Forty years since the first moon landing, a University professor has used samples from that historic mission to make a giant leap forward in the search for water on the moon. Using a novel approach, James Greenwood, Research Assistant Professor of Earth and Environmental Sciences, found the highest concentration of water from any lunar sample.
In 2008, scientists from Brown University studied volcanic glass from the moon. The glass came from a fire fountain of volcanic lava, which then froze over. Astronauts were drawn to these formations because of their orange and green colors, which stood out from the bleak lunar environment. The scientists analyzed these samples using an ion probe technique and found trace amounts of water.
Greenwood studied their research and came up with an idea to use this same process on moon rocks. He had studied Martian rocks and other meteorites before, but he had never studied any lunar samples. In order to get his hands on moon rocks, he had to write a proposal to the Curation and Analysis Planning Team for Extraterrestrial Materials (CAPTEM), a group of lunar and planetary scientists.
“[CAPTEM] didn’t like my idea at first,” Greenwood said. “They said I couldn’t do it and that all the [moon] rocks were dry.”
But he finally convinced CAPTEM to give him the samples. Greenwood took the moon rocks to the University’s Scanning Electron Microscope (SEM) to look for apatite, the same mineral that makes up our teeth, which he believed could contain water.
“Finding water in the moon is a big deal, so [apatite] is one of the first things I looked for when I got the samples,” Greenwood said.
After failing to find the mineral, Greenwood obtained new samples, which he found did contain apatite. In June he brought the samples to Hokkaido University in Sapporo, Japan, where he and a team of scientists studied Martian rocks with an ion microprobe. One night, Greenwood and his team had some extra time with the machine. Since any time with the ion microprobe is valuable—it costs about $2,500 per day to use—they decided to test some of Greenwood’s lunar samples.
“We put a few of them in there, and lo and behold, the first one we looked at seemed to have quite a bit of water,” Greenwood said. “It turned out that this sample had the most water of all the samples we looked at, so we got lucky.”
Greenwood and his team then measured the isotopic concentration of the water. Based on the ratio of deuterium and hydrogen in the water, Greenwood proved that the water in the lunar samples was not from Earth. This ratio is similar to that of water found in comets, which Greenwood believes could be the source of the water.
Lacking time with the machine to continue their study, Greenwood went back in October for two weeks to confirm all of the data.
“Our preliminary results suggest that the moon has groundwater systems,” Greenwood said. “This would be a whole new world of hydrothermal geology that would be created.”
After presenting their results at the 41st Lunar and Planetary Science Conference in Texas this March, Greenwood and his team are now planning on looking at different samples to learn more about the distribution of water on the moon. He believes that this will give them insight into where the water originated from and where it is concentrated in the moon.
“This discovery confirms our idea that the lunar mantle has quite a bit of water,” Greenwood said. “Not as much as the Earth’s mantle, but maybe ten times less.”
These important discoveries will lead to many further developments in planetary science, but one wonders why Greenwood’s breakthrough took so long.
“[Scientists] didn’t have this ion probe technique back then, and the techniques they did have were more sample intensive and not as precise,” Greenwood said. “So the going theory was that the moon was dry. No one tried this technique, even though it could have been done since the early 1990s.”
As for any companies thinking of ways to exploit this new discovery, Greenwood does not have any words of encouragement.
“I don’t think we can go to the moon and drill and make bottled water,” Greenwood said. “But if we could, that water would be expensive. It’d go for a million dollars per bottle.”
Even though Greenwood believes finding life on the moon is improbable, the discovery of water is the first step in unearthing any potential life forms.
“Planetary science was born from the moon studies,” Greenwood said. “One of the most important measurements they ever tried to make was finding water on the moon. Water is your key to life.”