Enlisting the aid of the ship's three service robots drones, which he eventually names Huey, Dewey, and Louie, Lowell stages a fake premature explosion as a ruse, and sends the Valley Forge careening away from the space freighter fleet, towards Saturn. Injured and alone with the three drones, Lowell reprograms them to perform surgery on his leg. Lowell and the drones set out into deep space to maintain the forest.
The ship passes through the rings of Saturn and the three drones are outside the ship on maintenance duty, when Drone 3 is blown away from the ship, leaving two remaining drones. The ship, and the precious dome, emerge undamaged on the other side of the rings.
Lowell jettisons the last dome to safety with Dewey, and arms nuclear charges to destroy himself and his spacecraft, thus ensuring the preservation of the last dome. The final scene shows a well-lit forest greenhouse drifting into deep space, the last drone tending to its care.