A reaction control system (RCS) is a subsystem of a spacecraft whose purpose is attitude control and steering by the use of thrusters. An RCS system is 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). This is in contrast to a spacecraft's main engine, which is only capable of providing thrust in one direction, but is much more powerful.
RCS systems often use combinations of large and smaller (vernier) thrusters, to allow different levels of response from the combination.
Reaction control systems are used:
- for attitude control during re-entry;
- for stationkeeping in orbit;
- for close maneuvering during docking procedures;
- for control of orientation, or 'pointing the nose' of the craft;
- as a backup means of deorbiting;
- for Harrier "jump jet" stabilisation during operations below stall speed.
Because spacecraft only contain a finite amount of fuel and there is little chance to refill them, some alternative reaction control systems have been developed so that fuel can be conserved. For stationkeeping, some spacecraft (particularly those in geosynchronous orbit) use high-specific impulse engines such as arcjets, ion thrusters, or Hall effect thrusters. To control orientation, a few spacecraft use momentum wheels which spin to control rotational rates on the vehicle.
Read more about Reaction Control System: Location of Thrusters On Space Capsules, Location of Thrusters On Spaceplanes
Famous quotes containing the words reaction, control and/or system:
“In contrast to revenge, which is the natural, automatic reaction to transgression and which, because of the irreversibility of the action process can be expected and even calculated, the act of forgiving can never be predicted; it is the only reaction that acts in an unexpected way and thus retains, though being a reaction, something of the original character of action.”
—Hannah Arendt (19061975)
“If someone does something we disapprove of, we regard him as bad if we believe we can deter him from persisting in his conduct, but we regard him as mad if we believe we cannot. In either case, the crucial issue is our control of the other: the more we lose control over him, and the more he assumes control over himself, the more, in case of conflict, we are likely to consider him mad rather than just bad.”
—Thomas Szasz (b. 1920)
“It would be enough for me to have the system of a jury of twelve versus the system of one judge as a basis for preferring the U.S. to the Soviet Union.... I would prefer the country you can leave to the country you cannot.”
—Joseph Brodsky (b. 1940)