NAVSTAR 57, also known as USA 183 and as GPS 2R-M1 (and as GPS 2R-14), was launched by a Delta 2 rocket from Cape Canaveral AFS at 03:37 UT on 2005 September 26. It has three more frequency channels (with two more military and one more civilian), and is more secure against jamming and radiation than the older models. It is positioned in Slot 4 of Plane C, taking over the duties of the aging GPS 2A-20 (that was launched in 1993 May). All of the older members of the 28-satellite fleet were planned to be replaced with updated 2R-M versions within a few years. The initial orbital parameters of NAVSTAR 57 were period 357 min, apogee 20,328 km, perigee 266 km, and inclination 39.62 degrees.
The Global Positioning System (GPS) was developed by the US Department of Defense to provide all-weather round-the-clock navigation capabilities for military ground, sea, and air forces. Since its implementation, GPS has also become an integral asset in numerous civilian applications and industries around the globe, including recreational used (e.g., boating, aircraft, hiking), corporate vehicle fleet tracking, and surveying. GPS employs 24 spacecraft in 20,200 km circular orbits inclined at 55 degrees. These vehicles are placed in 6 orbit planes with four operational satellites in each plane. There are also four additional satellites orbiting as reserves.
GPS Block 2 was the operational system, following the demonstration system comprised of Block 1 (Navstar 1 - 11) spacecraft. These spacecraft are 3-axis stabilized, nadir pointing using reaction wheels. Dual solar arrays supplied 710 watts of power. They used S-band (SGLS) communications for control and telemetry and UHF cross-link between spacecraft. The payload consisted of two L-band navigation signals at 1575.42 MHz (L1) and 1227.60 MHz (L2). Each spacecraft carried 2 rubidium and 2 cesium clocks and nuclear detonation detection sensors. Built by Rockwell Space Systems for the US Air Force, the spacecraft measured 5.3 m across with solar panels deployed and had a design life of 7.5 years.
GPS navigational location had originally been at 100-meter accuracy for civilian use signals, and at 20-meter accuracy for military use signals. As of 2000 May 01, the DOD voided the intentional degradation of the accuracy for civilian use, and made it on a par with the military accuracy. But it retained the prerogative to degrade the accuracy at selected locations when necessary.
Alternate Names
Navstar 57
GPS 2R-14
USA 183
Facts in Brief
Launch Date: 2005-09-26
Launch Vehicle: Delta II
Launch Site: Cape Canaveral, United States