The Orbital Manoeuvring System consists of two liquid fuel [link to OMS/RCS fuel info below] engines located in pods on either side of the OrbiterÕs aft fuselage. Once the SRBs and ET have separated from the Orbiter, the OMS engines provide the vehicle with the thrust [link to glossary] it needs to enter into orbit, to move from one orbit to another, and to leave orbit and enter back into the EarthÕs atmosphere. The OMS is gimballed [link to glossary] to move slightly back and forth, as well as up and down. It is used to steer the Orbiter through major changes in location and position while in space.

Each OMS engine produces a thrust of 26 700 Newtons [link to Newton info in SRB section].