Cape Canaveral, Fla. ? Space shuttle Atlantis and its crew of six returned from the international space station Friday, ending a 4.5 million-mile voyage that accomplished major construction work.

“What an incredible adventure we’ve been on,” commander Jeffrey Ashby said.

Atlantis swooped through a slightly cloudy sky, wobbling a little in the wind on final approach. It turned out to be one of the stiffest crosswinds ever for a shuttle touchdown, but Ashby brought the ship down smoothly almost right on the center line.

Ashby, a Navy captain and Top Gun aviator, has 1,000 carrier landings to his credit, the most in the astronaut corps.

During their 11-day mission, Ashby and his crew successfully outfitted the space station with a $390 million girder that is part of a framework that will grow over the next 1 1/2 years and sprout power-generating solar wings.

It was an extensive addition: The girder is 45 feet long and 15 feet wide, and its unfolded radiator spans 75 feet.

As Atlantis glided to a safe touchdown, the space station and its three inhabitants were soaring 250 miles above the Gulf of Mexico. The station should have been a little higher, but an effort to boost its orbit, using an attached cargo ship, did not go as planned.

The 183-ton space station will grow 14 more tons when another girder practically a mirror image of the one just installed is ferried up next month by shuttle Endeavour. An even more important payload will be the replacements for American Peggy Whitson and her two Russian crewmates, who have been living aboard the orbiting complex since June.

The seven astronauts assigned to NASA’s next flight, in town for a practice countdown, got a glimpse of Atlantis coming home.

“It was great to see them pull off the mission so successfully. That makes us feel a lot better and we’re that much more prepared,” said the commander of the next mission, James Wetherbee.

Endeavour’s planned launch on Nov. 10 could be delayed, however, for a couple of unrelated reasons.

NASA intends to rip into Atlantis’ electronics as soon as possible to understand a failure in the pyrotechnic system during the Oct. 7 launch. The backup set of explosive charges intended to release bolts holding the shuttle’s boosters down on the pad did not fire when the countdown reached zero.

Also clouding Endeavour’s launch date is Russia’s investigation into a launch explosion earlier this week that killed a soldier on the ground. A modified version of the doomed rocket is supposed to take off Oct. 28, carrying two Russians and a Belgian and delivering a fresh lifeboat to the space station. But the mission could be postponed for further analysis.

NASA must wait for that flight to be completed before launching Endeavour, said shuttle manager Linda Ham.

Wetherbee said he and his crew were in no hurry.

“I hate to say this for any of the guests or people who are coming to watch a launch, but I’m not sure I care when we launch,” he said. “Someday we’ll launch … and that will be a great day for us.”