COSMOCHEMISTRY iLLUSTRATED

Water in the Lunar InteriorWater in the Lunar Interior

Francis McCubbin and co-workers measured the OH concentrations in lunar sample 15404,51 (collected from debris on boulder in the image on the left) and in lunar meteorite NWA 2977 (right).

Water in Lunar Interior

COSMOCHEMISTRY iLLUSTRATED

Water in the Lunar InteriorWater in the Lunar InteriorOH in Apatite:220-1000 ppm in 15404,514000-7000 ppm in NWA 2977

H2O in lunar interior appears to be ~1 to a few tens of ppm, much higher than previously thought, < 1 ppb.

Water in Lunar Interior

COSMOCHEMISTRY iLLUSTRATED

Implications of Lunar Water ContentImplications of Lunar Water ContentWater in the Moon raises questions about its origin by a giant impact:Dynamical calculations indicate that most of the Moon was formed from material that resided in the impactor. Did the impactor contain water? If so, how much?

Was some of it lost as the result of the large impact? Was a lot or a little lost?

Did some react with silicates in the proto-lunar disk?

Or was the water added later, to both Earth and Moon?

Why does the Moon contain a few parts per million to a few tens of parts per million water while the Earth contains much more, 500 to 1000 parts per million?

Canup (2004)

Water in Lunar Interior