using a manned maneuvering unit outside the U.S. Space Shuttle Challenger in 1984]] 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. Definition Until 2003, astronauts were sponsored and trained exclusively by governments, either by the military, or by civilian space agencies. However, with the first sub-orbital flight of the privately-funded SpaceShipOne in 2004, a new category of astronaut was created: the commercial astronaut. With the rise of space tourism, NASA and the Russian Federal Space Agency agreed to use the term "spaceflight participant" to distinguish those space trave