Humanity’s greatest challenge in becoming a multi-planet species may not be building bigger rockets or landing astronauts on Mars. Instead, it could come down to the question: Can humans safely conceive, carry pregnancies, and raise healthy children off Earth?

A new review published in Frontiers in Space Technologies argues that the answer to this question remains unclear. Drawing on decades of research on animal reproduction in space alongside emerging advances in artificial intelligence, biotechnology, synthetic biology, and cybernetic systems, the researchers suggest that future generations born off Earth may require technologies far beyond today’s medical capabilities.

In the most speculative sections of the paper, researchers even envision a scenario in which reproduction itself acts as a tool for helping humans gradually adapt to life in space.

Rather than presenting new experiments, the paper synthesizes existing evidence while outlining possible technological pathways that could someday enable permanent human settlements on the Moon, Mars, or even deeper into the solar system.

The central message is that surviving in space is only the first hurdle. Establishing self-sustaining civilizations will ultimately depend on whether human reproduction can succeed under conditions of microgravity, radiation, isolation, and other environmental stresses that evolution never prepared us to face.

“It is proposed that prenatal and early postnatal developmental stages may constitute critical biological windows for facilitating long-term adaptation to space,” researchers write. “Such interactions could ultimately transform reproduction and early development into active drivers of human evolution, contributing to the emergence of biologically distinct populations progressively adapted to diverse space environments.”

Despite more than six decades of human spaceflight, no human has ever conceived or carried a pregnancy in space. Therefore, science has little direct evidence about what would happen if astronauts attempted to start families off Earth. Nearly everything researchers know comes from studies involving animals ranging from sea urchins and fish to frogs, birds, mice, and rats.

The results are encouraging in some respects but troubling in others.

Several non-mammalian species have successfully reproduced in orbit. Medaka fish, for example, became the first vertebrates to reproduce in space, with fertilization rates comparable to those seen on Earth. Yet, even when reproduction occurs successfully, researchers have documented developmental abnormalities in some species, suggesting that space environments can slightly modify embryonic development.

Rodent studies paint an even more complicated picture. Fertilization is not impossible under microgravity, but early embryonic development frequently suffers. Experiments have shown reduced blastocyst formation, slower embryo development, lower live birth rates, and changes in gene expression. Other studies have linked space radiation to DNA damage, genomic instability, and developmental defects affecting the nervous system.

At the same time, some findings show surprising resilience. Mouse embryos cultured aboard the International Space Station have developed into apparently normal blastocysts under certain conditions. In contrast, freeze-dried mouse sperm stored in orbit for months later produced healthy offspring after returning to Earth.

These mixed findings suggest that reproduction may be biologically possible, but far from routine, under space conditions.

In their review, researchers also examined growing evidence that spaceflight affects male and female reproductive health even before conception occurs.

Microgravity and radiation appear capable of disrupting sperm production, reducing testosterone levels, altering ovarian function, impairing egg maturation, and interfering with hormone regulation.

Some studies suggest sperm can still swim under simulated microgravity, but lose their capability to navigate effectively toward an egg. Others report that radiation accelerates the depletion of ovarian follicles and increases DNA damage in reproductive cells.

More concerning is the possibility that some biological changes could be passed to future generations through epigenetic mechanisms. Experiments involving mice have suggested that spaceflight may alter gene regulation in sperm and influence gene expression in offspring, although the long-term significance is still unknown.

For women, pregnancy itself could present an even greater challenge. On Earth, pregnancy requires profound cardiovascular changes that help deliver oxygen and nutrients to a growing fetus. Microgravity, however, causes fluid redistribution, muscle loss, reduced blood volume, bone demineralization, and changes in cardiovascular function that could interfere with placental development and fetal growth. Radiation exposure, oxidative stress, circadian disruption, and limited medical support would only add to those risks.

Researchers argue that simply shielding astronauts from radiation may not be enough. Gravity itself appears to function as a biological signal that influences everything from cell organization to tissue development. That realization carries renewed interest in artificial gravity as a potential solution.

Instead of depending solely on habitats built on the Moon or Mars, future space settlements could include rotating structures that generate centrifugal force to recreate Earth-like gravity.

Such habitats have appeared in science fiction for decades, but researchers suggest they may ultimately become essential for healthy conception, pregnancy, childhood development, and multigenerational life off Earth.

Researchers propose dedicated orbital research platforms where scientists could systematically study reproduction under lunar, Martian, or custom-designed gravity levels before humans attempt permanent settlements.

Artificial intelligence also features prominently in the researchers’ vision of the future. They propose AI-powered “digital twins” capable of integrating biological, physiological, and environmental data to simulate how embryos, pregnancies, and developing children might respond to different gravitational and radiation environments. These computer simulations could help researchers examine scenarios that would be difficult, or ethically impossible, to test directly in humans.

Perhaps the paper’s most futuristic proposal is something the researchers call Synthetic Reproductive Adaptive Enhancement Technology, or SRAET. This speculative concept envisions highly automated reproductive systems combining artificial wombs, advanced reproductive biotechnology, biosensors, AI-assisted monitoring, and predictive developmental modeling into a closed-loop environment capable of supporting conception through birth under carefully controlled conditions.

The framework explores the controversial possibility that future advances in gene editing and synthetic biology could one day help humans adapt biologically to off-world environments.

Researchers emphasize that such ideas are still speculative and acknowledge the enormous ethical, biological, and safety concerns surrounding germline modification, off-target mutations, and multigenerational consequences. Rather than advocating immediate implementation, they present these possibilities as conceptual pathways that justify careful scientific and ethical discussion.

For fans of science fiction, many of these concepts may sound remarkably familiar. Yet, researchers attempt to ground their arguments in existing developmental biology, reproductive medicine, aerospace engineering, and space medicine while clearly distinguishing current evidence from future speculation.

In the end, researchers suggest that the future of human space travel may depend less on propulsion systems than on understanding how life develops under entirely new environmental conditions. If humanity hopes to establish permanent settlements off Earth, science will first need to ensure that future generations are able to begin life safely under alien skies.

“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,” researchers write. “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.”

Study: Ferraz M, Moeharram L. “Past, present and future of human reproduction and development in space.” Frontiers in Space Technologies. 2026.

Tim McMillan is a retired law enforcement executive, investigative reporter and co-founder of The Debrief. His writing typically focuses on defense, national security, the Intelligence Community and topics related to psychology. You can follow Tim on Twitter: @LtTimMcMillan.  Tim can be reached by email: tim@thedebrief.org or through encrypted email: LtTimMcMillan@protonmail.com 

A growing body of evidence suggests that leaving Earth may do far more than challenge the human body. According to a new study, the absence of gravity itself could temporarily reshape consciousness, loosening the brain’s most strongly ingrained assumptions and opening the door to altered perceptions, expanded awareness, and even experiences that resemble some aspects of psychedelic states.

As humanity prepares for longer stays on the Moon, commercial space tourism, and eventual missions to Mars, researchers contend that understanding what happens to the mind in microgravity may be just as important as understanding the engineering that gets astronauts there. According to them, gravity may not simply keep people anchored to the ground—it may also help anchor human consciousness itself.

In a new paper published in Frontiers in Psychology, researchers Dr. Annahita Nezami and Dr. Elisa Raffaella Ferre of Birkbeck, University of London, explored decades of neuroscience, psychology, and spaceflight research to propose that Earth’s gravitational pull acts as a deeply embedded “super-prior” within the brain. By disrupting this ancient reference point, microgravity may trigger widespread changes across neural networks that underpin perception, self-awareness, and emotional regulation.

“Human consciousness has evolved under the constant pull of terrestrial gravity, yet its role in shaping perception and awareness has received limited theoretical attention,” researchers write. “As spaceflight transitions from short missions to long-duration habitation, understanding how consciousness responds to non-terrestrial gravity becomes increasingly urgent.”

Every human brain evolved under the constant force of Earth’s gravity. From before birth onward, sensory systems constantly rely on gravity cues to determine which way is up, where the body is in space, and how to interpret movement.

Researchers argue that this constant exposure has made gravity one of the brain’s most reliable assumptions. In the language of predictive neuroscience, the brain constantly generates expectations about the world and updates them using incoming sensory information. Gravity, they say, functions as a basic expectation—a “1G super-prior”—that helps stabilize consciousness.

Remove that constant, and things begin to change.

In orbit, vestibular signals from the inner ear become unreliable. Visual, proprioceptive, and balance information no longer align as the brain evolved to expect. The resulting mismatch generates anticipation errors, forcing widespread recalibration.

Those changes are already well documented among astronauts. Space travelers commonly experience spatial disorientation, altered body perception, sleep disturbances, mood swings, and, in some cases, feelings of depersonalization or derealization—states in which individuals feel separated from themselves or perceive their surroundings as unreal.

Astronauts have also reported more positive and profound experiences. Many describe feeling “unmoored,” “expanded,” and deeply interconnected with humanity, or overwhelmed by awe while viewing Earth from orbit. This phenomenon, known as the Overview Effect, has been associated with lasting shifts in values, increased environmental concern, and enhanced feelings of oneness.

The study suggests that these experiences might originate from the same neurocognitive processes triggered when gravity’s stabilizing role is weakened.

“By perturbing the most stable embodied reference – gravity itself – spaceflight offers a rare window into how fundamental expectations shape consciousness,” researchers write. “The loosening of perceptual boundaries in microgravity has been proposed as a neurocognitive foundation for the Overview Effect.”

Brain imaging studies lend support to the idea. MRI scans of astronauts before and after extended-duration missions have revealed structural changes, including fluid redistribution, enlargement of brain ventricles, and gray matter remodeling. Functional MRI studies have also found changes in connectivity among vestibular, sensory, and default mode network regions involved in awareness and the combining of internal and external information.

Especially intriguing are changes observed in the default mode network, a system involved in introspection, self-referential thought, and consciousness. Activity inside this network appears to diminish after spaceflight, with some changes persisting for months after astronauts return to Earth.

Electroencephalography studies have likewise detected reductions in alpha-wave activity during and after missions, another sign that brain function is being reorganized in response to microgravity.

These neural changes led the researchers to an unexpected comparison.

Many of the same large-scale patterns recorded after spaceflight resemble effects previously documented under psychedelic compounds such as psilocybin and LSD. In both situations, highly organized brain networks appear to loosen, while communication between previously separate regions increases.

Researchers stress that the mechanisms are entirely different. Psychedelics act through serotonin receptors, whereas microgravity represents an environmental disruption rather than a pharmacological one. Yet both seem to converge by weakening the brain’s highest-level assumptions and increasing the combination of sensory information.

According to researchers, this convergence phenomenon suggests that spaceflight could provide scientists with a natural, drug-free model for studying transformative states of consciousness.

The researchers argue that terrestrial gravity, microgravity, and psychedelic states may represent different conditions along a spectrum defined by the strength of the brain’s deeply ingrained “1G super-prior.” As that stabilizing role weakens, top-down constraints relax, potentially increasing neuroplasticity and mental flexibility.

The implications go beyond astronaut health. Understanding how consciousness changes in unfamiliar environments may provide new clues to the neural foundations of self-awareness. It could also prove increasingly important as private citizens spend more time in space and human settlements expand away from Earth.

Researchers suggest that microgravity offers scientists something that cannot be replicated on Earth—a chance to observe what happens when one of evolution’s oldest assumptions suddenly disappears.

“By situating consciousness in an environment for which evolution offers no precedent, spaceflight positions microgravity as a powerful natural neurocognitive catalyst for transformative experience,” researchers write. “In stepping beyond Earth’s gravity, we gain a unique vantage point from which to examine the contingent foundations of human awareness and the conditions under which it can be fundamentally transformed.”

Tim McMillan is a retired law enforcement executive, investigative reporter and co-founder of The Debrief. His writing typically focuses on defense, national security, the Intelligence Community and topics related to psychology. You can follow Tim on Twitter: @LtTimMcMillan.  Tim can be reached by email: tim@thedebrief.org or through encrypted email: LtTimMcMillan@protonmail.com