Scientists have observed water molecules "hopping" around the surface of the moon via NASA's Lunar Reconnaissance Orbiter. According to the Southwest Research Institute (SwRI), the observations were made using the Lyman Alpha Mapping Project (LAMP) instrument aboard the orbiter, which allowed the team to examine the specific locations on the moon that show signs of water.
Previously, scientists believed that the moon had an arid climate. This changed in 2009 when NASA's Lunar Crater Observation and Sensing Satellite (LCROSS) probe discovered significant amounts of water locked in ice at the lunar south pole. Since then, scientists have observed smaller populations of water molecules attached to lunar soil, also known as regolith, with amounts varying depending on the time of day and location.
Now, the recent study — which is published in the Journal of Geophysical Research Letters— successfully tracks individual water molecules as they attach and detach from the moon's lunar soil. The data reveals that the hopping behavior is most common at higher latitudes and increased surface temperatures, which peak near lunar noon. For this reason, water locations vary throughout the day. The study also reveals the energy necessary to extract water molecules from lunar materials, which is helpful for the scientific understanding of how water binds to surfaces.
"This is an important new result about lunar water, a hot topic as our nation's space program returns to a focus on lunar exploration," Kurt Retherford, a co-author on the paper and the principal investigator of the LAMP instrument at SwRI in Texas, said in a NASA statement.
Typically, lunar water is difficult to measure from an orbiter because of the way that it reflects light from its surface. Due to this reflection, previous data on hopping water molecules suggested amounts too large to be explained by current theories. But the data in the new study is more consistent with what current laboratory experiments suggest is possible.
The presence of water on planetary bodies like the moon is important for many reasons, one being its potential resource for human explorers, as per Space.
"These results aid in understanding the lunar water cycle and will ultimately help us learn about accessibility of water that can be used by humans in future missions to the Moon," Amanda Hendrix, a senior scientist at the Planetary Science Institute and lead author of the paper, said in the NASA statement.
Water accessibility is important because it can be split to create rocket fuel—which could be used as a fuel source for future robotic missions — and for thermal management or radiation shielding. This would cut costs of future space missions because less materials would need to be launched from the Earth.
As of now, more research needs to be done to continue accounting for the effects of the lunar surface on water availability, but the new results are promising.