Water on the Moon: New Study Narrows Down the Most Likely Locations
Water likely accumulated on the moon slowly over billions of years, rather than during one significant event. This conclusion emerges from new research conducted by an international team of scientists, including Paul Hayne, a planetary scientist at the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado Boulder. The findings have been published in Nature Astronomy.
This study addresses a longstanding lunar mystery that has intrigued scientists for decades. Evidence from NASA missions and other sources indicates that water may be abundant on the moon, especially in the form of ice in the deep, shadowy craters surrounding the moon's South Pole. However, the mechanisms behind this ice accumulation remain unclear.
“It looks like the moon's oldest craters also have the most ice,” said Hayne. “That implies that the moon has been accumulating water more or less continuously for as much as 3 billion or 3.5 billion years.”
Significance of Water on the Moon
Water present on the lunar surface presents a golden opportunity for future astronauts: they could extract ice for drinking water or even generate rocket fuel by splitting the hydrogen and oxygen atoms contained within. As Oded Aharonson, the lead author of the study and a planetary scientist at the Weizmann Institute of Science in Israel, points out:
“Finding water beyond Earth in liquid and usable form is one of the most important challenges in astronomy.”
Potential Sources of Lunar Water
In discussing the potential sources of the moon's water, Hayne mentioned several possibilities:
- Volcanic activity: In the past, volcanoes might have transported water from deeper within the moon to its surface.
- Comet and asteroid impacts: Water could have arrived on the moon through impacts from celestial bodies like comets or asteroids.
- Solar wind: The solar wind—a continuous stream of charged particles emitted by the sun—may also play a role. Hydrogen from the solar wind bombards the moon, where it can combine with oxygen to produce water.
Cold Traps and Ice Accumulation
Regardless of its origin, scientists, including Hayne, are confident that ice has accumulated in regions known as "cold traps." These are craters on the lunar surface that are permanently shadowed, having not seen sunlight for potentially billions of years. Observations from the Lyman Alpha Mapping Project (LAMP) attached to NASA's Lunar Reconnaissance Orbiter (LRO) have discovered evidence for ice in these cold traps.
“What's clear is that the ice has a patchy distribution,” noted Hayne. “It's not concentrated in the same quantities in every crater. And there was no great explanation for that.”
Research Methodology
To investigate further, Hayne, Aharonson, and co-author Norbert Schörghofer analyzed lunar surface temperature data from the LRO's Diviner instrument. They created a series of computer simulations to estimate the evolution of lunar craters through time.
One aspect guiding their investigation was the orientation of the moon relative to Earth. Notably, the moon's axis has shifted throughout its history, meaning that craters currently in shadow may not always have been so. Through their simulations, the researchers created a list of lunar cold traps that have remained in darkness the longest.
Intriguingly, their simulations revealed that the moon's oldest and darkest craters also correspond with locations where LAMP detected the most prominent signs of ice accumulation.
Identifying Potential Ice Locations
These findings may be critical for future lunar exploration, as they highlight specific areas where researchers can search for water. For example, the Haworth Crater, situated near the South Pole, has likely been in shadow for over 3 billion years, making it a prime candidate for ice storage.
Continuing with their lunar research, Hayne aims to develop a new instrument called the Lunar Compact Infrared Imaging System (L-CIRiS) intended to be deployed near the moon's South Pole in late 2027. Such instruments will be indispensable for obtaining detailed observations of potential ice-bearing craters.
Conclusion: The Path Ahead
Ultimately, according to Hayne, determining the source of the moon's water will require in-situ sample analysis. “We will need to go to the moon to analyze those samples there or find ways to bring them from the moon back to Earth,” he emphasized.
Publication Information
The study has been published in Nature Astronomy (2026). You can access the full article via the DOI link.
