Astronauts aboard the US shuttle Discovery learned from mission control Sunday that they are cleared to return to Earth in one week after an inspection of the exterior of the spacecraft. There had been some concern about whether a dangling piece of fabric filler would have to be repaired during a spacewalk. But engineers decided it the fabric did not pose a hazard.

The five centimeter long piece of filler fabric dangles out from thermal tiles on Discovery's belly. Mission managers spent hours over the weekend trying to determine whether this posed a hazard to the shuttle's safe return to Earth on July 17.

In the end, engineers decided the drooping fabric was not a problem, sparing the astronauts a space walk to repair the tiles, and clearing the shuttle for landing.

This is the second mission since the Columbia disaster three years ago when the space shuttle burned up upon reentry into Earth's atmosphere, killing the seven-member crew. The shuttle's protective heat shield had been damaged during launch by a piece of hard insulating foam.

During last year's mission, several pieces of filler fabric came loose and astronauts carried out a repair during an anxious space walk. It took mission managers two days to make the repair decision.

This time around, shuttle orbiter projects manager Steve Poulos says the US space agency NASA has streamlined the process and engineers can make repair decisions in about half that time.

"Going into this flight we had an objective was to be able to by flight day six come in and say that the thermal protection system was cleared for re-entry and yes, in fact, we did meet that pre-flight objective," said Steve Poulos. "So, again, the amount of work and energy that's gone into this project cannot be overstated."

The astronauts were told the shuttle looked intact following an inspection of the shuttle's exterior on the second day of the mission, and a closer look on day four.

Astronaut Stephanie Wilson described the inspection as long and deliberate.

"We've been told we have a very clean vehicle and I certainly have no concerns about returning," said Stephanie Wilson.

An inspection of the leading edges of Discovery's wings will come at the end of the week when the shuttle undocks from the International Space Station. Only after this last inspection will Discovery be given final clearance to land.