THEY'RE CHANGING THE GUARD UP ON the Satellite of Love. At the end of this week's episode of Mystery Science Theater 3000 on Comedy Central (Sat., Oct. 23, 7 p.m. ET), Joel is loaded into an escape pod and shot back to Earth. Joel Hodgson, who created the show for a Minnesota UHF station five years ago, is stepping down as chief on-air quipster (he will remain on the writing staff). Next week (Oct. 30), the show is back with the theme song's lyrics altered to reflect that there's a new guy up there dodging meteors and watching bad movies. He's Don (Soul Train) Cornelius. Just kidding. The spaceman is Mike Nelson, the show's head writer since 1990. Like Hodgson, he seems like an unassuming, low-key kind of guy. Here's hoping MST3000 will retain its high level of hilarity. Happy orbiting, Mike.