In 2018, astronomers directly confirmed for the first time that water, in the form of ice, is on the moon’s surface. Aptly named water ice resides in the coldest, darkest parts of our planet’s satellite, like the shadow-shrouded craters that dot its polar regions, the deepest parts of which never see sunlight.
But new research published Monday verified a suspicion that researchers had long been unable to confirm. A team of scientists who studied a slice of the moon aboard NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA) — considered to be the world’s largest flying observatory — detected the first evidence that water molecules can exist on the unforgiving landscape of the sunlit lunar surface. That means that those molecules could be found across more parts of the moon than scientists previously imagined.
“Now we can really begin to try and understand the cycle of water on the moon,” Casey Honniball, the study’s lead author, said.
The discovery of molecular water on an illuminated part of the moon came as a surprise to Honniball and her team, who weren’t sure if their time on the observatory would reveal anything useful. Honniball said she’s “pretty sure” she screamed on the phone with her thesis advisor at the time when she realized what they had found.
More research is needed to answer the myriad questions raised by their discovery, and to determine what it could mean for NASA’s Artemis program, which aims to put “the first woman and next man on the moon” by 2024. But this latest revelation undoubtedly brings us another step closer to understanding the many mysteries of our closest celestial neighbor.
Here’s a look at three of those major questions, and the kind of research scientists will be pursuing next to answer them.
What does the lunar “water cycle” look like?
“Molecular water” doesn’t refer to any type of water we may picture here on Earth. It describes individual water molecules that are too spread out on the lunar surface to form either liquid water or ice.
The moon is continuously being hit with solar radiation at “full force,” Honniball said, and lacks a thick atmosphere like the one on our planet to protect it.
Regardless of how it looks to us from our perspective, half of the moon is always illuminated by the sun, in the same way that half of Earth experiences day while the other half experiences night. It takes the moon about 28 Earth days to both orbit our planet and complete a full rotation on its axis.
That means that if you stood at the same spot on the moon for a full cycle, both the lunar day and the lunar night would last approximately 14 Earth days. During that time, the moon’s surface goes through “vast temperature swings.” At the moon’s equator, daytime temperatures can reach 250 degrees Fahrenheit, while the night can get as cold as negative 208 degrees…