Scifi music began with filking, and the less said about that the better. But did you know that mega-popular band Blue Oyster Cult sang songs written by British scifi author Michael Moorcock? (One of those songs, "Black Blade," was a minor hit in the UK.) That's true scifi music for ya. And then there is the totally underground Massachusetts band Honest Bob and the Factory to Dealer Incentives, who sing about time cubes and Tatooine with feeling. Plus, one member of Honest Bob is an editor at New Scientist, which is serious cred.
And let us not forget that Judas Priest's song "Electric Eye" from way back in the 1980s is a brilliant dystopian vision of a world controlled by surveillance. OK, maybe not brilliant. But prescient! And very scifi.