The world of Barsoom is a romantic vision of a dying Mars, based on now outdated scientific ideas made popular by Astronomer Percival Lowell in the early 20th century. While depicting many outlandish inventions, and advanced technology, it is a savage, 'frontier' world, of honor, noble sacrifice and constant struggle, where martial prowess is paramount, and where many races fight over dwindling resources. It is filled with lost cities, heroic adventures and undiscovered ancient secrets. The series has inspired a number of well known science fiction writers, and also key scientists involved in both space exploration and the search for extraterrestrial life. It has informed and been adapted by many writers, in novels, short stories, television and film.