As an imaginative kid, fascinated with science fiction, and spending my formative childhood years during the late 70s and early 80s, I was fascinated with the new-fangled Space sets. In 1978, LEGO introduced a number of "lines" of sets that were themed. Space was always my favorite (although I grew up with a fair share of Castle and Town themed sets as well, of course.) In fact, it became traditional for us as kids to expect several LEGO sets each Christmas; at least one big one and several medium sized and smaller ones. And after opening presents, we'd go into the "boys' room", open up the LEGO sets, build them according to the instructions, almost immediately take them apart, mix their pieces in with our existing LEGOs, and then just spend the entire rest of the day (and much of the rest of the Christmas vacation) playing LEGOs. I've attached an image of the Galaxy Explorer, the very first "big spaceship" set in existance.
I didn't go on to be one of those adult Legomaniacs, who collects sets and builds all new designs as a hobby (which would, unfortunately, be a pretty expensive hobby, too) but I've never quite lost the mystique for the feel of those early Space sets, and the kinda campy, kinda cute and kinda clever later lines that developed after the fact. And I do pick up sets now and again for myself, that I won't even let the kids play with. I keep my toe in the water of fandom, anyway.
The original space line was fairly straightforward; it featured astronauts in space suits, and things like lunar rovers and space ships that seemed futuristic... yet not too much so. They were futuristic in the sense that the movie 2001 was futuristic in the late 60s when it was made; it all seemed pretty reasonable, all things considered. This wasn't necessarily true of the space sets; I remember even as a kid thinking it odd that flared rocket "exit chute" could be attached directly the back of the seat that an astronaut was supposed to sit in in his little tiny space-going flyer (where the heck is the actual engine?) but it had that same feel anyway.
Later on, Space diverged into multiple subthemes. Futuron was the first one, in the late 80s, followed closely by Blacktron, Space Police, and more. In fact, for a while it seemed that each theme had a three year life cycle, with a new theme appearing every year and an old theme phasing out. This lasted for quite some time, until the entire Space theme essentially disappeared at the very end of the 90s. The gap was filled temporarily by the Star Wars sets.
More recently, for whatever reason, LEGO has revived the space theme, and two subthemes have come out. One of them has apparently just launched within the last few months, and is a "re-do" of a classic theme, the Space Police idea. This is, in fact, the third version of Space Police. I've included an image of the new "big spaceship" of the line, as well as the original "big spaceship" from the old Space Police line. Enjoy.
Another thing I've discovered is that some of these older Legomaniacs have been putting their stuff online for years (actually, I've known that for years too, but the building standards and photography and Photoshop capabilities of them has improved, to the point where a lot of their work looks tons better than official stuff. Here's a few of my favorites, all snagged from the retro-blog http://www.neoclassicspace.com/.