Finding water beneath the Moon’s surface is much more difficult than it seems. Most deposits remain invisible in images taken from orbit. Geologists have suggested looking for them by detecting the faint tremors that occasionally shake the Moon’s interior. In frozen soil, such vibrations travel noticeably faster than in dry dust.
Why Lunar Ice Is Needed
Frozen water in lunar soil has clear practical value. Future laboratories and habitation modules will require a stable source of water, which can also be used to produce oxygen and components of rocket fuel. Transporting these supplies from Earth would be far more expensive.
The research team was led by Harrison Lisabeth of Lawrence Berkeley National Laboratory and included geologists from the University of Maryland and the University of Hawaii. The study was published in the peer-reviewed journal Science Advances, Universe Today reports.
The origin of this water has still not been definitively established. Some of it may have been delivered by comets and asteroids, while the rest may have been released through chemical reactions driven by the solar wind. It is more likely that these reserves accumulated over millions or even billions of years rather than appearing as the result of a single impact.
Wave Speed in Frozen Soil
During a moonquake, mechanical vibrations travel through the interior, and their speed depends on the density and elasticity of the rocks. On Earth, this property is used to determine the structure of subsurface layers. The same approach can also be applied to the Moon.
In an ice-rich area, waves travel two or three times faster than in dry regolith. Frozen water between dust grains makes the material more rigid, causing some of the energy to be reflected back. According to Nicholas Schmerr of the University of Maryland, these reflections can also be used to estimate the approximate volume of the deposit.
Ice deposits in shadowed craters are also valuable in their own right. They may preserve material delivered by comets during the early history of the Solar System. Nicholas Schmerr believes that studying such ice could clarify how water was distributed throughout the Solar System and where Earth’s oceans came from.
Three Ways to Detect Ice
The method was tested using three independent approaches, each modeling a different aspect of the problem. Researchers considered the properties of the soil itself, the thermal conditions of the polar regions, and the propagation of vibrations through the subsurface. All three approaches produced clear signatures of frozen water in the data.
The laboratory stage provided the clearest demonstration. Volcanic rock from Arizona was crushed into material almost identical to lunar dust, moistened and frozen, and then examined with X-rays. The images showed that ice fills the spaces between grains and binds them together like cement.
The Next Opportunity for Testing
The idea could soon be tested on the Moon itself. China’s Chang’e-7 spacecraft, carrying a seismometer, is being prepared for launch, with the launch window opening in late August 2026. The landing is planned on an illuminated ridge of Shackleton Crater near the lunar south pole, close to areas suspected of containing frozen water.
The next step will come under the U.S. program. As part of an Artemis mission in 2028, an environmental monitoring station equipped with instruments for recording vibrations is expected to reach the lunar surface. That should reveal whether the predicted signatures of ice appear under real lunar conditions.
