Questions immediately come up: no room for vegetation, eh? Where does the planet get its oxygen? It's phyto-plankton? It seems that if you take vegetation out of the equation that the Earth's food pyramid will pretty much collapse in on itself, and with it, the human population who are subsisting on...what?...space food sticks? Soylent green?
None of this seems to matter to the four ship-caretakers (Cliff Potts, Ron Rifkin, Jesse Vint and Bruce Dern), three of whom could care less about the fragile greenery, and Astronaut Freeman Lowell (Dern) being the one for whom the Mission is a sacred trust. Needless to say, the astro-nurserymen don't get along, Lowell's sole sympatico companions being the nursery-bots tending to the plants' daily needs.
Things quickly go to seed when word comes up from Mission Control that Earth doesn't give a rip anymore—budget cuts or some such—so they should just jettison the space-green-houses, blow 'em up, and return home. Rather than commit planticide, Lowell chooses, instead to go all-PETA and decide that his fellow agro-nauts' best function would be as fertlizer. A bit extreme, maybe, but we are talking about Bruce Dern here. And, to hide his crimes, he sends the ship into a collision course with Saturn's rings to try and convince Mission Control the ship will be destroyed. However, pesky-persistent techies that they are, NASA manages to find him, and Lowell must come up with a way of saving the plants and allaying any suspicions.
Douglas Trumbull did some of the FX work on 2001: A Space Odyssey, creating 3-D forced perspective lunar landscapes and perfecting the "slit-scan" technique—a frame-by-frame animated geometric horizon that made up the bulk of the "Star-gate" sequence near that film's end. Silent Running was his first directing feature, and he maintained a healthy career as director (Brainstorm), special effects guru (Close Encounters of the Third Kind, Star Trek: The Motion Picture, Blade Runner), and experimental pioneer with film formats (his "Showscan" became a staple at world's fairs displaying huge 70mm films at a reality-approaching 60 frames per second), and designer of thrill rides (for the Luxor and Universal Tours).
In Silent Running, Trumbull managed to make an ecological low budget sci-fi film, with illusion work that rivaled 2001—he even managed to make a realistic looking Saturn, something that wasn't possible years before with the Kubrick film. His robots were strange little non-humanoids forms that suggested walking amplifiers, and the story (and Dern's acting) makes them sympathetic little synth's. The ships designed for Silent Running were subsequently used for stock footage for years in such shows as "Battlestar Galactica" and Trumbull's considerable work served to influence the look and techniques that would be applied in Star Wars.*
Though Silent Running is not the greatest of films, it is not through lack of trying, as director, star and art team stretch their budget impressively and play it for all the drama it's worth. But the story is a little skimpy, the protagonist a bit bi-polar, and the conclusion not exactly rousing. A good study in movie-making, if not necessarily story-telling.