The Space Shuttle Endeavour is now docked to the International Space Station for an ambitious 16-day mission with a demanding five spacewalks, the most NASA has ever tried to accomplish during one space station mission.
The crews on the space shuttle and the space station greeted each other after docking late Wednesday night and exchanged gifts.
Later tonight they will start working on the next step of the mission -- a spacewalk to start installing a giant Canadian-made robot arm and to prepare to install the first of three parts of a Japanese-made science lab.
Before docking, the shuttle rotated 360 degrees for the now-routine photo inspection of the shuttle's exterior.
Those images will be analyzed for signs of damage, but regarding the mysterious object that was seen hurtling toward Endeavour during its launch, NASA already says it appears it did not strike the shuttle.
"You can see in the video there's clearly something coming from above the orbiter," Flight director Mike Moses said in an early morning briefing. "It passes behind the solid rocket booster. It doesn't go near the nose of the shuttle."
The heat-resistant underside of the shuttle has proved susceptible to debris strikes during liftoff and has been linked to at least one shuttle disaster.
This mission, designated STS-123, is one of a dozen that remain on NASA's shuttle manifest. All remaining shuttle flights, except for one to repair the Hubble Space Telescope, are dedicated to finishing construction of the space station.
The mission commander is Dominic Gorie, who is making his fourth flight. Beside him on the flight deck is pilot Gregory Johnson, who has waited nearly 10 years for his first flight.
There will be something of a Musical Chairs game on this flight, as there have been on past space station missions.
Spacewalker Garrett Reisman is staying behind as a member of the space station crew. His seat on the ride home will be taken by French Gen. Leopold Eyeharts, who was delivered to the station by the Shuttle Atlantis six weeks ago.
NASA and its international space agency partners are managing traffic on orbit. A new European-made robotic cargo ship, known as the Automated Transfer Vehicle or ATV, was launched from French Guiana, Saturday. It will hover in orbit until Endeavour has left and then dock with the station.
After the shuttles are retired, the space station will have to rely on the European ATV, plus Russian Soyuz and Progress spacecraft, for supplies and new crew members.
The next generation of American piloted ships, known as Orion, will not begin flying until the middle of the next decade. The last space shuttle flight, STS-133, is tentatively scheduled for the middle of 2010.