Triple oxygen isotopes of lunar water unveil indigenous and cometary heritage

Summary

Researchers analyzed the triple oxygen isotopic composition of lunar water in 9 Apollo samples to determine its origin. The results suggest that lunar water is primarily indigenous, with a signature similar to enstatite chondrites, and has been altered by cometary impacts.

Highlights

• The study analyzed the triple oxygen isotopic composition of lunar water in 9 Apollo samples.
• The results suggest that lunar water is primarily indigenous, with a signature similar to enstatite chondrites.
• Cometary impacts have altered the lunar water signature.
• The study found a large range in Δ′17O values across the 50°C, 150°C, and 1,000°C fractions.
• The data are consistent with meteoritic, likely micrometeoritic, input of oxygen.
• The study suggests that comets have a positive Δ′17O value between 0.75 and 1.75‰.
• The results have implications for the origin of water in the Earth-Moon system.

Key Insights

• The indigenous lunar water signature is likely inherited from the Earth, suggesting a common chemistry between the two bodies.
• The enstatite chondrite-like signature of lunar water implies that enstatite chondrites may have been a dominant source of water for the early Earth.
• The alteration of lunar water by cometary impacts suggests that comets have played a significant role in shaping the lunar water budget.
• The large range in Δ′17O values across the 50°C, 150°C, and 1,000°C fractions suggests that lunar water has been affected by multiple sources and processes.
• The consistency of the data with meteoritic, likely micrometeoritic, input of oxygen suggests that micrometeorites may have been an important source of water for the Moon.
• The positive Δ′17O value of comets suggests that comets may have inherited a molecular cloud-like Δ′17O signature.
• The study's results have implications for the origin of water in the Earth-Moon system and suggest that the Moon's water budget may be more complex than previously thought.

Mindmap

Citation

Thiemens, M. M., Martinez, M. H. N., & Thiemens, M. H. (2024). Triple oxygen isotopes of lunar water unveil indigenous and cometary heritage. In Proceedings of the National Academy of Sciences (Vol. 121, Issue 52). Proceedings of the National Academy of Sciences. https://doi.org/10.1073/pnas.2321069121