Water in the Moon

Image credit: © Oleg Zabielin / Alamy

The long-held notion of a bone-dry Moon was challenged in 2008, with the detection of water in some of the Apollo samples. Since then, lunar scientists have sought to understand how much water is in the Moon, where it is, and where it comes from. In this web focus, we present an overview article, research papers and opinion pieces that evaluate the evidence for water in the lunar interior and on the lunar surface and discuss its origin — whether it was added by cometary impacts, implanted by the solar wind, or indigenous to a Moon that may not, in fact, have formed dry.



Volatile lunacy p389


Over the past six years an increasingly complex view of water inside and on the surface of the Moon has emerged. Lunar water has moistened sticky questions, and so renewed lunar exploration efforts are needed to deepen our knowledge of the Earth–Moon system.



China's touch on the Moon p391 - 392

Long Xiao


As well as being a milestone in technology, the Chang'e lunar exploration programme establishes China as a contributor to space science. With much still to learn about the Moon, fieldwork beyond Earth's orbit must be an international effort.


Books & Arts

Moonlit society p393

Katherine Joy reviews Moon: Nature and Culture by Edgar Williams



News & Views

Planetary Science: Water and the lunar dynamo p400

Tamara Goldin




Heterogeneous distribution of water in the Moon pp401 - 408


Katherine L. Robinson & G. Jeffrey Taylor


The discovery of water in lunar samples in 2008 challenged the notion that the Moon's interior had lost all its volatiles. Since then, analyses of the water concentrations and isotopic compositions in lunar samples taken together suggest that the Moon is heterogeneously wet, which may lend clues to its origin.



Reorientation of the early lunar pole pp409 - 412

Futoshi Takahashi, Hideo Tsunakawa, Hisayoshi Shimizu, Hidetoshi Shibuya & Masaki Matsushima


An active core dynamo may have operated on the early Moon. Extraction of palaeomagnetic pole positions on the Moon from magnetic anomalies measured by the Lunar Prospector and Kaguya orbiters suggests that the ancient lunar dynamo experienced reversals and an ancient reorientation of the Moon rotated the geographic locations of the poles


From the archive


Books & Arts

Exhibition: Lunar reflections and astronaut geese p162

Tamara Goldin



News & Views

Planetary science: Wet moon dry Earth p746

Ninad Bondre


Planetary science: Water on the Moon pp586-588

David J. Lawrence


Analysis of the first Apollo samples suggested that Earth's only satellite was bone dry. Spacecraft data and improved analysis techniques now indicate that the Moon is more volatile-rich and complex than previously thought.

Planetary science: A distinct source for lunar water? pp74-75

François Robert


The origin of water in the Earth–Moon system is an open question. Geochemical analysis of the rocks retrieved by the Apollo missions show that lunar and terrestrial water are isotopically distinct, suggesting acquisition after the Moon's formation.

Planetary science: Lunar water from the solar wind pp766-767

Marc Chaussidon


The surface of the Moon is not totally devoid of water. Analyses of lunar soils reveal that impact glasses contain significant amounts of water, with an isotopic composition that is indicative of an origin from the solar wind.

Planetary science: Traces of ancient lunar water pp159-160

Erik H. Hauri


The presence of water in lunar volcanic rocks has been attributed to delivery after the Moon formed. Water detected in rocks from the ancient lunar highlands suggests that the Moon already contained water early in its history, and poses more challenges for the giant impact theory of Moon formation.



Hydrogen isotope ratios in lunar rocks indicate delivery of cometary water to the Moon pp79-82

James P. Greenwood, Shoichi Itoh, Naoya Sakamoto, Paul Warren, Lawrence Taylor & Hisayoshi Yurimoto


Water has been found in many lunar rock samples, but its sources are unknown. Isotopic analyses of Apollo samples of lunar mare basalts and highlands rocks suggest that a significant volume of water was delivered to the Moon by comets shortly after its formation by giant impact.

Direct measurement of hydroxyl in the lunar regolith and the origin of lunar surface water pp779-782

Yang Liu, Yunbin Guan, Youxue Zhang, George R. Rossman, John M. Eiler & Lawrence A. Taylor


Over the past few years, it has become clear that the Moon's surface is not entirely dry. The direct identification of hydroxyl in glasses produced in lunar soils by the impact of micrometeorites supports the idea that water was delivered to the lunar surface by the solar wind.

Water in lunar anorthosites and evidence for a wet early Moon pp177-180

Hejiu Hui, Anne H. Peslier, Youxue Zhang & Clive R. Neal


Water has been detected on the lunar surface and attributed to delivery by impacts and the solar wind to a dry early Moon. Spectroscopic detections of water in lunar anorthosites from the Apollo collection suggest that a significant amount of water is indigenous to the Moon.

Remote detection of magmatic water in Bullialdus Crater on the Moon pp177-180

R. Klima, J. Cahill, J. Hagerty & D. Lawrence


The remote detection of surface water indigenous to the Moon has proved difficult because of alternative sources, such as the solar wind. Spectroscopic observations of hydroxyl-bearing materials in Bullialdus Crater by the Chandrayaan-1 spacecraft are consistent with indigenous magmatic water that was excavated by impact from the lunar interior.

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