TDRS-7

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TDRS-7
TDRS-G at KSC.jpg
TDRS-G before launch
Mission type Communication
Operator NASA
COSPAR ID 1995-035B
Mission duration 10 years (planned)
14+ years (achieved)
Spacecraft properties
Manufacturer TRW
Launch mass 3,180 kilograms (7,010 lb)[1]
Start of mission
Launch date 13 July 1995, 13:41:55 (1995-07-13UTC13:41:55Z) UTC
Rocket Space Shuttle Discovery
STS-70 / IUS
Launch site Kennedy LC-39B
Orbital parameters
Reference system Geocentric
Regime Geostationary
Longitude 150° West (1995-1996)
171° West (1996-2003)
150.5° West (2004—?)
275.9° West
Perigee 35,767 kilometers (22,225 mi)
Apogee 35,803 kilometers (22,247 mi)
Inclination 14.09 degrees

TDRS-7, known before launch as TDRS-G, is an American communications satellite 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.

History[edit]

TDRS-7 is based on a custom satellite bus which was used for all seven first generation TDRS satellites.[2] Whilst similar to its predecessors, it differed from them slightly in that twelve G/H band (IEEE C band) transponders which had been included on the previous satellites were omitted.[3] It was the last communications satellite, other than amateur radio spacecraft, to be deployed by a Space Shuttle.

Launch[edit]

The launch of STS-70, carrying TDRS-7

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 GMT on 13 July 1995.[4] TDRS-G was deployed from Discovery around six hours after launch, and was raised to geosynchronous orbit by means of an Inertial Upper Stage.[4]

Deployment[edit]

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 on 14 July it reached apogee, and the second stage fired, placing TDRS-G into geostationary orbit.[5] At this point it received its operational designation, TDRS-7. It was placed at a longitude 150 degrees West of the Greenwich Meridian, where it underwent on-orbit testing.

Semi-retired[edit]

In May 1996 it was moved to 171° West where it was stored as an in-orbit spare, and subsequently entered service.[6] In December 2003, it was relocated to 150.5° West.[7] It arrived the next month, and was returned to storage as a reserve satellite.

References[edit]

  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. ^ Krebs, Gunter. "TDRS 7". Gunter's Space Page. Retrieved 2009-08-09. 
  4. ^ a b McDowell, Jonathan. "Launch Log". Jonathan's Space Page. Retrieved 2009-08-09. 
  5. ^ McDowell, Jonathan. "Index". Geostationary Orbit Catalog. Jonathan's Space Page. Retrieved 2009-08-09. 
  6. ^ "The TDRS-J satellite". Spaceflight Now. 2002-12-01. Retrieved 2009-08-09. 
  7. ^ "TDRS 7". TSE. Retrieved 2009-08-09.