Space Shuttle Orbital Maneuvering System

The Orbital Maneuvering System (OMS ) provides the drive and the Reaction Control System position control of the Space Shuttle after the main engines were shut down and the U.S. space shuttle reaches orbit.

The OMS consists of two rocket engines, which are housed in two separate enclosures at the rear. The thrusters are quite simple in their construction and use hypergolic fuel that consists of two components that are already ignite on contact. Wherein an ignition system is not necessary, which increases the system reliability and reduced weight.

The OMS engines will be needed for the orbit is reached. They are also responsible for changes in the orbital altitude and perform Rendezvousmanövern. The OMS is also used at the end of a mission for the to leave the orbit necessary braking of the orbiter ( deorbit burn ).

The OMS engines burn monomethyl hydrazine and nitrogen tetroxide and deliver a thrust of 27 kN and a specific impulse of 313 seconds. They are reusable for 100 missions and can fire a thousand times. The total burn time is 15 hours. The Shuttle is fuel for a change in velocity of about 300 m / s. OMS engine is movably mounted and can be pivoted in the vertical axis of ± 7 degrees in the plane of the transverse axis by ± 8 degrees. This makes it possible to align the thrust vector to the center of gravity of the orbiter. Otherwise, there would be an undesirable rotation of the orbiter.

The fuel tank of the OMS can be used for the operation of the rear RCS thrusters, as both systems use the same fuel combination. This maneuver is called OMS -to -RCS interconnect. Use the RCS for the OMS fuel nozzle is not possible because the RCS tanks are of considerably smaller dimensions.

In addition, the fuel of an OMS - pods can be used for operation of the other, this is referred to crossfeed. A filling of a fuel tank through the other is not intended and is prevented by valves.