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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. Starting in the 1950s up to 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. ==Definition== The criteria for what constitutes human spaceflight vary. The Fédération Aéronautique Internationale (FAI) Sporting Code for astronautics recognizes only flights that exceed an .〔(FAI Sporting Code, Section 8, Paragraph 2.12.1 )〕 In the United States, professional, military, and commercial astronauts who travel above an altitude of 〔(NASA – X-15 Space Pioneers Now Honored as Astronauts )〕 are awarded astronaut wings. , a total of 532 people from 36 countries have reached or more in altitude, of which 529 reached low Earth orbit or beyond. Of these, 24 people have traveled beyond Low Earth orbit, to either lunar or trans-lunar orbit or to the surface of the moon; three of the 24 did so twice: Jim Lovell, John Young and Eugene Cernan. The three astronauts who have not reached low Earth orbit are spaceplane pilots Joe Walker, Mike Melvill, and Brian Binnie. , under the U.S. definition 538 people qualify as having reached space, above altitude. Of eight X-15 pilots who exceeded in altitude, only one exceeded 100 kilometers (about 62 miles). Space travelers have spent over 41,790 man-days (114.5 man-years) in space, including over 100 astronaut-days of spacewalks.〔 As of 2008, the man with the longest cumulative time in space is Sergei K. Krikalev, who has spent 803 days, 9 hours and 39 minutes, or 2.2 years, in space. Peggy A. Whitson holds the record for the most time in space by a woman, 377 days. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Astronaut」の詳細全文を読む スポンサード リンク
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