Silent Running (1971)
Your basic early '70s eco-sciencer about the grubby "near future," but really all about the '70s, see? A young, scary, rodentlike Bruce Dern is Freeman Lowell, a man already wound a little too tight, shot into space to be the greenskeeper in one of several leviathan astro-terrariums containing all that remains of Earth's plant life. Of course, the folks on Earth footing the bill are taking a hard look at the costs of all this preserved-nature crap, and therein lies your conflict, OK? The relentless claustrophobic tedium of life in space is explored, and they put a bunch of little people into mini-robot costumes for scientific relief. It was a big deal at the time, really, but basically this is what happens when the special-effects guy directs the flick.