At least two pieces of debris were spotted Friday night in launch photos, Mission Control reported, and engineers were poring over the images to determine whether anything hit Endeavour. Mission Control told the astronauts there were no obvious signs of damage.
The spacecraft and its crew of seven were on track to hook up Sunday afternoon with the space station, currently home to three astronauts. The shuttle was delivering tons of equipment for remodeling, including a new bathroom, kitchenette, two sleeping compartments and an unprecedented recycling system for turning urine into drinking water.
"It's the eve of showtime," space station commander Mike Fincke told flight controllers on the ground. "Everyone get some rest. We're going to have a great day tomorrow."
The day centered around the shuttle inspections, standard procedure ever since Columbia shattered during re-entry in 2003.
During the afternoon, Ferguson's crew used the extra-long inspection boom to scrutinize Endeavour's right wing. The nose was next up, followed by the left wing. The painstaking job lasted well into the evening.
The shuttle wings and nose are especially vulnerable, taking the most heat when a shuttle descends through the atmosphere at the end of a flight. Even a seemingly minor gash could spell doom. Columbia was brought down by a hole in its wing the size of a dinner plate; all seven astronauts were killed.
Two pieces of debris were seen trailing Endeavour during Friday's liftoff, one at about a half-minute and the other just over two minutes into the flight. Shuttle officials initially thought the earlier piece may have been a narrow strip of thermal blanket that was yanked off the shuttle during launch, but images from the inspection showed no apparent damage, said flight director Mike Sarafin.
Analysts will continue studying images from that area at the tail of the shuttle, near the orbital-maneuvering engine pod on the left side, before reaching any conclusions, Sarafin said.
It's an area that does not get too hot during re-entry, so flight controllers are not overly concerned, said Leroy Cain, chairman of the mission management team. All the same, Mission Control asked the astronauts to photograph the area.
"You guys gave us some good pictures," Mission Control told Endeavour after the shuttle astronauts sent back images.
Cain said he had no information on the later piece of debris spotted in launch photos.
Virtually every inch of Endeavour will be photographed with zoom lenses when it approaches the space station late Sunday afternoon. Fincke ran through his picture-taking checklist with Mission Control on Saturday to make sure he had everything down.
A problem with a radio communication system on Endeavour that doubles as radar could force Ferguson to rely on a backup navigation system for Sunday's rendezvous.
Once Endeavour is docked, the astronauts will begin unloading and installing the approximately 14,000 pounds of home-improvement equipment. It's all crucial if NASA is to expand the size of the station crew from three to six by next summer.
The space station currently has one kitchen, one bathroom and three bedrooms. Endeavour's delivery will transform the orbiting outpost into a two-kitchen, two-bath, five-bedroom home.