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Earth through the bay door2.jpg
TDRS-D being deployed from Discovery
Mission type Communication
Operator NASA
COSPAR ID 1989-021B
Mission duration 10 years (design life)
22 years (actual)
Spacecraft properties
Manufacturer TRW
Launch mass 3,180 kilograms (7,010 lb)[1]
Start of mission
Launch date 13 March 1989, 14:57:00 (1989-03-13UTC14:57Z) UTC
Rocket Space Shuttle Discovery
Launch site Kennedy LC-39B
End of mission
Disposal Decommissioned
Deactivated December 2011 (2012-01)
Orbital parameters
Reference system Geocentric
Regime Geostationary
Longitude 41° West (1988-2005)
46° West (2005—2011)
Perigee 35,771 kilometers (22,227 mi)
Apogee 35,805 kilometers (22,248 mi)
Inclination 10.15 degrees

TDRS-4, known before launch as TDRS-D, is an American communications satellite which was operated by NASA as part of the Tracking and Data Relay Satellite System from 1989 until 2011. It was constructed by TRW, based on a custom satellite bus which was used for all seven of the first generation TDRS satellites.[2]


The launch of STS-29R, carrying TDRS-4

TDRS-D was launched aboard Space Shuttle Discovery during the STS-29R mission in 1989. Discovery launched from Launch Complex 39B at the Kennedy Space Center at 14:57:00 UTC on 13 March 1989.[3] TDRS-D was deployed from Discovery a few hours after launch, and was raised to geostationary orbit by means of an Inertial Upper Stage.[3]


The twin-stage solid-propellant Inertial Upper Stage made two burns. The first stage burn occurred shortly after deployment from Discovery, and placed the satellite into a geosynchronous transfer orbit. At 03:30 UTC on 14 March, it reached apogee, and the second stage fired, placing TDRS-D into geosynchronous orbit.[4] At this point it received its operational designation, TDRS-4. It was placed at a longitude 41 degrees west of the Greenwich Meridian,[5][6] from where it provided communications services to spacecraft in Earth orbit, including the Space Shuttle and International Space Station. In 2005, it was relocated to 46° West.[5]


TDRS-4 completed its planned mission in November 2011, and was subsequently removed to a disposal orbit 350 kilometres (220 mi) above GEO belt, per International Telecommunications Union (ITU) and United Nations (UN) recommendations, in early December 2011.[7] In May 2012 NASA reported that the orbit-raising manoeuvre had been completed successfully, and the spacecraft had been retired.[8]


  1. ^ "UCS Satellite Database". Union of Concerned Scientists. 2009-07-01. Retrieved 2009-08-09. 
  2. ^ Krebs, Gunter. "TDRS 1, 2, 3, 4, 5, 6". Gunter's Space Page. Retrieved 2009-08-09. 
  3. ^ a b McDowell, Jonathan. "Launch Log". Jonathan's Space Page. Retrieved 2009-08-09. 
  4. ^ McDowell, Jonathan. "Index". Geostationary Orbit Catalog. Jonathan's Space Page. Retrieved 2009-08-09. 
  5. ^ a b "TDRS 4". TSE. Retrieved 2009-08-09. 
  6. ^ "The TDRS-J satellite". Spaceflight Now. 2002-12-01. Retrieved 2009-08-09. 
  7. ^ Johnson, Nicholas (2011-12-05). "Space debris issues". audio file, @1:03:05-1:05:10. The Space Show. Retrieved 2011-12-08. 
  8. ^ "TDRS-4 Mission Complete; Spacecraft Retired From Active Service". NASA. 8 May 2012. Retrieved 11 May 2012.