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GPS-2A (Navstar-2A)


GPS-2A (Global Positioning System) or Navstar-2A (Navigation System using Timing And ranging) are improved satellites of the second generation of the GPS navigation system.

The Block IIA satellites were improved operational GPS satellites based on the GPS 2 series. They were designed to provide 180 days of operation without contact from the control segment. During the 180 day autonomy, degraded accuracy is evident in the navigation message.

In 1983 Rockwell was awarded a contract to build 28 Block II/IIA satellites.

The spacecraft was 3-axis stabilized, nadir pointing using reaction wheels. Two solar arrays supplied 710 Watts (EOL). S-Band (SGLS) communications were used for control and telemetry. A UHF channel provided cross-links between spacecraft. A hydrazine propulsion system was used for orbital correction. The payload included two L-Band navigation signals at 1575.42 MHz (L1) and 1227.60 MHz (L2). Each spacecraft carried 2 rubidium and 2 cesium clocks. Also carried as a secondary payload were nuclear detonation detection sensors (NDS).

The GPS-2A 13 and GPS-2A 15 satellites are equipped with laser retroreflectors. The Naval Research Laboratory (NRL) and NASA are conducting a joint experiment, the main purpose of which is to unambiguously differentiate between onboard clock errors and satellite ephemeris errors. It is anticipated that SLR tracking of both the GPS-35 and -36 satellites will ultimately reduce the satellite position uncertainty by over an order of magnitude.

Nation: USA
Type / Application: Navigation
Operator: US Air Force (USAF)
Contractors: Rockwell
Equipment: ?
Configuration: 3-Axis stabilized
Propulsion: Star-37XFP
Power: 2 deployable solar arrays, batteries
Lifetime: 7.5 years
Mass: 1816 kg
Orbit: 20200 km × 20200 km, 55.0
Satellite COSPAR Date LS Launch Vehicle Remarks
GPS-2A 1 (GPS SVN 23, Navstar 22, USA 66) 1990-103A 26.11.1990 CC LC-17A Delta-7925
GPS-2A 2 (GPS SVN 24, Navstar 23, USA 71) 1991-047A 04.07.1991 CC LC-17A Delta-7925 with Losat X
GPS-2A 3 (GPS SVN 25, Navstar 24, USA 79) 1992-009A 23.02.1992 CC LC-17B Delta-7925
GPS-2A 4 (GPS SVN 28, Navstar 25, USA 80) 1992-019A 10.04.1992 CC LC-17B Delta-7925
GPS-2A 5 (GPS SVN 26, Navstar 26, USA 83) 1992-039A 07.07.1992 CC LC-17B Delta-7925
GPS-2A 6 (GPS SVN 27, Navstar 27, USA 84) 1992-058A 09.09.1992 CC LC-17A Delta-7925
GPS-2A 7 (GPS SVN 32, Navstar 28, USA 85) 1992-079A 22.11.1992 CC LC-17A Delta-7925
GPS-2A 8 (GPS SVN 29, Navstar 29, USA 87) 1992-089A 18.12.1992 CC LC-17B Delta-7925
GPS-2A 9 (GPS SVN 22, Navstar 30, USA 88) 1993-007A 03.02.1993 CC LC-17A Delta-7925
GPS-2A 10 (GPS SVN 31, Navstar 31, USA 90) 1993-017A 30.03.1993 CC LC-17A Delta-7925 with SEDS 1
GPS-2A 11 (GPS SVN 37, Navstar 32, USA 91) 1993-032A 13.05.1993 CC LC-17A Delta-7925
GPS-2A 12 (GPS SVN 39, Navstar 33, USA 92) 1993-042A 26.06.1993 CC LC-17A Delta-7925 with PMG
GPS-2A 13 (GPS SVN 35, Navstar 34, USA 94) 1993-054A 30.08.1993 CC LC-17B Delta-7925
GPS-2A 14 (GPS SVN 34, Navstar 35, USA 96) 1993-068A 26.10.1993 CC LC-17B Delta-7925
GPS-2A 15 (GPS SVN 36, Navstar 36, USA 100) 1994-016A 10.03.1994 CC LC-17A Delta-7925 with SEDS 2
GPS-2A 16 (GPS SVN 33, Navstar 37, USA 117) 1996-019A 28.03.1996 CC LC-17B Delta-7925
GPS-2A 17 (GPS SVN 40, Navstar 28, USA 126) 1996-041A 16.07.1996 CC LC-17A Delta-7925
GPS-2A 18 (GPS SVN 30, Navstar 39, USA 128) 1996-056A 12.09.1996 CC LC-17A Delta-7925
GPS-2A 19 (GPS SVN 38, Navstar 44, USA 135) 1997-067A 06.11.1997 CC LC-17A Delta-7925

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