In the future, plant life on Earth is nearly extinct. Pocket forests have been preserved in enormous geodesic-dome greenhouses in space. One such ship, called Valley Forge, is just outside the orbit of Saturn. Freeman Lowell (Bruce Dern) is one of four crewmen aboard, the resident botanist who maintains the plants for the return to Earth someday, to begin its reforestation. He spends all his time in the domes.
Orders are given to jettison and destroy the domes and return the ships to commercial use. Four of the six have been destroyed, but Lowell rebels and decides to protect the forest. He kills one of his fellow crewmen who is planting explosives and is injured in the process. He jettisons and destroys one of the domes, killing the other crewmen, then programs the robot drones—Huey, Dewey, and Louie—to perform surgery on his leg, while the Valley Forge takes a dangerous trip through Saturn’s rings. Louie is lost in the process.
The ship sets out into deep space as he teaches Huey and Dewey how to plant trees and play poker. Huey is damaged by Lowell going crazy and driving a buggy recklessly. He refuses to leave Huey’s side during repairs. He is horrified that the plants are dying and tries to figure out why. The ship Berkshire contacts him to see if Valley Forge survived the trip, and he knows his crimes will eventually be discovered. We will gloss over the idea that a botanist couldn’t figure out that plants need light and go right to him setting up sunlamps. He jettisons the dome into deep space, hoping it will return when the human race wises up to the necessity of forests on Earth, then destroys the ship itself, killing himself and Huey, as Dewey continues to care for the last forest in the depths of space.
The film was directed by Douglas Trumbull, the special effects wizard who more or less brought us 2001. The ship interiors were filmed in the decommissioned Korean War aircraft carrier USS Valley Forge, residing in the Long Beach Naval Shipyard until it was scrapped shortly afterwards. The forest was created in the new aircraft hangar in Van Nuys, copied from the Missouri Botanical Garden’s Climatron Dome. Shown in the film are Valley Forge, Berkshire, and Sequoia. Mentioned are Yellowstone, Acadia, Blue Ridge, Glacier, and Mojave. Aboard the Valley Forge is the Bahia Honda Subtropical Forest.
The model of the ship was 25 feet long and took six months to build out of model-aircraft and tank kits, some of which was damaged during filming. One of the geodesic domes now resides in the Science Fiction Museum and Hall of Fame in Seattle. The drones were played by four bilateral amputees, the idea inspired by Johnny Eck, a sideshow performer in the early 20th Century. The soundtrack was written by Peter Schickele, also known as PDQ Bach. Joan Baez sang two songs. Reviews were not great, and the film was called simple-minded, but the technical bits were, as you might expect, excellent. John Dykstra was one of the model-makers. Saturn was replaced by Jupiter in the movie 2001and then turned up in Silent Running. Some shots of the ships were used later in Battlestar Galactica.
When 20th Century Fox sued Universal in 1978, claiming that Battlestar Galactica was a rip-off of Star Wars, Universal countersued, claiming that Star Wars was a rip-off of Silent Running. In actual fact, George Lucas asked permission of Douglas Trumbull to base R2-D2 on Huey, Dewey, and Louie. A tearful scene with Bruce Dern was inspired by his daughter’s death two years earlier. It is her watering can that Dewey is holding at the end. The Valley Forge was from Heinlein’s book Starship Troopers. Bruce Dern plays a botanist in this film and his daughter, Laura Dern, plays a paleo-botanist in Jurassic Park.