"Mission specialist" is one of two categories of astronauts in the U.S. space program. Mission specialist astronauts team up with astronaut pilots to form a space shuttle or station crew, and together they operate the spacecraft and carry out the mission's flight plan.
The National Aeronautics and Space Administration (NASA) created the term "mission specialist" in 1978 when it hired the first group of space shuttle astronauts. The agency recognized that in addition to the two pilot astronauts in the front seats of the space shuttle (the commander and the pilot), the spacecraft would require additional crew members to conduct orbital operations. One mission specialist would aid the pilots as the flight engineer. Other mission specialists would operate the shuttle's Canadian-built robot arm and leave the shuttle cabin in protective space suits to carry out extravehicular activity (EVA), commonly known as space walks. They would also have the primary responsibility for operating scientific experiments aboard the shuttle, either in the cabin or in a bus-size laboratory called Spacelab carried in the shuttle's cargo bay.
Because of these specialized responsibilities, NASA dropped the requirement that mission specialist candidates be aviators or test pilots. Instead, the administration sought persons with a strong scientific, engineering, or medical background. Successful candidates have at least a master's degree in the sciences or engineering, and many of them have earned a doctorate or medical degree. While undergoing their first year of training, all mission specialists become qualified air crew members in NASA's fleet of T-38 jet trainers. Once assigned to a flight, mission specialists receive the detailed training necessary to accomplish the mission's objectives: space station construction, microgravity research, satellite repair, robot arm or EVA operations, remote sensing of Earth or the universe, and other types of scientific experimentation.
Experienced mission specialists can expect to fly on the space shuttle every two to four years. Between flight assignments they support other shuttle or station crews in training and in orbit and participate in the assembly or testing of spaceflight hardware. On flights with complex scientific payloads a mission specialist may serve as the payload commander, advising the shuttle commander on the health and status of the experiment and overseeing its operations. Mission specialists are also eligible for a long-duration expedition (four to five months in length) aboard the International Space Station (ISS), where they can serve as flight engineers or commanders.
The most demanding skills required of mission specialists are those involved in robot arm operations or in conducting an EVA. To perform either task a mission specialist may train for hundreds of hours, using simulators that recreate the spaceflight environment. Arm operators learn to "fly" the arm on computer displays and then on a full-scale high-fidelity arm simulator. EVA astronauts train for weightlessness in a huge swimming pool that makes their space suits neutrally buoyant, giving them an accurate feel for the movements needed to work in freefall . Another important skill for mission specialists is teamwork; crewmembers must work closely together on critical tasks to minimize mistakes and ensure accuracy. With the wide range of skills required for future expeditions to the Moon, asteroids, or Mars, mission specialists will be an important part of the future astronaut corps.
see also Astronauts, Types of (volume 3); Career Astronauts (volume 1); Payload Specialists (volume 3); Payloads (volume 3); Space Shuttle (volume 3); Space Walks (volume 3); T-38 Trainers (volume 3); Women in Space (volume 3).
Thomas D. Jones
Cooper, Henry S.F., Jr. Before Lift-Off: The Making of a Space Shuttle Crew. Baltimore, MD: Johns Hopkins University Press, 1987.
Dyson, Marianne J. Space Station Science: Life in Free Fall. New York: Scholastic Reference, 1999.
Jones, Thomas D., and June A. English. Mission: Earth—Voyage to the Home Planet. New York: Scholastic Press, 1996.
How Do You Become an Astronaut? NASA Human Spaceflight. <http://www.spaceflight.nasa.gov/outreach/jobsinfo/astronaut.html>.