CIRCUIT FAILURE FORCES SHUTTLE'S PROMPT RETURN.

Byline: Associated Press 

NASA said it would try to bring Columbia back to Earth today without delay after a computer circuit involving the space shuttle's wing flaps, rudder and brakes failed.

The shuttle has three identical backup circuits, and the National Aeronautics and Space Administration said the seven astronauts were in no danger. But under the space agency's rules, the loss of even one of the circuits dictates a return to Earth as soon as possible.

Columbia's first opportunity to land was at 8:52 a.m. today (5:52 a.m. PST) at Kennedy.

Even before Thursday's problem, Columbia was scheduled to return today. But NASA had been prepared to let the shuttle stay in orbit a day or two longer if the weather at Cape Canaveral was bad.

After the circuit problem came up, NASA dispatched a team of about 75 people to the shuttle's occasional backup landing site at Edwards Air Force Base, in case the weather is better there.

"What we want to do is make sure we're doing the smart things," said NASA flight director Rich Jackson. "So we keep our options open by not only scrambling the A-team out there but continuing to observe the weather on both coasts."

The 15-day mission already has had its share of disappointments for the crew, including the loss of their satellite-on-a-cord, which broke loose and floated off into space while being used to generate electricity.

The circuit problem was discovered when Columbia's crew was making the usual day-before-landing check of the flight-control systems. One of four so-called command paths that relay data from these systems to the computer did not work.

This channel, like the others, controls the wing flaps, rudder, speed brake - all crucial for landing.

NASA always demands backup equipment for all essential systems, but a failure in one component raises the possibility that others could go, too.

Jackson said, to his knowledge, that this particular problem was unprecedented.

During Columbia's Feb. 22 liftoff, hot rocket gas singed two O-rings in the booster rockets, a concern to engineers but no threat to the crew. And an on-board gauge and caution light indicated that one of the three main engines wasn't working right at liftoff. It turned out to be a false alarm.

Three days later, as the crew was unreeling an Italian satellite on 12 miles of electrical cable, the American-made cord broke without warning, reducing a $400 million-plus experiment to space junk.