DMSP weather satellite atop Titan 2 rocket in launch pad clean room. Photo: Lockheed Martin Missiles & Space

A U.S. Air Force weather satellite will miss its planned launch date Saturday because engineers must conduct more tests to ensure the $250 million craft will work properly in space.

During recent testing, officials became concerned with a power supply box aboard the Defense Meteorological Satellite Program F15 spacecraft.

"When we ran through our last integrated test sequence, one of our boxes did something that we did not expect," said Col. Jeff Quirk, U.S. Air Force program director of DMSP. "Our troubleshooting is aimed at understanding why it did that and whether that is a problem for us operationally."

Military officials should know by Friday if the satellite can be cleared for launch on Sunday aboard Titan 2 rocket from Vandenberg Air Force Base in California.

"We believe we have a handle on (the problem), but we are going to make sure we have this correct before we launch," Quirk said.

Sunday's launch window will extend from 1738 to 1748 GMT (12:38-12:48 p.m. EST). Forecasters predict favorable weather conditions for launch.

The new satellite will enter service about a month after launch, replacing two older DMSP spacecraft.