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

communications satellite A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a transponder; it creates a communication channel between a source transmitter and a receiver at different locations on Earth. C ...

, of first generation, which is operated by

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...

as part of the

Tracking and Data Relay Satellite System The U.S. Tracking and Data Relay Satellite System (TDRSS) is a network of American communications satellites (each called a tracking and data relay satellite, TDRS) and ground stations used by NASA for space communications. The system was desig ...

. It was constructed by TRW as a replacement for

TDRS-B TDRS-B was an American communications satellite, of first generation, which was to have formed part of the Tracking and Data Relay Satellite System. It was destroyed in 1986 when the disintegrated 73 seconds after launch. Launch TDRS-B was la ...

, which had been lost in the ''Challenger'' accident, and was the last first generation TDRS satellite to be launched.

History

TDRS-7 is based on a custom

satellite bus A satellite bus (or spacecraft bus) is the main body and structural component of a satellite or spacecraft, in which the payload and all scientific instruments are held. Bus-derived satellites are opposed to specially produced satellites. Bus-d ...

which was used for all seven first generation TDRS satellites. Whilst similar to its predecessors, it differed from them slightly in that twelve G/H band (

C band (IEEE) The C band is a designation by the Institute of Electrical and Electronics Engineers (IEEE) for a portion of the electromagnetic spectrum in the microwave range of frequencies ranging from 4.0 to 8.0 gigahertz (GHz). However, the U.S. ...

) transponders which had been included on the previous satellites were omitted. It was the last communications satellite, other than amateur radio spacecraft, to be deployed by a Space Shuttle.

Launch

The TDRS-G satellite was deployed from during the

STS-70 STS-70 was the 21st flight of the Space Shuttle ''Discovery'', and the last of 7 shuttle missions to carry a Tracking and Data Relay Satellite (TDRS). This was the first shuttle mission controlled from the new mission control center room at the ...

mission in 1995. ''Discovery'' was launched from

Kennedy Space Center The John F. Kennedy Space Center (KSC, originally known as the NASA Launch Operations Center), located on Merritt Island, Florida, is one of the National Aeronautics and Space Administration's (NASA) ten field centers. Since December 1968 ...

Launch Complex 39B at 13:41:55 UTC on 13 July 1995. TDRS-G was deployed from ''Discovery'' around six hours after launch, and was raised to

geosynchronous orbit A geosynchronous orbit (sometimes abbreviated GSO) is an Earth-centered orbit with an orbital period that matches Earth's rotation on its axis, 23 hours, 56 minutes, and 4 seconds (one sidereal day). The synchronization of rotation and orbital ...

by means of an

Inertial Upper Stage The Inertial Upper Stage (IUS), originally designated the Interim Upper Stage, was a two-stage, solid-fueled space launch system developed by Boeing for the United States Air Force beginning in 1976 for raising payloads from low Earth orbit to h ...

Deployment

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 A geosynchronous transfer orbit or geostationary transfer orbit (GTO) is a type of geocentric orbit. Satellites that are destined for geosynchronous (GSO) or geostationary orbit (GEO) are (almost) always put into a GTO as an intermediate step f ...

. At 02:30 UTC on 14 July 1995 it reached

apogee An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any ellip ...

, and the second stage fired, placing TDRS-G into geostationary orbit. At this point, it received its operational designation, TDRS-7. It was placed at a

longitude Longitude (, ) is a geographic coordinate that specifies the east–west position of a point on the surface of the Earth, or another celestial body. It is an angular measurement, usually expressed in degrees and denoted by the Greek letter l ...

150.0° West of the

Greenwich Meridian The historic prime meridian or Greenwich meridian is a geographical reference line that passes through the Royal Observatory, Greenwich, Royal Observatory, Greenwich, in London, England. The modern IERS Reference Meridian widely used today ...

, 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. In December 2003, it was relocated to 150.5° West. It arrived the next month, and was returned to storage as a reserve satellite. Location of TDRS

References

{{DEFAULTSORT:Tdrs-7 Communications satellites in geostationary orbit Spacecraft launched in 1995 TDRS satellites Spacecraft launched by the Space Shuttle

History

Launch

Deployment

See also

References