KENNEDY SPACE CENTER, Fla. Nov. 7 — The shuttle Discovery glided to a safe landing here Wednesday, bringing to a close an eventful mission that combined challenging space station construction and emergency repairs.

Commander Pamela A. Melroy fired the shuttle’s braking rockets just before noon, Eastern time, beginning the return from orbit. The shuttle flew over North America from the northwest to the southeast and landed on the 15,000-foot landing strip shortly after 1 p.m.

The shuttle, which glides to its landing without power, could be seen passing high above the landing site as a speedy white dot. Its distinctive double sonic ba-BOOM could be heard moments after it passed overhead, bringing applause from the spectators at the runway. Commander Melroy then brought the craft around for its final approach, heading into a stiff headwind and touching down.

The mission started out as a pivotal moment in station construction, tightly packed with goals that included bringing up a new room — the Harmony module — and relocating an enormous solar array and truss from its temporary position atop the station to its permanent location on the left side. Moving the 35,000-pound array required two spacewalks and a nimble handoff between the robotic arms of the shuttle and station.

Along with those spacewalks and one to prepare Harmony’s external fittings, the mission also called for a fourth spacewalk in which astronauts would test repair techniques for the shuttle’s delicate thermal tiles, and a fifth to begin the work of preparing the station for the December visit of the shuttle Atlantis.

The first three spacewalks went smoothly, and the truss was moved successfully. But two problems caused mission managers to change their plans for the rest of the mission, including the remaining carefully-choreographed spacewalks.

The first was a problem with a rotary joint that keeps the right-side arrays facing the sun. Engineers had noticed the joint was vibrating oddly and using too much power; during the second spacewalk, Daniel M. Tani removed a cover from the joint and peeked in, and found that it was fouled with metal shavings, suggesting that some part of the joint was grinding itself down.

Mission managers decided to use the fourth spacewalk to thoroughly examination of the joint. But on Tuesday, as astronauts inside the station opened the newly-relocated solar array, a guide wire snagged on one of the folding panels’ hinges and tore two holes in the 110-foot-long array. The spacewalk plans were then changed again, this time to be devoted to a high-stakes, high-risk attempt to repair the torn array.

On Saturday, Dr. Scott E. Parazyinski rode the station robotic arm, extended with a sensor boom from the shuttle, to reach the array, snip the errant wires and apply five “cufflinks” that were built on board from precise instructions from the ground. The cufflink-like straps held, taking the strain off of the material around the tears, which allowed the damaged array to be fully extended.

Discovery’s seven astronauts included Commander Melroy, who is a retired colonel in the Air Force, the pilot, Col. George D. Zamka of the Marine Corps, Dr. Parazynski, Stephanie Wilson, Col. Doug Wheelock of the Army, Paolo Nespoli, an Italian representing the European Space Agency, and Daniel M. Tani, who flew up with the crew and remained aboard the station. The shuttle brought Clayton Anderson back to Earth on his 15th wedding anniversary; he lived and worked aboard the station since June.

In interviews from space on Tuesday, Mr. Anderson said that he expected readjustment to gravity might be a little rough. “I’m kind of optimistic, maybe overly so,” about his physical preparedness to deal with gravity again, he said, thanks to extensive exercise during his stay, but he was not sure of his balance. “The only part I don’t know about is how I will react with my vestibular system and the fact that I’ve been off the planet with minimal gravity for five months.”

Two hours after the landing, Commander Melroy and four members of her crew took part in the customary inspection of the underside of the vehicle. Mr. Nespoli and Mr. Anderson remained behind, though Commander Melroy said “they’re doing great,” and were just undergoing further medical tests.

“We are thrilled to be back home,” she said.

The end of this mission sets off a scramble aboard the International Space Station to prepare for the next one, with three spacewalks planned for the three-person crew aboard the station so that the orbiting outpost is ready for a new laboratory module, known as Columbus, that will be brought up aboard the shuttle Atlantis on a mission that will launch as early as Dec. 6.

-nytimes.com