In a breakthrough that could reshape future lunar exploration, NASA researchers have confirmed that the solar wind—a stream of charged particles from the Sun—can create water molecules on the Moon’s surface. This finding, published on March 17 in JGR Planets, offers new insights into how water may be forming naturally on the Moon, with critical implications for NASA’s Artemis missions targeting the lunar South Pole.
How Solar Wind Triggers Water Formation on the Moon
Unlike Earth, the Moon lacks a magnetic field or atmosphere, exposing it directly to the relentless barrage of solar wind, which is mostly made up of hydrogen protons. When these protons collide with the lunar regolith—a layer of loose, dusty rock on the Moon’s surface—they interact with oxygen atoms found in lunar minerals such as silica. This reaction forms hydroxyl (OH) and, in some cases, full water (H₂O) molecules.
“The exciting thing here is that with only lunar soil and a basic ingredient from the Sun, which is always spitting out hydrogen, there’s a possibility of creating water,” said Li Hsia Yeo, lead author of the study and a research scientist at NASA’s Goddard Space Flight Center. “That’s incredible to think about.”
Although previous spacecraft observations hinted at the presence of surface water or hydroxyl molecules, this is the first time the full water-formation process has been replicated in a laboratory, providing direct evidence of how the solar wind may actively contribute to water formation on the Moon.
Simulating 80,000 Years of Lunar Exposure
To test the theory, Yeo and her team designed a unique lab apparatus that replicated the Moon’s environment as closely as possible. Their system combined a solar particle beam, a vacuum chamber, and an infrared spectrometer, all enclosed to prevent any contamination from Earth’s atmosphere.
“It took a long time and many iterations to design the apparatus components and get them all to fit inside,” explained Jason McLain, a co-author and fellow research scientist at Goddard. “But it was worth it, because once we eliminated all possible sources of contamination, we learned that this decades-old idea about the solar wind turns out to be true.”
The team used Apollo 17 lunar samples, which they carefully baked to remove any moisture that might have been introduced on Earth. Over the course of several days, the samples were bombarded with high doses of solar-like particles, simulating what the Moon would experience over 80,000 years.
Spectral analysis of the dust showed a dip in light absorption at 3 microns, a wavelength associated with water and hydroxyl. The shape and width of the signal suggested that both hydroxyl and water were produced in the experiment.
What It Means for Lunar Exploration
These findings have major implications for future Moon missions. If the solar wind can continually generate trace amounts of water on the Moon, even in sunlit areas, it could significantly impact how NASA and other space agencies plan for in-situ resource utilization (ISRU) — the process of harvesting materials on-site for life support and fuel.
Notably, NASA’s Artemis program aims to establish a long-term human presence at the Moon’s South Pole, where water ice is thought to exist in permanently shadowed regions. The possibility that solar wind-driven processes can also produce surface water elsewhere on the Moon adds a potential new layer of resource availability.
Additionally, the researchers noted a daily cycle in water-related spectral signals, with stronger signatures in the cooler morning and weaker ones in the heat of lunar noon. This suggests a dynamic hydration cycle, where water and hydrogen molecules migrate or escape, but are constantly replenished by the solar wind.
The Bigger Picture
While micrometeorite impacts and other processes may contribute to lunar water, this study firmly establishes the solar wind as a primary source. Beyond the Moon, these findings also open new lines of inquiry for other airless bodies in the solar system—like asteroids and Mercury—where similar mechanisms might be at play.
By replicating this process on Earth using genuine lunar dust, NASA’s research team has closed a major gap in understanding how solar system chemistry plays out on the surface of celestial bodies. Future studies will aim to refine the process and assess whether this water is practically accessible for human use.
