Reaction control system

(Last edited: Monday, 2 October 2023, 5:48 PM)


Image Shepard, A., NASA. (1972, December). Apollo 14 LM RCS quads. Retrieved form

Image Shepard, A., NASA. (1972, December). Apollo 14 LM RCS quads. Retrieved form

Short Definition

Reaction control system (RCS) is a system of low-thrust engines that is used to control orientation of a spacecraft in space (attitude control) and for fine position and velocity adjustments.

Detailed Definition

The reaction control system of a spacecraft consists of multiple low-thrust engines that are placed symmetrically on the spacecraft equidistantly from its barycentre to ensure even force and torque distribution. Thrusters can provide thrust in any direction and combining thrusters in different positions allows acquiring force in any direction or torque in any plane, which enables the spacecraft to perform translational motion in any direction and any of roll, pitch and yaw rotations. RCS is used for attitude control (for example, to keep a telescope pointed at one object for a long time), precise manoeuvring (for example, while spacecraft docking), orbit correction and other purposes.


Reaction – re- (back, again, anew) + action (from French réaction)Control – from Anglo-French contreroller– exert authoritySystem – from Late Latin or Greek systema– an arrangement, organized whole, a whole compounded of parts

Sample Sentences

The spacecraft's reaction control system precisely adjusts the orientation and stability of the vehicle during maneuvers in the microgravity environment of space.

Translations in partner languages:

German: Reaktionskontrollsystem (RCS)

French: système de contrôle de la réaction (RCS)

Swedish: seaktionskontrollsystem (RCS)

Polish: system sterowania reakcyjnego (RCS)

Italian: sistema di controllo della reazione (RCS)

Translations in other languages:

Russian: Реактивная система управления

Ukrainian: Реактивна система керування


Colas, A. L., Valenzuela, J. G. (2020, August). Reaction Control System Performance Characterization using Vacuum Chamber Thrust Stand. Retrieved form

Boeing. (2006, November). ISS Motion Motion Control System. Retrieved from;topic=34777.0;attach=586775

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