HOUSTON (AP) – NASA cleared Atlantis for a Thursday landing after finding that the space shuttle appeared undamaged and concluding the discovery of unexplained space debris did not pose a serious problem.

Atlantis’ six astronauts completed two inspections of the space shuttle Wednesday to make sure it wasn’t damaged from the mysterious objects found floating outside the spacecraft. Landing was set for Thursday morning, a day later than originally scheduled.

“Nothing was found to be missing or damaged,” said Wayne Hale, space shuttle program manager. “So we feel very confident that we’re in for a very good landing opportunity.”

Mr. Hale said the crew would be well-rested for Thursday’s landing, despite the extra, improvised work using cameras and sensors at the end of the shuttle’s robotic arm and a 50-foot boom.

“It was a long day, especially for Fergie and Dan,” Atlantis commander Brent Jett radioed Mission Control, referring to pilot Chris Ferguson and astronaut Dan Burbank, who operated the robotic arm. “But you do what you need to do. … We understand everybody’s doing the right thing, so we’re happy to do what it takes.”

The decision to delay landing Atlantis on Wednesday was made a day earlier when a shuttle camera spotted an unknown object drifting away shortly after landing systems were put through a normal but bumpy trial run.

NASA officials said their best guess was that the object was a plastic filler placed in between thermal tiles which protect the shuttle from blasting heat. A second mystery object was spotted several hours later, midday Tuesday, by Mr. Burbank. But NASA said it appeared to be a garbage bag, which would unlikely be a damage risk.

During Wednesday’s inspections, the astronauts spotted three more pieces of floating debris. Mr. Jett described the objects as two rings and a piece of foil. He told Mission Control the first object, about 100 feet from the shuttle, was “a reflective cloth. … It’s not a solid metal structure.”

NASA downplayed the discovery of Wednesday’s objects, saying the fact that no problems were found with the shuttle was more important.

“It’s not uncommon to see little bits of pieces of things floating by,” said flight director Paul Dye.

NASA officials thought the debris may have come from the shuttle’s cargo bay.

“Typically, when we open the payload doors on the first day of flight, we will see objects,” landing flight director Steve Stich said. “It’s a little bit unusual to see objects maybe this late in the mission.”

NASA’s main concern was the status of the all-important heat shield, because a damaged shuttle skin led to the 2003 demise of the shuttle Columbia. NASA had not worked on a contingency plan of parking the shuttle at the international space station for astronauts’ safe haven, but would not have ruled that out if serious damage had been found.

___

On the Net:

NASA: http://www.nasa.gov