History, Present, and Future of NAVSTAR GPS System
Over at blackanthem there is an article discussing AFSPC’s (Air Force Space Command) plans to continue modernizing the NAVSTAR system. (NAVSTAR is the official name for the GPS system.) While the article focuses on the future, it also tells a little bit of the history of our current GPS system.
The years following the first and subsequent launches of Block I GPS satellites identified the need for continued development and improvements in the existing system. The first 11 satellites, launched between 1978 and 1985, demonstrated the value of GPS technology.
On April 27, 1995 the GPS system was declared fully operational by the AFSPC and could be considered the “birthdate” of GPS. Looking ahead, the GPS system will complete the Legacy Accuracy Improvement Initiative.
This initiative will add six of the NGA’s monitoring stations, located around the world, into the heart of the GPS Operational Control Segment operated by the Air Force’s 2nd Space Operations Squadron at Schriever Air Force Base, Colo.
Looking further ahead to 2013, BlockIIIA satellites will be put into commisison.
Block IIIA offers the opportunity for a crosslinked command and control architecture, allowing the entire GPS constellation to be updated from a single ground station instead of waiting for each satellite to orbit in view of a ground antenna. This will improve accuracy, integrity and reduce vulnerability of GPS signals. Block IIIA also supports a spot beam antenna that provides resistance to hostile jamming.