Definition
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). In the United States, professional, military, and commercial astronauts who travel above an altitude of 50 miles (80 km) are awarded astronaut wings.
As of June 20, 2011, a total of 654 people from 38 countries have reached 100 km (62 mi) or more in altitude, of which 520 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, 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, only one exceeded 100 kilometers (about 62 miles). Space travelers have spent over 30,400 man-days (83 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.
Read more about this topic: Astronaut
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