Shuttle Discovery comes one step closer to Return to Flight.
Space Shuttle Discovery has passed a major milestone in its Return to Flight preparations.
The shuttle orbiter's left-hand Orbital Maneuvering System, or OMS pod, was installed April 21.
Located on the vehicle's rear or aft end, the OMS engines are housed in two pods on opposite sides of the Space Shuttle Main Engines.
The Orbital Maneuvering System provides the necessary thrust for moving the vehicle while it's in space.
These tasks include establishing the proper orbit, changing to a different orbit, and rendezvous and docking maneuvers.
The OMS engines also perform the deorbit burn that begins the vehicle's descent back to Earth.
Discovery is slated to fly a crew of seven on mission STS-114 to the International Space Station.