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How Do Astronauts on the Space Station Stay in Touch with Earth?

The TDRS satellites help NASA stay in touch with the International Space Station. Credit: NASA

The TDRS satellites help NASA stay in touch with the International Space Station. Credit: NASA

Gemini 8 was in trouble. The spacecraft was spinning rapidly, the astronauts were fighting to stay conscious, and worst of all — they were out of the reach of NASA’s Mission Control.

The astronauts eventually did make contact during that 1966 mission, and splashed down safely. Still, the incident illustrated a weakness of having scattered ground stations staying in touch with orbiting spacecraft. NASA had a large network of stations, including ships and remote satellite dishes, but there were large gaps in coverage.

Today, NASA and Roscosmos (the Russian space agency) have virtually 100% communications contact with orbiting astronauts and cosmonauts in the International Space Station, including video. That’s due to a network of satellites called the Tracking and Data Relay Satellite system. The first of these satellites launched 30 years ago today (April 5) in 1983.

A United Launch Alliance Atlas V 401 rocket streaks away from Space Launch Complex 41 into the night sky over Cape Canaveral Air Force Station in Florida, carrying NASA's Tracking and Data Relay Satellite-K, TDRS-K, to orbit. Credit: NASA/Glenn Benson

A United Launch Alliance Atlas V 401 rocket streaks away from Space Launch Complex 41 into the night sky over Cape Canaveral Air Force Station in Florida, carrying NASA’s Tracking and Data Relay Satellite-K, TDRS-K, to orbit. Credit: NASA/Glenn Benson

TDRS includes seven operational satellites that are in geosynchronous orbit (essentially, in an orbit that keeps them above a fixed location on Earth.) The satellites are designed to serve spacecraft that are orbiting in low Earth orbit, above 45 miles (73 kilometers) in altitude. They’re spaced out to make sure that customers receive coverage throughout the orbit. Operations on the ground consist of two ground terminals located near Las Cruces, New Mexico.

Launching these satellites took years. Although the first satellite was deployed successfully, the second one was destroyed in the Challenger shuttle explosion of 1986. The rest of the first generation of TDRS satellites went into space between 1988 and 1995. Three more advanced satellites then launched between 2000 and 2002.

This means the TDRS fleet is getting pretty old, but luckily, there are fresh replacements on the way. TDRS-K launched in January and is still being tested before assuming operational status. TDRS-L will launch in 2014, and TDRS-M in 2015.

About 

Elizabeth Howell is the senior writer at Universe Today. She also works for Space.com, Space Exploration Network, the NASA Lunar Science Institute, NASA Astrobiology Magazine and LiveScience, among others. Career highlights include watching three shuttle launches, and going on a two-week simulated Mars expedition in rural Utah. You can follow her on Twitter @howellspace or contact her at her website.

Comments on this entry are closed.

  • David Herne April 5, 2013, 1:30 PM

    For the first few shuttle missions, the TDRSS was 2 years away and so astronauts and mission control still relied on ground stations. I helped establish one, Yarragadee in Western Australia. Ours was the first typically to provide a link to the shuttle after it re-entered the atmosphere. Such interesting and exciting times. (Incidentally, Quindars were still in use then.)

    • flashfast2000 April 6, 2013, 5:24 PM

      It’s cool when the ‘real’ experts contribute to articles like this one.

    • Jason Kurant April 13, 2013, 4:16 AM

      Thank you for sharing, David! What are quindars?

      • John Duff April 14, 2013, 4:27 PM

        From the Wikipedia entry for Quindar tones:
        Quindar tones, most often referred to as the “beeps” that were heard during the American Apollo space missions were a means by which remote transmitters on Earth were turned on and off so that the Capsule communicator (CapCom) could communicate with the crews of the spacecraft.
        http://upload.wikimedia.org/wikipedia/commons/5/56/Quindar_tones.ogg

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