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GPS (Navstar)


The GPS (Global Positioning System) or Navstar (Navigation System using Timing And ranging) were the first generation satellites of the GPS navigation system. The first two satellites were also called NDS (Navigational Development Satellite).

The Block I satellites were positioned in the same orbital planes as the later Block II, but at an inclination angle of 63 degrees. Block I consisted of the original concept validation satellites and reflect various stages of system development. Lessons learned from the 11 satellites were incorporated into later generations.

In 1974 Rockwell International was awarded a contract to build 8 Block I satellites. In 1978 the contract was extended to build an additional 3 Block I satellites.

The stellites were 3-axis stabilized, nadir pointing using reaction wheels. Dual solar arrays supplied over 400 Watts (EOL) and charged NiCd batteries. 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)

Nation: USA
Type / Application: Navigation
Operator: USAF
Contractors: Rockwell
Equipment: ?
Configuration: 3-Axis stabilized
Propulsion: Star-27
Power: 2 deployable solar arrays, batteries
Lifetime: 5 years
Mass: 759 kg
Orbit: 20200 km × 20200 km, 63.0
Satellite COSPAR Date LS Launch Vehicle Remarks
GPS 1 (Navstar 1, NDS 1, OPS 5111) 1978-020A 22.02.1978 Va SLC-3E Atlas-F SGS-1
GPS 2 (Navstar 2, NDS 2, OPS 5112) 1978-047A 13.05.1978 Va SLC-3E Atlas-F SGS-1
GPS 3 (Navstar 3, OPS 5113) 1978-093A 07.10.1978 Va SLC-3E Atlas-F SGS-1
GPS 4 (Navstar 4, OPS 5114) 1978-112A 11.12.1978 Va SLC-3E Atlas-F SGS-1
GPS 5 (Navstar 5, OPS 5117) 1980-011A 09.02.1980 Va SLC-3E Atlas-F SGS-1
GPS 6 (Navstar 6, OPS 5118) 1980-032A 26.04.1980 Va SLC-3E Atlas-F SGS-1
GPS 7 (Navstar 7) 1981-F 19.12.1981 Va SLC-3E F Atlas-E SGS-1
GPS 8 (Navstar 8, OPS 9794) 1983-072A 14.07.1983 Va SLC-3W Atlas-E SGS-2
GPS 9 (Navstar 9, USA 1) 1984-059A 13.06.1984 Va SLC-3W Atlas-E SGS-2
GPS 10 (Navstar 10, USA 5) 1984-097A 08.09.1984 Va SLC-3W Atlas-E SGS-2
GPS 11 (Navstar 11, USA 10) 1985-093A 09.10.1985 Va SLC-3W Atlas-E SGS-2