optimizing human adaptations for life in space. By analysing the interactions between genetic and environmental factors that influence plasticity, a better preparation for the specific physiological challenges presented by space environments can be achieved. This knowledge will enable us to develop targeted strategies and interventions that enhance resilience and adaptation in future human space explorers.

SRAET is therefore conceived not only as a reproductive-support technology, but also as a developmental platform through which controlled environmental exposure, biological regulation, and adaptive plasticity may interact during critical periods of human development.

Ultimately, the greatest challenge of human expansion beyond Earth may not be transporting humans into space, but understanding how life itself can develop, adapt, and evolve under space conditions. Within this context, reproduction and development may emerge as fundamental biological gateways through which long-term adaptation becomes possible. By integrating environmental regulation, developmental plasticity, cybernetic control, and biological modification, future adaptive reproductive systems could transform early development into an active interface between human biology and space environments.

Over sufficiently long timescales, such interactions could contribute to new evolutionary trajectories, leading to the emergence of human populations progressively adapted to diverse space conditions. In this sense, SRAET would not merely support reproduction beyond Earth; it would represent a developmental biotechnology through which humanity may begin to actively participate in shaping its own evolutionary future.

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Footnotes

Edited by: Joseph N. Pelton, International Space University, United States

Reviewed by: Frank Barnes, University of Colorado Boulder, United States

Charles R. Doarn, University of Cincinnati, United States