Reaction control system
This article needs additional citations for verification. (September 2014) |
A reaction control system (RCS) is a spacecraft system that uses
Reaction control systems are capable of providing small amounts of thrust in any desired direction or combination of directions. An RCS is also capable of providing torque to allow control of rotation (roll, pitch, and yaw).[1]
Reaction control systems often use combinations of large and small (vernier) thrusters, to allow different levels of response.
Uses
Spacecraft reaction control systems are used for:
- attitude control during different stages of a mission;[2]
- station keeping in orbit;
- close maneuvering during docking procedures;
- control of orientation, or "pointing the nose" of the craft;
- a backup means of deorbiting;
- ullage motors to prime the fuel system for a main engine burn.
Because spacecraft only contain a finite amount of fuel and there is little chance to refill them, alternative reaction control systems have been developed so that fuel can be conserved. For stationkeeping, some spacecraft (particularly those in
Location of thrusters on spacecraft
The
The Gemini spacecraft was also equipped with a hypergolic
The Apollo Command Module had a set of twelve hypergolic thrusters for attitude control, and directional reentry control similar to Gemini.
The Apollo Service Module and Lunar Module each had a set of sixteen R-4D hypergolic thrusters, grouped into external clusters of four, to provide both translation and attitude control. The clusters were located near the craft's average centers of mass, and were fired in pairs in opposite directions for attitude control.
A pair of translation thrusters are located at the rear of the Soyuz spacecraft; the counter-acting thrusters are similarly paired in the middle of the spacecraft (near the center of mass) pointing outwards and forward. These act in pairs to prevent the spacecraft from rotating. The thrusters for the lateral directions are mounted close to the center of mass of the spacecraft, in pairs as well.[citation needed]
Location of thrusters on spaceplanes
The suborbital X-15 and a companion training aero-spacecraft, the NF-104 AST, both intended to travel to an altitude that rendered their aerodynamic control surfaces unusable, established a convention for locations for thrusters on winged vehicles not intended to dock in space; that is, those that only have attitude control thrusters. Those for pitch and yaw are located in the nose, forward of the cockpit, and replace a standard radar system. Those for roll are located at the wingtips. The X-20, which would have gone into orbit, continued this pattern.
Unlike these, the
International Space Station systems
The International Space Station uses electrically powered control moment gyroscopes (CMG) for primary attitude control, with RCS thruster systems as backup and augmentation systems.[3][unreliable source?]
References
- ^ "REACTION CONTROL SYSTEM". science.ksc.nasa.gov.
- S2CID 225270552, retrieved 2022-09-27
- user-generated source]
External links
- NASA.gov
- Space Shuttle RCS Archived 2009-05-24 at the Wayback Machine