A Tale of Two Planetary Bodies: the Origin of Ice on the Moon and Mercury

The small obliquity of Mercury and the Moon causes topographic depressions found near their poles to cast highly persistent shadows. In the absence of an atmosphere, these permanently shadowed regions (PSRs) may cold-trap and preserve volatile species, such as water, for billions of years. On Mercury, observations in radar, surface reflectance and visible imagery detected pure, glacier-like ice deposits inside most of its north-pole permanent shadows. However, similar observations conducted on the Moon have found its polar cold-trapped ice to be surficial and patchy, and likely mixed with the regolith. In the talk, we will review the accumulation and destruction of ice within cold-traps, attempt to resolve the difference between the reservoirs of ice on Mercury and the Moon, and discuss the historic delivery of water to inner solar system