New research reveals that water and hydroxyl molecules are present across the Moon’s surface, far beyond the previously believed polar regions. Using data from NASA’s Moon Mineralogy Mapper (M3) aboard the Chandrayaan-1 mission, scientists discovered water locked in lunar minerals and hydroxyl created by solar wind interactions, spanning the entire Moon.
Scientists Confirm Water Exists All Over the Moon, Not Just at the Poles
By Lydia Amazouz
Published on September 22, 2024 15:29
Recent studies have significantly expanded our understanding of water on the Moon, revealing that it is not just confined to the polar regions but spread across the entire lunar surface.
Using data collected by NASA’s Moon Mineralogy Mapper (M3), aboard the Indian Space Research Organization’s Chandrayaan-1 spacecraft, scientists identified water and hydroxyl molecules (OH) across various regions of the Moon, altering previous beliefs that lunar water was mainly found in the permanently shadowed craters at the poles.
A New View of Lunar Water: Beyond the Poles
Previous studies had shown that water on the Moon was concentrated in the permanently shadowed craters near the poles, where ice could remain stable due to the lack of direct sunlight. These areas were believed to be the primary sources of lunar water, with the rest of the Moon’s surface thought to be mostly dry. However, the new data from the M3 instrument shows that water is present even in regions that receive direct sunlight.
This water is likely locked within minerals on the lunar surface, especially in anorthosite-rich regions of the Moon’s highlands. Roger Clark, the lead scientist from the Planetary Science Institute, explained, "Future astronauts may be able to find water even near the equator by exploiting these water-rich areas." This discovery opens up new possibilities for future lunar exploration, particularly for missions aimed at establishing sustainable human bases on the Moon. The ability to access water near the equator could significantly reduce the need to rely solely on the polar regions, making water extraction more feasible across a broader range of locations.
Hydroxyl Molecules andThe Role of Solar Wind
A crucial component of the newfound lunar water is the presence of hydroxyl molecules. Unlike traditional water (H2O), hydroxyl (OH) consists of one oxygen atom bonded to one hydrogen atom and is a key building block of water. These molecules form when solar wind—streams of charged particles from the Sun—interacts with the lunar surface. The solar wind supplies protons, which combine with oxygen atoms in lunar minerals to create hydroxyl.
Hydroxyl, while not as immediately useful as liquid water, is far more stable and widespread across the lunar surface. Clark noted, “We see a lunar surface with complex geology with significant water in the sub-surface and a surface layer of hydroxyl.” Over time, the solar wind causes some of this hydroxyl to degrade into hydrogen and oxygen, but much of it remains intact for millions of years. This long-lasting hydroxyl layer could potentially be used by future lunar missions to generate water, providing a crucial resource for astronauts.
The presence of hydroxyl also offers insights into the Moon’s geological history. Some of the hydroxyl found on the lunar surface was likely brought to the surface by volcanic activity and cratering over time, mixing with other materials to create a thin layer that persists across much of the Moon. This discovery changes the way scientists view the Moon’s interaction with the solar wind and its potential for hosting usable resources.
Mapping Lunar Water: the Moon Mineralogy Mapper
The identification of water and hydroxyl molecules across the lunar surface was made possible by the Moon Mineralogy Mapper (M3), an instrument that was aboard Chandrayaan-1, the first Indian mission to the Moon. The M3 used infrared spectroscopy to scan the Moon’s surface, breaking down sunlight reflected off the lunar surface into various wavelengths to detect the unique spectral signatures of water and hydroxyl molecules.
The M3 data, collected between 2008 and 2009, revealed that these water-related molecules were present not only near the poles but also at lower latitudes, scattered across various geological features on the Moon. By analyzing the infrared spectra of sunlight reflected off the Moon, scientists were able to pinpoint areas where water and hydroxyl are most abundant. The instrument detected water ice at the poles and hydroxyl-rich areas spread more evenly across the Moon’s surface, including some regions previously thought to be completely dry.
Clark emphasized the importance of this data in understanding the full picture of lunar water distribution, stating, “Knowing where water is located not only helps to understand lunar geologic history but also where astronauts may find water in the future.” This information will be vital for planning future lunar missions, especially those aimed at long-term human exploration and settlement.
Implications for Future Lunar Exploration
The discovery of widespread water and hydroxyl across the Moon has enormous implications for future crewed missions and lunar bases. Water is a critical resource for space exploration, not only for drinking but also for producing oxygen and fuel. Extracting water from the Moon itself could significantly reduce the need to transport large amounts of water from Earth, making lunar missions more cost-effective and sustainable.
There are several ways to harvest water on the Moon. One approach involves heating water-rich rocks, such as anorthosites, to release the trapped water molecules. Another option is to mine ice deposits found in the permanently shadowed craters at the poles, where water ice has been preserved for millions of years. These ice deposits are more immediately accessible, but transporting water from the poles to other lunar regions remains a logistical challenge.
Clark and his team suggest that both methods could be viable, depending on the location and needs of future missions. “The water-rich anorthosites should be a target for harvesting by lunar astronauts,” he explained. “You have to heat the rocks and soils to get water, but it could be a long-lasting supply for future lunar missions.” This process, while energy-intensive, could provide a reliable source of water for long-term lunar exploration, especially in areas where ice is not readily available.
The discovery of water and hydroxyl on the Moon also enhances the prospects for in-situ resource utilization (ISRU)—the practice of using local materials to support space missions. NASA and other space agencies are increasingly focused on sustainable exploration, and having access to lunar water resources is a key component of that strategy. This could pave the way for lunar bases that are more self-sufficient, reducing the need for costly resupply missions from Earth.