For small changes in location and position while in orbit, the Orbiter uses a system of clustered rocket engines called the reaction control system (RCS). The front and aft engines all point in different directions. Used in different combinations, they can propel the Orbiter in any direction. The RCS runs on liquid fuel [link to info below].

The aft pods each contain 12 primary engines and 2 Vernier engines [link to glossary]. The primary engines each produce a thrust of 3870 Newtons [link to Newton info in SRB section]. The two Vernier engines each produce a thrust of about 110 Newtons.