Lockheed Martin [LMT] won’t know if it has successfully fixed its Global Positioning System (GPS) III navigation payload issues until the payload is returned to the company in October following rigorous testing.

Lockheed Martin Vice President and General Manager of Military Space Mark Valerio told Defense Daily

Wednesday the company incorporated a number of fixes and design changes like separating components and inserting isolation material between components to prevent coupling in the radio frequency (RF) box. Valerio said these techniques have been incorporated in the mission data unit (MDU), or what he called the heart of a GPS III satellite’s timekeeping system.

Artist's rendering of a GPS III satellite. Photo: Lockheed Martin.
Artist’s rendering of a GPS III satellite. Photo: Lockheed Martin.

Valerio said once the navigation payload is returned to the company following a series of critical tests is when the company will know if it is truly “out of the woods.” The navigation payload is scheduled to be returned to Lockheed Martin in October, Valerio said. Lockheed Martin and payload provider Exelis [XLS] have been dealing with RF interference, or “crosstalk,” within the MDU of the navigation payload for about eight months, Valerio said.

The MDU, Valerio said, is currently in environmental testing, a critical phase in which Lockheed Martin and Exelis simulate conditions like extreme temperatures and vibrations the payload will face when it is launched into orbit. Before environmental testing, the payload went through a first round of ambient testing where the fixes were tested on a satellite. If environmental testing is successful, the payload will go through another round of ambient testing.

Following the second round of ambient testing, the payload will be incorporated with a panel composed of transmitters, harnesses and mulitplexers. Valerio said the navigation payload, with fixes, is due to be incorporated with the panel in the summertime, before its eventual return to Lockheed Martin.

Though panel-level testing is most important, the payload still has risk remaining after that testing, Valerio said. The payload will be then incorporated on the spacecraft for thermal vacuum testing, of which he said lies residual risk because it is Lockheed Martin’s “most perceptive test.” Thermal vacuum testing, Valerio said, is effective for finding things like connectors that aren’t mated properly.

“I say we’re not 100 percent until we’re through that panel delivery and this testing and the spacecraft level thermal vacuum testing,” Valerio said at the Satellite 2014 conference in Washington. Satellite 2014 is produced by Defense Daily parent company Access Intelligence LLC. “We’re ready to go, we just have to get that panel delivered (to us).”

Air Force Space Command (AFSPC) chief Gen. William Shelton said recently the service had approached other contractors in case Lockheed Martin and Exelis couldn’t solve their navigation payload issues. Craig Cooning, vice president and general manager of Boeing’s [BA] space systems, said Tuesday the company was approached by the Air Force to potentially produce a navigation payload. Boeing has created navigation payloads in the past and created the MDU for the GPS IIF series. Exelis provided the transmitters for GPS IIF. Boeing is also the prime contractor for GPS IIF.

Air Force Col. William Cooley, director of the service’s GPS directorate, said Friday he thought a modified RF card could be the solution to the GPS III navigation payload issues, but that all options were still on the table (Defense Daily, March 7). Lockheed Martin is under contract for the production of the first six GPS III satellites with the first four funded under the original contract and the fifth and sixth recently fully funded by an Air Force-exercised option on Dec. 13.

There have been a number of delays to the GPS III program due to the navigation payload issues. Shelton said in February the Air Force delayed the contracted launch availability date of fourth quarter 2015, but not the launch itself, and the navigation payload delivery date, which was “early” 2014 (Defense Daily, Feb. 7). Shelton had mentioned the payload issues as early as September.

GPS III is the Air Force’s next generation position, navigation and timing (PNT) satellite constellation.