Discovery carried Japan's prized Kibo lab, a 37-foot-long, 16-ton scientific workshop. The seven shuttle astronauts and three station residents will combine forces to install the bus-size lab on Tuesday.
The shuttle crew also brought a spare toilet pump for the orbiting outpost. The space station's Russian-built toilet broke nearly two weeks ago -- forcing the crew to perform manual flushes with extra water several times a day -- and engineers hope the new pump will take care of the problem.
Astronaut Gregory Chamitoff got his first look at what will be his home for the next six months. He is replacing Garrett Reisman, who has been living at the station since March.
"Garrett, you have a beautiful house," Chamitoff said. "Oh my God, it's so beautiful."
The two men hugged once the hatches between them swung open. It was a group embrace, actually, with the space station's two Russian residents joining in as well.
Also moving in for a half-year is a 12-inch action figure familiar to children almost everywhere: Buzz Lightyear, the character from the 1995 film "Toy Story" that's always yearning to blast off "to infinity and beyond." Disney sent up the toy as part of NASA's toys-in-space educational program.
Right before linking up with the space station, Kelly guided Discovery through a 360-degree somersault from 600 feet out, allowing Reisman and one of the space station's Russian residents to take zoom-in photos of the shuttle's belly. The back flip became standard procedure for shuttle flights following the 2003 Columbia tragedy; Columbia was brought down by a hole in the wing, left there by flyaway fuel-tank foam.
Imagery experts will pore over these digital pictures -- as well as the multitude of images from Saturday's launch -- to see whether Discovery is in good enough shape to re-enter safely on June 14. About five pieces of foam insulation broke off the external fuel tank during liftoff, and one or two of them may have hit the shuttle. But the pieces, it's believed, came off too late in the launch to do any damage.
NASA, meanwhile, has formed an investigation team to figure out why the launch pad sustained so much damage during Discovery's liftoff -- said to be the worst damage in 27 years of space shuttle history.
A large section of the flame trench -- 20 feet by 100 feet -- broke apart, and chunks of the large heat-resistant fire bricks and concrete mortar were scattered all the way out to the fence 1,800 feet away, possibly even farther. "We're combing the ground as we speak," NASA spokesman Bill Johnson said in the early afternoon.
The pieces of debris ranged in size from a pebble to entire bricks.
Johnson said it's unlikely any of the bricks hit Discovery because the flame trench is designed to deflect the flames at booster rocket ignition, as well as stones and other debris kicked up by all the power.
There have been no recent repairs to the Apollo-era flame trench that might have caused this sort of damage, and it's never broken like this before, Johnson said. "We'll just have to wait until the report comes in," he said.
NASA does not need to use the pad again until the next shuttle
launch in October.