NASA officials said space shuttle Discovery looks safe to fly home in a week.

But they stressed it will be another few days before the agency can conclusively give the shuttle a clean bill of health.

Agency officials said Discovery escaped damage from a potentially deadly chunk of foam that broke off from the fuel tank during liftoff. But they said the shuttle may have been struck in the wing by a much smaller piece.

Deputy shuttle program manager Wayne Hale said even if the small foam fragment did hit, the impact most likely caused no significant damage.

The mostly welcome news came after Mission Control received stunningly detailed photographs of Discovery taken by the crew aboard the International Space Station.

Meanwhile, in a briefing at the Johnson Space Center in Houston, Flight Operations Manager John Shannon said based on all of the data reviewed so far, Discovery "looks extremely good." He added officials haven't found any gouges deep enough to endanger Discovery.

But, Shannon said the chunk of foam that ripped off the external tank during launch is "unacceptable" and the design needs to be fixed. Launch damage from foam strikes is blamed for the Columbia disaster.

Shannon said redesigns since the 2003 disaster have fixed a lot of debris problems. He added on this launch there was "much less foam than we have seen" in previous launches.

But this could be the last shuttle mission for a while. NASA announced Wednesday it was grounding future shuttle flights because of the incident during Tuesday's launch. That's the same problem that damaged -- and ultimately doomed -- Columbia in 2003.

Discovery did a back flip before docking with the space station Thursday to give experts a better look at its belly.

Discovery Docks With International Space Station

For the first time in almost three years, a space shuttle is linked up with the International Space Station.

The seven crew members of Discovery boarded the station soon after docking, shaking hands and giving hugs to its three residents.

The combined crews will quickly get down to work, downloading pictures to controllers on the ground and getting a safety briefing. They'll also make preparations for three spacewalks and for possible additional inspections of Discovery's heat shield.

Discovery latched onto the space station after doing a high-flying somersault to allow those aboard the outpost to photograph the shuttle's belly for signs of damage.

Reaching the orbiting platform was one of the primary goals of the mission. Discovery will deliver supplies, as well as a replacement gyroscope to stabilize the station.

NASA Administrator Michael Griffin said that it appears right now that "the orbiter is in fact a clean bird."

Meanwhile, the space agency said the mysterious object that came flying off Discovery's fuel tank during liftoff Tuesday morning was a large piece of foam insulation, which might have doomed the spacecraft had it made contact. This time, though, NASA officials say Discovery wasn't damaged.

"You have to admit when you're wrong. We were wrong," shuttle program manager Bill Parsons said at a Wednesday evening news conference. "We need to do some work here, and so we're telling you right now, that the ... foam should not have come off. We've got to go do something about that."

Engineers believe the foam piece was 24 to 33 inches long, 10 to 14 inches wide, and just a few inches thick, only somewhat smaller than the chunk that smashed into Columbia's left wing during liftoff in January 2003.

The damage Columbia sustained that day caused the orbiter to break apart during re-entry, killing all seven astronauts aboard.

NASA expected some debris to fall off during Tuesday's launch, but officials said they won't know for a few days whether any of it will mean a risk to the crew.

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 2½ years and more than $1 billion trying to make the 20-year-old shuttles safe to fly.

Parsons said, "We won't be able to fly again" until the hazard is removed.

Meanwhile, on Wednesday Discovery astronauts started checking the outside of their spacecraft.

They were maneuvering a sensor-equipped robotic arm to see if any damage occurred during launch Tuesday. The examination focused on the shuttle's wings and nose -- one of the new procedures put in place since the 2003 Columbia tragedy.

At an 11 a.m. EDT Wednesday news conference, flight director Paul Hill said that much of the data from the various cameras and scans has been sent back to Earth and is being distilled into engineering reports. If any areas need additional reviews, those will likely happen on the fourth day of the flight.

Hill said the process worked well, but that it was a lot of work, requiring full-time attention from three of the seven crew members. NASA hopes not to have to do as much scanning on future flights, if it can rely on other sensors.

He noted that although some small damage was reported Tuesday, the shuttle has landed many times with some thermal protection system damage, so NASA knows what can be tolerated.

In orbit, astronauts have also tested the tools and equipment they'll use during some space walks.

Engineers on the ground are analyzing images and data from the launch to see if there were other incidents, NASA said on its Web site.