![]() ![]() The space probes Voyager 1 and Voyager 2 employ this method, and have used up about three quarters of their 100 kg of propellant as of July 2015. Thrusters may also be referred to as mass-expulsion control (MEC) systems, or reaction control systems (RCS). One method is to use small thrusters to continually nudge the spacecraft back and forth within a deadband of allowed attitude error.Three-axis stabilization is an alternative method of spacecraft attitude control in which the spacecraft is held fixed in the desired orientation without any rotation.The Pioneer 10 and Pioneer 11 probes in the outer solar system are examples of spin-stabilized spacecraft. If desired, the spinning may be stopped through the use of thrusters or by yo-yo de-spin. ![]() Propulsion system thrusters are fired only occasionally to make desired changes in spin rate, or in the spin-stabilized attitude. Main article: Spin stabilization Spin stabilization is accomplished by setting the spacecraft spinning, using the gyroscopic action of the rotating spacecraft mass as the stabilizing mechanism. It is often needed so that the spacecraft high-gain antenna may be accurately pointed to Earth for communications, so that onboard experiments may accomplish precise pointing for accurate collection and subsequent interpretation of data, so that the heating and cooling effects of sunlight and shadow may be used intelligently for thermal control, and also for guidance: short propulsive maneuvers must be executed in the right direction.Īttiude control of spacecraft is maintained using one of two principal approaches: The integrated field that studies the combination of sensors, actuators and algorithms is called guidance, navigation and control (GNC).Ī spacecraft's attitude must typically be stabilized and controlled for a variety of reasons. Spacecraft attitude control is the process of controlling the orientation of a spacecraft (vehicle or satellite) with respect to an inertial frame of reference or another entity such as the celestial sphere, certain fields, and nearby objects, etc.Ĭontrolling vehicle attitude requires sensors to measure vehicle orientation, actuators to apply the torques needed to orient the vehicle to a desired attitude, and algorithms to command the actuators based on (1) sensor measurements of the current attitude and (2) specification of a desired attitude. For attitude control of aircraft, see Aircraft flight dynamics. For the use in psychology, see Attitude change. ![]()
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