A new study published in the journal Science Advances suggests that the moon has significant amounts of water lurking in its interior. If the lunar mantle is indeed water-rich, colonizing the moon for future space explorations could be much easier.
Signature Of Lunar Water At Different Times Of The Day
Christian Wöhler, from TU Dortmund University in Dortmund, Germany, and colleagues used data from NASA's Moon Mineralogy Mapper instrument to better understand the behavior of water on the moon.
The researchers focused on the wavelengths of light on the moon, which serve as signatures of water, as well as the molecule hydroxyl whose composition is similar to that of the water sans one hydrogen atom.
The researchers also looked at the entire surface of the moon in the morning, midday and afternoon.
Stronger signs of water were detected at the highland regions at high latitudes during the morning and evening, which is justified if the sunlight gets rid of the molecules from the rocks there since sunlight tends to be stronger at midday.
In highlands closer to the equator, however, water was found to be nearly constant regardless of the time of the day suggesting that some of the water may be bound strongly enough to the rocks and thus able to resist evaporation.
"Although our results generally support the commonly accepted mechanism of H2O/OH formation by adsorption of solar wind protons, they suggest the presence of a more strongly bounded surficial H2O/OH component in the lunar highlands and parts of the mare regions, which is not removed by processes such as diffusion/thermal evaporation and photolysis in the course of the lunar day," the researchers wrote in their study published on Sept. 8.
Possible Reservoir At Large Depth
Earlier studies suggested that water on the moon possibly comes from the chemical reactions between protons in the solar wind and oxygen molecules in the lunar rocks but if this is the case, it means that the amount of water on the moon should vary much more with time. Researchers said that the time-of-day-dependent variations that they observed are weaker than expected.
The observations hint that something else could be at play. One possibility is that the water comes from the lunar interior.
"Possible sources are, amongst others, hydrated minerals or a reservoir at large depth," Wöhle said. "This would imply the presence of significant amounts of water in the lunar interior."