From the earliest times, people have looked up at the stars, the moon and the planets ? now, we know more about them than we ever have. Today, people can train to be astronauts, work in space, or join a future mission to Mars. From the earliest times, people have looked up at the stars, the moon and the planets ? now, we know more about them than we ever have. Today, people can train to be astronauts, work in space, or join a future mission to Mars.