EDWARDS AIR FORCE BASE, Calif. (AP) _ The Air Force aborted the launch of a satellite-bearing Pegasus rocket a minute before firing Thursday when the crew of its B-52 carrier plane discovered low batteries in a guidance system.

Fins on the back of the rocket that control its flight need the battery power to operate, said Capt. Derek Cossey.

The B-52, which was flying over the Pacific, headed back to Edwards Air Force Base where engineers planned to go over the equipment. A new launch date has not been set.

Cossey said it was too soon to know whether the battery leaked or if human error or some other problem was to blame.

The three-stage Pegasus rocket is to position the Space Test Experiment Platform Mission 2 satellite in a low Earth orbit. The satellite will test military radio communications.

The TRW-built satellite, powered by four fixed solar panels, weighs just 398 pounds. It carries a single experiment to evaluate radio communications and transmit information to several ground stations.

The cost of the satellite, launch and experiment is $34 million, said Valerie Arruda, spokeswoman for the Air Force's Space and Missile Systems Center at Los Angeles AFB in El Segundo.