NASA has discovered water on the sunward-facing surface of the moon, according to a live teleconference event that streamed live on the U.S. agency's website on Monday, Oct. 26 at 12:00 PM EDT.
The water molecules on the moon were detected in and around the Clavius crater on the southern hemisphere of the moon — on the scale of individual molecules too small to form puddles of liquid or blocks of ice.
The discovery was confirmed thanks to the Stratospheric Observatory for Infrared Astronomy (SOFIA).
UPDATE Oct. 26, 12:50 PM EDT: Water on sunlit moon surface subject to all of NASA's cutting-edge assets
"The previously detected hydrogen on the sunlit side of the moon is associated with water molecules," confirmed Paul Hertz, astrophysics division director at NASA Headquarters, Washington.
Ongoing studies of the newly-discovered moon water will leverage all of NASA's cutting-edge assets, and could have great import for NASA's forthcoming Artemis mission — slated to put the first woman and next man on the moon in 2024.
UPDATE Oct. 26, 12:45 PM EDT: SOFIA to fly again for more data, help create first water-resource map of moon
SOFIA is an airborne observatory — flying up to 42,000 ft (12,800 m) — climbing to an altitude above 99.9% of the water vapor in Earth's atmosphere, which blocks infrared light descending to our planet from space.
SOFIA is the only telescope on or off-world capable of giving remote access to this unique, 6.1-micron fingerprint of water.
This was the first time SOFIA observed the moon — and was intended to serve as a test case, said Naseem Rangwala, SOFIA's project scientist of NASA's Ames Research Center in Silicon Valley, California.
"What was essentially a test far exceeded our expectations," she said. Rangwala and her team are planning more flights with SOFIA — to gather more data and look for water in more sunlit locations on the moon.
"These observations will add to the data that NASA's next moon rover, the Viper mission, will collect to create the first water-resource map of the moon," explained Rangwala.
UPDATE Oct. 26, 12:35 PM EDT: Moon water outside of dark, cold craters much more accessible to humans
"It's far easier to travel when you don't have to carry everything with you that you might need for the entire trip," said Jacob Bleacher, NASA's chief exploration scientists of the Human Exploration and Operations Mission Directorate. Here on Earth we depend on gas stations or rest sites, allowing more efficient packing behavior.
In deep space exploration, water is an extremely critical resource — whether used for oxygen to breathe, a fuel supply, and of course for drinking. "But water is heavy, and therefore it's expensive to launch from the surface of the Earth," said Bleacher.
The less water we need to take on a space trip, the more space we have on a vessel to store other materials or devices (or astronauts). "We need to know more about the water to understand if and how we can use it for both science and exploration," he said.
We've known water is present in the coldest and darkest environments of the moon's permanently-shadowed craters, but these environments are hard to reach, and difficult to work in for sustained periods of time.
The SOFIA results show we may find usable water outside of these hard-to-reach craters. "Knowing more about that water [...] how much of it exists, whether it moves around" is crucial for our forthcoming revisit and exploration of the moon, explained Bleacher.
UPDATE Oct. 26, 12:30 PM EDT: No puddles of water, but protected under tiny 'glass shields' from meteor impacts
For roughly a decade, NASA scientists have known about the presence of hydrogen on the moon, said Casey Honniball, a postdoctoral fellow from NASA's Goddard Space Flight Center, during the teleconference.
While studying the moon's surface at a wavelength of 6.1 microns with SOFIA, the team behind the recent paper was able to distinguish water from other chemicals containing hydrogen.
"Water molecules are present on the surface of the moon," said Honniball. "We found the water on the moon's southern hemisphere at Clavius crater and its surrounding regions."
"Clavius is one of the largest craters visible from Earth," Honniball said. Her team detected water molecules at a concentration of roughly 100 to 400 parts per million — roughly the same as a 12 oz bottle of water within a cubic meter of volume of lunar soil.
These are not puddles, "but instead water molecules that are so spread apart that they do not form ice or liquid water," she said.
The water could come from solar wind, or micro-meteor impacts causing chemical reactions with hydrogen-based molecules.
Without a protective atmosphere, all water on the moon should be lost, but Honniball and her colleagues think water molecules may be trapped under tiny glass shields formed during micro-meteor impacts.
UPDATE Oct. 26, 12:20 PM EDT: Artemis moon program could benefit from presence of water
"Water is a precious resource in space," said Hertz during the teleconference. However, it's unknown whether water on the sunward-facing surface of the moon is accessible for human use as a viable resource.
UPDATE Oct. 26, 12:15 PM EDT: New fundamental questions about water persistence on harsh lunar surface
The water molecules — consisting of one oxygen and two hydrogen molecules — were detected via SOFIA's infrared spectrometer. This raises new exciting questions regarding how water is created, and how it can survive in the extremely harsh, arid conditions of the lunar surface, explained Hertz.
UPDATE Oct. 26, 12:05 PM EDT: Water exists on sunward-facing surface of moon
For the first time, water is confirmed present on a sunward-facing surface of the moon, explained Hertz.
In the past, several studies suggested all water on the moon only existed inside the moon's permanently-shadowed craters. The latest discovery of water confirmed on the sunward-facing surface of the moon is significant because it runs contrary to scientists who thought water under direct sunlight would not stay.
"Water might be distributed across the lunar surface, and might not limited to the cold shadowed places near the lunar poles, where we had previously discovered water-ice," explained Hertz.
NASA announces groundbreaking moon discovery
This forthcoming discovery comes on the heels of NASA's ongoing study of the moon with aims of furthering human space exploration, according to a NASA press release. The agency's Artemis program will send the first woman and next man to the lunar surface in 2024 to begin preparations for humankind's next giant leap to Mars sometime in the 2030s.
The study of the moon also helps us come to know the history of the inner solar system.