A payload specialist (PS) is an individual selected and trained by commercial or research organizations for flights of a specific payload on a crewed spacecraft mission. People assigned as payload specialists included individuals selected by the research community, a company or consortium flying a commercial payload aboard the spacecraft, and non-NASA astronauts designated by international partners. The term refers to both the individual and to the position on the Shuttle crew.
History
The National Aeronautics and Space Act of 1958 states that NASA should provide the "widest practicable and appropriate dissemination of information concerning its activities and the results thereof". The Naugle panel of 1982 concluded that carrying civilians—those not part of the NASA Astronaut Corps—on the Space Shuttle was part of "the purpose of adding to the public's understanding of space flight". Payload specialists usually fly for a single specific mission. Chosen outside the standard NASA mission specialist selection process, they are exempt from certain NASA requirements such as colorblindness. Roger K. Crouch and Ulf Merbold are examples of those who flew in space despite not meeting NASA physical requirements; the agency's director of crew training Jim Bilodeau said in April 1981 "we'll be able to take everybody but the walking wounded". Payload specialists were not required to be United States citizens, but had to be approved by NASA and undergo rigorous but shorter training. In contrast, a Space Shuttle mission specialist was selected as a NASA astronaut first and then assigned to a mission. Payload specialists on early missions were technical experts to join specific payloads such as a commercial or scientific satellite. On Spacelab and other missions with science components, payload specialists were scientists with expertise in specific experiments. The term also applied to representatives from partner nations who were given the opportunity of a first flight on board of the Space Shuttle (such as Saudi Arabia and Mexico), to Congressmen and the Teacher in Space program. Under Secretary of the Air Force Edward C. Aldridge Jr. was offered a seat to improve relations between NASA and the United States Air Force. NASA expected to also fly "citizen astronauts", ordinary Americans who could describe space to others. In August 1984 President Ronald Reagan announced the Teacher in Space Project, the first such program. NASA expected to fly reporters (Journalist in Space Project), entertainers, and creative types later. NASA categorized full-time international astronauts as payload specialists unless they received NASA mission specialist training, which some did. Bilodeau estimated that payload specialists would receive a couple of hundred hours of training over four or five weeks. International or scientific payload specialists were generally assigned a back-up who trained alongside the primary payload specialist and would replace them in the event of illness or other disability. Both primary and backup payload specialists received mission-specific and general training. Michael Lampton estimated that about 20% of his training was general, including firefighter school, capsule communicator duty, and use of Personal Egress Air Packs and the space toilet. He described training for Spacelab 1 as "going back to graduate school but majoring in everything"; as the first mission it tested Spacelab's versatility in "medical, metallurgical, remote sensing, astronomy, microgravity, lots more". Payload specialists operated experiments, and participated in experiments needing human subjects. Charles D. Walker recalled that Senator Jake Garn "and I were the obvious subjects" for Rhea Seddon's echocardiograph on STS-51-D. "We really didn't have much of a choice in whether we were going to be subjects or not. 'You're a payload specialist; you’re going to be a subject.'" Besides his own electrophoresis work, Walker operated an unrelated experiment for the University of Alabama Birmingham, and helped build homemade repair tools for a satellite launched on the mission. Payload specialists were flown from 1983 (STS-9) to 2003 (STS-107). The last flown payload specialist was the first Israeli astronaut, Ilan Ramon, who was killed in the Columbia disaster on mission STS-107 with the rest of the crew. Chinese professor Gui Haichao became the first Chinese payload specialist and the first since the Space Shuttle Columbia disaster, flying on Shenzhou 16.
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