A military communications satellite built primarily for nuclear war and launched last month at a cost of $1.3-billion has experienced a power failure in orbit, the Pentagon said Friday.
Senior Pentagon officials described the problem as a minor difficulty, but critics of the satellite program said it was significant.
Pentagon and congressional officials said information on the implications of the failure was classified as secret.
The satellite is to be the first of six Milstar satellites. The first two were designed in the 1980s to provide global communications during and after a six-month nuclear war.
The second one is being prepared for a future launching. The final four satellites are being redesigned to reflect the diminished likelihood of such a conflict.
"The bottom line is very simple: We had a very simple power unit failure," said Brig. Gen. Leonard Kwiatkowski, the Pentagon's program director for military satellite communications systems.
Kwiatkowski said the power loss was a minor mishap that would have no long-term effect on the satellite, other than reducing its anticipated seven-year life by perhaps four months.
"The satellite experienced a problem," he said. "The problem was associated with power to one of our satellite's computers. There was a temporary loss of power. The satellite is functioning normally." A backup power system has taken over from the failed unit, he said.
But another Pentagon official said the backup system was nearly identical to the primary system and thus could be vulnerable to the same flaw that knocked out the system it replaced.
Lou Rodrigues, a senior official of the General Accounting Office, the investigative arm of Congress, who has followed the Milstar program for more than three years, said the failure was significant.
"We just spent $1.3-billion to put a satellite in space that has a limited capability to begin with and it has a major problem," Rodrigues said.
John Pike, the director of space policy for the Federation of American Scientists, who has long been a critic of the Milstar program, said he found it "curious that a satellite that was supposed to be able to endure World War III couldn't endure a month in space."
Pike used an automotive analogy to describe the failure. "They're running on a spare tire, and the tire they just replaced turned out to be rotten," he said.
An Air Force spokesman, Maj. Dave Thurston, said the failure involved "a primary power distribution system," which distributes electricity from solar power panels to computers on board the satellite, he said.
Thurston declined to answer several questions about the failure, citing secrecy restrictions that have obscured many facts about the Milstar system.
All six Milstar satellites are scheduled to be in orbit after the turn of the century, at an estimated cost of more than $27-billion. The Milstar satellites will be the most expensive communications satellites ever created.
Research and development costs for the program have reached about $8-billion. Combined with the rockets to launch them, the spaced-based part of Milstar will cost roughly $10-billion to build. Each satellite costs about $110-million a year to operate once it is launched.
Billions more are being spent on Milstar's land-based terminals and data links for soldiers, sailors and fliers in the nuclear chain of command: bomber pilots, submarine commanders, covert special-operations units and, according to Pentagon budget plans, one-star generals inside lead-lined trucks that would serve as mobile command centers broadcasting orders during a nuclear war.