HOUSTON - As the day winds down for the astronaut crew of the space shuttle Discovery, the night promises to be busy for flight controllers and engineers back on Earth.

Discovery's early morning rendezvous and docking at the International Space Station (ISS) today generated a wealth of photographs of the orbiter's tile-covered undercarriage, which imaging specialists are now poring through to study the shuttle's thermal protection system. But so far, mission managers said, the orbiter looks fit to fly back to Earth.

"The initial report is that it looks extremely good and we have nothing to worry about on Discovery," said John Shannon, NASA's flight operations and integration manager for the space shuttle program. "But...it is a six-day process."

Engineers hard at work developing a comprehensive picture of the shuttles health are in the third day of a six-day evaluation, and the images taken by the ISS crew will only add to that, Shannon said during a mission status briefing.

"We got an excellent view," said Paul Hill, the mission's lead flight director, during the briefing. "It looks tremendous."

The space station crew, ISS Expedition 11 commander Sergei Krikalev and flight engineer John Phillips, took the images as Discovery's STS-114 commander guided the shuttle in a planned flip about 600 feet below the ISS before docking.

"It was nominal by all meaning of the word," Hill said of the shuttle-ISS rendezvous. "Like it was right out of a textbook."

The new photographs, which were downlinked to the ground earlier today, will aid shuttle engineers working to understand a chipped heat-resistant tile near Discovery's nose landing gear doors seen in other images, NASA officials said. They will also help robotics specialists work up guidelines for Discovery's STS-114 crew to follow should mission managers decide to use the shuttle's robot arm and orbital inspection boom to take second looks at specific regions of the orbiter.

"Our robotics team has already started working on a few trajectories based on the areas of interest that have been discussed," Hill said.

In a Wednesday press conference, deputy shuttle program manager Wayne Hale pointed out two potential areas on Discovery's belly that could be candidates for follow-up boom inspections. In addition to the chipped tile, Hale also identified an "area of interest" further back on the orbiter's belly.

Shannon said shuttle engineers are also going over images of Discovery's external tank, which shed much more foam insulation than expected during the orbiter's Tuesday launch. Imaging specialists estimate that the most visible chunk of foam insulation that popped off a protective ramp on Discovery's external tank - caught on film by a video camera attached to the tank - weighs about 0.9 pounds, though there were three other incidents of smaller foam loss, he added.

The foam loss from Discovery's external tank prompted shuttle program managers to say late Wednesday that until they understand how the foam popped loose, future orbiter flights would likely stay on the ground. The large, 0.9-pound chunk of foam did not strike Discovery, they added.

It was a chunk of external foam that doomed the space shuttle Columbia in 2003 after it struck the orbiter's left wing leading edge and punched through a vital heat-resistant panel. Columbia broke apart on Feb. 1, 2003 after hot atmospheric gases penetrated the hole gouged in its wing by the foam. Its seven-astronaut crew did not survive.

Discovery's STS-114 mission, more than two years in the making, was expected to prove NASA's modifications to shuttle external tanks would safeguard shuttles from damage. A follow-up mission, STS-121 aboard Atlantis, is poised to roll out to the launch pad at NASA's Kennedy Space Center in Cape Canaveral, Florida.

Shannon said that, while they are disappointed that external tank foam is still a launch hazard, shuttle workers, engineers and managers are not backing down from the problem.

"No one is folding their tents, no one is down in the mouth," Shannon said. "We have the data, and we're looking at it."

Meanwhile, in space the Discovery crew has been sent e-mails and data packages regarding the ongoing foam and tile investigations.

After docking today, the joint shuttle-ISS crew used the robotic arms aboard both the space station and Discovery to move the orbiter's inspection boom off clear of both spacecraft in order to free up room for tomorrow's installation of the Raffaello cargo module at orbital module.

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