The next-generation Global Positioning System satellites are designed to be interoperable with civilian GPS systems, are more accurate than predecessors and have enhanced anti-jamming capability.
"GPS is a global gold standard, providing accurate, reliable, continuous, free worldwide positioning, navigation and timing services," said Col. Bernie Gruber, director of the U.S. Air Force's Global Positioning Systems Directorate.
"And we are focused on delivering world-class space-based PNT capabilities to our users around the world.
"As the need for more capability increases, GPS III will allow us to affordably sustain and modernize the constellation by providing increased capabilities incrementally to better meet current and future needs."
The Air Force first contracted Lockheed Martin to build two GPS III satellites -- with an option for 10 more -- in 2008. The service, however, plans for a total of 32 satellites.
"The government has mapped an extremely sensible acquisition strategy for GPS III and we are focusing on executing the program to deliver these much needed capabilities to billions of users around the word," said Mark Valerio, vice president and general manager of Lockheed Martin's Surveillance and Navigation Systems line of business.
"As we produce more GPS III satellites, we aim to continually reduce the cost and cycle time of each space vehicle to ensure we deliver the greatest value to the Air Force."
Lockheed said building two satellites at the same time maximizes manufacturing efficiency.
The first launch for the system is scheduled for 2014.