These days, Star Trek is as mainstream a franchise as it gets. Back in the dark days of the late 70s, Star Trek was an also-ran show that only survived because of the pressure of the fans on the network. Leaping to the big screen was virtually unheard of and nobody knew what to expect. It makes perfect sense that an ad for a fan-based show like this would show up in the pages of Heavy Metal. Looking back on it now, it seems very weird. 

(Heavy Metal issue #34, January 1980 – Inside Front Cover Star Trek Ad)