Lucky Starr&rings Satr

This volume is the eighth and last in the Lucky Starr series for teenagers, originally published under the pseudonym Paul French. A secret agent for Earth's enemy, Sirius, has stolen some intelligence and escaped to the moons of Saturn. Lucky Starr and his friend Bigman race to Saturn only to discover an enemy base set up on Titan, Saturn's largest moon. Somehow they have to return to Earth and force the Sirians out of the Solar System without starting an interstellar war. The story line in Asimov's novel involves the settling of an "enemy" of Earth within Earth's region of space. It's amazing how close Asimov was to an analogous situation in recent history. A short while after this book appeared, there was a revolution in Cuba which resulted in the Soviet Union having an ally close to the U.S. mainland. More moons are now known to orbit Saturn than were known in 1958; there are at least twenty satellites. In the novel, two moons play central roles: Titan, the largest of Saturn's moons, and Mimas, which Asimov (in 1958) states is the moon closest to the planet. However, we now know of closer moons. A photograph of Mimas taken by a fly-by probe shows a giant impact crater having a diameter about one-third that of Mimas. The crater, now named Hershel, has walls of about 16000 feet in height and a central mountain reaching up to 20000 feet. Just as in Asimov's novel, Mimas appears to be made up of mostly water ice, with 20%-to-50% rock. Titan has a substantial atmosphere, mostly nitrogen with some methane.