The first expedition aboard international space station got a little longer on Wednesday when NASA announced a delay from February to March in launching space shuttle Discovery to ferry the three-man crew back to Earth.

The official portrait of Expedition One: Commander Shepherd (center) is flanked by pilot Gidzenko (right) and flight engineer Krikalev (left). National flags representing all the international partners run along the bottom. Photo: NASA

Originally scheduled for blastoff February 15 from the Kennedy Space Center, Discovery's launch has been pushed back to March 1 because of unplanned work ordered on the $2 billion spaceship before it can fly again. Ten steering thrusters on the shuttle are being replaced after some were found chipped, while others will be swapped to prevent leaks.

"We found four thrusters that need to be replaced," shuttle program chief Ron Dittemore said earlier this week. "It's our policy that when we change a jet out, we change all the jets on that particular manifold. If we don't do that, we have some risk of having leaking jets on the following flight.

"So that means even though four jets need to be replaced, we have to change out 10. And that's going to affect our schedule," he said.

Discovery atop the Shuttle Carrier Aircraft departs California's Edwards Air Force Base on its cross-country trek on November 2 bound for Kennedy Space Center in Florida. Photo: NASA-DFRC

The two-week slip was not a surprise. Shuttle workers had very little slack left in the processing schedule because Discovery's most recent mission in October was launched nearly a week late. Then bad weather diverted the shuttle's landing to California, forcing a time-consuming cross-country ferry flight back to the Cape.

The Expedition One crew led by commander Bill Shepherd, with pilot Yuri Gidzenko and flight engineer Sergei Krikalev were launched aboard a Russian Soyuz rocket on October 31 for a planned three-and-a-half month tour of duty to begin the continual human presence aboard the international space station.

Once Discovery is launched on the STS-102 mission, the shuttle will play taxicab. The Expedition Two crew -- Yuri Usachev, Jim Voss and Susan Helms -- will be brought to the station to replace their predecessors. Shepherd and company will ride Discovery back to Earth at the conclusion of the shuttle's 11-day mission on March 11.

Shepherd didn't seem bothered by the news his voyage in space was being extended, saying he was "banking on this maybe not being exactly per the plan anyway."

"We're fine with it," Shepherd told Mission Control. "We've got plenty of chow, all the food and water we can drink. Could use a couple more T-shirts, but, hey, we're getting by."

The other crew members for Discovery's upcoming mission include commander Jim Wetherbee, pilot Jim Kelly and mission specialists Andy Thomas and Paul Richards.

In other space shuttle news, engineers completed the first round of X-ray inspections of electrical cable connectors inside the solid rocket boosters of Atlantis on Tuesday. A second round of inspections was underway Wednesday to determine the integrity of the connectors, which are part of wiring that route commands to separate the boosters during flight.

Endeavour lifts off on November 30 with power-generating solar arrays for the international space station. Photo: NASA-KSC

The connectors are being checked because one of two explosive detonators in a strut connecting Endeavour's left-side solid-fuel booster failed to fire during launch November 30. The second detonator worked as planned and the booster separated safely.

NASA believes a broken electrical wire probably caused the detonator to not fire.

Shuttle managers are due to meet Thursday afternoon to review results of the inspections and ongoing engineering analysis. If Atlantis' boosters are giving a clean bill of health the shuttle could be rolled from its current location in Kennedy Space Center's 52-story Vehicle Assembly Building to launch pad 39A on Saturday. However, should additional inspections be ordered the rollout would be delayed further.

Atlantis had been slated for transport to the pad on Monday. But those plans were put on hold in light of the Endeavour problem. If Atlantis is not rolled out by early next week, officials say the targeted January 18 launch date cannot be met.

Atlantis' STS-98 mission will haul the U.S. research laboratory module, Destiny, to the international space station.