If one can remember back to when GPS was intentionally inaccurate for most people, one will appreciate the current quality of GPS. Yet at the same time, GPS is being improved further.
On July 16, 2011, the U.S. Air Force successfully launched GPS IIF-2 Space Vehicle Number (SVN) 63 carried aboard a United Launch Alliance Delta IV Medium rocket from Cape Canaveral Air Force Station, Florida.
The mission was launched aboard a Delta IV Medium+ (4,2) configuration launch vehicle featuring an ULA single common booster core powered by a Pratt & Whitney Rocketdyne (PWR) RS-68 main engine and two Alliant Techsystems (ATK) strap-on solid rocket motors. The payload was encased by a composite payload fairing and powered by the four-meter diameter upper stage using the PWR RL10B-2 engine. The GPS IIF-2 launch marked the eighth flight of the Delta IV Medium+ (4,2) configuration and the 17th flight of the Delta IV family of launch vehicles.
This is the second in the series of a dozen GPS satellites that Boeing has on contract with the Air Force. The satellite will join the GPS constellation of thirty operational satellites on-orbit providing precise positioning, navigation and timing services to users worldwide. SVN-63 will assume plane D, slot 2A position replacing SVN-24 after nearly twenty years of service. The satellite is expected to be available for navigation users worldwide next month.
GPS IIF-2 is the second in a series of next generation GPS satellites and will join a worldwide timing and navigation system utilizing 24 satellites in six different planes, with a minimum of four satellites per plane positioned in orbit approximately 11,000 miles above the earths' surface. The GPS IIF series provides improved accuracy and enhanced performance for GPS users.
The GPS IIF satellites will provide greater navigation accuracy to users through improvements in atomic clock technology and a more robust signal for commercial aviation and safety-of-life applications, known as the third civil signal (L5). Along with new and improved signals GPS IIF will have a longer design life of 12 years providing long-term service and reduced operating costs. GPS IIF will also continue to deploy the modernized capabilities that began with the modernized GPS IIR satellites, including a more robust military signal.