Tracking and data relay satellite: Difference between revisions

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A '''tracking and data relay satellite''' ('''TDRS''') is a type of [[communications satellite]] that forms part of the [[TDRSS|Tracking and Data Relay Satellite System]] (TDRSS) used by [[NASA]] and other United States government agencies for communications to and from independent "User Platforms" such as [[satellites]], balloons, aircraft, the [[International Space Station]], and remote bases like the [[Amundsen-Scott South Pole Station]]. This system was designed to replace an existing worldwide network of ground stations that had supported all of NASA's [[Human space flight|crewed flight missions]] and uncrewed satellites in low-Earth orbits. The primary system design goal was to increase the amount of time that these spacecraft were in communication with the ground and improve the amount of data that could be transferred. These TDRSS satellites are all designed and built to be launched to and function in [[geosynchronous orbit]], {{convert|35786|km|mi|abbr=on}} above the surface of the Earth.

The first seven TDRSS satellites were built by the [[TRW Inc.|TRW]] corporation. The three later versions have been manufactured by the [[Boeing]] corporation's [[Boeing Satellite Systems|Satellite Systems]] division. Thirteen satellites have been launched; however, one was destroyed in the [[Challenger disaster]]. TDRS-1 was decommissioned in October 2009.<ref name=T1decomm>{{cite web|url=http://spaceflightnow.com/news/n0910/13tdrs/ |title=Breaking News &#124; NASA retires 'queen' of tracking satellite fleet |publisher=Spaceflight Now |access-date= |accessdate=February 5, 2014}}</ref> TDRS-4 was decommissioned in December 2011. Ten TDRSS satellites are currently in service.<ref name="spacecomm">{{cite web|url=https://www.nasa.gov/directorates/heo/scan/services/networks/tdrs_main|title=Tracking and Data Relay Satellite (TDRS) &#124; NASA|last=|first=|date=Oct 22, 2019|website=|publisher=Spacecomm.nasa.gov|url-status=live|archive-url=|archiveaccess-date=|accessdate=October 22, 2019}}</ref> All of the TDRSS satellites have been managed by NASA's [[Goddard Space Flight Center]].<ref>{{cite web|url=http://www.nasa.gov/centers/goddard/news/topstory/2003/0403tdrs20th.html |title=NASA – Top Story – TDRS 20th Anniversary – April 03, 2003 |publisher=Nasa.gov |access-date= |accessdate=February 5, 2014}}</ref> The contract for TDRS versions L & K was awarded to Boeing on December 20, 2007.<ref>{{cite web|url=https://www.reuters.com/article/ousiv/idUSN2019803020071221 |title=Boeing to build NASA tracking, data relay satellites |publisher=Reuters |date=December 20, 2007 |accessdateaccess-date=February 5, 2014}}</ref> On November 30, 2011, NASA announced the decision to order an additional third-generation TDRS satellite, TDRS M.<ref name=NASA/>

==Operations==

The first tracking and data relay satellite was launched in 1983 on the [[Space Shuttle Challenger|Space Shuttle ''Challenger's'']] first flight, [[STS-6]]. The Boeing-built [[Inertial Upper Stage]] that was to take the satellite from Challenger's orbit to its ultimate [[geosynchronous orbit]] suffered a failure that caused it not to deliver the TDRS to the correct orbit. As a result, it was necessary to command the satellite to use its onboard [[Reaction control system|rocket thrusters]] to move it into its correct orbit. This expenditure of fuel reduced its capability to remain in a [[geostationary]] orbit; by late 1997 the orbit had changed to the point that the satellite was able to see the South Pole, and an uplink/downlink station was installed at [[Amundsen–Scott South Pole Station]] in January 1998;<ref name=southpole>{{cite web |url=http://antarcticsun.usap.gov/features/contentHandler.cfm?id=1742 |title=TDRS history |date=April 10, 2009}}</ref> TDRS-1 was an important communication uplink for Antarctic research until 2009.

The second tracking and data relay satellite was destroyed along with ''Challenger'' shortly after launch during the [[STS-51-L]] mission in January 1986. The next five TRW-built TDRSS satellites were successfully launched on other Space Shuttles. Three follow-up Boeing-built satellites were launched by [[Atlas rocket]]s in 2000 and 2002. A NASA Press Release<ref>{{cite web|url=http://www.nasa.gov/home/hqnews/2003/apr/HP_news_03130.html |title=NASA – Pioneer NASA Spacecraft Celebrates 20 Years of Service |publisher=Nasa.gov |access-date= |accessdate=February 5, 2014}}</ref> summarized the capabilities of the system as a whole:

<blockquote>"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."</blockquote>

The first generation of TDRS are planned to be retired in 2015.<ref name=NASA>{{cite web|url=http://www.nasa.gov/home/hqnews/2011/nov/HQ_C11-049_TDRS.html|title=NASA Exercises Contract Option For TDRS-M Satellite Decision Will Retain Hundreds of Jobs |date=November 30, 2011|publisher=NASA|accessdateaccess-date=December 12, 2011}}</ref>

==TDRSS ground terminals==

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==Design==

The communications systems of the TDRSS satellites were designed to support multiple missions at the same time. Each satellite has [[S band]], [[Ku band|K_u band]] (1st Gen only), and [[Ka band|K_a band]] (2nd gen only) electronic communication systems hardware that operate at different carrier frequencies and also support various data-rates.<ref>{{cite web|url=http://www.nasa.gov/centers/goddard/pdf/97440main_TDRS_fs_9.18.pdf |title= NASA Goddard TDRS Radio Frequency Systems (need Adobe Acrobat Reader)|publisher=Nasa.gov|accessdateaccess-date=February 5, 2014}}</ref> The newer Boeing satellites are able to support more communications than the older TRW-built satellites.

==Different versions of the TDRS ==

: ''Section source: NASA TDRSS official site''<ref>{{cite web|url=https://www.spacecomm.nasa.gov/spacecomm/programs/tdrss/default.cfm |title=Tracking and Data Relay Satellite (TDRS) &#124; NASA |publisher=Spacecomm.nasa.gov |date=November 13, 2013 |accessdateaccess-date=February 5, 2014}}</ref>

* First generation TDRS: models A to G

* Second generation TDRS: models H to J

* Third generation TDRS: models K to M<ref>{{cite web|url=http://space.skyrocket.de/doc_sdat/tdrs-11.htm |title=TDRS 11, 12, 13 (TDRS K, L, M) |publisher=Space.skyrocket.de |access-date= |accessdate=August 18, 2017}}</ref>

* Launch site: [[Cape Canaveral]], United States

* Launch vehicle: [[Space shuttle]], [[Atlas II]] or [[Atlas V]] booster

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===TDRS background===

:''Source: NASA: TDRS A Satellite''<ref name=tdrsa>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1983-026B |title=NASA – NSSDC – Spacecraft – Details |publisher=Nssdc.gsfc.nasa.gov |date=August 16, 2013 |accessdateaccess-date=February 5, 2014}}</ref>

TDRS-A was the first of TDRSS multiple satellite tracking system. The system is a concept utilizing communication satellite technology that improves and economizes the satellite tracking and [[telemetry]] operations. The base three [[geosynchronous satellites]] (one a standby) track and receive data from satellites for relay to a ground station. The two primary active satellites are separated in orbit by at least 130 degrees longitude.