The crew of STS-127 make their way to the Astrovan that will take them to the launch pad of Space Shuttle Endeavour. CSA Astronaut Julie Payette, pictured in the second row, waves to the crowd. July 15, 2009. (Image: NASA)
Space Shuttle crew members need to be highly skilled in every shuttle system for operations to run smoothly and safely. They are assigned to specialized duties on board the Shuttle in one of the following positions:
Space Shuttle Endeavour launches in a plume of smoke and fire en route to the International Space Station. On board are the seven-member STS-127 crew, which includes CSA Astronaut and Mission Specialist Julie Payette. Endeavour delivered the Japanese Experiment Module's Exposed Facility and the Experiment Logistics Module-Exposed Section, payloads that completed the assembly of the Japan Aerospace Exploration Agency's Kibo laboratory. July 15, 2009. (Image: NASA)
Canadian Space Agency Astronaut Steve MacLean, Payload Specialist during STS-52, peers out from an aft-deck window of Space Shuttle Columbia. October 22 to November 1, 1992. (Image: NASA)
STS-85 Mission Specialist Stephen Robinson (left) and Payload Specialist CSA Astronaut Bjarni Tryggvason check out an emergency egress slidewire basket at the 195-foot level of Launch Pad 39A during Terminal Countdown Demonstration Test activities for that mission. (Image: NASA)
Each Shuttle flight requires a minimum of four crewmembers to operate safely, of which there must be at least one commander, one pilot, and two mission specialists. Until 1995, Canadian astronauts were only authorized to fly on the Shuttle as payload specialists. Today, however, all Canadian astronauts are trained as mission specialists.
The term "payload" refers to any cargo aboard the Shuttle other than what is necessary for Shuttle operations. For example, equipment to be put into orbit and materials used in scientific experiments are considered payloads.
The End of an Era
Space Shuttle Atlantis returns to the Kennedy Space Center, concluding Mission STS-115. CSA Astronaut Steve MacLean was a crewmember. September 21, 2006. (Image: NASA)
After over 30 years of operations, the Space Shuttle program will wind down in 2011. Two flights remain, STS-134 in April and STS-135 in July. To ferry astronauts to the Space Station after the last shuttle, NASA intends on buying seats on the Russian Soyuz spacecraft and through private companies.