From here. Quote:
"The urge that led to this has, I believe, three components. Ray Bradbury instinctually understood two, and was a poet of the third.
The first is survival. This is why primitive humans did not stay home when the climate changed and the herds moved and vegetation became more lush elsewhere. To do so would have meant extinction. During the first migrations out of Africa the world population was in the low thousands. We are now a planet of over seven billion people facing the crises of climate change caused by our rapid technological growth, hoping we can deal with it if only knowledge can win out over ignorance. But even without climate change, the balance of population to resources is putting a negative pressure on all of us. Can the exploration of Mars and going back to the moon -- even going beyond both -- relieve that pressure? If so, not quickly, not easily, but eventually? The possibility of a positive answer compels us.
The second component has provided the name for the current rover: Curiosity. We have become a knowledge-seeking species, it is as ingrained in us genetically as the need for survival. To have the capacity to go the stars and explore and to not do so, would be the greatest of sins -- the denial of our nature.
The third component is either more primitive than the other two, or more advanced. I'm not quite sure which, which may be why it is best expressed through art, and why Ray was so effective at expressing it. It is a purely instinctual urge not to be confined, that feeling some of us have when we look up at a night sky -- especially away from city lights -- and see the Milky Way, of which we are a part, and ask, "Why?" Why must we be confined to this thin slice of atmosphere, why must we but a smudge of life on only this one small planet, when the whole of our solar system, possibly the Milky Way, maybe the universe, is out there for us if we but only...."