International Space Station Assembly Flight 3A
Discovery and its seven-member crew will set the stage for future
International Space Station assembly missions during STS-92 by delivering
Pressurized Mating Adapter 3, or PMA 3, and an exterior framework
structure, the Z1 Truss, to the station. The STS-92 astronauts will
conduct four space walks and use Discovery's robot arm to install
the Z1 Truss and connect PMA 3 to the space station's Unity Connecting
Truss will be the first permanent latticework structure for
the space station, very much like a girder, setting the stage for
the future addition of the station's major trusses or backbones.
The Z1 fixture will also serve as the platform on which the huge
U.S. solar arrays will be mounted on the next shuttle assembly flight,
STS-97. It includes
power distribution components, four flat discs that will be used
to control the station's attitude, communications equipment, temperature
control system hardware, space walk/extravehicular aids and power,
data and coolant connections.
3 will provide a place for an orbiter to dock with the U.S.
segment of the International Space Station. PMA 3 includes latches
and hooks to be used in docking, space walk aids, heaters and temperature
control equipment, electrical power subsystem, and data cables that
can be hooked up to a docked spacecraft. PMA 3 will not be used
for docking until assembly flight 4A.