Was the moon ever damp?
A new analysis of lunar samples from the early 1970s suggests that Earth's moon may have held small amounts of water.
Prevailing theories about the moon's formation say it was created when a Mars-sized object slammed into Earth. The collision sent debris flying into space, which later coalesced into our planet's natural satellite. Any water involved in this collision would most likely have evaporated in the vacuum of space, leaving the moon arid.
When American astronauts visited in the moon from 1969 to 1972, they took back samples that confirmed the moon was dry. But more advanced analysis in the past five years has challenged this belief.
The team led by Notre Dame geologist Hejiu Hui studied one type of rock found on the moon called plagioclase, which serves as a chemical time capsule. Plagioclase is believed to have formed inside the magma ocean inside the young moon's core, floating up to form the crust later.
The tiny samples of water were found in glass beads inside rocks found on the moon's surface. It's thought that the glass beads were formed by volcanic eruptions during the moon's tumultuous early days. Some have suggested that these rocks may have been exposed to an alien water source after being ejected from the moon's molten core.
Using a microscope with a spectrometer, the researchers found that the rock samples actually contained an extremely tiny amount of water. While the samples are drier than an Earthly desert, containing 6 parts per million of water, it was still wetter than scientists believed the moon to be.
"Somehow we still detect this amount of water," Hui told the Los Angeles Times. So that makes things interesting."
The team estimates that the young moon's magma core could have included 320 parts per million of water. Later, this core crystalized, and the researchers suggest that it could have been as much as 1.4 percent water.
These new findings raise a lot of questions about what we know about the formation of our moon.
"It's thought that the moon's formation involved the materials getting very hot, and it's usually assumed that little water would have survived through that," Paul Warren, a UCLA cosmochemist not involved in the study, told the LA Times. "It opens up quite a mystery as to how the moon came through what we think was a very hot genesis process, with this much water."
