As evidence has mounted in recent decades that Jupiter's moon Europa hosts a potentially habitable liquid water ocean larger than all of Earth's combined, NASA has made this 'ocean moon' an exploration priority. Excitement about the real possibility for life on Europa has prompted new lines of scientific inquiry and inspired science fiction authors to feature Europa in new works of speculative fiction. Before the 1980s, Europa figured into the pantheon of science fiction, but only as an exotic port of call, with little to distinguish it from a completely imagined planet except its name and location (such as in E.E. Smith's Spacehounds of IPC). To understand Europa's newfound prominence, we must understand a little about the history of planetary science and the mindset of the early science fiction writers of last century.
War of the Worlds, John Carter, 'little green men.' These familiar terms come from the golden age of 20th-century science fiction. Mars has inspired visions of advanced alien civilizations for more than 130 years, since Giovanni Schiaparelli's first maps from 1877 showing 'canali' were confirmed and the new features sensationalized as great works of alien ingenuity by Percival Lowell in the ensuing decades. Scientists seriously debated the possibility of intelligent life on Mars for 40 years thereafter, until Lowell's death in 1916.
Mars captured the imagination of scholars and artists, creating the modern space science fiction genre at a time when an industry in pulp magazines and comic book was just coming into existence. Amazing Stories, most prominent among these, was started by Hugo Gernsback (eponym of the highest award in science fiction, the Hugo), who credited his inspiration to reading Percival Lowell's work as a child.