WASHINGTON – Frustrated with progress on a new ground system for the next-generation of GPS  satellites the Pentagon hopes to start launching just over a year from now, the U.S. Air Force awarded Lockheed Martin a $96 million contract modification Feb. 4 to adapt the existing ground system to serve as a stop-gap measure.

Raytheon is the prime contractor for the service’s next-generation GPS ground system, known as the Operational Control Segment, or OCX. That system has faced continuing technical difficulties and needs at least two additional years of work, Air Force officials said in December. The delay has been a sore point for Air Force leaders, who say that because of the lag they will be unable to immediately leverage the full capabilities of the GPS 3 satellites, which include better accuracy and higher-power signals

The Air Force has warned  it would consider other options, including negotiating with Lockheed Martin to modify the existing GPS ground system, known as the Architecture Evolution Program, to work with the GPS 3 satellites until more of the Raytheon system is ready.

The Feb. 4 contract, which runs through 2019, calls for Lockheed Martin to prepare for “contingency operations” until OCX can operate the GPS 3 satellites, according to an announcement from the Pentagon.

Specifically, the Air Force has been worried it would not have a system to handle the GPS 3 satellites’ primary positioning, navigation and timing functions. Those functions include command and control of the GPS 2 and GPS 3 satellites and are part of what is included in what as known as Block 1 of the OCX program.

The first GPS 3 satellite is expected to launch no earlier than the second quarter of 2017. The Air Force told SpaceNews Jan. 28 it could launch as many as four GPS 3 satellites before OCX Block 1 is complete. The full OCX program, which encompassed two blocks, and includes further modernization is not expected to be completed sooner than 2021.

Michelle Lammers, a Raytheon spokeswoman, declined to comment.

Like many satellite programs, the GPS 3 system’s most advanced capabilities are dependent on the ground infrastructure. OCX is expected to offer improved information assurance and cyberprotection while automating various GPS 3 satellite operating functions.

Raytheon has struggled with the OCX program since winning the prime contract in 2010. The program was restructured in 2014, nearly doubling the contract value, to around $1.6 billion, and delaying key milestones.

An April report from the U.S. Government Accountability Office said the OCX program’s cost ultimately would exceed $2 billion. The Air Force is currently calculating a new cost estimate. Frank Kendall, the Pentagon’s acquisition czar, is expected to meet with Raytheon officials later this month to discuss that estimate.