GPS-2 (Navstar-2)

GPS-2 [USAF]

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

The Block II satellites were the first full scale operational GPS satellites. They were designed to provide 14 days of operation without contact from the control segment.

Rockwell was the prime contractor, building a single Block 2 SVN 12 qualification vehicle under a 1981amendment to the Block I contract. 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).