Silent Running (1972)

Character mistake: While he may not have figured it out the moment he found the forest dying, certainly a botanist like Freeman Lowell would know plants need light to survive.

Freeman Lowell: It calls back a time when there were flowers all over the Earth... and there were valleys. And there were plains of tall green grass that you could lie down in - you could go to sleep in. And there were blue skies, and there was fresh air... and there were things growing all over the place, not just in some domed enclosures blasted some millions of miles out in to space.

Trivia: The space ship "Valley Forge" from Silent Running was re-used in one episode of the television series "Battlestar Galactica" (1978-1979). It was called the "agro-ship," used to grow food for the colonists.