Way" and the 1981 short story "The Iceworm Special" by Joe Martino, and provide raw material for a weapon in the 1935 short story "Menace from Saturn" by Clifton B. Kruse. One of the rings is painted red by a religious group in the 1977 short story "Equinoctial" by John Varley, while another faction seeks to undo the colour change. In Asimov's 1986 novel Foundation and Earth, the rings allow for positive identification of the Solar System in the far future. Owing to the aesthetic appearance of the rings, the vicinity of Saturn is a popular setting for spacecraft in visual media. Moons Saturn's moons, especially Titan, have generally received more attention from writers than the planet itself. The satellite system hides a large circular sentient artificial world in John Varley's 1979–1984 Gaea trilogy that begins with the novel Titan. Titan As a comparatively Earth-like world, Titan has attracted attention from writers as a place that could be colonized by humans and inhabited by extraterrestrial life. Early depictions of native inhabitants of the moon appear in the form of giant protozoa in Bob Olsen's 1932 short story "Captain Brink of the Space Marines" and enormous thinking spiders in Edwin K. Sloat's 1932 short story "Loot of the Void". Stanley G. Weinbaum's 1935 short story "Flight on Titan" features telepathic threadworms, the first appearance of what would later become a recurring image of Titanian life as similar to terrestrial slugs. The 1941 novel Sojarr of Titan by Manly Wade Wellman tells the tale of a human child who grows up orphaned on Titan, inspired by Edgar Rice Burroughs' Tarzan books. Titan became more popular as a setting for science fiction stories in the 1950s as advances in planetary science revealed the harsh conditions of Mars and Venus. The 1951 novel The Puppet Masters by Robert A. Heinlein tells the story of an alien invasion by parasitic mind-controlling "slugs" from Titan that can be defeated only by a plague from the jungles of Venus, and slug-like aliens from Titan exert indirect influence on humans on Earth by having them play games in the 1963 novel The Game-Players of Titan by Philip K. Dick. The colonization of Titan is depicted in the 1954 novel Trouble on Titan by Alan E. Nourse, the 1961 short story "Saturn Rising" by Arthur C. Clarke depicts efforts to attract tourists to the moon, and the 1975 novel