Communication Satellites By Daniela

What are communication satellites, and what are they used for?

Communication satellites are satellites that have been stationed in space for the purpose of providing telecommunications. Communication satellites are spacecrafts that orbit the Earth. Satellites are radio relay stations in space. They receive radio signals sent from Earth and then send signals back down to a different part of the Earth.

One satellite in space can replace hundreds of relay stations on the ground. Early communication satellites weighed about the same as a television set, but today they can weigh as much as four family cars and be as big as a bus. A modern communication satellite can handle television programs, thousands of telephone calls and internet information at the same time.
Communication Satellites send information to Earth. Phone messages, radio signals, photos and information are the main purposes for communication satellites.
How are satellite signals received?

Satellites communicate by using radio waves to send signals to the antennas on the Earth. The antennas then capture those signals and process the information coming from those signals. Information can include:

  • Scientific data (like the pictures the satellite took)
  • The health of the satellite.
  • Where the satellite is currently located in space.
Satellites can't send information to the ground if the ground stations are hidden from view. Tracking Data Relay Satellites pass the communication satellites information to the ground stations on Earth.
How are satellite signals used?

Nine TDRS (Tracking Data Relay Satellites) sit about 35,400 kilometres above the Earth and are able to forward information from a satellite until it reaches the appropriate ground station in view, to that TDRS at either White Sands, New Mexico or Guam Island. TDRS can also send information from the ground to the satellite to tell the satellite what to do (take a picture, turn a sensor or off, send stored data back or change its orbit). TDRS allows NASA to have global coverage of all the satellites-24 hours a day- without having to build extra ground stations on Earth.

When were they first used?

Communication satellites have been around since 1958. The first communication satellites moved fast across the sky, like shooting stars. Radio aerials on Earth had to turn to keep pointing at them. Today, most communication satellites orbit above the same place on Earth. Aerials on Earth can stay still, pointing at the same spot in space, instead of spinning. The first type of satellite communication was Syncom 3 in 1964.

Echo, was NASA’s first communication satellite. It was a passive spacecraft based on a balloon design. Echo was made by an engineer at the Langley Research Centre. Echo was made of Mylar, the satellite measured 30m in diameter. Once in orbit, the air in the balloon expanded and Echo began its task of reflecting radio transmissions from one ground station to another. Echo could be seen from Earth with the naked eye.

First Pass of Echo 1 Satellite Over the Goldstone Tracking Station
How Many Satellites Orbit The Earth?
Time lapse 1957 - 2015

(White Dots = Satellites)


Created with images by NASA Goddard Photo and Video - "GPM Core Observatory" • SpaceX-Imagery - "satellite orbit spacex"

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