CAPE CANAVERAL, Fla. The planned launch next month of the International Space Stations first science lab could be delayed significantly so technicians can replace a damaged cable on shuttle Atlantis booster separation system.

Atlantis and five astronauts now are scheduled to blast off Jan. 18 on a mission to deliver the U.S. Destiny laboratory to the new international station.

That target launch date, however, could be pushed back a week or more if a cable replacement job requires Atlantis to be disconnected from its 15-story external tank and attached solid-fuel rocket boosters.

"Thats the question right now," said Kennedy Space Center spokesman Joel Wells. "Its one of those things that would be a worst-case [repair] scenario."

Engineers over the weekend discovered a damaged electrical cable designed to route crucial computer commands to small explosive devices used to separate the shuttles twin solid-fuel rocket boosters from the ships external liquid-fuel tank during flight.

The discovery was made during inspections that were ordered after problems cropped up with shuttle Endeavours booster separation system during its Nov. 30 launch.

One of two explosive cartridges used to separate a lower strut holding Endeavours left-hand solid rocket booster to the shuttles 15-story fuel tank failed to fire in flight. A back-up detonator, however, did fire and the 149-foot (45-meter) booster separated cleanly from the external fuel tank.

Had both explosive cartridges failed, however, Endeavour and its five-man crew could have been lost.

Engineers traced the problem to a damaged cable, and then ordered tests and inspections on the two boosters that will help propel Atlantis and its four-man, one-woman crew into orbit.

One of the cables associated with the same lower strut on Atlantis left-hand booster failed a signal-relaying test over the weekend. Further inspection showed that the outer shielding designed to protect electrical connectors within the cable was brittle and crumbling.

NASA mission managers almost certainly will order a replacement. That work, however, could require Atlantis and its bullet-shaped fuel tank to be removed from a mobile launcher platform so technicians can replace the damaged cable.

In that case, the Jan. 18 launch likely would face a delay of a week or more.

Atlantis had been scheduled to move out to its oceanside launch pad Dec. 11, but those plans were put on hold until technicians could inspect cables associated with its booster-separation system.

The move was tentatively rescheduled for today, but NASA scrapped that plan when the damaged cable was discovered. The Jan. 18 launch date, meanwhile, could face a delay equal to the amount of time it takes to replace the faulty cable.

A delay would be the second in as many weeks for NASAs shuttle program. A planned Feb. 15 launch of shuttle Discovery and a fresh space station crew last week was delayed until March 1 so technicians could replace faulty shuttle jet thrusters.

Consequently, a planned Feb. 26 return to Earth for the three-man crew now working on the station now is being postponed until March 12.