Silent Running

Bruce Dern plays Freeman Lowell, a botanist and astronaut assigned to a spaceship that has the last of Earth's forests in enclosed domes attached to its exteriors. When the order comes from Earth to destroy the domes, and return to Earth, Freeman's fellow crewmen are ecstatic, but he is enraged at the order, thinking it wrongheaded and stupid, so he sets out to ignore the order, and save the domes, even if that means he has to take extreme measures with his crew mates...

Sobering, thoughtful, well acted and directed(by Douglas Trumbull) ecological science fiction tale is really an allegory about humanity's treatment of nature, and what would happen if it was taken to its logical outcome. Though the extreme situation presented here is unlikely(I sincerely hope!) this film works because of its absolute sincerity, with three robots named Huey, Dewey, and Louie, who will play a key role by the film's deeply moving ending, which may bring a tear(s) to the eye.