The National Aeronautics and Space Administration (NASA, pronounced /ˈnæsə/) is an Executive Branch agency of the United States government, responsible for the nation's civilian space program and aeronautics and aerospace research. Since February 2006, NASA's self-described mission statement is to "pioneer the future in space exploration, scientific discovery and aeronautics research."
NASA was established by the National Aeronautics and Space Act on July 29, 1958, replacing its predecessor, the National Advisory Committee for Aeronautics (NACA). The agency became operational on October 1, 1958. NASA has led U.S. efforts for space exploration since, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and has been developing the manned Orion spacecraft.
NASA science is focused on better understanding Earth through the Earth Observing System, advancing heliophysics through the efforts of the Science Mission Directorate's Heliophysics Research Program, exploring bodies throughout the Solar System with advanced robotic missions such as New Horizons, and researching astrophysics topics, such as the Big Bang, through the Great Observatories and associated programs. NASA shares data with various national and international organizations such as from the Greenhouse Gases Observing Satellite.
After the Soviet space program's launch of the world's first artificial satellite (Sputnik 1) on October 4, 1957, the attention of the United States turned toward its own fledgling space efforts. The U.S. Congress, alarmed by the perceived threat to national security and technological leadership (known as the "Sputnik crisis"), urged immediate and swift action; President Dwight D. Eisenhower and his advisers counseled more deliberate measures. Several months of debate produced an agreement that a new federal agency was needed to conduct all non-military activity in space. The Advanced Research Projects Agency (ARPA) was also created at this time to develop space technology for military application.
From late 1957 to early 1958, the National Advisory Committee for Aeronautics (NACA) began studying what a new non-military space agency would entail, as well as what its role might be, and assigned several committees to review the concept. On January 12, 1958, NACA organized a "Special Committee on Space Technology", headed by Guyford Stever. Stever's committee included consultation from the Army Ballistic Missile Agency's large booster program, referred to as the Working Group on Vehicular Program, headed by Wernher von Braun, a German scientist who became a naturalized US citizen after World War II.
On January 14, 1958, NACA Director Hugh Dryden published "A National Research Program for Space Technology" stating: