Scientists have hypothesized since the 1960s that the Sun is a source of ingredients that form water on the Moon. When a stream of charged particles known as the solar wind smashes into the lunar surface, the idea goes, it triggers a chemical reaction that could make water molecules.   

Now, in the most realistic lab simulation of this process yet, NASA-led researchers have confirmed this prediction.  

The finding, researchers wrote in a March 17 paper in JGR Planets, has implications for NASA’s Artemis astronaut operations at the Moon’s South Pole. A critical resource for exploration, much of the water on the Moon is thought to be frozen in permanently shadowed regions at the poles.  

“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,” Li Hsia Yeo, a research scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “That’s incredible to think about,” said Yeo, who led the study. 

Solar wind flows constantly from the Sun. It’s made largely of protons, which are nuclei of hydrogen atoms that have lost their electrons. Traveling at more than one million miles per hour, the solar wind bathes the entire solar system. We see evidence of it on Earth when it lights up our sky in auroral light shows. 

Most of the solar particles don’t reach the surface of Earth because our planet has a magnetic shield and an atmosphere to deflect them. But the Moon has no such protection. As computer models and lab experiments have shown, when protons smash into the Moon’s surface, which is made of a dusty and rocky material called regolith, they collide with electrons and recombine to form hydrogen atoms.

Then, the hydrogen atoms can migrate through the lunar surface and bond with the abundant oxygen atoms already present in minerals like silica to form hydroxyl (OH) molecules, a component of water, and water (H₂O) molecules themselves.  

Scientists have found evidence of both hydroxyl and water molecules in the Moon’s upper surface, just a few millimeters deep. These molecules leave behind a kind of chemical fingerprint — a noticeable dip in a wavy line on a graph that shows how light interacts with the regolith. With the current tools available, though, it is difficult to tell the difference between hydroxyl and water, so scientists use the term “water” to refer to either one or a mix of both molecules.

Many researchers think the solar wind is the main reason the molecules are there, though other sources like micrometeorite impacts could also help by creating heat and triggering chemical reactions. 

Spacecraft measurements had already hinted that the solar wind is the primary driver of water, or its components, at the lunar surface. One key clue, confirmed by Yeo’s team’s experiment: the Moon’s water-related spectral signal changes over the course of the day.  

In some regions, it’s stronger in the cooler morning and fades as the surface heats up, likely because water and hydrogen molecules move around or escape to space. As the surface cools again at night, the signal peaks again. This daily cycle points to an active source — most likely the solar wind—replenishing tiny amounts of water on the Moon each day.  

To test whether this is true, Yeo and her colleague, Jason McLain, a research scientist at NASA Goddard, built a custom apparatus to examine Apollo lunar samples. In a first, the apparatus held all experiment components inside: a solar particle beam device, an airless chamber that simulated the Moon’s environment, and a molecule detector. Their invention allowed the researchers to avoid ever taking the sample out of the chamber — as other experiments did — and exposing it to contamination from the water in the air. 

“It took a long time and many iterations to design the apparatus components and get them all to fit inside,” said McLain, “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.” 

Using dust from two different samples picked up on the Moon by NASA’s Apollo 17 astronauts in 1972, Yeo and her colleagues first baked the samples to remove any possible water they could have picked up between air-tight storage in NASA’s space-sample curation facility at NASA’s Johnson Space Center in Houston and Goddard’s lab. Then, they used a tiny particle accelerator to bombard the dust with mock solar wind for several days — the equivalent of 80,000 years on the Moon, based on the high dose of the particles used. 

They used a detector called a spectrometer to measure how much light the dust molecules reflected, which showed how the samples’ chemical makeup changed over time. 

In the end, the team saw a drop in the light signal that bounced to their detector precisely at the point in the infrared region of the electromagnetic spectrum — near 3 microns — where water typically absorbs energy, leaving a telltale signature.  

While they can’t conclusively say if their experiment made water molecules, the researchers reported in their study that the shape and width of the dip in the wavy line on their graph suggests that both hydroxyl and water were produced in the lunar samples.  

By Lonnie Shekhtman

NASA’s Goddard Space Flight Center, Greenbelt, Md.

NASA and the U.S. Geological Survey (USGS) welcomed a community of government, industry, and international partners to explore current technology needs around natural resources – both on Earth and “off world.” During a workshop held in February at NASA’s Ames Research Center in California’s Silicon Valley, participants discussed technologies that will improve the ability to detect, assess, and develop resources, such as critical minerals and water ice to be found on our Moon, other planets and their moons, and asteroids.

More than 300 attendees, taking part in person and virtually, worked to define the elements needed to find and map resources beyond Earth to support the growing space economy. These include sensors to image the subsurface of planetary bodies, new platforms for cost-effective operations, and technologies that enable new concepts of operation for these systems.

Scientific studies and measurements of off-world sites will be key to detecting and characterizing resources of interest, creating an important synergy with technology goals and helping to answer fundamental science questions as well.

The workshop was the third in a series called Planetary Subsurface Exploration for Science and Resources. By leveraging the expertise gained from decades of resource exploration on this planet and that of the space technology and space mission communities, NASA and USGS aim to spark collaboration across industry, government, and academia to develop new concepts and technologies.

You would not expect to see NASA at a car show—but that’s exactly where Johnson Space Center employees were from Jan. 29 to Feb. 2, 2025, driving the future of space exploration forward. 

At the Houston AutoBoative Show, a fusion of the auto and boat show, NASA rolled out its Artemis exhibit at NRG Center for the first time, introducing vehicle enthusiasts to the technologies NASA and commercial partners will use to explore more of the lunar surface than ever before. 

The Artemis exhibit stood alongside some of the world’s most advanced cars and boats, offering visitors an up-close look at lunar terrain vehicle mockups from Astrolab, Intuitive Machines, and Lunar Outpost. Later this year, NASA will select the rover that will fly to the Moon as humanity prepares for the next giant leap. 

In addition to the rovers, the exhibit featured a mockup of JAXA’s (Japan Aerospace Exploration Agency) pressurized rover, designed as a mobile habitat for astronauts, and Axiom Space’s lunar spacesuit, developed for Artemis III astronauts. 

These capabilities will allow astronauts to explore, conduct science research, and live and work on the lunar surface.  

Johnson Director Vanessa Wyche visited the Artemis exhibit to highlight the importance of these technologies in advancing lunar exploration. Every lesson learned on the Moon will help scientists and engineers develop the strategies, technologies, and experience needed to send astronauts to Mars.  

“By bringing the excitement of lunar exploration to the AutoBoative Show, NASA aims to inspire the next generation of explorers to dream bigger, push farther, and help shape humanity’s future in space,” Wyche said.  

NASA’s Artemis campaign is setting the stage for long-term human exploration, working with commercial and international partners to establish a sustained presence on the Moon before progressing to Mars. 

To make this vision a reality, NASA is developing rockets, spacecraft, landing systems, spacesuits, rovers, habitats, and more.  

Some of the key elements on display at the show included:

• The Orion spacecraft – Designed to take astronauts farther into deep space. Orion will launch atop NASA’s Space Launch System (SLS) rocket, carrying the crew to the Moon on Artemis missions and safely returning them to Earth.

• Lunar terrain vehicles – Developed to transport astronauts across the rugged lunar surface or be remotely operated. NASA recently put these rover mockups to the test at Johnson, where astronauts and engineers, wearing spacesuits, ran through critical maneuvers, tasks, and emergency drills—including a simulated crew rescue.

• Next-gen spacesuits and tools – Through Johnson’s Extravehicular Activity and Human Surface Mobility Program, astronauts’ gear and equipment are designed to ensure safety and efficiency while working on the Moon’s surface.

Guests had the chance to step into the role of an astronaut with interactive experiences like: 

• Driving a lunar rover simulator – Testing their skills at the wheel of a virtual Moon rover. 

• Practicing a simulated Orion docking – Experiencing the precision needed to connect to Gateway in lunar orbit. 

• Exploring Artemis II and III mission roadmaps – Learning about NASA’s upcoming missions and goals. 

Attendees also discovered how American companies are delivering science and technology to the Moon through NASA’s Commercial Lunar Payload Services initiative. 

“Everyone can relate to exploration, so it was great to teach people the importance lunar rovers will have on astronauts’ abilities to explore more of the lunar surface while conducting science,” said Victoria Ugalde, communications strategist for the Extravehicular Activity and Human Surface Mobility Program, who coordinated the lunar rovers’ appearance at the show. 

Check out the rovers contracted to develop lunar terrain vehicle capabilities below.