Orbiting satellites: Electrical power is solar. A small amount of compressed gas or other rocket fuel is used for attitude and orbit correction. A broadcasting satellite may have enough panels and batteries to produce 15 kW of power for its transponders 24/7. In practice, the panels degrade rapidly - and at the end of life, the satellite will be able to support considerably fewer transponders than when new.
Deep space probes: Once you get past about mars - the sunlight is too feeble to produce useful power. Electrical power in these probes is usually produced by a radio-isotope thermal generator (usually plutonium 238). The power from such generators is extremely feeble, and correspondingly the transmitters are very, very weak - about the same power as a cell phone. You need
huge, incredibly precisely aimed dishes, super sensitive receivers and advanced signal processing techniques to decode the signal once it gets to earth.
I thought maneuvering was controlled by rotating Gyros.
many satellites use 'reaction wheels'. These are gyro like devices, that if the satellite starts to spin in one direction, an electric motor is used to change the speed of the rotating center. Due to Newton's first law, the opposite change is made to the satellite's rotation.
Eventually, the reaction wheel reaches it's maximum speed - when this happens, the wheel is braked - but the satellite is stopped from going into an out of control spin, by simultaneous activation of a thruster that exactly cancels out the effect of braking the wheel. Using a wheel, drastically reduces the number of times that thrusters must be fired, saving fuel.
