NASA officials would not say why German astronaut Hans Schlegel, 56, was being replaced, but Atlantis' commander, Stephen Frick, requested a private medical conference with flight surgeons shortly after reaching the space station.
"I will just say it's not going to impact any of the objectives of this mission," said John Shannon, chairman of the mission management team. "It will cause us to rearrange a few activities."
Shannon refused to elaborate, citing medical privacy, but noted that it was not a life-threatening condition. Schlegel's status for the second spacewalk of the mission was still uncertain, he said.
Schlegel, a two-time space flier, was supposed to venture outside with American Rex Walheim on the first two spacewalks. Love was supposed to go out with Walheim on only the third spacewalk.
The two crews were supposed to unload Columbus and attach it to the station Sunday. Just a few hours after the station and the shuttle linked up, Mission Control informed the astronauts about the delay.
Mission Control said Schlegel's crewmate, Stanley Love, would take his place. Love trained for the work, just in case.
It was a rare and unsettling change in plans for NASA, which typically prepares for every aspect of a shuttle mission -- particularly spacewalks -- for months and even years.
The delay in installing Columbus and carrying out the first spacewalk prompted NASA to add a 12th day to the mission. Yet another day could be added; NASA had hoped to spend an extra day at the space station to help set up Columbus.
The two spacecraft linked up as they passed more than 200 miles above Australia. Just over an hour later, the 10 space travelers -- seven shuttle astronauts and three station residents -- threw open the hatches, laughing and shouting.
Just before docking, Atlantis did a 360-degree backflip so station commander Peggy Whitson and her crew could photograph the shuttle's thermal shielding. Nearly 300 photos were beamed back to Earth so engineers could look for any signs of launch damage.
Mission Control requested extra pictures of a torn thermal blanket on Atlantis' right orbital maneuvering system pod, back near the tail. The small tear was along a seam, and occurred during the launch, said flight director Mike Sarafin.
Engineers were analyzing the tear and whether it posed a hazard for re-entry at flight's end. The exact size of the peeled-up section was unknown, but it appeared to be smaller than one that required spacewalking repairs last June. Coincidentally, that tear was in a blanket on Atlantis' left orbital maneuvering system pod.
"It's probably not that big of an issue, but we're off looking at it," Sarafin told reporters.
The photos of the shuttle's thermal shielding tiles are standard procedure, ever since the destruction of Columbia in 2003. Columbia's wing was gashed at liftoff by a chunk of fuel-tank insulating foam. Only a small amount of foam is believed to have come off Atlantis' tank, and none of it appeared to seriously damage the shuttle.
Saturday was Whitson's 48th birthday, and the shuttle astronauts wished her all the best. She said Columbus' arrival was a great way to celebrate.
"We are looking forward to helping you over the next couple of days unpacking and enjoying your birthday present," the European Space Agency's Mission Control radioed from Germany.
Europeans have waited an agonizingly long time to see Columbus in orbit.
The original plan called for Columbus to be launched in 1992 to mark the 500th anniversary of Christopher Columbus' voyage to the New World. But years passed as NASA redesigned the space station. Then station construction ended up being stalled, and then the shuttle fleet was grounded for 2 1/2 years following the Columbia tragedy.
Atlantis will remain at the space station until next weekend. The shuttle astronauts will perform three spacewalks, beginning Sunday, to help install Columbus and complete other station chores.
Space station astronaut Daniel Tani was especially happy to see Atlantis and its French crewman, Leopold Eyharts, who will take his place aboard the orbiting outpost. Tani will return to Earth on the shuttle, ending a four-month mission.
Sarafin said the docking went well, despite the failure of one
of Atlantis' three guidance and navigation computers early
Saturday. Only two are needed for the job.
