Tracking and Data Relay Satellite

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First Generation TDRS

Second Generation TDRS

TDRS-G at Kennedy Space Center

A Tracking and Data Relay Satellite (TDRS) is one of a network of communications satellites of the Tracking and Data Relay Satellite System (TDRSS) used by NASA and other United States government agencies for communication to satellites or the International Space Station. The system was designed to replace an existing network of ground stations that had supported all of NASA's manned flight missions. The prime design goal was to increase the time spacecraft were in communication with the ground and improve the amount of data that could be transferred.

The initial seven satellites were built by TRW; later, three versions have been put together by Boeing's Satellite Systems division. 10 satellites have been launched. 9 satellites are still in service. All were managed by NASA Goddard Space Flight Center.^[1] The contract for TDRS versions L & K was awarded to Boeing on December 20, 2007.^[2]

Operations

The first TDRS was launched in 1983 on the Space Shuttle Challenger's first flight, STS-6. The Boeing-built Inertial Upper Stage that took the satellite from Challenger's orbit to its ultimate geostationary orbit did not deliver to the correct orbit. As a result, the satellite was forced to use its onboard thrusters to get it to the correct orbit. This reduced its operational lifetime, and has since been reduced to part-time duty supporting Antarctic communications.

The second was lost on the Challenger's 10th mission when it was destroyed with the Challenger shortly after liftoff on STS-51-L in 1986. The next five were launched on other shuttles. The three Boeing-built successors were launched on Atlas rockets in 2000 and 2002. A NASA Press Release^[3] summarized the capabilities of the system as a whole:

"Working solo, TDRS-1 provided more communication coverage, in support of the September 1983 Shuttle mission, than the entire network of NASA tracking stations had provided in all previous Shuttle missions."

Design

The communications systems on the TDRS satellites were designed to support multiple missions at the same time. Each satellite has S band, K_u band (1st Gen only) and K_a band (2nd gen only) systems which support multiple data-rates.^[4] The newer Boeing satellites are able to support more communications than the older TRW-built satellites, however, they have had significantly shorter and more problematic lifetimes.

Variants and history

Section source: NASA TDRSS Official Site^[5]

• First Generation TDRS: models A thru G
• Second Generation TDRS: models H thru J
• Third Generation TDRS: models K thru L (M and N are planned)^[6]

Launch history

Sub-section source: NSSDC Master Catalog Display: Spacecraft

Note: while a TDRS is in development, it is given a letter name, but once it is accepted on orbit, it is then referred to by a number (TDRS-A during development and before on-orbit acceptance, and TDRS-1 after acceptance on orbit and put into operations use)

See also

• SCaN Program
• Space Network
• Deep Space Network
• Near Earth Network
• Eastern Range

Notes

Wikimedia Commons has media related to: Tracking and Data Relay Satellite System

Note: all references were accessed Oct. 10, 2007

References

• NASA's Goddard Space Flight Center TDRSS Official Page

External links

• NASA's TDRSS program overview page
• View current TDRS constellation (Java applet)

v • d • e Tracking and Data Relay Satellites 1st Generation TDRS-1 · TDRS-B · TDRS-3 · TDRS-4 · TDRS-5 · TDRS-6 · TDRS-7 2nd Generation TDRS-8 · TDRS-9 · TDRS-10 3rd Generation TDRS-K · TDRS-L · TDRS-M · TDRS-N Tracking and Data Relay Satellite System · List of TDRS satellites