Protosolar hydrogen source for water in the Moon and the Early Earth

Abstract: Since the first report of the detection of water in-situ in lunar volcanic glasses, the origin of endogenous water in the Moon has been a matter of long-standing debate. The current best estimate of the hydrogen isotopic composition of the Moon is similar to that of the present-day bulk-silicate Earth. Measurements of hydrogen in phosphates and volcanic glasses of lunar samples have revealed heterogeneities in hydrogen abundance and isotopic signatures, highlighting the presence of distinct reservoirs in the lunar interior. With recent improvements in analytical protocols for measuring hydrogen in-situ, it has become possible to target less-water-rich but more primitive phases in lunar samples such as nominally anhydrous minerals, suggesting a lighter hydrogen isotopic composition for the proto-Moon compared to the present-day bulk-silicate Earth. In this talk, we will comprehend the discovery steps of indigenous lunar water and their implication for the early Earth’s origin of water.