In the realm of lunar exploration, one of the hottest topics remains the accessibility of water ice at the moon’s south pole. As NASA’s Artemis program aims to establish a sustainable human presence on the moon, the potential of exploiting lunar water ice has become a high priority. Scientists believe that water ice could reside in permanently shadowed regions (PSRs) within extremely cold traps where gases can freeze solid. However, discussions at the recent Space Resources Roundtable, held at the Colorado School of Mines, highlighted the significant data gaps and challenges in confirming the viability of these resources.
Technical Challenges in Exploration
Norbert Schörghofer, a senior scientist at the Planetary Science Institute, pointed out the significant technical obstacles in exploring these promising sites. “The most ice is expected in old large permanently shadowed craters, but no missions go there because of the technical challenges of landing in the dark and operating in the extreme cold,” Schörghofer explained.
Recent data from the Korea Aerospace Research Institute’s Korea Pathfinder Lunar Orbiter, also known as Danuri, have tempered expectations. Launched in December 2022, Danuri’s NASA-funded ShadowCam instrument was intended to capture high-resolution images of the moon‘s PSRs to map water ice distribution. However, ShadowCam did not detect the anticipated ice, suggesting that accessible surface ice might be less prevalent than hoped.
Subsurface Ice and Historical Evidence
Despite these findings, Schörghofer remains optimistic about subsurface ice. “Although ShadowCam found no evidence for ice in the lunar cold traps, there is still strong evidence for ice in the subsurface,” he said. This theory is supported by data from past missions, including NASA’s Lunar Prospector and the Lunar Reconnaissance Orbiter, both equipped with neutron spectrometers that detected hydrogen indicative of water.
Future Missions and Technological Innovations
Ben Bussey, chief scientist for Intuitive Machines, emphasized the need for physical confirmation of water ice to drive both human and robotic exploration. “Physical confirmation of water ice could represent a significant impetus to human and robotic exploration,” he noted.
Bussey also highlighted the challenges in harvesting lunar water. Even if abundant reservoirs are found, accessing them might prove difficult, especially within PSRs. The water could be so dispersed that extracting it would require processing vast amounts of lunar soil.
In pursuit of clearer answers, Intuitive Machines plans to send a hopper to the lunar south pole in late 2024 as part of NASA’s Commercial Lunar Payload Services (CLPS) initiative. Targeting Shackleton Ridge, this mission aims to operate for roughly 10 days using available sunlight. The lander will carry the Polar Resources Ice-Mining Experiment-1 to analyze regolith water content and search for other volatiles.
Innovative Approaches to Water Detection
Additionally, the mission will deploy a Micro Nova Hopper, a propulsive drone designed to traverse the lunar surface. Funded by NASA, this drone will carry a neutron spectrometer provided by Puli Space Technologies of Hungary into the permanently shadowed Marston crater. “This will provide the first direct surface measurement of hydrogen, a key indicator for the presence of water,” Bussey said.
The search for water ice on the moon remains a complex and evolving challenge. While technological advancements and upcoming missions hold promise, significant questions about the location, quantity, and feasibility of harvesting lunar water ice still need to be answered. The success of these endeavors is crucial for the future of sustained human exploration and utilization of lunar resources in the Artemis era.
