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. Although generally reserved for professional space travelers, the terms are sometimes applied to anyone who travels into space, including scientists, politicians, journalists and tourists.[1][2] The root "naut" derives from "nautes", Greek for "sailor." [3]
NASA astronaut Bruce McCandless II using a Manned Maneuvering Unit outside Space Shuttle Challenger on shuttle mission STS-41-B in 1984.
Until 2002, astronauts were sponsored and trained exclusively by governments, either by the military or by civilian space agencies. With the suborbital flight of the privately funded SpaceShipOne in 2004, a new category of astronaut was created: the commercial astronaut.
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