NASA said a day-long video survey of the shuttle spotted no obvious damage from objects seen floating away, reports CBS News correspondent Peter King.
"We're just pretty optimistic about getting into Kennedy either tomorrow or the next day, so that's encouraging," Brent Jett radioed Mission Control, referring to the landing site at the Kennedy Space Center in Florida.
The crew had hoped to land Wednesday, but even if these mystery objects hadn't come up, they wouldn't have been able to because of weather problems in Florida: low ceilings and showers.
Atlantis had been scheduled to touch down on Wednesday, but the landing was postponed so the astronauts would have an extra day in space for two inspections of the shuttle's wings and nose cap. The first inspection used cameras on the shuttle's 50-foot robotic arm, while the second examination attached a 50-foot boom with cameras and sensors to the end of the robotic arm.
NASA managers didn't see anything that concerned them during the initial inspection using the shuttle's robotic arm.
"It was a long day, especially for Fergie and Dan," said Jett, 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 delay earlier when a shuttle camera spotted an unknown object drifting away shortly after landing systems were put through a normal but bumpy trial run. Mission Control informed the astronauts that the shuttle wouldn't have been able to land Wednesday anyway because of cloudy weather at the Kennedy Space Center
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 astronaut Dan Burbank. But NASA said it appeared to be a garbage bag, which would not likely be a damage risk.
During Wednesday's inspections, the astronauts spotted three more pieces of floating debris.
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 or a mechanic looking-cloth. ... It's not a solid metal structure."
NASA downplayed the discovery of Wednesday's objects, saying the important question was whether an in-depth inspection of the shuttle showed no damage to Atlantis' heat shield. NASA managers planned to issue a verdict after a late morning meeting.
"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 has not worked on a contingency plan of parking the shuttle at the international space station for astronauts' safe haven, but has not ruled that out if serious damage was found.
"We are going to verify that our critical heat shield is in good shape for entry to the best of our ability," shuttle program manager Wayne Hale said.
As King reported Tuesday, Hale confirmed Wednesday that NASA used Department of Defense assets in Maui to photograph Atlantis.