TDRS-G at KSC.jpg
TDRS-G before launch at Kennedy Space Center
Mission typeCommunication
COSPAR ID1995-035B
SATCAT no.23613
Mission durationPlanned: 10 years
Elapsed: 26 years, 20 days
Spacecraft properties
Launch mass2108 kg [1]
Dimensions17.3 metres long
14.2 metres wide
Power1700 watts
Start of mission
Launch date13 July 1995, 13:41:55 (1995-07-13UTC13:41:55) UTC
RocketSpace Shuttle Discovery
STS-70 / IUS
Launch siteKennedy Space Center, LC-39B
ContractorRockwell International
Orbital parameters
Reference systemGeocentric orbit
RegimeGeostationary orbit
Longitude150.0° West (1995–1996)
171.0° West (1996–2003)
150.5° West (2003–)
Epoch14 July 1995 [2]

TDRS-7, known before launch as TDRS-G, is an American communications satellite, of first generation, which is operated by NASA as part of the Tracking and Data Relay Satellite System. It was constructed by TRW as a replacement for TDRS-B, which had been lost in the Challenger accident, and was the last first generation TDRS satellite to be launched.


TDRS-7 is based on a custom satellite bus which was used for all seven first generation TDRS satellites.[3] Whilst similar to its predecessors, it differed from them slightly in that twelve G/H band (C band (IEEE)) transponders which had been included on the previous satellites were omitted.[4] It was the last communications satellite, other than amateur radio spacecraft, to be deployed by a Space Shuttle.


The launch of STS-70, carrying TDRS-G

The TDRS-G satellite was deployed from Space Shuttle Discovery during the STS-70 mission in 1995. Discovery was launched from Kennedy Space Center Launch Complex 39B at 13:41:55 UTC on 13 July 1995.[5] TDRS-G was deployed from Discovery around six hours after launch, and was raised to geosynchronous orbit by means of an Inertial Upper Stage.[5]


The twin-stage solid-propellent Inertial Upper Stage made two burns. The first stage burn occurred around an hour after deployment from Discovery, and placed the satellite into a geosynchronous transfer orbit. At 02:30 UTC on 14 July 1995 it reached apogee, and the second stage fired, placing TDRS-G into geostationary orbit.[6] At this point, it received its operational designation, TDRS-7. It was placed at a longitude 150.0° West of the Greenwich Meridian, where it underwent on-orbit testing. In May 1996, it was moved to 171.0° West where it was stored as an in-orbit spare, and subsequently entered service.[7] In December 2003, it was relocated to 150.5° West.[8] It arrived the next month, and was returned to storage as a reserve satellite.

Location of TDRS as of 26 May 2020
Location of TDRS as of 18 March 2019


  1. ^ "UCS Satellite Database". Union of Concerned Scientists. 1 July 2009. Retrieved 9 August 2009.
  2. ^ "NASA - NSSDCA - Spacecraft - Trajectory Details". Retrieved 2 May 2018. Public Domain This article incorporates text from this source, which is in the public domain.
  3. ^ Krebs, Gunter. "TDRS 1, 2, 3, 4, 5, 6". Gunter's Space Page. Retrieved 9 August 2009.
  4. ^ Krebs, Gunter. "TDRS 7". Gunter's Space Page. Retrieved 9 August 2009.
  5. ^ a b McDowell, Jonathan. "Launch Log". Jonathan's Space Page. Retrieved 9 August 2009.
  6. ^ McDowell, Jonathan. "Index". Geostationary Orbit Catalog. Jonathan's Space Page. Retrieved 9 August 2009.
  7. ^ "The TDRS-J satellite". Spaceflight Now. 1 December 2002. Retrieved 9 August 2009.
  8. ^ "TDRS 7". TSE. Retrieved 9 August 2009.