WASHINGTON — Continuing a trend that has long hampered U.S. military space programs, the projected cost of a next-generation ground-control system for the U.S. Air Force’s GPS navigation constellation has grown by $1 billion in the last year, according to a report by Congress’ watchdog agency.

In a report released March 28, the Government Accountability Office (GAO) said the contractor on the GPS Operational Control Segment (OCX), Raytheon Intelligence and Information Systems of Aurora, Colo., underestimated the scope and complexity of key program elements. The report, “Defense Acquisitions: Assessments of Selected Weapon Programs,” said the OCX issue is typical of the of ground-segment development struggles that have plagued Pentagon space programs for years.

The Air Force delayed the launch of the first next-generation GPS 3 satellite from April 2014 to May 2015 to ensure that the initial OCX capability is in place for satellite test and checkout. Preliminary cost estimates on OCX increased by 43 percent last year, to almost $3.7 billion, according to the report.

The steep increase is part of a long-lasting, stubborn trend in military space programs. The GAO said the combined price tag for seven space and missile defense programs it studied in the last two years has increased by $4 billion.

The OCX is expected to support the GPS 3 constellation’s stringent accuracy, anti-jam and information assurance requirements. The system also will be backward compatible with the current generation of GPS satellites.

Raytheon won the $886.4 million prime contract to develop the OCX in February 2010. The full system was supposed to be ready by 2016. But Gen. William Shelton, commander of Air Force Space Command, said in April 2012 that the full capability date could be pushed back to 2017.

“The program has experienced significant requirements instability and schedule delays while in technology development,” the report reads. “The contractor initially underestimated the scope and complexity of the necessary information assurance requirements which required additional personnel with the necessary expertise and increased government management.”

A Raytheon spokeswoman, Kim Warth, referred questions to the Air Force.

Steve Moran, Raytheon’s director of GPS mission solutions, said in June that the OCX contract had undergone significant changes during the previous six months, including the addition of a launch and checkout capability in December 2011. Previously Boeing, prime contractor on the GPS 2F satellites now being launched, had been considered for that responsibility.

Information assurance, a primary OCX requirement, also proved to be a “big challenge,” Moran said. “It is very important that we protect this system against the current and evolving cyber threats because they are real and the nation can’t afford to have this system compromised,” he said.

GAO investigators echoed that sentiment in interviews, saying cyberthreats continue to change and can be technologically difficult to defend against.

Information assurance problems have also plagued the Navy’s Mobile User Objective System (MUOS). That program will rely on a network of four satellites and four main ground stations to provide cellphone-like communications to mobile forces. The estimated total cost of the program grew by about $515 million from June 2010 to Sept. 2012, a review of multiple GAO reports shows.

“Accurately forecasting the scope and quantity of future requirements and estimating associated costs are problematic,” the report said of the MUOS program.

Investigators also looked at the Precision Tracking Space System program, a proposed constellation of satellites that would track ballistic missiles during the midcourse portion of the flight.

The GAO report said the total price tag of the program could be $18 billion to $37 billion. Officials with the U.S. Missile Defense Agency, which is developing the tracking satellites, disputed the GAO’s estimate, but did not offer another figure that they would allow to be printed, according to the report.

The GAO also said the long-beleaguered Space Based Infrared System missile warning program continues to have problems, specifically with the third and fourth satellites, which are still under construction. The program experienced a break in production after the second satellite, forcing prime contractor Lockheed Martin Space Systems of Sunnyvale, Calif., to requalify certain components.

“According to the program, development challenges, test failures, and technical issues have resulted in significant cost growth and schedule delays for production of the third and fourth satellites,” the report read.

The satellites are scheduled for delivery in late 2015 and 2016, respectively.

The nation’s primary missile shield, the Ground-based Midcourse Defense system, also had a hefty increase. The total cost of the program jumped by about $1.7 billion, or about 4 percent. The program is trying to recover from consecutive failures in 2010.

Mike Gruss is a senior staff writer for SpaceNews. He joined the publication in January 2013 to cover military space. Previously, he worked as a reporter and columnist for The Virginian-Pilot in Norfolk, Va. and The Journal Gazette in Fort Wayne, Ind. He...