Skip to Content

Finding Water on the Moon

An advanced type of mass spectrometry has detected water in lunar particles.

Last week’s announcement of the discovery of evidence of water in lunar volcanic glass beads brought back from the moon during the Apollo missions in 1971–a finding that is causing scientists to rethink the conventional theory of the moon’s formation–was made possible by recent advances in an analytical technique called nano secondary ion mass spectroscopy or NanoSIMS.

Analyzing tiny samples: The French company CAMECA has made an instrument called the nano secondary ion mass spectrometer (NanoSIMS) that is being used by scientists to analyze small particles, such as the lunar volcanic glass beads from the Apollo missions. Using the instrument, scientists were able to discover evidence of water in the lunar samples. This particular instrument is located in the Laboratory for Space Sciences at Washington University, in St. Louis.

NanoSIMS, which was developed by the French company CAMECA, is a variation of an established technique called secondary ion mass spectroscopy (SIMS), but it has a higher spatial resolution and can measure a handful of elements simultaneously, says Frank Stadermann, a senior research scientist at the Laboratory for Space Sciences at Washington University, in St. Louis.

With SIMS, a high-energy ion beam is focused on the surface of a sample. The impact of the beam causes atoms to be ejected from the surface; some of the atoms get ionized and then pass through a mass spectrometer that determines the composition of the sample material. The NanoSIMS instrument has an ion beam that can focus down to a diameter of less than one micrometer, whereas previous SIMS technology could only focus down to around 20 micrometers.

While researchers have been using NanoSIMS to study the isotopic composition of small particles, such as planetary dust and volcanic glasses, this is the first time that the technique has been able to detect traces of hydrogen. “The key part was, we developed a method for measuring very low water content on other SIMS instruments and applied the same methodology on the NanoSIMS,” says Erik Hauri, a staff scientist with the Carnegie Institution for Science, in Washington, DC, and one of several authors of the study last week describing evidence of water in lunar samples. “This allowed us to take measurements on a very small spatial scale. The limit for detecting water was about 50 parts per million at best. We developed a way to detect as little as five parts per million of water, and surprisingly, we found up to 46 parts per million in these tiny glass beads.”

The study was published on July 10 in the journal Nature and conducted by scientists from Brown University, Carnegie Institution for Science, and Case Western Reserve University.

Lunar particles: These lunar volcanic glasses were analyzed using NanoSIMS to show the presence of water in the interior of the moon. The green glass beads were collected from the Apollo 15 landing site at Hadley Rille on the moon. They represent volcanic deposits formed early in the moon’s geological history.

To enable the technology to detect such a small amount of hydrogen, Hauri first improved the vacuum of the instrument. Any free gas gets deposited on the sample surface, contaminating it. Prior generations of the instrument have, on average, detection limits around 100 parts per million, but with a better vacuum the scientists were able to achieve a detection limit of five parts per million.

Hauri’s technique also included using a different high-energy primary ion beam. Most SIMS instruments use a beam of oxygen ions and collect positively charged ions. Instead, Hauri used a cesium beam to measure negatively charged hydroxyl ions that are ejected from the sample. The cesium ion beam is a much more sensitive method of analyzing water, says Hauri.

NanoSIMS has also allowed scientists to, for the first time, simultaneously measure several elements in the samples instead of just one, says Claude Lechene, a professor at Harvard Medical School and the director of the National Resource for Imaging Mass Spectrometry, in Cambridge, MA. In previous technology, if scientists wanted to analyze more than one element, they would have had to adjust the magnetic field. “The new system can measure five or seven masses concurrently,” says Stadermann, making the analysis much more efficient.

Stadermann says that the new work is an excellent use of the NanoSIMS technology. “This is one of the many steps of the broader uses of NanoSIMS,” says Stadermann. “I fully anticipate that there will be many more discoveries being made using the technology. You have capabilities that you did not have with instruments before.”

Keep Reading

Most Popular

DeepMind’s cofounder: Generative AI is just a phase. What’s next is interactive AI.

“This is a profound moment in the history of technology,” says Mustafa Suleyman.

What to know about this autumn’s covid vaccines

New variants will pose a challenge, but early signs suggest the shots will still boost antibody responses.

Human-plus-AI solutions mitigate security threats

With the right human oversight, emerging technologies like artificial intelligence can help keep business and customer data secure

Next slide, please: A brief history of the corporate presentation

From million-dollar slide shows to Steve Jobs’s introduction of the iPhone, a bit of show business never hurt plain old business.

Stay connected

Illustration by Rose Wong

Get the latest updates from
MIT Technology Review

Discover special offers, top stories, upcoming events, and more.

Thank you for submitting your email!

Explore more newsletters

It looks like something went wrong.

We’re having trouble saving your preferences. Try refreshing this page and updating them one more time. If you continue to get this message, reach out to us at with a list of newsletters you’d like to receive.