UH Scientists Discover First Evidence of Ice on Moon

Click to enlarge. Graphic courtesy of UH Mānoa SOEST.

Though scientists have long suspected the existence of water ice on the surface of the Moon, a new study by a team of scientists led by researchers from the University of Hawai‘i at Mānoa School of Ocean and Earth Science and Technology (SOEST) has discovered the first direct evidence.

“We found that the distribution of ice on the lunar surface is very patchy, which is very different from other planetary bodies such as Mercury and Ceres where the ice is relatively pure and abundant,” said the study’s lead author, Shuai Li, a postdoctoral researcher at the Hawai‘i Institute of Geophysics and Planetology (HIGP) in SOEST. “The spectral features of our detected ice suggest that they were formed by slow condensation from a vapor phase either due to impact or water migration from space.”

The newly discovered water ice lies exposed on the lunar surface in areas known as permanently shaded regions (PGRs), which remain shrouded in continual darkness.

Shuai Li, a postdoctoral researcher at the Hawai‘i Institute of Geophysics and Planetology (HIGP) and lead author of the study. Courtesy photo.

Using data gathered by India’s Moon Mineralogy Mapper (M3) aboard the Chandrayaan-1—a mission launched in 2008—the team discovered features similar to pure water ice measured in a lab. Their findings were validated by other datasets obtained by the Lunar Orbiter Laser Altimeter (LOLA), the Lyman-Alpha Mapping Project (LAMP) and the Diviner instrument aboard NASA’s Lunar Reconnaissance Orbiter (LRO) mission.

The finding is the first direct evidence of water ice on the lunar surface. Li said he was surprised by the discovery.

“While I was interested to see what I could find in the M3 data from PSRs, I did not have any hope to see ice features when I started this project,” he said. “I was astounded when I looked closer and found such meaningful spectral features in the measurements.”

“The patchy distribution and smaller abundance of ice on the Moon compared with other planetary bodies suggest that the delivery, formation, and retention processes of water ice on the Moon are very unique,” said Paul Lucey, a professor at HIGP and co-author of the study.

“Given that the Moon is our nearest planetary neighbor, understanding the processes which led to water ice on the Moon provides clues to understand the origin of water on Earth and throughout the solar system,” said Li. “A future Moon mission is needed to examine the whole lunar PSRs to map out all water ices and understand the processes which led to water on the Moon. This work provides a roadmap for future exploration of the Moon, particularly the potential of water ice as a resource.”