Water on the moon? It’s not quite what you might think

This composite image of the moon using Clementine data from 1994 is the view we are most likely to see when the moon is full. Credit: NASA To learn about NASA's LRO project go to: http://www.nasa.gov/mission_pages/LRO/main/index.html NASA Goddard Space Flight Center contributes to NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s endeavors by providing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Join us on Facebook

JACKSONVILLE, Fla. – NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA) has confirmed, for the first time, water on the sunlit surface of the moon. This discovery indicates that water may be distributed across the lunar surface and not limited to cold, shadowed places.

SOFIA has detected water molecules (H2O) in Clavius Crater, one of the largest craters visible from Earth, located in the moon’s southern hemisphere. Previous observations of the moon’s surface detected some form of hydrogen but were unable to distinguish between water and its close chemical relative, hydroxyl (OH). Data from this location reveal water in concentrations of 100 to 412 parts per million – roughly equivalent to a 12-ounce bottle of water – trapped in a cubic meter of soil spread across the lunar surface.

“We had indications that H2O – the familiar water we know – might be present on the sunlit side of the Moon,” said Paul Hertz, director of the Astrophysics Division in the Science Mission Directorate at NASA headquarters in Washington. “Now we know it is there. This discovery challenges our understanding of the lunar surface and raises intriguing questions about resources relevant for deep space exploration.”

How did they do it?

SOFIA is basically a giant telescope in a 747 aircraft flying above the water vapor in our atmosphere so it can see the moon. Flying at altitudes of up to 45,000 feet, this modified Boeing 747SP jetliner with a 106-inch diameter telescope reaches above 99% of the water vapor in Earth’s atmosphere to get a clearer view of the infrared universe. The declaration of water on the moon is a combination of a few missions, going back as far as 1999:

  • The first indication of water on the moon came in 1999 from Cassini during a lunar fly by while on it’s way to Saturn
  • In 2009, Deep Impact found water on the Moon’s North Pole, a concentration of H20 molecules driven by temperature (rather than solar radiation), and that the replenishment of hydrogen ions may be from solar winds.
  • In 2018, SOFIA began detecting water molecules in sunlight through spectral analysis on the moon.
This illustration highlights the Moon’s Clavius Crater with an illustration depicting water trapped in the lunar soil there, along with an image of NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA) that found sunlit lunar water.

What does it mean?

When you hear that NASA found water on the moon, you may be thinking of placid lakes you can see — but that’s not the case. Instead, the study suggests that most of the water is stored in glass created during meteor impacts or “voids between grains sheltered from the harsh lunar environment,” water was also observed to be a local geologic thing, not one spread across the surface of the moon.

Under NASA’s Artemis program, the agency is eager to learn all it can about the presence of water on the moon in advance of sending the first woman and next man to the lunar surface in 2024 and establishing a sustainable human presence there by the end of the decade.

As a comparison, the Sahara desert has 100 times the amount of water than what SOFIA detected in the lunar soil. Despite the small amounts, the discovery raises new questions about how water is created and how it persists on the harsh, airless lunar surface.

Water is a precious resource in deep space and a key ingredient of life as we know it. Whether the water SOFIA found is easily accessible for use as a resource remains to be determined.

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