Eugene Cernan

The moon is bland in color. I call it shades of gray. You know, the only color we see is what we bring or the Earth, which is looking down upon us all the time. And to find orange soil on the moon was a surprise.

Curiosity is the essence of human existence. 'Who are we? Where are we? Where do we come from? Where are we going?'... I don't know. I don't have any answers to those questions. I don't know what's over there around the corner. But I want to find out.

Supplying fuel for a Mars expedition from the lunar surface is often suggested, but it's hard to make it pay off - Moon bases are expensive, and just buying more rockets to launch fuel from Earth is relatively cheap.