The communications system involves the equipment used to receive signals from Earth and send signals back to Earth. The main signals that are sent and received involve tracking, telemetry and command. Tracking involves satellite positioning—the satellite needs to communicate its location so that scientists can make any necessary adjustments. These adjustments are the command component, which involves any directions scientists send from Earth that change what the satellite is doing, including adjusting its position or rate of data collection, etc. Lastly, the satellite sends the data it is collecting back to Earth. The technology of automatic measurements and transmission of the data back to a receiving source is known as
telemetry.
Various computers onboard allow scientists to track and command the satellite, as well as to assemble the data for the satellite to send back to the scientists. Then the satellite needs a way to transmit the data, and amplify the signal such that it can be received on Earth. To transmit data, the satellite has one or more
antennae, a round dish that reflects a signal to a focal point for transmission. To amplify the signal, satellites have
transponders. Transponders shift the frequency of signals and amplify them so that Earth can receive them.
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Parts of a Satellite |
Maneuvering |
Power Supply |
Thermal Controls | Communications Devices |
OCO-2 and ASCENDS |
NASA Missions