Commander Michael Bloomfield, making his first landing at the controls of a space shuttle, guided Atlantis to a smooth touchdown on Runway 33 at the Kennedy Space Center today to close out a near-flawless space station assembly mission.

Enjoying a spectacular view as the shuttle plunged across sunny central Florida, Bloomfield and his crewmates announced their arrival with a double sonic boom that rattled windows for miles around.

After giving rookie pilot Stephen Frick a few minutes of "stick time" flying Atlantis through a sweeping right overhead turn, Bloomfield took over and guided the ship to a tire-smoking touchdown on Runway 33 at 12:26:57 p.m. to close out an 11-day flight.

"Houston, Atlantis, wheels stopped," Bloomfield radioed mission control as the shuttle rolled to a halt.

"Bloomer, we copy wheels stopped," replied astronaut Charles Hobaugh at the Johnson Space Center. "That was a great landing and a great way to end a mission that has been superb in all respects. You've attached the beginning of the backbone of the station in addition to setting a record for EVA in ISS assembly."

"OK, copy, Scorch, and thanks to the entire team. We feel very privileged to have been a small part of that team."

Mission duration for the 109th shuttle flight, which included a space station record 28 hours and 22 minutes of spacewalk assembly time, was 10 days 19 hours 42 minutes and 38 seconds.

Bloomfield, Frick, flight engineer Ellen Ochoa and spacewalkers Steven Smith, Rex Walheim, Jerry Ross and Lee Morin plan to spend the night at the Kennedy Space Center before flying home to Houston early Saturday.

The astronauts accomplished the primary goal of their mission April 11 when the $600 million S0 truss (pronounced S-zero) and its $190 million mobile transporter were attached to the top of the international space station's Destiny laboratory module.

The 27,000-pound truss segment is the central element in a nine-segment truss that eventually stretch longer than a football field and carry the station's main solar power arrays and ammonia coolant radiators.

S0 provides the structural attachment for the entire beam and routes power cables and ammonia coolant lines into and out of the space station complex. It is equipped with four computers, GPS receivers and laser ring gyros to provide station location and orientation information as well as electronic converters and other power conditioning equipment.

The mobile transporter, attached to rails running along the forward face of S0, eventually will carry the station's Canadarm2 space crane back and forth to various work sites to install outboard truss elements, radiators and solar arrays.

The arm currently is mounted on the Destiny module and Ochoa, assisted by station engineer Daniel Bursch, used it April 11 to mount S0 atop the lab. Smith and Walheim then carried out a spacewalk to complete the first set of structural attachments and to make critical electrical connections.

Morin and Ross, making his world record seventh flight, then completed the connections during a second spacewalk two days later. During a third excursion the next day, this one by Smith and Walheim, the station's arm was re-wired to receive power from the truss. That was a critical step that had to be completed before the arm can be mounted on the mobile transporter for continued assembly.

During a final spacewalk Tuesday, Ross and Morin completed a variety of lower-priority tasks before the shuttle undocked Wednesday, leaving Bursch, Expedition 4 commander Yury Onufrienko and Carl Walz behind. Ross now ranks second on the world spacewalk records list with 58 hours and 18 minutes of EVA time in a U.S.-record nine spacewalks.

Onufrienko and his crewmates, meanwhile, spent the day today readying the station for their brief departure early Saturday to move the lab's Soyuz lifeboat from a docking port on the Zarya propulsion module to the Pirs docking compartment attached to the Zvezda command module. The crew is scheduled to undock at 5:02 a.m. EDT and to redock at 5:35 a.m.

That will clear the Zarya port for arrival of a fresh Soyuz April 27. The Russian spacecraft are rated for six months in orbit and the capsule currently attached is nearing the end of its orbital lifetime.

The new Soyuz will be delivered by commander Yuri Gidzenko, Italian astronaut Roberto Vittori and South African space tourist Mark Shuttleworth, who paid the Russians more than $10 million - the exact amount is not clear - to become the second tourist to visit the space station.

NASA's next station flight is scheduled for liftoff May 30 when the shuttle Endeavour will carry the lab's next full-time crew into space: Expedition 5 commander Valeri Korzun, flight engineer Sergei Treschev and NASA astronaut Peggy Whitson. Onufrienko, Bursch and Walz will return to Earth aboard Endeavour to wrap up a six-month stay in space.