Ringworld is a 1970 science fiction novel by Larry Niven, set in his Known Space universe and considered a classic of science fiction literature. Ringworld tells the story of Louis Wu and his companions on a mission to the Ringworld, a rotating wheel artificial world, an alien construct in space in diameter. Niven later added three sequel novels and then cowrote, with Edward M. Lerner, four prequels and a final sequel; the five latter novels constitute the Fleet of Worlds series. All the novels in the Ringworld series tie into numerous other books set in Known Space. Ringworld won the Nebula Award in 1970, as well as both the Hugo Award and Locus Award in 1971. Plot summary On planet Earth in 2850 AD, Louis Gridley Wu is celebrating his 200th birthday. Despite his age, Louis is in perfect physical condition due to the longevity drug boosterspice. He meets Nessus, a Pierson's puppeteer, who offers him a mysterious job. Intrigued, Louis eventually accepts. Speaker-to-Animals (Speaker), who is a Kzin, and Teela Brown, a young human woman who becomes Louis's lover, also join the crew. On the puppeteer home world, they are told that the expedition's goal is to investigate the Ringworld, a gigantic artificial ring, to see if it poses any threat. The Ringworld is about one million miles (1.6 million km) wide and approximately the diameter of Earth's orbit (which makes it about 584.3 million miles or 940.4 million km in circumference), encircling a sunlike star. It rotates to provide artificial gravity 99.2% as strong as Earth's from centrifugal force. The Ringworld has a habitable, flat inner surface (equivalent in area to approximately three million Earths), a breathable atmosphere and a temperature optimal for humans. Night is provided by an inner ring of shadow squares which are connected to each other by thin, ultra-strong wire. When the crew completes their mission, they will be given the starship in which they travelled to the puppeteer home world; it is orders of magnitude faster than any possessed by humans or Kzinti. When they reach the vicinity of the Ringworld, they are unable to contact anyone, and their ship, the Lying Bastard, is disabled by the Ringworld's automated meteoroid-defense system. The severely damaged vessel collides with a strand of shadow-square wire and crash-lands near a huge mountain, "Fist-of-God". As the fusion drive is destroyed, they are unable to launch back into space