GPS satellite blocks
Generations of US navigation satellites / From Wikipedia, the free encyclopedia
GPS satellite blocks are the various production generations of the Global Positioning System (GPS) used for satellite navigation. The first satellite in the system, Navstar 1, was launched on 22 February 1978.[1] The GPS satellite constellation is operated by the 2nd Space Operations Squadron (2SOPS) of Space Delta 8, United States Space Force.
![Thumb image](http://upload.wikimedia.org/wikipedia/commons/thumb/e/e5/GPS24goldenSMALL.gif/320px-GPS24goldenSMALL.gif)
![Thumb image](http://upload.wikimedia.org/wikipedia/commons/thumb/8/8d/Orbits_around_earth_scale_diagram.svg/640px-Orbits_around_earth_scale_diagram.svg.png)
![Thumb image](http://upload.wikimedia.org/wikipedia/commons/thumb/4/4b/Animation_of_GPS_satellite_orbits.gif/320px-Animation_of_GPS_satellite_orbits.gif)
USA-242 · USA-239 · USA-151 · Earth
Note: This animation does not reflect actual orbits which are approximately 350 times denser than these.
The GPS satellites circle the Earth at an altitude of about 20,000 km (12,427 miles) and complete two full orbits every day.[2]