The search for water on the Moon has been a major focus of scientific exploration. However, a recent analysis of lunar craters has brought forth some unexpected findings that challenge our previous assumptions. According to physicists Norbert Schörghofer and Raluca Rufu, most of the craters that contain permanent shadows, which were considered potential reservoirs of water ice, are actually too young to retain ancient water ice. This discovery has significant implications for future Moon missions and calls for a reassessment of our understanding of water on the lunar surface.
One of the key areas of interest in the search for water on the Moon has been permanently shadowed regions (PSRs) within deep craters. It was believed that these PSRs could serve as cold traps where water ice could accumulate over billions of years. However, the new analysis suggests that these PSRs have not been shielded from the Sun for a sufficient length of time to accumulate significant amounts of ice. The age of the craters has been found to be younger than 2.2 billion years, indicating that ancient water ice reservoirs are not expected.
The reassessment of lunar craters and their potential for water ice accumulation was prompted by a previous study that aimed to reconcile the rate at which the Moon is moving away from Earth with its estimated age. The researchers found that the resonance between Earth and the Moon would have caused variations in the lunar recession rate, leading to changes in the lunar axis orientation. This discovery prompted Schörghofer to delve deeper into the implications for the search for water ice on the Moon, ultimately leading to the realization that the PSRs are much more recent than previously thought.
Scientists believe that early in the history of the Solar System, the inner planets, including the Moon, were bombarded by comets and asteroids in an event known as the Late Heavy Bombardment. This, coupled with the Moon’s volcanism during its hot and malleable phase, would have released water from its interior. If the PSRs existed during this time, they could have captured a substantial amount of water ice. However, based on recent models of the Moon’s spin-axis reorientation and the evolution of the Earth-Moon distance, it is now clear that the PSRs are much younger. Therefore, any water ice present in these regions is also more recent.
NASA’s Artemis III mission, aimed at returning humans to the Moon, is currently selecting landing sites based partly on the proximity of PSRs. However, the new findings have raised concerns about the viability of these sites as water sources. On the positive side, evidence for water ice has already been found in PSRs, suggesting that older craters may contain more water than younger ones. The identification of older craters will be crucial in narrowing down potential landing sites for future crewed and uncrewed missions.
The reevaluation of lunar craters and the presence of water ice on the Moon challenges our preconceived notions about this celestial body. The absence of ancient water ice reservoirs implies that other sources and mechanisms need to be considered. Future research will focus on examining alternative locations and processes that may contribute to the presence of water on the Moon. This new perspective will allow scientists to refine their understanding of lunar water and inform future explorations.
The recent analysis of lunar craters has shed light on the true nature of water on the Moon. Contrary to previous assumptions, most of the craters containing permanent shadows are too young to retain ancient water ice. This discovery has significant implications for future Moon missions, requiring a reevaluation of landing site selection and the search for alternative sources of water. Although the presence of water on the Moon is undeniable, we must now refine our understanding of its origins and distribution on the lunar surface.