Payload specialist was the designation given to astronauts trained for a single, specific mission on the United States space shuttle. The space shuttles were launched by the U.S. National Aeronautics and Space Administration (NASA) from 1981 through 2011. Most of the people who served on shuttle crews were selected for astronaut training in a highly competitive process. Payload specialists, on the other hand, were not selected for full astronaut training. The most common duty of a payload specialist was to perform a scientific experiment. There were 60 payload specialists who flew aboard the shuttle over the course of its operation. Several of them flew more than one mission.
Many payload specialists came from outside the United States. They flew aboard the shuttle to operate scientific experiments for their home countries. Some of them later received further training as international mission specialists. A mission specialist had duties similar to those of a payload specialist. But a mission specialist also received full astronaut training. Payload specialists that became international mission specialists included the Canadian engineer Marc Garneau and the Japanese scientist Mamoru Mohri.
Other payload specialists were U.S. military officers on classified missions to deploy military spacecraft. In January 1985, for example, the American engineer and Air Force pilot Gary Eugene Payton flew his sole space mission as a military payload specialist.
Employees of private companies have also flown as payload specialists. The American engineer Charles Walker flew on three missions for the aerospace company McDonnell Douglas. Walker conducted experiments in the development of a machine used to separate biological substances.
Three members of the U.S. Congress have flown as payload specialists. Senator Edwin J. (Jake) Garn flew aboard the shuttle in 1985. Representative Bill Nelson did so in 1986. Garn and Nelson both had important roles in ensuring that NASA received funding from congress. Senator John H. Glenn, Jr., flew as a payload specialist in 1998. In doing so, he became the oldest person to enter space at age 77. Before entering politics, Glenn had become the first American to orbit Earth in 1962.
The shuttle program was eventually terminated in 2011, following the loss of the shuttle Columbia on Feb. 1, 2003. Among the seven crew members killed was payload specialist Ilan Ramon, the first Israeli astronaut.
