GPS IIA in assembly Credit - Hughes

The Navstar GPS constellation worked in concert with ground receivers to give precise location information to military and civilian users anywhere in the world. Use of GPS receivers revolutionized civilian and military operations of every kind by providing precise location information. GPS Block 2 was the Operational system, following the Demonstration system comprised of Block 1 spacecraft. The Block 2A were "Advanced" versions of this spacecraft (mass 1816 kg). The complete basic constellation had 24 spacecraft in 6 high-altitude orbit planes. (4 slots per plane). In addition, on-orbit spares were placed in some planes in a fifth slot.

The spacecraft was 3-axis stabilized, nadir pointing using reaction wheels. Dual 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 were nuclear detonation detection sensors.

Launches were originally scheduled for Proton, Atlas, and Delta. Satellite costs $ 50 million for Block 2 and $ 40 million for Block 2A. Rockwell was the prime contractor, building a single Block 2 SVN 12 qualification vehicle under a 1981amendment to the Block I contract. This was followed in 1983 with a contract for 28 Block 2 and 2A satellites.

Design Life: 7.5 years. Typical orbit: 20,200 km / 12 hr period; 55 deg inclin; 6 planes. Length: 3.40 m (11.10 ft). Span: 5.30 m (17.30 ft). Mass: 1,665 kg (3,670 lb). Main Engine: Star 27. Electrical System: 2 solar panels. Electric System: 0.71 average kW.

• 1989 February 14 - USA 35 - Program: Navstar. Launch Site: Cape Canaveral. Launch Complex: LC17A. Launch Vehicle: Delta. Mass: 1,665 kg (3,670 lb). Perigee: 21,480 km (13,340 mi). Apogee: 21,758 km (13,519 mi). Inclination: 56.60 deg. Period: 777.00 min.
  First launch of second generation / operational Global Positioning System. Placed in Plane E Slot 1 of the constellation. Suffered a shutdown of its onboard reaction wheels on March 26, 2000. Decommissioned on April 14, 2000 and replaced by GPS 2R-4.

• 1989 June 10 - USA 38 - Program: Navstar. Launch Site: Cape Canaveral. Launch Complex: LC17A. Launch Vehicle: Delta. Mass: 1,665 kg (3,670 lb). Perigee: 19,849 km (12,333 mi). Apogee: 20,514 km (12,746 mi). Inclination: 54.80 deg. Period: 718.00 min.
  Global Positioning System. Placed in Plane B Slot 3.

• 1989 August 18 - USA 42 - Program: Navstar. Launch Site: Cape Canaveral. Launch Complex: LC17A. Launch Vehicle: Delta. Mass: 1,665 kg (3,670 lb). Perigee: 21,509 km (13,365 mi). Apogee: 21,576 km (13,406 mi). Inclination: 56.40 deg. Period: 773.80 min.
  Global Positioning System. Retired.

• 1989 October 21 - USA 47 - Program: Navstar. Launch Site: Cape Canaveral. Launch Complex: LC17A. Launch Vehicle: Delta. Mass: 1,665 kg (3,670 lb). Perigee: 21,190 km (13,160 mi). Apogee: 21,236 km (13,195 mi). Inclination: 53.30 deg. Period: 760.20 min.
  Global Positioning System. Placed in Plane A Slot 5.

• 1989 December 11 - USA 49 - Program: Navstar. Launch Site: Cape Canaveral. Launch Complex: LC17B. Launch Vehicle: Delta. Mass: 1,665 kg (3,670 lb). Perigee: 19,992 km (12,422 mi). Apogee: 20,371 km (12,657 mi). Inclination: 55.40 deg. Period: 718.00 min.
  Global Positioning System. Placed in Plane D Slot 3.

• 1990 January 24 - USA 50 - Program: Navstar. Launch Site: Cape Canaveral. Launch Complex: LC17A. Launch Vehicle: Delta. Mass: 1,665 kg (3,670 lb). Perigee: 21,168 km (13,153 mi). Apogee: 21,226 km (13,189 mi). Inclination: 55.00 deg. Period: 759.50 min.
  Global Positioning System. Retired.

• 1990 March 26 - USA 54 - Program: Navstar. Launch Site: Cape Canaveral. Launch Complex: LC17A. Launch Vehicle: Delta. Mass: 1,665 kg (3,670 lb). Perigee: 20,960 km (13,020 mi). Apogee: 21,156 km (13,145 mi). Inclination: 53.70 deg. Period: 753.80 min.
  Global Positioning System. Declared unusable on 21 May 1996 at 22:42 following two uncommanded changes in frequency standards.

• 1990 August 2 - USA 63 - Program: Navstar. Launch Site: Cape Canaveral. Launch Complex: LC17A. Launch Vehicle: Delta. Mass: 1,665 kg (3,670 lb). Perigee: 19,896 km (12,362 mi). Apogee: 20,468 km (12,718 mi). Inclination: 54.70 deg. Period: 718.00 min.
  Global Positioning System. Placed in Plane E Slot 2.

• 1990 October 1 - USA 64 - Program: Navstar. Launch Site: Cape Canaveral. Launch Complex: LC17A. Launch Vehicle: Delta. Mass: 1,665 kg (3,670 lb). Perigee: 20,002 km (12,428 mi). Apogee: 20,363 km (12,652 mi). Inclination: 55.40 deg. Period: 718.00 min.
  Global Positioning System. Placed in Plane D Slot 5.

• 1990 November 26 - USA 66 - Program: Navstar. Launch Site: Cape Canaveral. Launch Complex: LC17A. Launch Vehicle: Delta. Mass: 1,816 kg (4,003 lb). Perigee: 19,978 km (12,413 mi). Apogee: 20,384 km (12,666 mi). Inclination: 54.90 deg. Period: 717.90 min.
  Global Positioning System. Placed in Plane E Slot 5.

• 1991 July 4 - USA 71 - Program: Navstar. Launch Site: Cape Canaveral. Launch Complex: LC17A. Launch Vehicle: Delta. Mass: 1,816 kg (4,003 lb). Perigee: 20,043 km (12,454 mi). Apogee: 20,319 km (12,625 mi). Inclination: 55.60 deg. Period: 717.90 min.
  Global Positioning System. Placed in Plane D Slot 1.

• 1992 February 23 - USA 79 - Program: Navstar. Launch Site: Cape Canaveral. Launch Complex: LC17B. Launch Vehicle: Delta. Mass: 1,816 kg (4,003 lb). Perigee: 20,032 km (12,447 mi). Apogee: 20,332 km (12,633 mi). Inclination: 54.20 deg. Period: 718.00 min.
  Global Positioning System. Placed in Plane A Slot 2.

• 1992 April 10 - USA 80 - Program: Navstar. Launch Site: Cape Canaveral. Launch Complex: LC17B. Launch Vehicle: Delta. Mass: 1,816 kg (4,003 lb). Perigee: 20,082 km (12,478 mi). Apogee: 20,277 km (12,599 mi). Inclination: 54.50 deg. Period: 717.90 min.
  Global Positioning System. Retired 15 August 1997.

• 1992 July 7 - USA 83 - Program: Navstar. Launch Site: Cape Canaveral. Launch Complex: LC17B. Launch Vehicle: Delta. Mass: 1,816 kg (4,003 lb). Perigee: 19,962 km (12,403 mi). Apogee: 20,400 km (12,600 mi). Inclination: 54.90 deg. Period: 718.00 min.
  Global Positioning System. Placed in Plane F Slot 2.

• 1992 September 9 - USA 84 - Program: Navstar. Launch Site: Cape Canaveral. Launch Complex: LC17A. Launch Vehicle: Delta. Mass: 1,816 kg (4,003 lb). Perigee: 19,909 km (12,370 mi). Apogee: 20,453 km (12,708 mi). Inclination: 54.50 deg. Period: 718.00 min.
  Global Positioning System. Placed in Plane A Slot 4.

• 1992 November 22 - USA 85 - Program: Navstar. Launch Site: Cape Canaveral. Launch Complex: LC17A. Launch Vehicle: Delta. Mass: 1,816 kg (4,003 lb). Perigee: 20,038 km (12,451 mi). Apogee: 20,325 km (12,629 mi). Inclination: 55.50 deg. Period: 718.00 min.
  Global Positioning System. Placed in Plane F Slot 4.

• 1992 December 18 - USA 87 - Program: Navstar. Launch Site: Cape Canaveral. Launch Complex: LC17B. Launch Vehicle: Delta. Mass: 1,816 kg (4,003 lb). Perigee: 20,038 km (12,451 mi). Apogee: 20,324 km (12,628 mi). Inclination: 54.70 deg. Period: 718.00 min.
  Global Positioning System. Placed in Plane F Slot 5.

• 1993 February 3 - USA 88 - Program: Navstar. Launch Site: Cape Canaveral. Launch Complex: LC17A. Launch Vehicle: Delta. Mass: 1,816 kg (4,003 lb). Perigee: 20,006 km (12,431 mi). Apogee: 20,359 km (12,650 mi). Inclination: 54.80 deg. Period: 718.00 min.
  Global Positioning System. Placed in Plane Plane B Slot 1.

• 1993 March 30 - USA 90 - Program: Navstar. Launch Site: Cape Canaveral. Launch Complex: LC17A. Launch Vehicle: Delta. Mass: 1,816 kg (4,003 lb). Perigee: 20,072 km (12,472 mi). Apogee: 20,293 km (12,609 mi). Inclination: 55.00 deg. Period: 718.00 min.
  Global Positioning System. Placed in Plane C Slot 3.

• 1993 May 13 - USA 91 - Program: Navstar. Launch Site: Cape Canaveral. Launch Complex: LC17A. Launch Vehicle: Delta. Mass: 1,816 kg (4,003 lb). Perigee: 20,017 km (12,437 mi). Apogee: 20,345 km (12,641 mi). Inclination: 55.10 deg. Period: 718.00 min.
  Global Positioning System. Placed in Plane C Slot 4.

• 1993 June 26 - USA 92 - Program: Navstar. Launch Site: Cape Canaveral. Launch Complex: LC17A. Launch Vehicle: Delta. Mass: 1,816 kg (4,003 lb). Perigee: 20,112 km (12,496 mi). Apogee: 20,250 km (12,580 mi). Inclination: 54.60 deg. Period: 717.90 min.
  Global Positioning System. Placed in Plane A Slot 1.

• 1993 August 30 - USA 94 - Program: Navstar. Launch Site: Cape Canaveral. Launch Complex: LC17B. Launch Vehicle: Delta. Mass: 1,816 kg (4,003 lb). Perigee: 20,110 km (12,490 mi). Apogee: 20,255 km (12,585 mi). Inclination: 54.90 deg. Period: 718.00 min.
  Global Positioning System. Placed in Plane B Slot 4.

• 1993 October 26 - USA 96 - Program: Navstar. Launch Site: Cape Canaveral. Launch Complex: LC17B. Launch Vehicle: Delta. Mass: 1,816 kg (4,003 lb). Perigee: 20,104 km (12,492 mi). Apogee: 20,260 km (12,580 mi). Inclination: 55.10 deg. Period: 718.00 min.
  Global Positioning System. Placed in Plane D Slot 4.

• 1994 March 10 - USA 100 - Program: Navstar. Launch Site: Cape Canaveral. Launch Complex: LC17A. Launch Vehicle: Delta. Mass: 1,816 kg (4,003 lb). Perigee: 20,000 km (12,000 mi). Apogee: 20,366 km (12,654 mi). Inclination: 53.90 deg. Period: 718.00 min.
  Final element of initial GPS constellation. Placed in Plane C Slot 1.

• 1996 March 28 - USA 117 - Program: Navstar. Launch Site: Cape Canaveral. Launch Complex: LC17B. Launch Vehicle: Delta. Mass: 1,816 kg (4,003 lb). Perigee: 20,106 km (12,493 mi). Apogee: 20,257 km (12,587 mi). Inclination: 54.60 deg. Period: 718.00 min.
  Placed in Plane C Slot 2 of the constellation.

• 1996 July 16 - USA 126 - Program: Navstar. Launch Site: Cape Canaveral. Launch Complex: LC17A. Launch Vehicle: Delta. Mass: 1,816 kg (4,003 lb). Perigee: 20,127 km (12,506 mi). Apogee: 20,237 km (12,574 mi). Inclination: 55.10 deg. Period: 717.90 min.
  Placed in Plane E Slot 3 of the constellation.

• 1996 September 12 - USA 128 - Program: Navstar. Launch Site: Cape Canaveral. Launch Complex: LC17A. Launch Vehicle: Delta. Mass: 1,816 kg (4,003 lb). Perigee: 20,042 km (12,453 mi). Apogee: 20,320 km (12,620 mi). Inclination: 54.70 deg. Period: 718.00 min.
  Placed in Plane B Slot 2 of the constellation.

• 1997 November 6 - USA 134 - Program: Navstar. Launch Site: Cape Canaveral. Launch Complex: LC17A. Launch Vehicle: Delta. Mass: 1,816 kg (4,003 lb). Perigee: 19,970 km (12,400 mi). Apogee: 20,394 km (12,672 mi). Inclination: 55.00 deg. Period: 718.00 min.
  Final GPS Block 2A satellite. Placed in Plane A Slot 3.