They came because they were afraid or unafraid, because they were happy or unhappy, because they felt like Pilgrims or did not feel like Pilgrims. There was a reason for each man. They were leaving bad wives or bad jobs or bad towns; they were coming to find something or leave something or get something, to dig up something or bury something or leave something alone. They were coming with small dreams or large dreams or no dreams at all. But a government finger pointed from four-color posters in many towns: THERE'S WORK FOR YOU IN THE SKY: SEE MARS! and the men shuffled forward, only a few at first, a double-score, for most men felt great illness in them even before the rocket fired into space. And this disease was called The Loneliness, because when you saw your home town dwindle to the size of your fist, and then lemon-size and then pin-size and vanish in the fire-wake, you felt you had never been born, there was no town, you were nowhere, with space all around, nothing familiar, only other strange men.
And when the state of Illinois, Iowa, Missouri, or Montana vanished into cloud seas, and, doubly, when the United States shrank to a misted island and the entire planet Earth became a muddy baseball tossed away, then you were alone, wandering in the meadows of space, on your way to a place you couldn't imagine. ~Ray Bradbury, The Martian Chronicles
*image taken by NASA's Phoenix Mars Lander, June 10, 2008, from here