Ah, well. Here's my list anyway :-)
Veterans of the Psychic Wars by Blue Oyster Cult.
Needle Gun by Hawkwind
Why Me? by The Planet P Project (80's rawk!)
Planet Caravan - both the original version by Black Sabbath and cover version by Pantera.
Drive-In Saturday by David Bowie. A futuristic doo-wop song about teenagers who have to relearn the art of seduction and romance through watching ancient 20th century erotic videos. Or something like that.
And of course, *no* list of great sci-fi rock would be complete without Jan Terri's classic (heh heh heh) Journey to Mars
Blue Oyster Cult: E.T.I. (Extra Terraestrial Intelligence)
http://www.youtube.com/watch?v=sYkvpNR8BGU