Emotion, that great big unexplored planet, had been exerting an irresistible pull on her wits.

Is there some law that says an unexplored planet has to be dangerous?

Men and women who land on unexplored planets.

Outside was an unexplored planet, made dangerous by ignorance.

"Arrakis is a huge planet, mostly unexplored and only sparsely inhabited."

"When I injected myself with cordrazine, a landing party followed me down to that unexplored planet."

One year after his posting, he was killed in an avalanche during a survey mission to an unexplored planet.

"Anyone would think you were setting out for an unexplored planet."

There are no medical centers on unexplored planets.

The problem was, on an unexplored planet, how far could a bunch of nine-year-old kids go?