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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 (Navstar 35) and GPS-2A 15 (Navstar 36 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 (Navstar 23, USA 66) 1990-103A 26.11.1990 CC LC-17A Delta-7925
GPS-2A 2 (Navstar 24, USA 71) 1991-047A 04.07.1991 CC LC-17A Delta-7925 with Losat X
GPS-2A 3 (Navstar 25, USA 79) 1992-009A 23.02.1992 CC LC-17B Delta-7925
GPS-2A 4 (Navstar 28, USA 80) 1992-019A 10.04.1992 CC LC-17B Delta-7925
GPS-2A 5 (Navstar 26, USA 83) 1992-039A 07.07.1992 CC LC-17B Delta-7925
GPS-2A 6 (Navstar 27, USA 84) 1992-058A 09.09.1992 CC LC-17A Delta-7925
GPS-2A 7 (Navstar 32, USA 85) 1992-079A 22.11.1992 CC LC-17A Delta-7925
GPS-2A 8 (Navstar 29, USA 87) 1992-089A 18.12.1992 CC LC-17B Delta-7925
GPS-2A 9 (Navstar 22, USA 88) 1993-007A 03.02.1993 CC LC-17A Delta-7925
GPS-2A 10 (Navstar 31, USA 90) 1993-017A 30.03.1993 CC LC-17A Delta-7925 with SEDS 1
GPS-2A 11 (Navstar 37, USA 91) 1993-032A 13.05.1993 CC LC-17A Delta-7925
GPS-2A 12 (Navstar 39, USA 92) 1993-042A 26.06.1993 CC LC-17A Delta-7925 with PMG
GPS-2A 13 (Navstar 35, USA 94) 1993-054A 30.08.1993 CC LC-17B Delta-7925
GPS-2A 14 (Navstar 34, USA 96) 1993-068A 26.10.1993 CC LC-17B Delta-7925
GPS-2A 15 (Navstar 36, USA 100) 1994-016A 10.03.1994 CC LC-17A Delta-7925 with SEDS 2
GPS-2A 16 (Navstar 33, USA 117) 1996-019A 28.03.1996 CC LC-17B Delta-7925
GPS-2A 17 (Navstar 40, USA 126) 1996-041A 16.07.1996 CC LC-17A Delta-7925
GPS-2A 18 (Navstar 30, USA 128) 1996-056A 12.09.1996 CC LC-17A Delta-7925
GPS-2A 19 (Navstar 38, USA 135) 1997-067A 06.11.1997 CC LC-17A Delta-7925