Page 25 - Curriculum Visions Dynamic Book

Getting satellites into higher orbits
The Space Shuttle is designed for low-altitude orbiting (about 480 km). Many satellites need to be placed in orbit higher than this, and some extra boosters are required, of which
the inertial upper stage (IUS) is the most commonly used. It weighs about 20,000 kg and can place 2,500 kg of payload into geostAtionAry orbit.
The inertial upper stage uses support equipment installed in the orbiter to operate it and deploy it into space. Essentially, it is an engine that is temporarily attached to the payload and used to steer it into its proper orbit or to launch it into space. It has a computer guidance system that is controlled from Earth, not by the orbiter. It is maneuvered using engine gimbAls and a set of small engines that work like those on the Shuttle.
Once the IUS has accomplished its mission, it is released from the satellite.
geostAtionAry orbit A circular orbit 35,786 km directly above the Earth’s equator.
gimbAls A framework that allows anything inside it to move in a variety of directions.
pAyloAd The spacecraft that is carried into space by a launcher.
 Intertial upper stage carrying a satellite into higher orbit.
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