Space shuttle Atlantis and its crew of seven returned to Earth on Friday after spending a week at the international space station installing a 44-foot girder.

The weather was ideal for the early afternoon touchdown: a gentle breeze and scattered clouds.

The astronauts' homecoming brings to an end an 11-day mission that began April 8.

"That was a great landing and a great way to end a mission that has been superb in all respects," Mission Control radioed moments after the 12:27 p.m. landing. "You've attached the beginning of the backbone of the station."

The space station and its three occupants were crossing the Florida peninsula and heading out over the Atlantic as the shuttle rolled down the runway. Attack helicopters were on patrol as part of the heightened security put in place after the Sept. 11 attacks.

Commander Michael Bloomfield and his crew left space station Alpha 27,000 pounds heavier with the addition of the aluminum girder, the first piece of a framework that will ultimately extend 356 feet by 2004. Solar wings and radiators will be bolted to it, giving the orbiting outpost more power for laboratories to be added in the future.

Spacewalkers ventured out four times to install the $600 million beam. They also tested a $190 million railcar mounted to tracks on the girder.

The three-man crew aboard Alpha still has to complete two more months of a six-month stay. They are scheduled to return in June.

Astronaut Jerry Ross made history with his flight aboard Atlantis. He became the first person to fly in space seven times. Also, his nine spacewalks -- two on this flight -- are a U.S. record at a total of 58 hours.

"They all have unique qualities," Ross said Thursday about his seven missions. "I felt the same on this one as I did on the first one. ... Great crew to fly with, incredible mission to perform, totally excited about the entire event, and the spacewalks were indescribable."