Orbital Maneuvering System. These liquid-propellant rocket engines are mounted on the aft fuselage of a spacecraft, most notably the Space Shuttle. They provide the necessary delta-v for orbit insertion, major orbital corrections, rendezvous, and the critical deorbit burn. They typically rely on hypergolic propellants that ignite on contact, eliminating the need for complex ignition systems.
We're go for the OMS burn to circularize our orbit.
Related terms
Burn
A scheduled firing of a spacecraft propulsion system to alter its trajectory.
Deorbit burn
A retrograde engine firing that slows a spacecraft enough to re-enter the atmosphere.
Hypergolic
Describing a rocket propellant combination that ignites spontaneously upon contact.
Delta-v
The total change in velocity a spacecraft can achieve using its available propellant.