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Payload Specialists

Payload specialists are persons who have been designated by the National Aeronautics and Space Administration (NASA) or its commercial or international partners to serve as crewmembers in association with a specific payload and/or to accomplish a specific mission objective. Payload specialists include persons other than NASA astronauts who have specialized onboard duties; they may be added to the crew manifest if there are unique requirements or activities and more than the minimum crew size is needed. Individuals selected for crew assignment under the Space Flight Participant Program or similar programs also are referred to as payload specialists.

The payload specialist category represents an evolution in astronaut specialization. The first astronauts were required to have jet aircraft flight experience and engineering training. They conducted all operational and scientific activities aboard the spacecraft. Later, the emphasis shifted away from flight experience and toward superior academic qualifications. Some astronaut applicants were invited on the basis of their educational background alone. These were scientist astronaut candidates, so called because applicants were required to have a doctorate or equivalent experience in the natural sciences, medicine, or engineering.

During the era of the space shuttle, astronauts were further classified as space shuttle commanders and pilots responsible for controlling and operating the vehicle; mission specialists, who work with the commander and the pilot and are responsible for coordinating selective shuttle operations; and payload specialists with specialized onboard duties. Today the crew of each launched spacecraft is composed of astronauts or cosmonauts drawn from these categories.

Crew assignments for commander, pilot, and one or more mission specialists are drawn from among the cadre of NASA astronauts, whereas payload specialists are taken from among the selected and trained personnel designated by NASA or the commercial or international partner involved in the specific spaceflight mission. When payload specialists are required, they are nominated by NASA, the foreign sponsor, or the designated payload sponsor. In the latter two cases, these individuals may be cosmonauts or astronauts designated by other nations, individuals selected by a company or consortium flying a commercial payload aboard the spacecraft, or persons selected through some other formal selection process. In the case of NASA or NASA-related payloads, the nominations are based on the recommendations of the appropriate Investigator Working Group.

Although payload specialists are not strictly part of NASA's astronaut candidate program, they must have the appropriate education and training for the payload or experiment. Payload specialists have had a wide range of backgrounds, ranging from scientists and researchers to technicians and even a U.S. senator and congressional representative. Nevertheless, all payload specialist applicants must meet certain physical requirements and must pass NASA space physical examinations with varying standards that depend on classification.