Astronauts aboard the U.S. space shuttle Atlantis prepared Wednesday for their imminent return to Earth, provided Florida's fickle weather cooperates.
Touchdown at the Kennedy Space Center is scheduled for 1:55 p.m. EDT Thursday, although cloudy skies and thunderstorms could prompt NASA to keep Atlantis in orbit for a 14th day. The shuttle blasted off June 8 to install new solar power panels aboard the international space station.
Shuttle commander Frederick Sturckow, pilot Lee Archambault and flight engineer Steven Swanson test-fired Atlantis' steering jets and checked landing systems in preparation for touchdown.
Engineers were still reviewing images of a final inspection of the shuttle's heat shield before flight directors clear Atlantis to leave orbit. Analysis of debris seen floating away from the shuttle as it pulled out of its docking berth at the station Tuesday also was under way.
Neither review was expected to impact Atlantis' landing plans.
The only questionable condition was the weather. Low-lying clouds and possible thunderstorms could delay the shuttle's landing until Friday or later. The shuttle has enough fuel and supplies to stay in space through Sunday, said Phil Engelhauf, head of NASA's flight directors office.
Return to Earth's gravity
While the flight crew worked on preparing Atlantis for landing, astronauts James Reilly, John "Danny" Olivas, Patrick Forrester and returning space station crew member Sunita Williams stowed equipment and packed loose items in the shuttle's middeck.
The crew also set up a reclined chair for Williams, who has not felt the tug of gravity for more than six months. She set an endurance record for the longest spaceflight by a woman during her stint aboard the space station.
In an inflight interview, Williams confessed that despite her disciplined and rigorous exercise routine, she was a little nervous about re-adapting to Earth's gravity.
"I've never done this before," said the first-time flier.
Williams was replaced by rookie astronaut Clayton Anderson, who is scheduled to stay aboard the outpost until October.
During their nine-day stay at the space station, astronauts hooked up a large new metal beam that holds a pair of solar wings and a rotary joint so the panels can track the sun for power.
They also folded up an older solar wing that will be moved to a new location and repaired a small tear in a piece of insulation that is part of the shuttle's heat shield,
The crew conducted four spacewalks, which also helped prepared the $100 billion orbital outpost for the arrival of new laboratories built by Europe and Japan.
The flight was the first of four NASA plans for this year.
The U.S. space agency plans 12 more construction missions to the space station, which is slightly more than halfway built, before the shuttle fleet is retired in 2010.