Receiving Space Shuttle Astronaut Voice Communications

Press Release From: Kennedy Space Center
Posted: Thursday, April 20, 2000

KSC Contact: George Diller
KSC Release No. 40-00

Space Shuttle air-to-ground communication is transmitted on one of two designated S-band frequencies. Because the S-Band voice is digitized, it is unintelligible. When the orbiter is above the horizon, air-to-ground voice on the UHF band can be heard either on 259.7 mhz or 296.8 mhz. However these frequencies are primarily used only during launch and landing. It will, of course, be necessary to know if and when the Space Shuttle will be above the horizon at your location. Unless you are near a NASA tracking station, you will hear only the "downlink," or one side of the conversation, which will be the astronauts talking to ground controllers.

On some missions, the Space Shuttleís orbital inclination is 28.45 degrees, meaning the orbiter travels no farther north in the U.S. than the latitude of Cape Canaveral, the Canary Islands in the Atlantic Ocean region or Midway Island in the Pacific, which limits geographical voice coverage. However, flights which rendezvous with the International Space Station and many scientific Space Shuttle missions have higher inclinations, ranging between 39 degrees and 57 degrees. At these inclinations, voice may be heard as far north as the Gulf of Alaska, Hudson Bay in Canada, and the Hebrides in Scotland.

During all Space Shuttle flights, air-to-ground voice (both uplink and downlink) and video from the orbiter are transmitted on NASA Television which is a C-band satellite transmission on GE-2, Transponder 9C, (3880.0 mhz). This is a geostationary satellite with an orbital location of 85 degrees West. Audio only is also available on 6.8 mhz. GE-2 can be received in all 50 states and much of Canada, Mexico and the Caribbean. While the Space Shuttle is in orbit, this system is always broadcasting. The signal is not encoded, or scrambled, and may be picked up with a home satellite receiver. Some cable television companies carry it, at least on a limited basis. NASA Television is also available on a continuous basis on two direct satellite-to-home broadcast systems, Dish Network and DirectTV.

The Space Shuttle on-orbit communications through the Tracking and Data Relay Satellite (TDRS) system uses S-band and K-band. This is encoded and also transmitted digitally, so it is not possible for a home satellite system to receive air-to-ground voice or television from TDRS.

The Amateur Radio Club at the Goddard Space Flight Center in Greenbelt, Maryland, WA3NAN, retransmits the air-to-ground Space Shuttle communications on shortwave frequencies. The best reception on each frequency will vary based on the time of day. The frequencies are:

  • 3.860 mhz
  • 7.185 mhz
  • 14.295 mhz
  • 21.395 mhz
  • 28.650 mhz

Some amateur radio organizations retransmit NASA Television or mission audio. As an example, an amateur radio FM transmitter, located on Merritt Island near Gate 2 at the Kennedy Space Center, retransmits Space Shuttle air- to-ground communications on 146.94 mhz. Mission Audio is also transmitted by the amateur radio club at the Goddard Space Flight Center on frequency 147.45 mhz, and by the club at the Johnson Space Center in Houston on 146.64 mhz. The signals can be received for about 25 miles. An amateur television transmitter (ATV) in Cocoa, Fla., retransmits NASA Television on 421.25 mhz. This can be received with a normal cable-ready television set on Channel 57 by using an external antenna. The signal can be received for at least 20 miles.

Transmitters of various power on other frequencies are provided by local amateur radio organizations in cities around the country. A list of amateur retransmissions of audio or video/audio from NASA TV is available on the World Wide Web at

Some Space Shuttle missions also carry amateur radio transmitters called SAREX (Shuttle Amateur Radio Experiment). As the schedule permits, amateur radio operators can have their call sign confirmed directly by an astronaut. When the flight crew is busy, a "computer packet module" will automatically transmit a computer message. For further information on the SAREX program frequencies, contact the American Radio Relay League, 225 Main Street, Newington, CT 06111, (860) 594-0200. A SAREX Worldwide Web Page from the NASA Goddard Space Flight Center may be found at

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