Silent Running was originally released in March 1972. It was a modestly budgeted (made for about $1 million) science fiction film, but one with a very big environmental message which is still relevant today: We have to protect our forests. 

A documentary crew followed director Douglas Trumbull and his cast and crew as they made the film, primarily shooting on the decommissioned US Navy aircraft carrier Valley Forge in California. This is one of the better documentaries showing the behind the scenes goings on of a great film.