Most of the Moon's Water Remains Chemically Bound in Its Deep Interior, Study Shows

A recent study reveals that most of the moon's water is likely chemically bound in its deep interior. The findings, published on July 13, 2026, suggest significant implications for understanding the Earth-moon system's formation and evolutionary history.

New Discoveries About Lunar Water

For decades, scientists believed the moon was anhydrous, containing very little water. This perception shifted in 2009 when NASA's Lunar Crater Observation and Sensing Satellite (LCROSS) provided evidence of water ice in permanently shaded regions of the moon. However, the new research indicates that water is also present in the moon's interior, primarily as hydroxide (OH) bound to minerals.

Neil Bowles, a professor of planetary science at the University of Oxford, noted, "The Apollo samples appeared to be so dry, which was puzzling. This new understanding of water's presence in the moon's interior is crucial for understanding the initial water budget of our Earth-moon system, formed about 4.5 billion years ago after a Mars-sized impactor struck Earth."

The Role of Apatite in Water Retention

The study highlights the discovery of apatite, a mineral that can hold water within its crystal structure. Bowles explained, "Apatite shows that the moon had water and it's still present in the interior, basically bound to minerals." This contradicts earlier analyses that suggested the moon was extremely dry.

Despite setbacks in lunar exploration, such as the failed Lunar Trailblazer mission in early 2025, researchers remain hopeful about uncovering more about lunar water. Bowles is optimistic that a spare Lunar Thermal Mapper instrument will contribute to future lunar exploration missions, particularly in mapping water's distribution on the moon.

The Importance of Understanding Lunar Water

Understanding the moon's water is scientifically significant as it provides insights into how water is transported within the solar system. Bowles emphasized, "Extracting water from the polar regions would tell us how it was brought there and would preserve a record of that delivery process in the solar system." This knowledge could enhance our understanding of water's movement and its eventual arrival on Earth.

• Significant findings on moon's water abundance
• Apatite discovered as a key mineral for water retention
• Future missions aim to explore lunar water distribution

As the moon continues to be a focal point for scientific inquiry, researchers are eager to gather more evidence to understand its formation and influence on Earth.