WASHINGTON — Lockheed Martin Space Systems of Denver will build the third and fourth satellites in the next-generation GPS 3 navigation constellation under a $238 million contract modification awarded by the U.S. Air Force, the company announced Jan. 12.

By ordering two satellites at once, the Air Force will benefit from production efficiencies at Lockheed Martin, the company said in a press release.

GPS 3 is the Air Force’s next generation of navigation, positioning and timing satellites featuring improved accuracy and signal power for jamming resistance. The first of the satellites is scheduled for launch in 2014.

Lockheed Martin in May 2008 won a contract valued at $1.4 billion to develop and build the first two satellites, with options for up to 10 additional spacecraft. As many as 32 GPS 3 satellites could be ordered, with upgrades to be introduced incrementally.

In a separate release issued Jan. 11, Lockheed Martin announced it had won a $21.5 million Air Force contract to support the launch and early in-orbit operations of the GPS 3 satellites. Lockheed Martin will work closely with Raytheon, developer of the next-generation GPS 3 ground segment, to meet the targeted launch date for the first satellite, the press release said.

Warren Ferster is the Editor-in-Chief of SpaceNews and is responsible for all the news and editorial coverage in the weekly newspaper, the spacenews.com Web site and variety of specialty publications such as show dailies. He manages a staff of seven reporters...