WASHINGTON — The U.S. Air Force and National Security Agency (NSA) are revising their space acquisition approaches to avoid a repeat of the encryption-equipment problems that have driven up the cost of a new generation of highly secure communications satellites, the service said.

The revised strategy entails placing more emphasis on encryption-related issues in satellite procurements, and establishing a research and development program in satellite encryption technology, the Air Force said in a statement released to the media Dec. 21.

Problems with NSA-supplied encryption equipment are the main culprits in the cost-growth spurt on the Air Force’s Advanced Extremely High Frequency (EHF) satellite program. In its statement, the service said it notified Congress Dec. 3 that the program’s cost was expected to rise by 20 percent.

The statement did not provide cost figures, but congressional aides said the Air Force’s 2005 budget request, submitted to Capitol Hill last February, estimated the cost of building and launching three Advanced EHF satellites at about $5 billion. Pentagon sources said late last year that the Air Force was projecting the cost growth at $750 million, but noted that an independent analysis by the Office of the Secretary of Defense produced a far higher estimate of $2.5 billion.

The Air Force, which disagrees with the independent analysis, was nonetheless obligated to notify Congress of the cost growth due to a U.S. law known as the Nunn-McCurdy provision. That law also will require the Air Force to justify the continuation of the program if its projected cost growth reaches 25 percent.

The Advanced EHF satellites are intended to replace the Air Force’s existing Milstar constellation , which provides secure, jam-proof communications under the harshest conditions. The Milstar constellation is expected to remain healthy up to nine more years, according to the Air Force statement.

Lockheed Martin Space Systems of Sunnyvale, Calif., is the Advanced EHF prime contractor, with Northrop Grumman Space Technology of Redondo Beach, Calif., responsible for the main satellite payload.

The NSA and the military satellite communications program office at the Air Force Space and Missile Systems Center, which is managing the procurement, took several measures to reduce the developmental risk associated with the encryption equipment, the Air Force statement said. But those efforts proved unsuccessful, and delivery of the hardware to the contractor was delayed as a result, the statement said.

Those delays have pushed the launch of the first Advanced EHF satellite from 2007 to 2008. The statement said the encryption problem and associated cost growth was not behind the Air Force decision, taken late last year, to buy just three Advanced EHF satellites and then proceed with the follow-on Transformational Satellite communications program. Congress ultimately could reverse that decision.

Other issues affecting the Advanced EHF program include the need to replace certain “critical electronic parts and added payload component testing,” the Air Force said. But while contributing to the program’s rising cost, those factors have not affected the launch schedule, the statement said.

The Advanced EHF encryption problem is not limited to the satellites. The Air Force recently had to modify its contract with Boeing Air Force Systems of Anaheim, Calif., for the Advanced EHF-compatible Family of Behind Line of Sight Terminals, raising its value from $273 million to $315 million, the Air Force acknowledged in a written response to questions Dec. 22.

The reason was an encryption problem with the COMSEC/TRANSEC System chip for the ground terminals, according to program officials at the Air Force Space and Missile Systems Center in Los Angeles.

The Air Force hopes to avoid encryption problems on future programs by updating its latest space acquisition strategy, which was issued in October 2003 following a review of key programs that have suffered major delays and cost growth, the Air Force said in the Dec. 21 statement. The updated strategy will place greater emphasis on encryption issues at key points in satellite development cycles, the Air Force said.

In addition, the NSA is working with other intelligence agencies to establish a new research and development program designed to incorporate the latest encryption technologies into satellites without disrupting their schedules, the Air Force statement said.

The revised encryption acquisition strategy is being applied to the Transformational Satellite communications program, a challenging development effort that is expected to dramatically increase the amount of bandwidth available to the U.S. military starting around the middle of next decade, the statement said.