The research team consisted of American scientists from Brown University (Providence, Rhode Island), Carnegie Institution for Science (Washington, D.C.), and Case Western Reserve University (Cleveland, Ohio), along with French engineers from Cameca Instruments.

The press release by Erik Hauri, of the Department of Terrestrial Magnetism, Carnegie Institution for Science, appears in the EurekAlert article: “Moon water discovered: Dampens Moon-formation theory”

Hauri led in the effort to develop the new techniques that allowed the group to detect the extremely small amounts of water in glasses and minerals of the lunar samples.

The discovery by the team is important because scientists have looked for water in lunar materials for nearly forty years, since Apollo 11 touched down on the Moon in 1969. However, they have been unable to find it due to the inability of technology, so most lunar scientists had concluded that moon rocks do not contain water.

The new technique called SIMS was able to measure molecules within the lunar samples that were on the order to two magnitudes lower than with past techniques. The technique is able to discern down to four or five water molecules per million, what is usually called parts per million (ppm).

In actuality, the members found up to 46 parts per million of water molecules in the tiny volcanic glass beads brought back from the Moon in the lunar samples.

Haui stated, "For the past four decades, the limit for detecting water in lunar samples was about 50 parts per million (ppm) at best. We developed a way to detect as little as 5 ppm of water. We were really surprised to find a great deal more in these tiny glass beads, up to 46 ppm."

Also making the discovery possible was the work of engineers from Cameca Instruments, who manufactured the NanoSIMS instrument that made the measurements of the lunar materials. The Cameca NanoSIMS instrument is an ion microprobe that was designed to measure ultra-fine features of trace elements and isotopes.

The technology used by the Cameca group is a refinement of a technique secondary ion mass spectrometry (SIMS). The SIMS technique allows for the composition of solid surfaces and thin films to be measured by "sputtering" (depositing while in vacuum) the surface with a focused “primary” (cesium) ion beam and, then, collecting and analyzing the secondary ions that are ejected.

The lunar samples used for this first-ever discovery of water on the Moon came from Moon rocks scooped up by astronauts on two NASA Apollo Moon missions.

Within the Moon rocks were tiny beads of volcanic glass. These glasses actually contained the water. Most of the water was found in the middle portion of the glass volume, and less in the outer portions of it.

The fact that water was found in higher concentrations in the middle of the glass beads than its outer volume tells scientists that most of the water on the Moon was lost during volcanic activity on the Moon.

Additional information about the results of this study are on page 2.

---

Because so much water was lost during volcanic activity on the Moon, these scientists think that early in the Moon’s history it may have contained about 750 water molecules per million, which is similar to what is presently found in the upper mantle of Earth.

James Van Orman, from Case Western Reserve University, was one of the group members of the study.

Orman wrote the numerical model that helped produce the discovery. He stated, "We looked at many factors over a wide range of cooling rates that would affect all the volatiles simultaneously and came up with the right mix. A droplet cooling at a rate of about 3° F to 6° F per second over 2 to 5 minutes between the time of eruption and when the material was quenched or rapidly cooled matched the profiles for all the volatiles, including the loss of about 95% of the water.”
 
The conclusions of this study—that very miniscule amounts of water are contained in moon rocks—may eventually led scientists to find water ice in dark areas of craters in the polar regions of the Moon—areas where the Sun does not shine.

The discovery is also important because it puts into question how the Moon was formed. Most planetary scientists contend that the “giant impact” theory holds the key to the Moon’s beginning. It states that a Mars-sized object collided with the Earth about 4.5 billion years ago.

The “giant impact” is theorized to have melted both bodies and, because of the collision, flung materials out and into orbit around the early Earth. Some of the material eventually formed the Moon. If this theory is true, then the intense heat from the collision would have vaporized the lightest of elements, including water.

However, scientist, now know based on this study, that water was not entirely vaporized in this so-called impact that formed the Moon. This new study now suggests that water may have come from the interior of the Moon and was eventually sent up to the lunar surface by volcanic action over three million years ago.

This study does not disprove the "giant impact" theory, only questions some parts of it.

The research is published in the July 10, 2008 issue of Nature.

Please read the EurekaAlert article “Moon water discovered: Dampens Moon-formation theory”, which contains additional information on this important discovery.

Other interesting articles on the discovery of water on the Moon include: Scientific American website “Moon Once Harbored Water, Lunar Lava Beads Show” and Sky and Telescope: “Water in Moon Dust Raises Questions”