With two of their three spacewalks completed, the astronauts aboard the linked shuttle-station complex focused Thursday on getting the new Columbus lab up and running.
NASA extended Atlantis' mission by a day on Wednesday to give the crew more time to work on the lab, Europe's main contribution to the international space station.
Computer problems that had hindered the activation process were fixed by Thursday, and the space station crew hoped to be able to begin science operations as soon as Atlantis departs next week.
Even though they had the afternoon off, the 10 space travelers kept busy inside Columbus, filling the experiment racks, turning on smoke detectors and setting up the video and ventilation systems.
The international space station is now about the size of an airliner on the inside, astronaut Daniel Tani said Thursday.
"I would say it's about the size of ... maybe a 767 or so, from the first-class section all the way to the back bathrooms," Tani said. "It takes probably a good 20 seconds or so to float your way from the front of the space station all the way to the back tip now. And now we have a left turn that we have to make at the far end to come into the Columbus."
He added: "It's very nice and roomy here."
Tani has been living on the space station since October, and will be aboard Atlantis when it undocks Monday. He said it will be sad to leave, but added that he can't wait to see his wife and two young daughters.
The crew also prepared for the third and final spacewalk of Atlantis' visit.
Americans Rex Walheim and Stanley Love will attach two scientific experiments to the outside of Columbus, retrieve an old space station gyroscope and, if there's time, examine a tiny chip on a handrail near the spacewalk hatch and a jammed solar rotary joint.
The chip — discovered by Love during Monday's spacewalk and thus dubbed Love Crater — is the apparent result of a micrometeorite strike. It may be where spacewalking astronauts have torn their gloves over the past year or so. To find out, Walheim and Love will run a spare glove over the hole to see if the material snags.
As for the rotary joint, Walheim and Love would inspect it but not attempt any repairs. It's been broken since last fall, and other astronauts have gone out to see what might be causing the metal parts to grind, clogging the joint with shavings.
The rotary joint is needed for the solar wings on that side of the space station to automatically track the sun.
The astronauts got a special call Thursday from German Chancellor Angela Merkel. She asked German astronaut Hans Schlegel how he was doing; he had to sit out Monday's spacewalk because of an undisclosed illness, but was well enough to float outdoors Wednesday.
Schlegel, 56, has declined to discuss his condition and did not mention it in his answer, instead talking about how perfectly the Columbus module is working.
"We feel excellent, and it couldn't be any better," he said.
Schlegel looked and sounded fit on Wednesday as he participated in a nearly seven-hour spacewalk to replace a depleted nitrogen tank from the space station. The high-pressure nitrogen gas is needed to flush ammonia through the station's cooling lines.
Atlantis will remain at the space station until Monday. That makes for a 13-day flight, with touchdown now set for Feb. 20. The shuttle's thermal shielding has been completely cleared for re-entry.
AP reporter Liz Austin Peterson also contributed to this report.