Water on the moon's surface evaporates roughly 10 times faster under direct sunlight than scientists previously calculated, according to new laboratory research that could reshape plans for farming and water harvesting at future lunar bases. The study, published in a peer-reviewed journal and reported by Phys.org, found that simulated lunar soil loses its water content far more quickly when exposed to sunlight than existing models assumed.
The finding matters because water is the single most valuable resource for any long-term human presence on the moon. NASA's Artemis program aims to land astronauts near the lunar south pole, where permanently shadowed craters are believed to hold billions of tons of water ice. That ice would need to be extracted, stored, and used for drinking water, oxygen, and rocket fuel — all while most of the lunar surface spends roughly 14 Earth days in continuous sunlight followed by 14 days of darkness.
The research team tested how water behaves when bound to simulated lunar regolith, the powdery soil that covers the moon's surface, under conditions mimicking lunar sunlight. Water that had been absorbed into the soil escaped at a rate about 10 times higher than earlier estimates suggested, according to the study's results. That means any water exposed on the sunlit surface — whether from ice deposits, astronaut activity, or irrigation for crops — would disappear faster than mission planners have budgeted for.
Plant cultivation is central to the strategy for sustaining crews on the moon, since resupply missions from Earth cost tens of thousands of dollars per kilogram. Any greenhouse or hydroponic system on the lunar surface would need to conserve water with near-total efficiency, and the new evaporation figures suggest open or semi-open growing systems may be unworkable.
The moon's surface temperature swings from about 250 degrees Fahrenheit (120 Celsius) in sunlight to minus 208 Fahrenheit (minus 130 Celsius) in shadow, one of the most extreme ranges in the solar system. That environment, combined with near-vacuum conditions, means liquid water cannot exist on the surface for long without containment. The new study sharpens how quickly that loss occurs.
China's Chang'e missions and India's Chandrayaan-3 lander have also targeted lunar water ice, and both countries have announced plans for crewed lunar missions in the 2030s. The competition to characterize and eventually exploit lunar water has become a central driver of the new space race.
The study's authors did not test water in permanently shadowed regions, where temperatures stay low enough for ice to remain stable for billions of years. Those cold traps remain the most promising target for water extraction, but the new data suggests that transporting or processing that ice in sunlight will require sealed, rapid-transfer systems rather than the slower handling methods earlier models allowed for.
