sources, and the possibility of transport of spacecraft components on an icy body’s surface into a subsurface liquid environment. The key to understanding this transport is to examine the geologic processes that can promote surface-subsurface exchange, to determine the rate at which they occur, the depth to which they penetrate, the influence of materials other than water ice mixed into the icy shells, and the role of liquid water in their operation. The concept of a “no-mans land” that bars transport of material into the subsurface also deserves closer scrutiny. When examined through this lens, and in combination with observed surface geology, several icy bodies may fall into the category of no concern. Further spacecraft exploration and reconnaissance of icy body geology and surface characteristics will continue to improve understanding of the global material transport cycles of icy bodies.

Recommendation: Research should be undertaken to understand global chemical cycles within icy bodies and the geologic processes occurring on these bodies that promote or inhibit surface-subsurface exchange of material.

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