CAPE CANAVERAL, Fla. (AP) _ The Air Force has formally declared mission failure for an $800 million satellite that was launched into an orbit thousands of miles too low last week.

The announcement on Tuesday was needed before the Air Force could appoint a board to investigate the accident, spokesman Aaron Renenger said.

It was the third failed mission in 8 1/2 months involving the Air Force's Titan IV rocket program.

Air Force controllers have stabilized the Milstar communication satellite and extended its electricity-generating solar wings since its launch Friday aboard a Titan IV rocket.

But the satellite remains in a lopsided orbit with a high point of only 3,100 miles. That orbit poses no threat of an uncontrolled fall through the atmosphere, officials said.

The Air Force has yet to determine whether the satellite can be boosted using on-board fuel and thrusters, whether it can be of any use where it is, or how to eventually dispose of it. It's too soon to say whether the satellite will be able to achieve its original mission, Renenger said.

An investigation board will begin its work this week at Cape Canaveral Air Station. Preliminary indications are that the Titan IV worked fine during the first several minutes of the flight, but an upper-stage rocket misfired and failed to put the Milstar in its intended 22,300-mile-high orbit.

It was the third failed mission in a row for the Air Force's Titan IV, with losses totaling $3 billion.

The trouble began last August when a Titan IV carrying a spy satellite blew up shortly after liftoff. Then a missile-warning satellite was placed in too low of an orbit following its launch aboard a Titan IV on April 9.