The National Aeronautics and Space Administration (NASA) is an independent agency of the U.S. federal government responsible for the nation's civilian space program and for aeronautics and aerospace research. NASA was established in 1958, succeeding the National Advisory Committee for Aeronautics (NACA). The new agency was to have a distinctly civilian orientation, encouraging peaceful applications in space science.

Since its establishment, most U.S. space exploration efforts have been led by NASA, including the Apollo Moon landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion spacecraft, the Space Launch System, and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program, which provides oversight of launch operations and countdown management for uncrewed NASA launches.

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 spacecraft 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.

Since 2011, NASA's budget has been approximately $19 billion annually.