The Quatermass Experiment is a British science-fiction serial, broadcast by BBC Television in the summer of 1953, and re-staged by BBC Four in 2005. Set in the near future against the background of a British space programme, it tells the story of the first manned flight into space, overseen by Professor Bernard Quatermass of the British Experimental Rocket Group. When the spaceship that carried the first successful crew returns to Earth, two of the three astronauts are missing, and the third is behaving strangely. It becomes clear that an alien presence entered the ship during its flight, and Quatermass and his associates must prevent the alien from destroying the world. Originally comprising six half-hour episodes, it was the first science-fiction production to be written especially for an adult television audience. Previous written-for-television efforts such as Stranger from Space (1951–52) were aimed at children, whereas adult entries into the genre were adapted from literary sources, such as R.U.R. (1938 and again in 1948) and The Time Machine (1949). The serial was the first of four Quatermass productions to be screened on British television between 1953 and 1979. As well as spawning various remakes and sequels, The Quatermass Experiment inspired much of the television science fiction that followed it, particularly in the United Kingdom, where it influenced successful series such as Doctor Who and Sapphire and Steel.