The first satellite, pictured above, in the U.S. Air Force's GPS 3 program recently passed its thermal vacuum test. Credit: Lockheed Martin.

WASHINGTON – Lockheed Martin has pushed back the delivery of the first satellite in the U.S. Air Force’s next generation of positioning, navigation and timing satellites by four months after discovering a problem with the navigation payload, the company said Sept. 14.

Lockheed Martin officials had said in March that they had planned to deliver the first of the GPS-3 satellites to the Air Force in August, but now expect the satellite to be available in December.

While the Air Force previously has said the satellite would launch no earlier than 2017, some industry officials expect that a 2018 launch is more likely especially as the Pentagon absorbs delays with the next-generation GPS ground system known as the Operational Control Segment.

“During our rigorous navigation payload testing, we discovered a capacitor type on the payload that had not been properly qualified per the program’s approved parts control plan,” Chip Eschenfelder, a Lockheed Martin spokesman said in a Sept. 14 email to SpaceNews. “Upon discovering the issue, we took immediate corrective action with the payload provider to qualify the capacitor. The capacitor qualification test forecast completion is December 2016.”

The GPS 3 program is more than 28 months behind schedule, owing largely to previous problems with the advanced navigation payload developed by Exelis Geospatial Systems of Rochester, New York, now owned by Harris Corp.

In a Sept. 14 statement, Ellen Mitchell, a Harris spokeswoman, said the capacitor was one of 28,000 parts used in the payload and had been provided by a sub-contractor. Harris did not identify the sub-contractor.

Lockheed Martin Space Systems is the prime contractor on the GPS 3 program and is under contract to build eight next-generation satellites. The contract includes options for up to four more satellites, and the Air Force has told Congress it expects to execute options for at least two of those satellites. The Government Accountability Office estimates the total GPS 3 program will cost about $5 billion.

The Sept. 14 announcement comes as the Air Force is in the early stages of a competition for the next batch of satellites that is expected to begin with the 11th space vehicle. Lockheed Martin, Boeing and Northrop Grumman are vying for contracts and are expected to include new digital navigation payloads as part of their bids.

Mike Gruss covers military space issues, including the U.S. Air Force and Missile Defense Agency, for SpaceNews. He is a graduate of Miami University in Oxford, Ohio.