PROVIDENCE – A Brown University researcher has published a new study of lunar satellite data that could provide the strongest evidence yet found to support the presence of water beneath the moon’s surface.
Ralph Milliken – an associate professor in Brown’s Department of Earth, Environmental and Planetary Science – co-authored the study with University of Hawaii researcher and recent Brown Ph.D. graduate Shuai Li, who collaborated with Milliken as part of his thesis.
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Milliken and Li’s work built on the discoveries of earlier scientists, including Brown geologist Alberto Saal, who in 2008 detected trace amounts of water in samples of volcanic glass brought back from NASA’s Apollo 15 and Apollo 17 missions to the moon. Since scientists believe the glass was formed by the explosive eruption of magma coming from the lunar interior, this discovery led some to believe that the moon’s mantle could be water-rich.
To uncover whether the Apollo samples were circumstantial anomalies or might represent the majority of the moon’s interior, Milliken and Li examined satellite data from the Moon Mineralogy Mapper, an imaging spectrometer that flew aboard India’s Chandrayaan-1 satellite and captured information about the moon’s surface from orbit.
The satellite data suggested evidence of water in nearly all of the large pyroclastic deposits previously mapped across the moon’s surface, including the deposits near the Apollo landing sites where the original water-bearing samples were collected.
“By looking at the orbital data, we can examine the large pyroclastic deposits on the moon that were never sampled by the Apollo or Luna missions,” said Milliken. “The fact that nearly all of them exhibit signatures of water suggests that the Apollo samples are not anomalous, so it may be that the bulk interior of the moon is wet.”
If accurate, the findings could dispel the assumption of previous scientists that the hydrogen necessary to create water was all burned off in the interplanetary collision that created the moon early in the solar system’s history.
In addition, the research could also have implications for future lunar exploration. Although the volcanic glass samples don’t contain a lot of water – about 0.05 percent by weight, Milliken and Li said – the pyroclastic deposits on the moon’s surface are large, and the water could potentially be extracted.
“Other studies have suggested the presence of water ice in shadowed regions at the lunar poles, but the pyroclastic deposits are at locations that may be easier to access,” said Li. “Anything that helps save future lunar explorers from having to bring lots of water from home is a big step forward, and our results suggest a new alternative.”
Milliken and Li’s research was funded by the NASA Lunar Advanced Science and Exploration Research Program and published in the July issue of Nature Geoscience.
Kaylen Auer is a PBN contributing writer.
