A big piece of insulating foam flew off Discovery's fuel tank about two minutes after liftoff Tuesday. A video camera captured a small piece of tile flying off the vehicle's underside.
But experts say it is a minor damage though they grounded future shuttle flights.
"Until we're ready, we won't go fly again. I don't know when that might be," shuttle program manager Bill Parsons was quoted as saying by AP in a briefing Wednesday evening.
He and other managers do not believe the flying debris that snapped off the external fuel tank harmed Discovery, threatening a safe return of its seven astronauts.
"Call it luck or whatever, it didn't harm the orbiter," Parsons said. If the foam had broken away earlier in flight when the atmosphere is thicker, increasing the acceleration and likelihood of impact it could have caused catastrophic damage to Discovery, the AP reports.
Although the piece of tile that came off Discovery measures only an inch or two across, the damage caused concern because of the location of the tile on a door covering the landing gear compartment. The other chipped tile is also on the shuttle's underside, but closer to one of the wings, according to USA Today.
Meanwhile Wednesday, astronauts aboard Discovery used a 100-foot robot arm, equipped with lasers and a camera, to inspect the heat shield on the shuttle's nose and wings for holes or scratches. The inspection did not turn up any dramatic problems.
Two astronauts also tested equipment that they will use during three planned spacewalks. During the spacewalks, the pair will try out repair techniques for the shuttle's tiles and carbon panels, replace a gyroscope that helps orient the space station, and install a storage platform on the station.
The search for vulnerabilities continues today. Two space station crewmen will photograph the approaching Discovery as it performs a slow backflip 600 feet out. The photographs will focus on the shuttle's belly. Spy satellites will also photograph the shuttle in orbit.
Discovery's 12-day mission will resupply the International Space Station and test new methods of inspecting the shuttle for damage.
If NASA officials determine there is dangerous damage, the shuttle could dock at the space station until a rescue mission is launched.
The loss of a chunk of debris, a vexing problem NASA thought had been fixed, represents a tremendous setback to a space program that has spent 2 1/2 years and over $1 billion trying to make the 20-year-old shuttles safe to fly.