The 'S' in NASA stands for "Space." NASA is an acronym for the National Aeronautics and Space Administration, which is the United States government agency responsible for the nation's civilian space program and for aeronautics and aerospace research. Founded in 1958, NASA plays a crucial role in advancing human knowledge through various missions, including manned spaceflights, robotic explorations of other planets, and Earth science research. The agency has contributed significantly to our understanding of space and technology, including famous missions such as the Apollo moon-landing program and the Mars Rover explorations.