Harvard-Smithsonian Center for Astrophysics scientists studying water ice believed to be stored in the Moon’s ‘pits of eternal darkness’ have concluded that there likely isn’t enough of this critical resource to support long-term future human colonies, meaning visions of large-scale cities on Earth’s largest natural satellite may be more science fiction than science fact.

Conversely, the researchers calculated that smaller settlements with fewer than 10,000 human colonists could have enough accessible water to survive for centuries. They also suggested that other technological advances in water harvesting or advances in scanning techniques that explore below the top few meters of surface regolith may reveal significant amounts of hidden lunar water.

Water Ice Stored in Moon’s Pits of Eternal Darkness

The Moon’s surface is covered with visible evidence of asteroid collisions. Along with its textured appearance, some of these massive impact craters contain areas that are permanently shaded from direct sunlight.

The Harvard-Smithsonian research team behind the new study said some of the earliest “pits of eternal darkness” could be over one million years old. More critically, they can maintain a temperature of 110K, or just above absolute zero. At this low temperature, frozen water ice trapped in the sunless craters won’t lose more than a millimeter of thickness to space every billion years.

When announcing the new study, the researchers noted that “a succession of Moon-orbiting missions” has mapped out possible locations of stored water ice since 2013. The results suggested that the Moon’s pits of eternal darkness may contain as much as a billion tons, with the largest concentrated around the Moon’s northern and southern poles.

Since those missions, scientists and industrialists have begun to speculate about the viability of long-term human lunar habitation. Unlike astronauts trapped in capsules or space stations, lunar colonists could theoretically possess enough on-site water to support farming, full-service bathroom facilities, and production of hydrogen-based fuels.

Still, researchers wondered if one billion tons of stored water ice is enough to support the types of cities that billionaire industrialists and science fiction authors have proposed.

On-Site Solar Power Could Support One-Million-Person Lunar City

To start, the team modeled how long large human settlements ranging from 100,000 to one million people could survive on the water stored in lunar pits of eternal darkness. This included water-recycling rates up to 98%, as achieved on the International Space Station (ISS).

After running the numbers, the team found mixed results.

First, even colonies up to one million humans wouldn’t run out of power. The team said that number is based on solar power generation and excludes nuclear reactors.

Instead, the Harvard-Smithsonian team proposed constructing one-kilometer-tall solar energy towers near the rims of the craters. Their models suggest that an array of towers covered in photovoltaic arrays could generate three gigawatts of usable electricity.

The team noted that the materials needed to build solar panels, including the primary ingredient, silicon, are plentiful on the Moon, meaning future lunar colonists could manufacture new solar power-generating towers on-site. Such lunar colonists could theoretically maintain enormous AI data centers near these towers capable of servicing paying customers back on Earth.

“That would be the start of a true lunar economy,” the research team explained.

Even Generous Water Ice Estimates Limit Large Lunar Colonies

When the researchers crunched the water numbers, long-term lunar habitability became significantly more dubious. In fact, most estimates had future lunar colonists exhausting the most generous one-billion-ton projected supply of water ice within “a few years.”

When researchers modeled an ISS-level water recycling efficiency level using those same water estimates, a colony of one million humans would run out of water “in just over a century.”

“And today’s best estimates of the amount of water on the Moon are about 30 times less than a billion tons, shortening the time to water exhaustion by the same factor,” they add.

For example, if more conservative ‘pits of eternal darkness’ water ice estimates are closer to reality, the researchers said that “even a small city” likely wouldn’t make it past a decade before they had tapped the Moon dry.

Untapped Sources Could Improve Long-Term Habitation Prospects

Fortunately, the news was not all bad. When the team assumed a smaller “Moon village” of over one thousand people, up to a larger settlement of 10,000, the researchers found that the water ice stored in the Moon’s pits of eternal darkness “would instead be sustainable for several centuries or more.”

The team also suggested alternate solutions for supporting a larger, long-term lunar settlement. These included potential improvements in water recycling, improved farming efficiency, or mining nearby asteroids for water.

The team also noted that additional pockets of stored lunar water ice may be awaiting discovery, suggesting that finding such lunar water may be easier than achieving sufficient farming and recycling efficiency improvements.

“Current water surveying techniques do not reach below the surface more than a few meters, while the rubble-like rocks of the surface regolith typically extend tens of meters down and may contain water in the cold traps,” they explained.

The study “No Cities on the Moon: a Billion Tons of Water is not enough for Sustainability” was published in Frontiers in Space Technology. 

Christopher Plain has spent the last six years as Associate News Editor and Head Science Reporter at The Debrief. Follow and connect with him on X, learn about his novels at plainfiction.com, or email him at christopher@thedebrief.org.

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Deep within the labyrinthine caves of northeastern Mexico dwells a remarkable species of fish, the blind Mexican cavefish (Astyanax mexicanus), whose evolutionary journey over hundreds of thousands of years has led it to adapt to a life shrouded in perpetual darkness. This fish has lost its eyes and pigmentation, hallmark traits of cave-dwelling organisms, while simultaneously acquiring a suite of physiological and behavioral adaptations tailored to survive in nutrient-scarce subterranean environments. Its dual existence as both a sighted surface fish and numerous independently evolved cave forms presents a unique biological system for examining how extreme environments drive evolutionary changes in brain structure, sensory processing, and behavior.

Researchers from Florida Atlantic University, collaborating with experts from institutions across the United States, have leveraged cutting-edge genetic and imaging technologies to decipher the neural underpinnings that distinguish cavefish from their surface relatives. By employing genetically engineered lines of this species that express fluorescent markers in their neurons, the scientists conducted real-time, whole-brain imaging at cellular resolution, unveiling intricate patterns of neural activity in response to sensory stimuli. This approach allowed direct comparison of neural circuitry when fish were exposed to alternating light and dark conditions, providing profound insights into how evolution recalibrates brain function to orchestrate behavior appropriate for radically different environments.

The study, recently published in Science Advances, reveals an astonishing reversal in sensorimotor behavior between the two ecotypes. Whereas surface fish exhibit increased locomotor activity upon sudden darkness—presumably an adaptive mechanism to enhance exploration for light sources—the cavefish respond inversely, with heightened activity triggered by light exposure. This counterintuitive response is theorized to serve as an adaptive avoidance strategy, steering cavefish away from illuminated cave entrances where predation risk and environmental fluctuations are higher. Such behavioral rewiring exemplifies how neural circuits can be evolutionarily repurposed rather than completely reinvented.

Central to this behavioral dichotomy is the alteration of activity within the posterior tuberculum, a brain region long implicated in sensorimotor integration and motivational states. The researchers identified not only region-specific shifts in activity patterns but also characterized a previously undescribed neuronal cell type that appears to play a pivotal role in mediating light-evoked responses. Intriguingly, neurons that in surface fish were activated by darkness exhibited robust activation in cavefish under light stimulus, underscoring the concept of evolutionary neural circuit reutilization. This finding challenges conventional assumptions that new behaviors necessitate de novo neural architectures and instead supports a model where existing circuits are modified to generate novel functional outputs.

Further mechanistic insights emerged from the investigation of dopaminergic signaling pathways. Dopamine, a neurotransmitter extensively involved in motor control, reward processing, and sensory modulation across vertebrates, was found to be centrally implicated in mediating these light-driven behavioral shifts. The study demonstrates that evolutionary tuning of dopamine circuits underlies the behavioral adaptation in cavefish, representing a conserved neurochemical axis modified through natural selection. This work sheds light on the plasticity and evolutionary potential of neuromodulatory systems in shaping species-specific behaviors.

These findings have significant implications beyond the realm of evolutionary biology. Since dopaminergic circuits are highly conserved from fish to mammals, understanding how these systems adapt to environmental pressures provides a window into fundamental brain functions relevant to health and disease. For example, alterations in dopamine signaling underlie numerous neurodevelopmental and neurodegenerative disorders in humans, including Parkinson’s disease, schizophrenia, autism spectrum disorders, and attention deficit hyperactivity disorder (ADHD). By elucidating natural mechanisms of dopamine circuit modification, this research may inform therapeutic strategies targeting related pathologies characterized by dysregulated sensory processing and motor responses.

The genetically controlled inheritance of photokinetic behavior further underscores the robustness of these adaptations. Crossbreeding experiments between surface fish and cavefish yielded hybrid offspring exhibiting a spectrum of activity responses to light and dark, confirming that these sensorimotor traits are encoded within the genome. Dissecting the genetic loci and developmental pathways responsible for remodeling neural circuits remains a crucial next step. Such investigations promise to unravel molecular drivers of behavioral evolution and highlight how genetic variation translates into neural and behavioral diversity.

The blind Mexican cavefish stands as an exemplary model system to probe how sensory systems are sculpted by evolutionary forces and how brains dynamically reconfigure to interpret environmental signals. By disentangling the neural rewiring that facilitates survival in total darkness, researchers gain a clearer picture of how sensory inputs are transformed into adaptive motor outputs. This contributes to a broader understanding of brain evolution applicable across vertebrates and illustrates nature’s ingenuity in leveraging existing neural frameworks to solve complex ecological challenges.

Through advanced imaging and behavioral quantification, the Florida Atlantic University team has carved new ground in charting the neural circuit modifications that underpin a dramatic shift from dark-evoked to light-evoked photokinesis. This work provides a compelling paradigm illustrating that evolution does not invariably mandate the invention of novel structures but can preferentially repurpose and recalibrate pre-existing neural substrates to generate behavioral novelty.

The evolutionary narrative of the blind Mexican cavefish enriches our comprehension of neuroecology—the study of how nervous systems evolve in response to environmental variables. It reveals that sensory deprivation, far from being a mere loss, can instigate intricate neural and behavioral innovations that confer selective advantages. Such insights deepen our appreciation for the complexity and flexibility inherent in neural systems when confronted with extreme ecological niches.

Finally, this research exemplifies the power of integrative methodologies combining genetics, neurobiology, and behavioral science to unravel the enigma of brain evolution. It paves the way for future interdisciplinary studies to identify specific genes orchestrating neural circuit plasticity, decode developmental mechanisms driving neuronal subtype specification, and ultimately connect genotype to phenotype in a context of evolutionary adaptation.

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Subject of Research: Animals

Article Title: Evolution of a central dopamine circuit underlies adaptation of a light-evoked sensorimotor response in the blind cavefish

News Publication Date: 22-May-2026

Web References:
DOI: 10.1126/sciadv.adv3770

Image Credits: Florida Atlantic University

Keywords: Evolutionary biology, Brain, Neurons, Sensory neurons, Photoreceptors, Neurological disorders, Neurodegenerative diseases, Parkinson’s disease, Schizophrenia, Fish, Brain activity maps, Behavioral ecology, Ecological adaptation, Neural pathways, Dopamine pathways

The ongoing wars are grabbing headlines, but the true battle lies in the spiritual realm for human souls. It's a struggle against dark forces that infiltrate positions of power and influence, even within churches, presenting a deceptive facade. This battle requires the full armor of God to withstand.