NASA

The National Aeronautics and Space Administration — NASA — is the civilian agency that runs the American space program. It was created in 1958, a direct response to the shock of the Soviet Union's Sputnik satellite, to ensure the United States would not fall behind in the new arena of space.

Within just over a decade, NASA went from launching its first astronaut to landing humans on the moon. The Mercury, Gemini, and Apollo programs built on one another at a furious pace, driven by Cold War urgency and President Kennedy's pledge to reach the moon before the decade was out — a goal met in July 1969.

After Apollo, NASA turned to the reusable Space Shuttle, the building of the International Space Station, and a fleet of robotic explorers — the Hubble Space Telescope, Mars rovers, and probes that reached the outer planets and beyond. Its science transformed humanity's understanding of the universe.

NASA has endured tragedy, including the loss of the Challenger and Columbia shuttle crews, and shifting political support and budgets. But it remains the symbol of American achievement in space — and of the nation's capacity, when it chooses, to attempt the seemingly impossible.