Astronauts

An astronaut or cosmonaut is a person trained by a human spaceflight program to command, pilot, or serve as a crew member of aspacecraft. 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 2002, astronauts were sponsored and trained exclusively by governments, either by the military, or by civilian space agencies. With the sub-orbital flight of the privately-funded SpaceShipOne in 2004, a new category of astronaut was created: the commercial astronaut.

As of June 20 2011, a total of 523 people from 38 countries^[5] have reached 100 km (62 mi) or more in altitude, of which 520 reached Low Earth orbit or beyond.^[6][7] 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.^[8]The criteria for what constitutes human spaceflight vary. The Fédération Aéronautique Internationale (FAI) Sporting Code for astronautics recognizes only flights that exceed an altitude of 100 kilometers (62 mi).^[3] In the United States, professional, military, and commercial astronauts who travel above an altitude of 50 miles (80 km)^[4] are awardedastronaut wings.

Under the U. S. definition, as of June 20 2011, 529 people qualify as having reached space, above 50 miles (80 km) altitude. Of eight X-15 pilots who exceeded 50 miles (80 km) in altitude, seven reached above 50 miles (80 km) but below 100 kilometers (about 62 miles).^[9] Space travelers have spent over 30,400 person-days (or a cumulative total of over 83 years) in space, including over 100 astronaut-days of spacewalks.^[9][10] 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.^[11][12] Peggy A. Whitson holds the record for the most time in space by a woman, 377 days.^[13]