"Deep Space Homer" is an episode that I've repeatedly seen pop on on many fans' Top 10 lists. While I personally don't think it even makes the Top 20 or even 30, it's still a great episode, featuring some of the best guest performances I've seen in the series. The first act of this episode pokes fun at the sad truth that nobody really gives a damn about space launches anymore, by featuring Homer complain to NASA via phone that he's sick of having to sit through their boring coverage. The NASA leaders get an idea, by sticking ordinary schmoes (in the case, Homer and Barney) on a voyage into space, accompanied by actual qualified astronauts.
Then follows a series of training courses, followed by the voyage itself. Things go haywire when Homer releases a bag of patato ships, causing a case of ants to escape and clog the ship's instruments. The gang gets in a fight, featuring Homer using an inanimate carbon rod as a saber (which won "Worker of the Week" at SNPP), which he accidentally uses to lock the hatch tight. While Buzz Aldrin declares Homer the mission's savior when they arrive back on Earth, the media gives the carbon rod the credit for saving the mission.
"Stupid carbon rod. It's all just a popularity contest!"
Probably the main problem with this episode is some over-the-top wackiness for The Simpsons. "2001 Space Odyssey" is parodied numerous times in this episode alone, and while some of them, like Homer devouring the suspended potato chips in space, are absolutely hilarious (probably the funniest part of the entire episode), other moments, like the ending with the Homer fetus encapsulated in space, are pretty idiotic. Still, the good far outweighs the bad.