Shuttle Discovery chased the international space station in orbit Wednesday as its seven astronauts geared up for a laser inspection of their ship's wings. It was the first full day of what NASA considers to be the most complicated space station construction mission yet. The shuttle was to reach the station Thursday. NASA's space operations chief, Bill Gerstenmaier, said after Tuesday's liftoff that the astronauts face a tremendous series of challenges, but noted, "I can't think of a better start to this mission than what we got today." It was the third on-time shuttle launch in a row. At least six pieces of foam insulation came off Discovery's fuel tank during liftoff, but because that occurred after the crucial first two minutes, the debris posed no risk to the shuttle, officials said. "It's preliminary only, but it did look like a clean ascent," Mission Control informed Discovery's commander Pamela Melroy, only the second woman to lead a shuttle crew. Astronauts woke up early Wednesday to "Lord of the Dance," which begins with the lyrics "I danced in the morning when the earth was begun, I danced in the moon and the stars and the sun." Melroy said it was one of her favorites songs and thanked her husband, Doug, for tipping off Mission Control. Melroy and her crew were to use a laser-tipped inspection boom Wednesday to check Discovery's vulnerable wings and nose, standard procedure since the Columbia accident. They will go extra slow, however, for a thorough check of three wing panels that may have cracks just beneath a protective coating. Even though NASA's own safety group wanted to delay the launch, senior managers decided a week ago that wing repairs were unnecessary. NASA is extra sensitive about launch debris and the shuttle's thermal shielding ever since a hole in the wing brought down Columbia in 2003, the result of a strike by a slab of fuel-tank foam. A much smaller piece of foam broke off a bracket on the fuel tank during the last launch in August, possibly along with ice, and gouged Endeavour's belly. That led to changes to Discovery's fuel tank to prevent dangerous ice buildup from the super-cold propellants. Discovery's primary payload is an Italian-built compartment, about the size of a small bus, that will serve as the docking port for science labs due to arrive beginning in December. Italian astronaut Paolo Nespoli is personally delivering the pressurized chamber, called Harmony. During their 1½-week station visit, the astronauts must install Harmony, relocate a giant girder and set of solar wings, extend those solar wings and radiators, and test a thermal tile repair kit. Five spacewalks are planned, which will be the most ever conducted while a shuttle is docked at the station. Astronaut Daniel Tani will move into the station once Discovery docks. He will replace Clayton Anderson, who will return to Earth on the shuttle after five months in space.