Tests for the next generation of Global Positioning System satellites produced positive results, making way for further work to begin on a U.S. Air Force GPS program seen as crucial to military, commercial and civilian uses in the coming decades.

Aerospace giant Lockheed Martin, which announced the successful tests of its GPS III Non-Flight Satellite Testbed, said the tests involved high-fidelity pathfinding events.

USAF is in the forefront of a program to replace the aging U.S. system.

"GPS III is a critically important program for the Air Force, affordably replacing aging GPS satellites in orbit, while improving capability to meet the evolving demands of military, commercial and civilian users," Lockheed Martin said.

GPS satellites are used by the NAVSTAR GPS. Navstar 1, the first satellite in the system, was launched Feb. 22, 1978. The GPS satellite constellation is operated by the U.S. Air Force 50th Space Wing. Rockwell International was awarded a contract in 1974 to build the first eight Block I satellites for the program.

The GPS III Non-Flight Satellite Testbed completed "a series of high-fidelity pathfinding events, which validate the process and facility for vehicle integration checkout, as well as signals interference testing, that the next-generation satellites" of GPS III will go through before delivery for launch, the manufacturer said.

Hailed as "an innovative investment" by U.S. Air Force under the original GPS III development contract, GNST is a full-sized GPS III satellite prototype which has helped to identify and resolve development issues prior to integration and test of the first GPS III space vehicle.

The company says USAF has adopted a rigorous "back-to-basics" acquisition approach and the GNST has gone through the development, test and production process for the GPS III program first, significantly reducing risk for the flight vehicles, improving production predictability, increasing mission assurance and lowering overall program costs.

During the trials the GNST completed thermal vacuum chamber trail blazing, demonstrating facility, mechanical and electrical ground equipment integration, and ran a series of vehicle integration tests.

GNST also completed Passive Intermodulation and Electromagnetic Compatibility testing, which assures that multiple high-powered signals generated from the satellite's navigation downlink transmissions, or transmitted from the hosted nuclear detection system payload on the satellite, do not interfere with each other or themselves.

"As the GNST serves as a pathfinder for the GPS III program, its successful completion of this testing validates that development risks have been retired and our engineering and technology is sound for the flight vehicles being built," said Keoki Jackson, vice president for Lockheed Martin's navigation systems mission area.

The GNST is now being prepared for shipment to Cape Canaveral U.S. Air Force Station, Fla., for more risk reduction activities.

The company says GPS III satellites will deliver three times better accuracy than current equipment and outpace growing global threats that could disrupt GPS service. It has as much as eight times improved anti-jamming signal power and features enhancements to spacecraft design life and a new civil signal designed to be interoperable with international global navigation satellite systems.

Lockheed Martin is currently under contract for production of the first four GPS III satellites, SV 1-4, and has received advanced procurement funding for long-lead components for the fifth, sixth, seventh and eighth satellites, SV 5-8.

The first GPS III satellite is due for launch availability in 2014.

Lockheed Martin has headquarters in Bethesda, Md., and employs 118,000 people worldwide. The company reported net sales of $47.2 billion last year.