Fairy stories are, in my imagination, rooted in an Earth-centered universe--visitors from beyond the world come out of moonshadows and thistle dew, through hexes and conjurings and toadstool rings--not from metal tubes in the night sky.
Stories of space travellers, on the other hand, don't seem to have room in them for fey folk. There seems to be a fundamental incompatibility in these two kinds of fantasy worlds. Take for example the leprechaun: does he peek from under the shamrock leaf under the twin suns of Tatooine? Surely his fairy door or rainbow road can reach distant stars (distant from Earth, that is) just as easily as our own Sun, right?
Or are Earth's fairies bound to the earth, and not from Another Realm at all? Then could every world have their own weefolk and nature spirits? Well, of course they could. Thinking it through, the mismatch seems less now, but I welcome any discussion about how this issue has been treated in the past, in the games you love that I'm ignorant of, or in the forests of your own fancy.