Lucky Starr and the Moons of Jupiter is the fifth 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 August 1957. It is the only novel by Asimov set in the Jovian system. Setting Lucky Starr and the Moons of Jupiter takes place in the Jovian system. In the mid-1950s, when the novel was written, Jupiter had twelve known satellites. The first half of the novel takes place on what was then the outermost known satellite, Jupiter IX, discovered by Seth Barnes Nicholson in 1914. Jupiter IX had been given the unofficial name 'Hades' in 1955, but in the novel Asimov mistakenly refers to it as Adrastea, which was the unofficial name of Jupiter XII. The confusion doubtless arose from the fact that Jupiter IX was the twelfth farthest known satellite, while Jupiter XII was the ninth farthest known satellite. In 1975, the International Astronomical Union gave Jupiter IX the official name Sinope. Asimov describes Jupiter IX as being 89 miles in diameter, but its diameter is now thought to be only 23 miles. Part of the novel is also set on Io, the innermost of the Galilean moons. Io is depicted as having a thin atmosphere of methane, and fields of ammonia snow and ice, as well as rivers of liquid ammonia. Plot summary For six years, Jupiter IX has been the site of a secret project to develop an antigravity, or Agrav, space drive; but the Council of Science learns that information from the project is released to the enemy Sirians. A month after returning from Mercury, protagonists David "Lucky" Starr and John Bigman Jones are sent to Jupiter IX to investigate, bringing a V-frog to aid the investigation. Upon reaching IX, Starr and Bigman are warned away by the head of the project, Commander Donahue, who argues the men on the project are angry at investigation and may threaten Starr's safety. Starr and Bigman land nevertheless, and are met by a large group of workers led by a man named Red Summers, who insists that Starr take part in a duel in an Agrav corridor against a much larger man called Big Armand. During the duel, Bigman realizes Summers is sabotaging Starr's Agrav harness and forces Summers to stop at gunpoint, whereupon Starr wins