GOLDEN, Colorado – A hot topic for lunar researchers is whether water ice is an easily accessible source at the lunar south pole, as experts have long assumed. The search for usable water ice is a high priority on NASA’s Artemis agenda as the agency seeks to establish a sustainable human presence on the Moon.
Lunar water ice is believed to reside within permanent shadow regions, or PSRs, contained in super-cold cold traps where gases can freeze into their solid form. However, experts at the Space Resources Roundtable held from June 4 to 7 on the campus of the Colorado School of Mines drew attention to the lack of data supporting the prospect of using water ice on the Moon. While there appears to be strong evidence that water is present, a host of questions remain that, left unanswered, challenge the assumption that explorers will be able to tap into it.
Technical challenges
“Most of the ice is expected in the large old craters with permanent shadows, but no mission goes there because of the technical challenges of landing in the dark and operating in extreme cold,” said Norbert Schörghofer, a senior scientist at Hawaii-based Institute of Planetary Sciences. SpaceNews.
However, hopes that there might be abundant water ice on the lunar surface were dashed by data from the Korea Aerospace Research Institute’s Korea Pathfinder Lunar Orbiter, also known as Danuri. It entered lunar orbit in December 2022 and is now scheduled to continue its lunar observation mission until December 2025.
Danuri carries ShadowCam, a NASA-funded instrument built at Arizona State University to collect high-resolution images of the Moon’s PSRs from lunar orbit to infer the distribution and accessibility of water ice and other substances unstable. According to Schörghofer, ShadowCam did not find the water the researchers had hoped to see.
“Although ShadowCam found no evidence for ice in cold lunar traps, there is still strong evidence for ice in the subsurface,” Schörghofer said. This ice may be present outside cold traps at shallow depths, a finding that can be verified with a single well, he said.
Schörghofer added that several orbital missions have found evidence of water buried on the Moon, pointing to an instrument aboard NASA’s Lunar Prospector spacecraft that orbited the Moon from January 1998 to August 1999 and an instrument provided by Russia on the Lunar Orbiter of NASA’s Discovery now in orbit. Both lunar orbiters picked up a neutron spectrometer instrument that detected hydrogen, assumed to be in the form of water.
“Physical confirmation of water ice could represent a significant boost for human and robotic exploration,” said Ben Bussey, chief scientist for Intuitive Machines.
Scanning for water
While hinting at evidence from multiple sensors that ice may be abundant on the moon, Bussey said what is not known is the location, amount and form of lunar water — and whether it is possible to harvest it.
“Physical confirmation of water ice could represent an important impetus for human and robotic exploration,” Bussey said.
“There is a possibility that even if abundant water reservoirs exist, it may be very difficult to access,” Bussey said. SpaceNews, such as water ice lurking within PSRs. It could be that the water is so widespread that extracting the source would mean processing large amounts of lunar regolith, he said.
Bussey said the next important piece of the puzzle will come from an Intuitive rover planned to fly to the lunar south pole under NASA’s Commercial Lunar Payload Services (CLPS) initiative, specifically targeting Shackleton Ridge, on late in 2024. This area receives enough sunlight to power a lander for a roughly 10-day mission.
The lunar lander also carries the NASA-funded Polar Resource Ice Mining Experiment-1 to assess the water content of the regolith and search for other volatiles in the polar lunar landing zone.
This region provides a clear line of sight to Earth for continuous communications and could serve as a potential destination for later human exploration.
If the robotic landing succeeds, it will deploy a Micro Nova Hopper – a propulsion drone funded by NASA. This drone is designed to bounce across the lunar surface, Bussey said, and will carry a neutron spectrometer provided by Puli Space Technologies of Hungary on the permanently shadowed floor of Marston Crater.
“This will provide the first direct measurement of surface hydrogen, a key indicator of the presence of water,” Bussey said.