Moon water has been one of those things often dismissed as more fiction than science, but new evidence has surfaced to suggest that lunar H2O exists.
When the Apollo 15 and 17 missions brought moon rocks back to Earth, trace amounts of water within the rock were initially passed off as moisture from our planet’s atmosphere that seeped into the non-airtight sample containers as the astronauts prepared to touch down. Water on the moon was viewed as a myth at worst and speculation at best.
Though our satellite may not have bragging rights to the extensive oceans that are thought to exist beneath the icy surface of Saturn’s moon Enceladus, recent analysis of Apollo archival data and additional research has unearthed proof of water (OH/H2O or hydroxyl/water) molecules trapped in volcanic glass beads that are billions of years old. These beads are believed to have formed when magma erupted from the surface of the moon in fiery plumes.
Scientists Ralph Miliken and Shuai Lee were able to detect these micro-beads, which are found in scattered volcanic deposits, with data from the Moon Mineralogy Mapper (aka M3 or M-cubed) imaging spectrometer. M3 orbited our satellite on India’s Chandrayaan spacecraft from 2008-2009 and had previously detected unusually high amounts of trapped water in these deposits when compared with average moon dust. Their research determined that the volcanic beads came into being far below the lunar surface.
“The water that we observe in the glass beads in these ancient fire fountain deposits came from the interior of the moon,” Milliken said. “This tells us that there is water in the moon’s mantle, and because the magma for these eruptions comes from very deep (several hundreds of kilometers down), there must be water in the deep interior of the moon.”
While this may not be H2O as we know it, because it exists as molecules within the moon’s mantle (think the moisture in Earth’s mantle) rather than in liquid form, water is water. It isn’t even the first time that the idea of the moon being bone-dry was challenged. Scientists re-examining the Apollo samples had confirmed the existence of water molecules in the volcanic beads in 2008. Their estimate was that the ancient moon’s interior must have held as much water as the Caribbean Sea, despite all those volcanoes making it anything but a vacation destination. H2O molecules were later proven to be bound to phosphate minerals in volcanic moon rocks. These could only have formed deep beneath the surface.
“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 Miliken. “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.”
The evidence could drastically change how science views the lunar formation. While the dominant theory involves an intense impact with enough energy to vaporize water, alternative thinking that sees the water as having been delivered by later comet and asteroid impacts has started to arise.
Water on (and in) the moon also means that future moon-bound astronauts may not need to bring much from the home planet. Now that will really be mission accomplished.