Understanding the reachability of water ice by future in-situ experiments near the lunar poles is crucial for supporting growing exploration plans and constraining the uncertainties on its genesis and distribution. To achieve this objective, we perform a thorough three-dimensional mapping of the distribution of water ice in the lunar polar regions (70° onward), integrating radar, optical, and neutron detector observations from the Lunar Reconnaissance Orbiter mission (LRO). Our analysis reveals ∼5-to-8-fold larger expanse of subsurface water ice (∼1-3 m depth) compared to surface water ice (up to 1 m depth) for the north and south poles, respectively. Our investigation cannot rule out the possibility of deep-seated water ice deposits in the lunar poles that remains beyond the detection capabilities of existing instruments on LRO. Moreover, we find that the extent of water ice in the northern polar region (∼1100 ± 74 km) is twice that in the southern polar region (∼562 ± 54 km). Our mapping also suggests that the dichotomous latitudinal distribution and the antipodal longitudinal distribution of water ice are likely driven by Mare volcanism and preferential cratering. We provide additional evidence that outgassing during Imbrian volcanism was probably the primary source of subsurface water ice in the lunar poles, which favors larger expanse over meteoritic sources.

中文翻译：

---

月球上水冰的可达性和成因

通过未来在月球两极附近的原位实验了解水冰的可达性对于支持不断发展的探索计划并限制其起源和分布的不确定性至关重要。为了实现这一目标，我们综合了月球勘测轨道飞行器任务 (LRO) 的雷达、光学和中子探测器观测结果，对月球极区（70° 以上）的水冰分布进行了彻底的三维测绘。我们的分析表明，与地表水冰（深度达 1 m）相比，北极和南极的地下水冰面积（深度达 1-3 m）分别大 5 至 8 倍。我们的调查不能排除月球两极存在深层水冰沉积的可能性，这种沉积仍然超出了月球勘测轨道飞行器现有仪器的探测能力。此外，我们发现北极地区（∼1100 ± 74 km）的水冰范围是南极地区（∼562 ± 54 km）的两倍。我们的绘图还表明，水冰的二分纬度分布和对映纵向分布可能是由海火山活动和优先陨石坑驱动的。我们提供了额外的证据，表明雨纪火山活动期间的排气可能是月球两极地下水冰的主要来源，这有利于比陨石来源更大的范围。