An astronaut or cosmonaut is a person trained by a human spaceflight program to command, pilot, or serve as a crew member of a spacecraft. While generally reserved for professional space travelers, the term is sometimes applied to anyone who travels into space, including scientists, politicians, journalists, and tourists.^[1][2]

Until 2003, astronauts were sponsored and trained exclusively by governments, either by the military, or by civilian space agencies. With the sub-orbital fl...
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