Gemini 3 was the first crewed mission in NASA's Project Gemini and was the first time two American astronauts flew together into space. On March 23, 1965, astronauts Gus Grissom and John Young flew three low Earth orbits in their spacecraft, which they nicknamed Molly Brown. It was the first U.S. mission in which the crew fired thrusters to change the size and shape of their orbit, a key test of spacecraft maneuverability vital for planned flights to the Moon. It was also the final crewed flight controlled from Cape Kennedy Air Force Station in Florida, before mission control functions were moved to a new control center at the newly opened Manned Spacecraft Center in Houston, Texas.

The National Aeronautics and Space Administration (NASA ) is an independent agency of the U.S. federal government responsible for the civilian space program, as well as aeronautics and space 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 US space exploration efforts have been led by NASA, including the Apollo Moon landing missions, the Skylab space station, and later the Space Shuttle. NASA is supporting the International Space Station and is overseeing the development of the Orion spacecraft, the Space Launch System, Commercial Crew vehicles, and the planned Lunar Gateway space station. The agency is also responsible for the Launch Services Program, which provides oversight of launch operations and countdown management for uncrewed NASA launches.

NASA's 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 such as New Horizons; and researching astrophysics topics, such as the Big Bang, through the Great Observatories and associated programs.