For years, scientists have known that water and ice exist on the moon in some form, likely at its poles in deep, dark craters.
Previously, SOFIA managed to find traces of "some form of hydrogen", but it was too hard to tell the difference between the actual water (H2O) and hydroxyl (OH), which are really similar in terms of chemical composition.
Scheduled to begin construction in cislunar orbit in 2024, the Gateway outpost is meant to act as a staging point for missions to the lunar surface, and deep space, and, ultimately, for the first crewed missions to Mars.
Using the SOFIA observatory's infrared instruments to study the moon from an altitude of 45,000 feet, researchers were able to detect the distinct chemical fingerprints of water in Clavius Crater.
"This is exciting because the expectation is that any water present on a sunlit surface of the moon would not survive the lunar day", Paul Hertz, director of the astrophysics division at NASA headquarters in Washington, D.C., said in a news briefing Monday.
Water is a precious resource in deep space and a key ingredient of life as we know it. But the new finding suggests that water may be present across more of the lunar surface, beyond just areas that are frigid and permanently in shadow.
Micrometeorites raining down on the lunar surface, carrying small amounts of water, could deposit it on the lunar surface upon impact. It's unclear how the water gets on the surface, how much of it exists, whether it moves around and if it replenishes over time, he said. "Yet somehow we're seeing it".
And Francis Rocard, a solar system specialist at the National Center for Space Studies in France, said that the water molecules that were thrown during the fall of these objects probably fell to the bottom of these craters, where they remained "trapped forever" by the cold.
Several forces could be at play.
For the first time, researchers have succeeded in clearly distinguishing between a water molecule (two parts hydrogen and one part oxygen) and another chemical compound mixed with it is hydroxyl (one part hydrogen and one part oxygen).
They'll have a better idea of the sources "if we can get down on the surface and analyze samples of the ice", Hayne said. Another possibility is that the water could be hidden between grains of lunar soil and sheltered from the sunlight - potentially making it a bit more accessible than water trapped in beadlike structures.
It will serve as a rendezvous point for astronauts traveling to lunar orbit aboard NASA's Space Launch System (SLS) and Orion prior to transit to low-lunar orbit and the surface of the Moon. "It's incredible that this discovery came out of what was essentially a test, and now that we know we can do this, we're planning more flights to do more observations". This agreement is an important element in a broad effort by the United States to engage global partners in sustainable lunar exploration and to demonstrate technologies necessary for a future human mission to Mars.