Study reveals origins of lunar water and its connection to earth's early history

The team analyzed water in nine samples from the Apollo lunar mission, using a high-precision triple oxygen isotope technique. This method, developed by Dr. Morgan Nunn Martinez of the University of California, San Diego, separates water into its various binding phases—loosely bound, tightly bound, and trapped within minerals—via stepwise heating at 50°C, 150°C, and 1,000°C. Their findings provide crucial evidence that lunar water has a dual heritage: one part originating from early Earth-like material and another delivered through cometary impacts.

"This is a major step forward in unraveling where lunar water comes from," Dr. Maxwell Thiemens of the AMGC research group of the VUB explained. "Our data suggest that the Moon inherited water tracing back to Earth's formation, followed by later contributions from comets, delivering the water reservoirs we see today."

Three key results are central to the report. An early Earth signature: The oxygen isotopic composition closely matches enstatite chondrites, a meteorite type believed to be the building blocks of the Earth. There are also clear signs of cometary contribution: A significant portion of lunar water shows isotopic similarities to comets. A reducedimportance of solar wind: the study challenges the prevalent theory that the majority of lunar water was produced in situ via solar interactions with lunar silicates, presenting instead a complex mixing of sources.

This discovery is timely as nations and private enterprises intensify their efforts to establish permanent lunar bases. Understanding the water’s origins and distribution could have significant implications for sustaining human presence on the Moon.

"The data not only enhance our understanding of the Moon’s past but also pave the way for future space exploration and resource utilization. These findings should redefine how we think about water as a resource for long-term lunar habitation." Thiemens concludes.

This research has the potential to shape lunar and planetary science for decades to come, offering a deeper connection between Earth's water-rich environment and the Moon’s arid surface. With Artemis missions on the horizon, this pioneering study provides a crucial foundation for future exploration and resource planning.

Reference:

M.M. Thiemens, M.H.N. Martinez, M.H. Thiemens, Triple oxygen isotopes of lunar water unveil indigenous and cometary heritage, Proc. Natl. Acad. Sci. U.S.A. 121 (52) e2321069121, https://doi.org/10.1073/pnas.2321069121 (2024)