Titan

Titan is a science fiction novel by American writer John Varley, the first book in his Gaea Trilogy, published in 1979. It won the 1980 Locus Award for Best Science Fiction Novel and was nominated for both the Nebula Award for Best Novel in 1979, and the Hugo Award for Best Novel in 1980. Plot A scientific expedition to the planet Saturn in 2025, aboard the ship Ringmaster, discovers a strange satellite in orbit around the planet. Commanding the ship is Cirocco Jones, a tall NASA career woman, aided by astronomer Gaby Plauget, the clone twin physicists April and August Polo, pilot Eugene Springfield, physician Calvin Greene and engineer Bill (whose last name is never given). As they reach the satellite they realize it is a huge hollow torus, a Stanford torus habitat. Before they can report this, the ship is entangled in cables from the object. The crew is rendered unconscious and later wake up inside the habitat. Initially separated, Cirroco and Gaby find each other and travel together through the world inside the torus to find the rest of the crew. They find Calvin living as a companion inside a Blimp, an intelligent gasbag a kilometer long, one of many that swim forever in the air inside the habitat. Calvin can speak to the blimp and understand its responses, which consist of whistles. His blimp's name is Whistlestop, in human terms. Calvin helps Gaby and Cirocco find the other crew members (except April). He ultimately decides to leave his human companions to live with the blimp permanently.