Rendezvous with Rama
Rendezvous with Rama is a science fiction novel by Arthur C. Clarke1 (1973) in which a vast and apparently derelict alien spacecraft arrives in the solar system. A ship is sent from Earth to investigate before the enigmatic craft, called Rama, disappears. The astronauts given the task of exploring the hollow cylindrical interloper are able to decipher some, but by no means all, of the extraterrestrial vehicle's puzzles. From the ubiquitous trilateral symmetry of its structures to its cylindrical sea and machine-island, Rama's secrets are clues to the nature of the advanced civilization that built it. But who, and where, are the Ramans, and what do they want with humans? Perhaps the answer lies with the busily working biots, or the sealed-off buildings, or the inaccessible "southern" half of the enormous cylinder.
Clarke collaborated with Gentry Lee in writing several Rama sequels, beginning with Rama II.
1. Clarke, Arthur C. Rendezvous with Rama. Harcourt, Brace, Jovanovich (1973).