Study Assesses Strategies to Bring Back Water from the Moon
Universities Space Research Association Explore Multiple Possibilities
In a recent study, researchers from the University of New Mexico and Universities Space Research Association's Lunar and Planetary Institute (LPI) examined the shadowed regions near the Moon's south pole to assess strategies for returning water ice and other volatiles from the Moon. They examined how sampling methods might impact the scientific interpretations of materials returned by Artemis and other future missions. The science team aimed to identify strategies to preserve the maximum amount of information from these valuable samples.
"The orbital data provide a reliable framework from which to plan surface exploration for missions like those of the Artemis program."
Dr. Julie Stopar, USRA
Parts of the Moon's shadowy polar regions experience extreme temperatures reaching as low as 25 to 50 Kelvin (-400°F), with many areas never receiving direct sunlight. Thus, permanently shadowed regions can act as cold traps, preserving volatiles including water, carbon dioxide, and other chemical species. Volatile materials are crucial to study in detail to determine the sources and timing of their delivery to the Moon's surface. The findings were published in a special issue of The Proceedings of the National Academy of Sciences (PNAS).
Universities Space Research Association's Senior Scientist Dr. Julie Stopar at the LPI analyzed orbital data and provided information about the permanently shadowed regions in terms of temperatures and volatile stability along generalized routes within surface exploration zones.
"The orbital data provide a reliable framework from which to plan surface exploration for missions like those of the Artemis program. However, we haven't yet been to visit these areas, so we don't really know for sure exactly how much water ice there is, or what form it's in… and what else we might find with it," Stopar said.
The Artemis missions will collect many lunar samples in sealed containers and return them to Earth for detailed analysis. Once disturbed or sampled, these materials are no longer in exactly the same state as they would have been on the Moon. This includes changes to the pressure or temperature they are exposed to. Volatile materials are sensitive to temperature and pressure changes and can change states if they are no longer stable under different conditions. Some samples would be best preserved at very low temperatures, but replicating the Moon's environment is very challenging. The questions addressed in this study are what types of information can be gained from these samples and, equally important, what information will be lost by allowing them to warm to some degree after sampling.
Bringing samples containing volatiles back to Earth requires careful planning. Low-temperature sample preservation, or "cold storage," can be used to reduce the chemical changes in sampled volatiles during transit, improving the overall science outcomes later. However, cold storage is technically challenging to achieve. By visiting the south polar regions and studying the materials there, we will certainly gain invaluable insight into what's at the Moon's poles, but sampling and studying volatiles requires aligning science and exploration goals with sampling and curation approaches.