The shuttle Discovery swooped through a partly cloudy sky and settled to a smooth landing today at the Kennedy Space Center, bringing the international space station's outgoing crew back to Earth after five-and-a-half months in weightlessness.

Discovery touches down on Runway 15 at Kennedy Space Center. Photo: NASA-KSC

Running one orbit late because of rain showers near the runway, commander Scott Horowitz and pilot Frederick Sturckow fired Discovery's twin braking rockets at 1:15:09 p.m. and glided to a picture-perfect touchdown on runway 15 at the Florida spaceport at 2:22:58 p.m.

"Houston, Discovery is wheels stopped. And for transfer, items 106, 107 and 108 are complete," Horowitz radioed, jokingly referring to Expedition Two commander Yury Usachev, Susan Helms and James Voss.

"Welcome home to all of you and especially Yury, Susan and Jim, it's great to have you back on Earth," replied astronaut Kenneth Cockrell from Houston.

Horowitz, Sturckow, flight engineer Daniel Barry and Patrick Forrester made the trip back to Earth on Discovery's upper deck. Usachev, Voss and Helms flew home resting on their backs in recliners mounted on the shuttle's lower deck.

"We're really happy to have taken part in delivering Expedition Three into orbit and they're having a great mission right now up there on the space station," Horowitz said on the runway just before 4 p.m. "Expedition Two's doing really great. In fact, we were surprised, some of them looked like they were doing a little better than us when they got off the vehicle today.

"So they're real troupers, they had a great mission," he said. "Discovery flew perfect and we wanted to thank everybody for an outstanding job."

Launched March 8, the Expedition Two crew logged 167 days and seven hours off the planet. They were replaced by Expedition Three commander Frank Culbertson, Vladimir Dezhurov and Mikhail Tyurin on Aug. 13, the day after Discovery docked with the outpost.

The drag chute is deployed to slow Discovery after touchdown. Photo: NASA-KSC

A team of U.S. and Russian flight surgeons was standing by at the Kennedy Space Center to assist Usachev and his crewmates off the shuttle. All three plan to fly back to the Johnson Space Center on Friday after physical exams, reunions with friends and family members and initial rehabilitation.

The Expedition Two astronauts exercised vigorously in orbit using a motorized treadmill, a stationary bike and elastic resistance bands. Voss said Monday he planned to walk off the shuttle, if able.

"We've all been exercising a lot up here, especially on the treadmill," he said. "We've been running and walking for a little over an hour every day. And this seems to be doing very well because the shuttle crew came up, said that the treadmill exercises we were doing were quite tiring. It sounds like the countermeasures we're doing are working."

But Taddeo said it would take several months for the astronauts to regain their pre-launch health and stamina. While lost muscle mass can be regained fairly quickly, restoring lost bone material takes longer.

"Generally, people say they're feeling pretty good by just a couple of days out," he said. "But they'll tell you they've still got some muscle soreness and they may be walking funny. ... It depends on the individual. But most people don't really start feeling strong again until maybe two to three months out."

Discovery rolls out on Runway 15 with the Vehicle Assembly Building at backdrop. Photo: NASA-KSC

Voss plans to move back into his home as soon as he returns to Houston. Helms, who gave up her apartment before launch, said she will move into a new apartment her father has been setting up. Usachev will undergo initial rehabilitation in Houston and fly back to Russia in about two weeks.

"The first week is going to involve some fairly light workouts for them," Taddeo said. "So they'll be doing some jogging in the pool, they'll be doing some active and passive stretching, they'll be getting some massage for muscle soreness.

"The second week, we might start some lap swimming in the pool, we may start some more vigorous walking. We will start some very light-weight resistive exercises, doing some squats, that sort of thing."

In a month or so, "you can start thinking about some light jogging, adding some additional weight to your resistive regime," Taddeo said. "It's just a ramp up over those 45 days. We're going to tailor it to the individual. Some people may make faster progress, some people may make slower progress."