The term "astronaut" derives from the Greek words meaning "space sailor," and refers to all who have been launched as crew members aboard NASA spacecraft bound for orbit and beyond. Since the inception of NASA's human space flight program, we have also maintained the term "astronaut" as the title for those selected to join the NASA corps of astronauts who make "space sailing" their career profession. The term "cosmonaut" refers to those space sailors who are members of the Russian space program.

The crew of each launched spacecraft is made up of astronauts or cosmonauts drawn from the various categories described in these pages. The crew assignments and duties of commander, pilot, Space Shuttle mission specialist, or International Space Station flight engineer are drawn from the NASA professional career astronauts. A special category of astronauts typically titled "payload specialist" refers to individuals selected and trained by commercial or research organizations for flights of a specific payload on a space flight mission. At the present time, these payload specialists may be cosmonauts or astronauts designated by the international partners, individuals selected by the research community, or a company or consortia flying a commercial payload aboard the spacecraft.

These biographies are prepared by the Astronaut Office of the Johnson Space Center and are provided through the Internet as a public service to the World Wide Web community.

This resource has been assembled over more than a decade by internet encyclopedist Eric W. Weisstein with assistance from the internet community.

Eric Weisstein's World of Science is written and maintained by the author as a public service for scientific knowledge and education. Although it is often difficult to find explanations for technical subjects that are both clear and accessible, this web site bridges the gap by placing an interlinked framework of mathematical exposition and illustrative examples at the fingertips of every internet user.