Lucky Starr and the Rings of Saturn is the final novel in the Lucky Starr series, six juvenile science fiction novels by Isaac Asimov that originally appeared under the pseudonym Paul French. The novel was first published by Doubleday & Company in 1958. It was the last novel to be published by Asimov until his 1966 novelization of Fantastic Voyage, and his last original novel until 1973's The Gods Themselves. Lucky Starr and the Rings of Saturn is the only novel by Asimov set in the Saturnian system. Setting Lucky Starr and the Rings of Saturn is set mostly within the Saturnian system, depicted as accurately as the knowledge of the late 1950s allowed. At that time, only nine satellites had been discovered, the innermost known satellite being Mimas. Asimov describes Mimas as being 340 miles in diameter, but its diameter is now known to be 240 miles. Several of the novel's chapters are set on Titan, which was then thought to be the third largest satellite in the Solar System, after Ganymede and Triton. Its atmosphere is described as "almost as thick as Earth's" and composed mostly of methane. It is now known that Titan is the second largest satellite in the Solar System after Ganymede, and that its atmosphere is denser than Earth's and is 98.4% nitrogen and only 1.6% methane. The final chapters take place on the asteroid Vesta, which Asimov notes is the brightest of the asteroids. At the time, it was believed that Vesta was 215 miles in diameter, although its mean diameter is now known to be closer to 330 miles. Plot summary Six weeks after returning from the Jovian system, David "Lucky" Starr learns that Jack Dorrance, the chief of a Sirian spy ring uncovered by Starr in the Jovian system, has escaped from Earth. Starr and his sidekick Bigman Jones follow Dorrance to the Saturnian system, where Dorrance tries to lose them in Saturn's rings, but his ship is destroyed by a ring fragment. A Sirian ship then contacts Starr and informs him that the Sirians have built a colony on Titan and claimed it for Sirius, contrary to the traditional principle that inhabitants of one world in a stellar system have sovereignty over the entire system, even those parts without permanent settlements. Starr orders the pursuing Terrestrial fleet back to Earth; but returns with Bigman and Councilman Ben Wessilewsky to the