Study finds less than 20% of Moon’s dark craters hold ice, raises tough questions for colonization plans

In a revelation that could reshape plans for living on the Moon, scientists have uncovered troubling news hidden deep within its darkest craters. A fresh analysis of satellite scans by researchers at the University of Hawaii at Mānoa, using data from the ShadowCam aboard South Korea’s KPLO mission, shows there is far less water ice in the Moon’s permanently shadowed regions (PSRs) than once believed. With the revised estimates dramatically lower than earlier hopes, the dream of sustainable lunar colonies just got a lot more complicated.

Back in 2018, researchers at the University of Hawaii had estimated that about 30% of the surface area within the Moon’s PSRs contained water ice — a finding that sparked excitement for the prospects of long-term human presence on the Moon. But new scans from the ShadowCam, which launched aboard the Korea Pathfinder Lunar Orbiter (KPLO) in 2022, paint a less optimistic picture. The updated analysis suggests that the actual ice coverage is likely closer to 20%.

Water ice on the Moon has always been seen as a cornerstone for future exploration. It could provide drinking water, oxygen, rocket fuel, and even serve as a resource for construction materials. The University of Hawaii’s 2018 discovery of surface-exposed water ice, particularly in regions that never see sunlight, seemed like a major breakthrough.

Using the highly sensitive ShadowCam, the research team scanned the lunar surface, relying on the way water ice reflects light more strongly than lunar rock. Initial assessments pegged ice content between 5% and 30% across PSRs. However, Jordan Ando, a graduate student in Shuai Li’s laboratory, revisited the high-resolution images and found the reflectivity lower than anticipated. "The lunar surface did not show the widespread brightening we expected," Ando noted, leading to the lowered estimate of less than 20% ice.

The reduced potential for easily accessible water ice could have serious consequences for plans to establish lunar colonies. With water crucial for sustaining life and producing fuel, missions may have to rethink how they source vital resources. 

Yet the search is far from over. Scientists are exploring the possibility of hidden reservoirs below the Moon’s surface. Emily S. Costello, a researcher at the Hawaii Institute of Geophysics and Planetology, is spearheading efforts to develop Cosmic Ray Radar technology. This cutting-edge system could one day detect underground ice layers by using cosmic rays to penetrate the lunar surface.