Communications satellite. Composite artwork of a communications satellite orbiting the Earth. The Earth with its white clouds is seen on a starfield. The satellite has two long solar cell arrays (blue) to produce power, and a number of round dish antennae to receive and transmit communication signals. These satellites act as relay vehicles for radio signals. Communications satellites usually have a high geostationary orbit so that they maintain the same position over Earth. They may be used to relay telephone and fax messages, computer data, and to broadcast television signals.