Saturn 3 (1980)

Not the third part of a trilogy, the film's title refers to an orbiting space station within which the majority of the story takes place; positioned near Saturn's third moon, its role is to provide food research for an overcrowded Earth.
Sitting pretty in the isolation is old man Adam (Kirk Douglas) and his three-decades younger lover Alex (Farrah Fawcett). Adam's dirty old man utopia is threatened when a visitor from Earth (Harvey Keitel) arrives, bringing with him a robotic device that could make the existing duo's role obsolete.
The darkly lit corridors and believable space suits are great, but I won't pretend for a second that it's a good film. It's pretty terrible, especially the acting of all three stars, but for some reason I'm still able to enjoy it. As such, the scoring below is very much on the generous side.

2½ direct inputs out of 5