Any of you remember the movie "Silent Running" ?
http://www.imdb.com/title/tt0067756/
It was a very good movie. ....about a guy (Bruce Dern) who with a few others maintained a space station of all of the earth's non-human life. It was kept there because the world didn't need living animals and plants anymore, and was kind of like a Noah's Ark. Then..... !!!! ..... the earth decides they don't need it anymore, so they are ordered to blow it up! Anyway.... it's a good movie and if you can find it, i recommend it.