Since cosmic radiation alters surface composition, Curiosity can drill into rock to extract pristine material from below.

CNN: Curiosity opening Martian frontier?

Phase II, planned for 2011, will identify both aquifers down to 3, 000 meters below the surface, study soil composition and aquifer replenishment, and prioritize areas for agricultural development.

UNESCO: launches initiative to identify groundwater and alleviate water shortages in Iraq | United Nations Educational, Scientific and Cultural Organization

Observations of the material coating the dark face of Iapetus indicate it has a similar composition to the surface material on Phoebe.

BBC: New ring detected around Saturn

The amount of charge that can be stored depends on the surface area of the electrodes, the strength and composition of the insulation between them, and how close they are together.

ECONOMIST: Electricity storage