The Air Force launched the fifth GPS IIF satellite aboard a United Launch Alliance Delta IV launch vehicle from Cape Canaveral on Feb. 20 in the first launch of a GPS satellite this year. The launch window opened at 8:40 p.m. EST, and takeoff was achieved at the end of a 19 minute window after being briefly delayed by high solar activity.
Built by Boeing, the GPS IIF satellites include features such as a second civilian signal (L2C) for dual frequency GPS receivers, a third new civilian signal (L5) for commercial aviation and safety-of-life purposes, improved atomic clock accuracy, and an increased design life of 12 years.
They will replace the GPS Block IIA satellites, which have a lifespan of 7.5 years and were launched between 1990 and 1999. The GPS IIF-5 will replace the USA-135, which will be moved into a backup slot, joining the 31-satellite constellation, according to NASA Spaceflight.
The GPS Block IIF satellites are intended as an interim solution to keep GPS operational until the GPS Block IIIA satellites can be used. The next-generation Block IIIA series are expected to affordably replace the legacy GPS satellites and broadcast at higher power levels, delivering more effective anti-jamming capabilities and three times the accuracy. The GPS Block IIIA satellite program delivery date was recently delayed from 2014 to 2015.
After Korean Airlines flight 007 was shot down after navigational errors led it into Soviet airspace in 1983, President Ronald Reagan announced that GPS would be made available for public use without cost. Since then, the U.S. military has maintained and upgraded the system as older satellites reach the end of their operational lifespans.
"Since the inception of GPS, the Air Force has constantly strived to work with industry and other countries to develop newer and better ways to use GPS signals. The launch of new capabilities is a critical part of the modernization plan to improve operations, sustainment and overall GPS service," said Col. Bill Cooley, director of the Space and Missile Systems Center's Global Positioning Systems Directorate, as reported by Space Ref.http://defensesystems.com/articles/2014/02/21/air-force-gps-iif-launch.aspx
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