The Moons of Jupiter

This is the sixth book in the Lucky Starr series, originally published under the pseudonym Paul French. In this volume, Starr and Bigman Jones travel to a moon of Jupiter to discover the cause of a series of accidents on a secret project to develop a space craft with an antigravity engine. They uncover a spy of Earth's enemy, Sirius. Jupiter IX is called Adrastea in the novel; however, now Adrastea is referred to as Jupiter XV (more (16) satellites are known now than were known in 1957). It is one of the closest moons to Jupiter's surface and could not be the moon referred to in the novel. In an introduction written in 1978, Asimov apologizes for some of the scientific inaccuracies in the story due to all of the new information that had been discovered since 1957. Besides the number of moons, Jupiter's magnetosphere would present severe difficulties to space travelers. The intense radiation field that surrounds Jupiter would be fatal to travelers unless some new method is available to counter the problem. It is also doubtful that the characters would have landed on Io due to its large degree of volcano activity (there are at least eight active volcanos). There is also evidence that Io forms a ring (or torus) around Jupiter consisting of ionized sulfur and oxygen. In 1989, it was discovered from infrared spectroscopy using Earth-based equipment that Io has hydrogen sulfide on its surface. The characters in the novel also land on Amalthea (Jupiter V). This moon, discovered in 1892, is small and has a low orbit. Also unknown in either 1957 and 1978 was the fact that Jupiter has a single faint ring encircling the planet, a ring not detected by Earth-based observatories.