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FOR SCIENCE...Global Communications

Applications Technology Satellites (ATS-6) If you look At Home, you will see the role NASA played in developing satellite TV transmission technology. But TV signals are only one kind of data transmitted by satellites. Telephone signals, computer data, and computer images are also beamed around the world via satellite.

Many American companies sell satellite data transmission services. These commercial space communications systems evolved from high-risk technology developed and tested in orbit by NASA in the 1960s and 1970s. This technology base allowed the US telecommunications industry to lead the way in building and operating communications satellites.

NASA’s series of Applications Technology Satellites (ATS) were launched between 1966 and 1974. These satellites (ATS-6 shown above) stimulated advancements in telecommunications technologies in areas such as:

  • geosynchronous orbit (GEO) - orbiting with the Earth so that the satellite is always above a particular spot on the ground
  • satellite stabilization - keeping the satellite from wobbling in orbit
  • use of digital computers
  • solid state high-power transmitters
  • large antennae that provide high quality signals to small ground receivers
  • advanced materials (such as graphite composites) for building satellites

GEO satellitesNASA also pioneered the use of GEO satellites to “look down on" low Earth orbit (LEO) satellites. The GEO satellites relay data between the lower LEO satellites. Data is also relayed from the LEO satellite through the GEO satellite and down to the ground. This technology means that NASA and satellite companies can operate their satellites with a minimum of ground stations.

NASA has deployed six of its own Tracking and Data Relay Satellites. TDRSS is a network of GEO satellites that provides communications and tracking services to the Space Shuttle and other low-earth orbiting spacecraft.

The latest in a long line of NASA experimental communications satellites is the Advanced Communications Technology Satellite (ACTS) (shown at left). Launched in September 1993, ACTS serves as a "switchboard in the sky." ACTS is being used by industry, universities, and government to develop new satellite services, including real-time TV transmission to airliners.

Today, commercial companies are taking the lead in providing satellite services to the public. However, with ACTS, NASA remains on the forefront of developing satellite and data transmission technology.