New research provides evidence that the Moon’s crust formed from material that was originally wet, challenging the prevailing notion that the early Moon was bone dry. The findings suggest our lunar neighbor had a more dynamic history than previously thought.
Traces of Water Found in Ancient Lunar Meteorite
A team led by researchers from the University of Oklahoma analyzed a meteorite called NWA 2727, which originated from the lunar crust and landed on Earth as a meteorite millions of years ago. Using advanced spectroscopy techniques, they detected traces of water in minerals within the rock [1].
The meteorite sample contained about 6 parts per million of water – not much compared to Earth, but significantly more than expected for the Moon. The water was not in liquid form, but rather chemically bound up in certain mineral structures. Still, lead researcher Zachary Sharples said this shows the early lunar crust contained a small amount of indigenous water when it first formed over 4 billion years ago.
“The Moon was thought to be dry, with any water in the lunar interior resulting from meteorites striking its surface,” Sharples said. “This discovery changes our fundamental understanding of the Moon’s water history” [2].
Lunar Magma Ocean Theory Challenged
The findings challenge the prevalent “lunar magma ocean” theory about the Moon’s origins. This theory posits that the outer layer of molten rock covering the early Moon surface should have almost completely degassed water and other volatiles into space. Any remnants would have been negligible.
“The assumption has been that the lunar magma ocean degassed completely, and the Moon was bone dry,” said Sharples [3].
While the lunar magma ocean concept helps explain the Moon’s basic chemistry, these new discoveries show it does not tell the whole story.
“The lunar magma ocean model can’t explain the water we found in the meteorite,” Sharples said. “Somewhere between the formation of the Moon and the creation of this rock, water was introduced into the early lunar crust” [4].
Wet Moon Origins?
So where did the traces of water come from? Researchers theorize that as the Moon was forming, collisions with water-bearing comets and asteroids likely delivered water. Some of this water was apparently retained, even though most volatiles should have escaped into space.
Another possibility is that some hydrogen from the solar nebula was implanted directly into the lunar crust when it crystalized. Further analysis will be needed to distinguish between these mechanisms.
“Either way, this early lunar crust was not completely dehydrated,” said Sharples [5]. “These findings will shape how we think about the Moon’s formation and orbital evolution”.
Key Takeaways
- Traces of water were detected in a lunar meteorite, challenging assumptions that the early Moon’s crust was bone dry
- This indicates the lunar magma ocean theory does not fully explain the Moon’s origins
- Water was likely delivered by collisions with asteroids and comets in early history
- More research needed to understand the source and implications of the found water
Past Hints of Lunar Water
In fact, there have been growing hints that the Moon is not as dry as we once thought. Over a decade of observations from satellites have detected evidence of surface water ice concentrated near the lunar poles. This is likely accumulated from solar wind interactions with surface regolith.
Several lunar missions have also found traces of water bound up chemically in volcanic lunar glass and rocks. But these involved samples from much younger geological periods.
The traces of water found in this meteorite sample are uniquely ancient, making up a basal crust formed over 4.3 billion years ago. They thus provide a key new window into the earliest eras of lunar formation.
What This Means for Future Exploration
The revelations about the wet origins of the Moon’s crust open up new questions about lunar evolution and dynamics. But they also have key implications for future lunar habitation by humans.
“Anytime you find water in a lunar sample, it is significant,” said Sharples [6]. “Water has incredible scientific and life-sustaining value. It dictates so many processes.”
Having access to water sources will be vital for long-term lunar stays by astronauts. Water can be split into oxygen and hydrogen – providing breathable air and rocket fuel components. It may also be used for agriculture or drinking if purified.
While the trace amounts in lunar crust rocks would not be practical to extract, they hint at the Moon’s overall water budget being higher than assumed. More water ice reserves could potentially be mined from polar craters or below the surface in certain lunar regions. This could aid ambitious NASA Artemis plans for a sustainable Moon base within this decade.
“Any evidence of water enhances potential manned missions to the Moon,” said Sharples [7]. “Water is crucially important for human habitation on the lunar surface.”
Outlook Going Forward
Researchers will conduct more analyses on lunar samples to better map out ancient water reserves. Additional spectroscopy approaches can detect water signatures in minerals at part-per-million sensitivities.
Experts also stress we must understand the history of lunar water if we wish to extract and use it in future. Learning how water originated and migrated below the surface can guide prospecting efforts.
Said lead scientist Sharples: “We have to understand theMoon’s water history to effectively harvest water there for human space exploration” [8].
Unraveling secrets of the Moon’s wetter past thus promises both scientific insights and practical aids for ambitious NASA Moon base plans in coming years. This research marks a key step on the path back to the lunar surface – and potential springboards deeper into space beyond.
| Sample Type | Approx. Lunar Depth | Water Concentration |
|---|---|---|
| Lunar Meteorite | Ancient Crust | 6 ppm |
| Lunar Volcanic Glass | Surface Deposits | <700 ppm |
| Lunar Rocks | Shallow Subsurface | 100s ppm |
| Lunar Polar Ice | Surface Regolith | ~1-2% |
Table 1. Comparison of various lunar sample types and measured water content over history
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