Space Shuttle is developed by the National Aeronautics
and Space Administration. NASA coordinates and manages
the Space Transportation System (NASA's name for the
overall Shuttle program.) The Space Shuttle system consists
of four primary elements: an orbiter spacecraft, two
Solid Rocket Boosters (SRB), an external tank to house
fuel and three Space Shuttle main engines.
The space shuttle is the world's first
reusable spacecraft, and the first spacecraft in history
that can carry large satellites both to and from orbit.
The shuttle launches like a rocket, maneuvers in Earth
orbit like a spacecraft and lands like an airplane.
Each of the three space shuttle orbiters now in operation
-- Discovery, Atlantis and Endeavour -- is designed
to fly at least 100 missions.