potential – adj. possible

deposit – n. a layer of a substance that has developed from a natural or chemical process

frontier – n. the limits of what is known or what has been done before in an area of knowledge or activity

subsurface – n. the area below Earth's surface

polar – adj. relating to the north or south pole regions

plain – n. a large area of flat land

glacier – n. a very large area of ice that moves slowly down a slope or valley or over a wide area of land

mission – n. the flight of a spacecraft to perform a certain task or job